// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.

module FSharp.Compiler.Interactive.Shell

// Prevents warnings of experimental APIs - we are using FSharpLexer
#nowarn "57"

#nowarn "55"
#nowarn "9"

[<assembly: System.Runtime.InteropServices.ComVisible(false)>]
[<assembly: System.CLSCompliant(true)>]
do ()

open System
open System.Collections.Generic
open System.Diagnostics
open System.Globalization
open System.IO
open System.Text
open System.Threading
open System.Reflection
open System.Runtime.CompilerServices
open Internal.Utilities
open Internal.Utilities.Collections
open Internal.Utilities.FSharpEnvironment
open Internal.Utilities.Library
open Internal.Utilities.Library.Extras
open FSharp.Compiler
open FSharp.Compiler.AbstractIL
open FSharp.Compiler.AbstractIL.Diagnostics
open FSharp.Compiler.AbstractIL.IL
open FSharp.Compiler.AbstractIL.ILBinaryReader
open FSharp.Compiler.AbstractIL.ILBinaryWriter
open FSharp.Compiler.AbstractIL.ILDynamicAssemblyWriter
open FSharp.Compiler.AccessibilityLogic
open FSharp.Compiler.CheckDeclarations
open FSharp.Compiler.CheckExpressions
open FSharp.Compiler.CodeAnalysis
open FSharp.Compiler.CompilerOptions
open FSharp.Compiler.CompilerConfig
open FSharp.Compiler.CompilerDiagnostics
open FSharp.Compiler.CompilerImports
open FSharp.Compiler.CompilerGlobalState
open FSharp.Compiler.CreateILModule
open FSharp.Compiler.DependencyManager
open FSharp.Compiler.Diagnostics
open FSharp.Compiler.EditorServices
open FSharp.Compiler.DiagnosticsLogger
open FSharp.Compiler.Features
open FSharp.Compiler.IlxGen
open FSharp.Compiler.Interactive
open FSharp.Compiler.InfoReader
open FSharp.Compiler.IO
open FSharp.Compiler.Lexhelp
open FSharp.Compiler.NameResolution
open FSharp.Compiler.ParseAndCheckInputs
open FSharp.Compiler.OptimizeInputs
open FSharp.Compiler.ScriptClosure
open FSharp.Compiler.Symbols
open FSharp.Compiler.Syntax
open FSharp.Compiler.SyntaxTrivia
open FSharp.Compiler.Syntax.PrettyNaming
open FSharp.Compiler.SyntaxTreeOps
open FSharp.Compiler.TcGlobals
open FSharp.Compiler.Text
open FSharp.Compiler.Text.Range
open FSharp.Compiler.Text.Layout
open FSharp.Compiler.Xml
open FSharp.Compiler.Tokenization
open FSharp.Compiler.TypedTree
open FSharp.Compiler.TypedTreeOps
open FSharp.Compiler.BuildGraph

//----------------------------------------------------------------------------
// For the FSI as a service methods...
//----------------------------------------------------------------------------

type FsiValue(reflectionValue: obj, reflectionType: Type, fsharpType: FSharpType) =
    member _.ReflectionValue = reflectionValue

    member _.ReflectionType = reflectionType

    member _.FSharpType = fsharpType

[<Sealed>]
type FsiBoundValue(name: string, value: FsiValue) =
    member _.Name = name

    member _.Value = value

[<AutoOpen>]
module internal Utilities =
    type IAnyToLayoutCall =
        abstract AnyToLayout: FormatOptions * obj * Type -> Layout
        abstract FsiAnyToLayout: FormatOptions * obj * Type -> Layout

    type private AnyToLayoutSpecialization<'T>() =
        interface IAnyToLayoutCall with
            member _.AnyToLayout(options, o: obj, ty: Type) =
                Display.any_to_layout options ((Unchecked.unbox o: 'T), ty)

            member _.FsiAnyToLayout(options, o: obj, ty: Type) =
                Display.fsi_any_to_layout options ((Unchecked.unbox o: 'T), ty)

    let getAnyToLayoutCall (ty: Type) =
        if ty.IsPointer then
            let pointerToNativeInt (o: obj) : nativeint =
                System.Reflection.Pointer.Unbox o
                |> NativeInterop.NativePtr.ofVoidPtr<nativeptr<byte>>
                |> NativeInterop.NativePtr.toNativeInt

            { new IAnyToLayoutCall with
                member _.AnyToLayout(options, o: obj, ty: Type) =
                    let n = pointerToNativeInt o
                    Display.any_to_layout options (n, n.GetType())

                member _.FsiAnyToLayout(options, o: obj, ty: Type) =
                    let n = pointerToNativeInt o
                    Display.any_to_layout options (n, n.GetType())
            }
        else
            let specialized = typedefof<AnyToLayoutSpecialization<_>>.MakeGenericType [| ty |]
            Activator.CreateInstance(specialized) :?> IAnyToLayoutCall

    let callStaticMethod (ty: Type) name args =
        ty.InvokeMember(
            name,
            (BindingFlags.InvokeMethod
             ||| BindingFlags.Static
             ||| BindingFlags.Public
             ||| BindingFlags.NonPublic),
            null,
            null,
            Array.ofList args,
            CultureInfo.InvariantCulture
        )

    let ignoreAllErrors f =
        try
            f ()
        with _ ->
            ()

    let getMember (name: string) (memberType: MemberTypes) (attr: BindingFlags) (declaringType: Type) =
        let memberType =
            if memberType &&& MemberTypes.NestedType = MemberTypes.NestedType then
                memberType ||| MemberTypes.TypeInfo
            else
                memberType

        declaringType.GetMembers(attr)
        |> Array.filter (fun m -> 0 <> (int (m.MemberType &&& memberType)) && m.Name = name)

    let rec tryFindMember (name: string) (memberType: MemberTypes) (declaringType: Type) =
        let bindingFlags =
            BindingFlags.Instance ||| BindingFlags.Public ||| BindingFlags.NonPublic

        match declaringType |> getMember name memberType bindingFlags with
        | [||] -> declaringType.GetInterfaces() |> Array.tryPick (tryFindMember name memberType)
        | [| m |] -> Some m
        | _ -> raise <| AmbiguousMatchException(sprintf "Ambiguous match for member '%s'" name)

    let getInstanceProperty (obj: obj) (nm: string) =
        let p =
            (tryFindMember nm MemberTypes.Property <| obj.GetType()).Value :?> PropertyInfo

        p.GetValue(obj, [||]) |> unbox

    let setInstanceProperty (obj: obj) (nm: string) (v: obj) =
        let p =
            (tryFindMember nm MemberTypes.Property <| obj.GetType()).Value :?> PropertyInfo

        p.SetValue(obj, v, [||]) |> unbox

    let callInstanceMethod0 (obj: obj) (typeArgs: Type[]) (nm: string) =
        let m = (tryFindMember nm MemberTypes.Method <| obj.GetType()).Value :?> MethodInfo

        let m =
            match typeArgs with
            | [||] -> m
            | _ -> m.MakeGenericMethod(typeArgs)

        m.Invoke(obj, [||]) |> unbox

    let callInstanceMethod1 (obj: obj) (typeArgs: Type[]) (nm: string) (v: obj) =
        let m = (tryFindMember nm MemberTypes.Method <| obj.GetType()).Value :?> MethodInfo

        let m =
            match typeArgs with
            | [||] -> m
            | _ -> m.MakeGenericMethod(typeArgs)

        m.Invoke(obj, [| v |]) |> unbox

    let callInstanceMethod3 (obj: obj) (typeArgs: Type[]) (nm: string) (v1: obj) (v2: obj) (v3: obj) =
        let m = (tryFindMember nm MemberTypes.Method <| obj.GetType()).Value :?> MethodInfo

        let m =
            match typeArgs with
            | [||] -> m
            | _ -> m.MakeGenericMethod(typeArgs)

        m.Invoke(obj, [| v1; v2; v3 |]) |> unbox

    let colorPrintL (outWriter: TextWriter) opts layout =
        let renderer =
            { new LayoutRenderer<NoResult, NoState> with
                member r.Start() = NoState

                member r.AddText z s =
                    let color =
                        match s.Tag with
                        | TextTag.Keyword -> ConsoleColor.White
                        | TextTag.TypeParameter
                        | TextTag.Alias
                        | TextTag.Class
                        | TextTag.Module
                        | TextTag.Interface
                        | TextTag.Record
                        | TextTag.Struct
                        | TextTag.Union
                        | TextTag.UnknownType -> ConsoleColor.Cyan
                        | TextTag.UnionCase
                        | TextTag.ActivePatternCase -> ConsoleColor.Magenta
                        | TextTag.StringLiteral -> ConsoleColor.Yellow
                        | TextTag.NumericLiteral -> ConsoleColor.Green
                        | _ -> Console.ForegroundColor

                    DoWithColor color (fun () -> outWriter.Write s.Text)

                    z

                member r.AddBreak z n =
                    outWriter.WriteLine()
                    outWriter.Write(String.replicate n " ")
                    z

                member r.AddTag z (tag, attrs, start) = z

                member r.Finish z =
                    outWriter.WriteLine()
                    NoResult
            }

        layout |> Display.squash_layout opts |> LayoutRender.renderL renderer |> ignore

        outWriter.WriteLine()

    let reportError m =
        let report errorType err msg =
            let error = err, msg

            match errorType with
            | ErrorReportType.Warning -> warning (Error(error, m))
            | ErrorReportType.Error -> errorR (Error(error, m))

        ResolvingErrorReport report

    let getOutputDir (tcConfigB: TcConfigBuilder) =
        tcConfigB.outputDir |> Option.defaultValue ""

/// Timing support
[<AutoSerializable(false)>]
type internal FsiTimeReporter(outWriter: TextWriter) =
    let stopwatch = Stopwatch()
    let ptime = Process.GetCurrentProcess()
    let numGC = GC.MaxGeneration

    member tr.TimeOp(f) =
        let startTotal = ptime.TotalProcessorTime
        let startGC = [| for i in 0..numGC -> GC.CollectionCount(i) |]
        stopwatch.Reset()
        stopwatch.Start()
        let res = f ()
        stopwatch.Stop()
        let total = ptime.TotalProcessorTime - startTotal
        let spanGC = [ for i in 0..numGC -> GC.CollectionCount(i) - startGC[i] ]
        let elapsed = stopwatch.Elapsed

        fprintfn
            outWriter
            "%s"
            (FSIstrings.SR.fsiTimeInfoMainString (
                (sprintf "%02d:%02d:%02d.%03d" (int elapsed.TotalHours) elapsed.Minutes elapsed.Seconds elapsed.Milliseconds),
                (sprintf "%02d:%02d:%02d.%03d" (int total.TotalHours) total.Minutes total.Seconds total.Milliseconds),
                (String.concat
                    ", "
                    (List.mapi (sprintf "%s%d: %d" (FSIstrings.SR.fsiTimeInfoGCGenerationLabelSomeShorthandForTheWordGeneration ())) spanGC))
            ))

        res

    member tr.TimeOpIf flag f = if flag then tr.TimeOp f else f ()

/// Manages the emit of one logical assembly into multiple assemblies. Gives warnings
/// on cross-fragment internal access.
type ILMultiInMemoryAssemblyEmitEnv
    (
        ilg: ILGlobals,
        resolveAssemblyRef: ILAssemblyRef -> Choice<string, Assembly> option,
        dynamicCcuName: string
    ) =

    let typeMap = Dictionary<ILTypeRef, Type * ILTypeRef>(HashIdentity.Structural)
    let reverseTypeMap = Dictionary<ILTypeRef, ILTypeRef>(HashIdentity.Structural)
    let internalTypes = HashSet<ILTypeRef>(HashIdentity.Structural)
    let internalMethods = HashSet<ILMethodRef>(HashIdentity.Structural)
    let internalFields = HashSet<ILFieldRef>(HashIdentity.Structural)
    let dynamicCcuScopeRef = ILScopeRef.Assembly(IL.mkSimpleAssemblyRef dynamicCcuName)

    /// Convert an ILAssemblyRef to a dynamic System.Type given the dynamic emit context
    let convAssemblyRef (aref: ILAssemblyRef) =
        let asmName = AssemblyName()
        asmName.Name <- aref.Name

        match aref.PublicKey with
        | None -> ()
        | Some (PublicKey bytes) -> asmName.SetPublicKey bytes
        | Some (PublicKeyToken bytes) -> asmName.SetPublicKeyToken bytes

        match aref.Version with
        | None -> ()
        | Some version -> asmName.Version <- Version(int32 version.Major, int32 version.Minor, int32 version.Build, int32 version.Revision)

        asmName.CultureInfo <- System.Globalization.CultureInfo.InvariantCulture
        asmName

    /// Convert an ILAssemblyRef to a dynamic System.Type given the dynamic emit context
    let convResolveAssemblyRef (asmref: ILAssemblyRef) qualifiedName =
        let assembly =
            match resolveAssemblyRef asmref with
            | Some (Choice1Of2 path) ->
                // asmRef is a path but the runtime is smarter with assembly names so make one
                let asmName = AssemblyName.GetAssemblyName(path)
                asmName.CodeBase <- path
                FileSystem.AssemblyLoader.AssemblyLoad asmName
            | Some (Choice2Of2 assembly) -> assembly
            | None ->
                let asmName = convAssemblyRef asmref
                FileSystem.AssemblyLoader.AssemblyLoad asmName

        let typT = assembly.GetType qualifiedName

        match typT with
        | null -> error (Error(FSComp.SR.itemNotFoundDuringDynamicCodeGen ("type", qualifiedName, asmref.QualifiedName), range0))
        | res -> res

    /// Convert an Abstract IL type reference to System.Type
    let convTypeRefAux (tref: ILTypeRef) =
        let qualifiedName =
            (String.concat "+" (tref.Enclosing @ [ tref.Name ])).Replace(",", @"\,")

        match tref.Scope with
        | ILScopeRef.Assembly asmref -> convResolveAssemblyRef asmref qualifiedName
        | ILScopeRef.Module _
        | ILScopeRef.Local ->
            let typT = Type.GetType qualifiedName

            match typT with
            | null -> error (Error(FSComp.SR.itemNotFoundDuringDynamicCodeGen ("type", qualifiedName, "<emitted>"), range0))
            | res -> res
        | ILScopeRef.PrimaryAssembly -> convResolveAssemblyRef ilg.primaryAssemblyRef qualifiedName

    /// Convert an ILTypeRef to a dynamic System.Type given the dynamic emit context
    let convTypeRef (tref: ILTypeRef) =
        if tref.Scope.IsLocalRef then
            assert tref.Scope.IsLocalRef
            let typ, _ = typeMap[tref]
            typ
        else
            convTypeRefAux tref

    /// Convert an ILTypeSpec to a dynamic System.Type given the dynamic emit context
    let rec convTypeSpec (tspec: ILTypeSpec) =
        let tref = tspec.TypeRef
        let typT = convTypeRef tref
        let tyargs = List.map convTypeAux tspec.GenericArgs

        let res =
            match isNil tyargs, typT.IsGenericType with
            | _, true -> typT.MakeGenericType(List.toArray tyargs)
            | true, false -> typT
            | _, false -> null

        match res with
        | null ->
            error (
                Error(FSComp.SR.itemNotFoundDuringDynamicCodeGen ("type", tspec.TypeRef.QualifiedName, tspec.Scope.QualifiedName), range0)
            )
        | _ -> res

    and convTypeAux ty =
        match ty with
        | ILType.Void -> Type.GetType("System.Void")
        | ILType.Array (shape, eltType) ->
            let baseT = convTypeAux eltType

            if shape.Rank = 1 then
                baseT.MakeArrayType()
            else
                baseT.MakeArrayType shape.Rank
        | ILType.Value tspec -> convTypeSpec tspec
        | ILType.Boxed tspec -> convTypeSpec tspec
        | ILType.Ptr eltType ->
            let baseT = convTypeAux eltType
            baseT.MakePointerType()
        | ILType.Byref eltType ->
            let baseT = convTypeAux eltType
            baseT.MakeByRefType()
        | ILType.TypeVar _tv -> failwith "open generic type"
        | ILType.Modified (_, _, modifiedTy) -> convTypeAux modifiedTy
        | ILType.FunctionPointer _callsig -> failwith "convType: fptr"

    /// Map the given ILTypeRef to the appropriate assembly fragment
    member _.MapTypeRef(tref: ILTypeRef) =
        if tref.Scope.IsLocalRef && typeMap.ContainsKey(tref) then
            typeMap[tref] |> snd
        else
            tref

    /// Map an ILTypeRef built from reflection over loaded assembly fragments back to an ILTypeRef suitable
    /// to use on the F# compiler logic.
    member _.ReverseMapTypeRef(tref: ILTypeRef) =
        if reverseTypeMap.ContainsKey(tref) then
            reverseTypeMap[tref]
        else
            tref

    /// Convert an ILTypeRef to a dynamic System.Type given the dynamic emit context
    member _.LookupTypeRef(tref: ILTypeRef) = convTypeRef tref

    /// Convert an ILType to a dynamic System.Type given the dynamic emit context
    member _.LookupType(ty: ILType) = convTypeAux ty

    /// Record the given ILTypeDef in the dynamic emit context
    member emEnv.AddTypeDef (asm: Assembly) ilScopeRef enc (tdef: ILTypeDef) =
        let ltref = mkRefForNestedILTypeDef ILScopeRef.Local (enc, tdef)
        let tref = mkRefForNestedILTypeDef ilScopeRef (enc, tdef)
        let key = tref.BasicQualifiedName
        let typ = asm.GetType(key)
        //printfn "Adding %s --> %s" key typ.FullName
        let rtref = rescopeILTypeRef dynamicCcuScopeRef tref
        typeMap.Add(ltref, (typ, tref))
        reverseTypeMap.Add(tref, rtref)

        for ntdef in tdef.NestedTypes.AsArray() do
            emEnv.AddTypeDef asm ilScopeRef (enc @ [ tdef ]) ntdef

        // Record the internal things to give warnings for internal access across fragment boundaries
        for fdef in tdef.Fields.AsList() do
            match fdef.Access with
            | ILMemberAccess.Public -> ()
            | _ ->
                let lfref = mkRefForILField ILScopeRef.Local (enc, tdef) fdef
                internalFields.Add(lfref) |> ignore

        for mdef in tdef.Methods.AsArray() do
            match mdef.Access with
            | ILMemberAccess.Public -> ()
            | _ ->
                let lmref = mkRefForILMethod ILScopeRef.Local (enc, tdef) mdef
                internalMethods.Add(lmref) |> ignore

        match tdef.Access with
        | ILTypeDefAccess.Public
        | ILTypeDefAccess.Nested ILMemberAccess.Public -> ()
        | _ -> internalTypes.Add(ltref) |> ignore

    /// Record the given ILModuleDef (i.e. an assembly) in the dynamic emit context
    member emEnv.AddModuleDef asm ilScopeRef (mdef: ILModuleDef) =
        for tdef in mdef.TypeDefs.AsArray() do
            emEnv.AddTypeDef asm ilScopeRef [] tdef

    /// Check if an ILTypeRef is a reference to an already-emitted internal type within the dynamic emit context
    member _.IsLocalInternalType(tref: ILTypeRef) =
        tref.Scope.IsLocalRef && internalTypes.Contains(tref)

    /// Check if an ILMethodRef is a reference to an already-emitted internal method within the dynamic emit context
    member _.IsLocalInternalMethod(mref: ILMethodRef) =
        mref.DeclaringTypeRef.Scope.IsLocalRef && internalMethods.Contains(mref)

    /// Check if an ILFieldRef is a reference to an already-emitted internal field within the dynamic emit context
    member _.IsLocalInternalField(fref: ILFieldRef) =
        fref.DeclaringTypeRef.Scope.IsLocalRef && internalFields.Contains(fref)

type ILAssemblyEmitEnv =
    | SingleRefEmitAssembly of ILDynamicAssemblyWriter.cenv * ILDynamicAssemblyEmitEnv
    | MultipleInMemoryAssemblies of ILMultiInMemoryAssemblyEmitEnv

type internal FsiValuePrinterMode =
    | PrintExpr
    | PrintDecl

type EvaluationEventArgs(fsivalue: FsiValue option, symbolUse: FSharpSymbolUse, decl: FSharpImplementationFileDeclaration) =
    inherit EventArgs()
    member _.Name = symbolUse.Symbol.DisplayName
    member _.FsiValue = fsivalue
    member _.SymbolUse = symbolUse
    member _.Symbol = symbolUse.Symbol
    member _.ImplementationDeclaration = decl

/// User-configurable information that changes how F# Interactive operates, stored in the 'fsi' object
/// and accessible via the programming model
[<AbstractClass>]
type FsiEvaluationSessionHostConfig() =
    let evaluationEvent = Event<EvaluationEventArgs>()

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract FormatProvider: IFormatProvider

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract FloatingPointFormat: string

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract AddedPrinters: Choice<Type * (obj -> string), Type * (obj -> obj)> list

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract ShowDeclarationValues: bool

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract ShowIEnumerable: bool

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract ShowProperties: bool

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract PrintSize: int

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract PrintDepth: int

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract PrintWidth: int

    /// Called by the evaluation session to ask the host for parameters to format text for output
    abstract PrintLength: int

    /// The evaluation session calls this to report the preferred view of the command line arguments after
    /// stripping things like "/use:file.fsx", "-r:Foo.dll" etc.
    abstract ReportUserCommandLineArgs: string[] -> unit

    /// The evaluation session calls this to ask the host for the special console reader.
    /// Returning 'Some' indicates a console is to be used, so some special rules apply.
    ///
    /// A "console" gets used if
    ///     --readline- is specified (the default on Windows + .NET); and
    ///     not --fsi-server (which should always be combined with --readline-); and
    ///     GetOptionalConsoleReadLine() returns a Some
    ///
    /// "Peekahead" occurs if --peekahead- is not specified (i.e. it is the default):
    ///     - If a console is being used then
    ///         - a prompt is printed early
    ///         - a background thread is created
    ///         - the GetOptionalConsoleReadLine() callback is used to read the first line
    ///     - Otherwise call inReader.Peek()
    ///
    /// Further lines are read as follows:
    ///     - If a console is being used then use GetOptionalConsoleReadLine()
    ///     - Otherwise use inReader.ReadLine()

    abstract GetOptionalConsoleReadLine: probeToSeeIfConsoleWorks: bool -> (unit -> string) option

    /// The evaluation session calls this at an appropriate point in the startup phase if the --fsi-server parameter was given
    abstract StartServer: fsiServerName: string -> unit

    /// Called by the evaluation session to ask the host to enter a dispatch loop like Application.Run().
    /// Only called if --gui option is used (which is the default).
    /// Gets called towards the end of startup and every time a ThreadAbort escaped to the backup driver loop.
    /// Return true if a 'restart' is required, which is a bit meaningless.
    abstract EventLoopRun: unit -> bool

    /// Request that the given operation be run synchronously on the event loop.
    abstract EventLoopInvoke: codeToRun: (unit -> 'T) -> 'T

    /// Schedule a restart for the event loop.
    abstract EventLoopScheduleRestart: unit -> unit

    /// Implicitly reference FSharp.Compiler.Interactive.Settings.dll
    abstract UseFsiAuxLib: bool

    /// Hook for listening for evaluation bindings
    member _.OnEvaluation = evaluationEvent.Publish

    member internal x.TriggerEvaluation(value, symbolUse, decl) =
        evaluationEvent.Trigger(EvaluationEventArgs(value, symbolUse, decl))

/// Used to print value signatures along with their values, according to the current
/// set of pretty printers installed in the system, and default printing rules.
type internal FsiValuePrinter(fsi: FsiEvaluationSessionHostConfig, outWriter: TextWriter) =

    /// This printer is used by F# Interactive if no other printers apply.
    let DefaultPrintingIntercept (ienv: IEnvironment) (obj: obj) =
        match obj with
        | null -> None
        | :? System.Collections.IDictionary as ie ->
            let it = ie.GetEnumerator()

            try
                let itemLs =
                    unfoldL // the function to layout each object in the unfold
                        (fun obj -> ienv.GetLayout obj)
                        // the function to call at each step of the unfold
                        (fun () -> if it.MoveNext() then Some((it.Key, it.Value), ()) else None)
                        ()
                        // the maximum length
                        (1 + fsi.PrintLength / 3)

                let makeListL itemLs =
                    (leftL (TaggedText.tagText "["))
                    ^^ sepListL (rightL (TaggedText.tagText ";")) itemLs
                       ^^ (rightL (TaggedText.tagText "]"))

                Some(wordL (TaggedText.tagText "dict") --- makeListL itemLs)
            finally
                match it with
                | :? IDisposable as d -> d.Dispose()
                | _ -> ()

        | _ -> None

    /// Get the print options used when formatting output using the structured printer.
    member _.GetFsiPrintOptions() =
        { FormatOptions.Default with
            FormatProvider = fsi.FormatProvider
            PrintIntercepts =
                // The fsi object supports the addition of two kinds of printers, one which converts to a string
                // and one which converts to another object that is recursively formatted.
                // The internal AddedPrinters reports these to FSI.EXE and we pick them up here to produce a layout
                [
                    for x in fsi.AddedPrinters do
                        match x with
                        | Choice1Of2 (aty: Type, printer) ->
                            yield
                                (fun _ienv (obj: obj) ->
                                    match obj with
                                    | null -> None
                                    | _ when aty.IsAssignableFrom(obj.GetType()) ->
                                        let text = printer obj

                                        match box text with
                                        | null -> None
                                        | _ -> Some(wordL (TaggedText.tagText text))
                                    | _ -> None)

                        | Choice2Of2 (aty: Type, converter) ->
                            yield
                                (fun ienv (obj: obj) ->
                                    match obj with
                                    | null -> None
                                    | _ when aty.IsAssignableFrom(obj.GetType()) ->
                                        match converter obj with
                                        | null -> None
                                        | res -> Some(ienv.GetLayout res)
                                    | _ -> None)
                    yield DefaultPrintingIntercept
                ]
            FloatingPointFormat = fsi.FloatingPointFormat
            PrintWidth = fsi.PrintWidth
            PrintDepth = fsi.PrintDepth
            PrintLength = fsi.PrintLength
            PrintSize = fsi.PrintSize
            ShowProperties = fsi.ShowProperties
            ShowIEnumerable = fsi.ShowIEnumerable
        }

    /// Get the evaluation context used when inverting the storage mapping of the ILDynamicAssemblyWriter.
    member _.GetEvaluationContext(emEnv: ILAssemblyEmitEnv) =
        match emEnv with
        | SingleRefEmitAssembly (cenv, emEnv) ->
            {
                LookupTypeRef = LookupTypeRef cenv emEnv
                LookupType = LookupType cenv emEnv
            }
        | MultipleInMemoryAssemblies emEnv ->
            {
                LookupTypeRef = emEnv.LookupTypeRef
                LookupType = emEnv.LookupType
            }

    /// Generate a layout for an actual F# value, where we know the value has the given static type.
    member _.PrintValue(printMode, opts: FormatOptions, x: obj, ty: Type) =
        // We do a dynamic invoke of any_to_layout with the right System.Type parameter for the static type of the saved value.
        // In principle this helps any_to_layout do the right thing as it descends through terms. In practice it means
        // it at least does the right thing for top level 'null' list and option values (but not for nested ones).
        //
        // The static type was saved into the location used by RuntimeHelpers.GetSavedItType when RuntimeHelpers.SaveIt was called.
        // RuntimeHelpers.SaveIt has type ('a -> unit), and fetches the System.Type for 'a by using a typeof<'a> call.
        // The funny thing here is that you might think that the driver (this file) knows more about the static types
        // than the compiled code does. But it doesn't! In particular, it's not that easy to get a System.Type value based on the
        // static type information we do have: we have no direct way to bind a F# TAST type or even an AbstractIL type to
        // a System.Type value (I guess that functionality should be in ilreflect.fs).
        //
        // This will be more significant when we print values other then 'it'
        //
        try
            let anyToLayoutCall = getAnyToLayoutCall ty

            match printMode with
            | PrintDecl ->
                // When printing rhs of fsi declarations, use "fsi_any_to_layout".
                // This will suppress some less informative values, by returning an empty layout. [fix 4343].
                anyToLayoutCall.FsiAnyToLayout(opts, x, ty)
            | PrintExpr -> anyToLayoutCall.AnyToLayout(opts, x, ty)
        with
        | :? ThreadAbortException -> wordL (TaggedText.tagText "")
        | e ->
#if DEBUG
            printf "\n\nPrintValue: x = %+A and ty=%s\n" x ty.FullName
#endif
            printf "%s" (FSIstrings.SR.fsiExceptionDuringPrettyPrinting (e.ToString()))
            wordL (TaggedText.tagText "")

    /// Display the signature of an F# value declaration, along with its actual value.
    member valuePrinter.InvokeDeclLayout(emEnv, ilxGenerator: IlxAssemblyGenerator, v: Val) =
        // Implemented via a lookup from v to a concrete (System.Object,System.Type).
        // This (obj,objTy) pair can then be fed to the fsi value printer.
        // Note: The value may be (null:Object).
        // Note: A System.Type allows the value printer guide printing of nulls, e.g. as None or [].
        //-------
        // IlxGen knows what the v:Val was converted to w.r.t. AbsIL data structures.
        // Ilreflect knows what the AbsIL was generated to.
        // Combining these allows for obtaining the (obj,objTy) by reflection where possible.
        // This assumes the v:Val was given appropriate storage, e.g. StaticField.
        if fsi.ShowDeclarationValues && not v.LiteralValue.IsSome then
            // Adjust "opts" for printing for "declared-values":
            // - No sequences, because they may have effects or time cost.
            // - No properties, since they may have unexpected effects.
            // - Limit strings to roughly one line, since huge strings (e.g. 1 million chars without \n are slow in vfsi).
            // - Limit PrintSize which is a count on nodes.
            let declaredValueReductionFactor =
                10 (* reduce PrintSize for declared values, e.g. see less of large terms *)

            let opts = valuePrinter.GetFsiPrintOptions()

            let opts =
                { opts with
                    ShowProperties = false // properties off, motivated by Form props
                    ShowIEnumerable = false // seq off, motivated by db query concerns
                    StringLimit = max 0 (opts.PrintWidth - 4) // 4 allows for an indent of 2 and 2 quotes (rough)
                    PrintSize = opts.PrintSize / declaredValueReductionFactor
                } // print less

            let res =
                try
                    ilxGenerator.LookupGeneratedValue(valuePrinter.GetEvaluationContext emEnv, v)
                with _ ->
                    None

            match res with
            | None -> None
            | Some (obj, objTy) ->
                let lay = valuePrinter.PrintValue(FsiValuePrinterMode.PrintDecl, opts, obj, objTy)
                if isEmptyL lay then None else Some lay // suppress empty layout

        else
            None

    /// Format a value
    member valuePrinter.FormatValue(obj: obj, objTy) =
        let opts = valuePrinter.GetFsiPrintOptions()
        let lay = valuePrinter.PrintValue(FsiValuePrinterMode.PrintExpr, opts, obj, objTy)
        Display.layout_to_string opts lay

    /// Fetch the saved value of an expression out of the 'it' register and show it.
    member valuePrinter.InvokeExprPrinter(denv, infoReader, emEnv, ilxGenerator: IlxAssemblyGenerator, vref: ValRef) =
        let opts = valuePrinter.GetFsiPrintOptions()

        let res =
            ilxGenerator.LookupGeneratedValue(valuePrinter.GetEvaluationContext emEnv, vref.Deref)

        let rhsL =
            match res with
            | None -> None
            | Some (obj, objTy) ->
                let lay = valuePrinter.PrintValue(FsiValuePrinterMode.PrintExpr, opts, obj, objTy)
                if isEmptyL lay then None else Some lay // suppress empty layout

        let denv =
            { denv with
                suppressMutableKeyword = true
            } // suppress 'mutable' in 'val mutable it = ...'

        let denv =
            { denv with
                suppressInlineKeyword = false
            } // dont' suppress 'inline' in 'val inline f = ...'

        let fullL =
            if Option.isNone rhsL || isEmptyL rhsL.Value then
                NicePrint.prettyLayoutOfValOrMemberNoInst
                    denv
                    infoReader
                    vref (* the rhs was suppressed by the printer, so no value to print *)
            else
                (NicePrint.prettyLayoutOfValOrMemberNoInst denv infoReader vref
                 ++ wordL (TaggedText.tagText "="))
                --- rhsL.Value

        colorPrintL outWriter opts fullL

/// Used to make a copy of input in order to include the input when displaying the error text.
type internal FsiStdinSyphon(errorWriter: TextWriter) =
    let syphonText = StringBuilder()

    /// Clears the syphon text
    member _.Reset() = syphonText.Clear() |> ignore

    /// Adds a new line to the syphon text
    member _.Add(str: string) = syphonText.Append str |> ignore

    /// Gets the indicated line in the syphon text
    member _.GetLine fileName i =
        if fileName <> stdinMockFileName then
            ""
        else
            let text = syphonText.ToString()
            // In Visual Studio, when sending a block of text, it  prefixes  with '# <line> "file name"\n'
            // and postfixes with '# 1 "stdin"\n'. To first, get errors file name context,
            // and second to get them back into stdin context (no position stack...).
            // To find an error line, trim upto the last stdinReset string the syphoned text.
            //printf "PrePrune:-->%s<--\n\n" text;
            let rec prune (text: string) =
                let stdinReset = "# 1 \"stdin\"\n"
                let idx = text.IndexOf(stdinReset, StringComparison.Ordinal)

                if idx <> -1 then
                    prune (text.Substring(idx + stdinReset.Length))
                else
                    text

            let text = prune text
            let lines = text.Split '\n'
            if 0 < i && i <= lines.Length then lines[i - 1] else ""

    /// Display the given error.
    member syphon.PrintDiagnostic(tcConfig: TcConfig, diagnostic: PhasedDiagnostic) =
        ignoreAllErrors (fun () ->
            let severity = FSharpDiagnosticSeverity.Error

            DoWithDiagnosticColor severity (fun () ->
                errorWriter.WriteLine()
                diagnostic.WriteWithContext(errorWriter, "  ", syphon.GetLine, tcConfig, severity)
                errorWriter.WriteLine()
                errorWriter.WriteLine()
                errorWriter.Flush()))

/// Encapsulates functions used to write to outWriter and errorWriter
type internal FsiConsoleOutput(tcConfigB, outWriter: TextWriter, errorWriter: TextWriter) =

    let nullOut = new StreamWriter(Stream.Null) :> TextWriter

    let fprintfnn (os: TextWriter) fmt =
        Printf.kfprintf
            (fun _ ->
                os.WriteLine()
                os.WriteLine())
            os
            fmt

    /// uprintf to write usual responses to stdout (suppressed by --quiet), with various pre/post newlines
    member _.uprintf fmt =
        fprintf (if tcConfigB.noFeedback then nullOut else outWriter) fmt

    member _.uprintfn fmt =
        fprintfn (if tcConfigB.noFeedback then nullOut else outWriter) fmt

    member _.uprintfnn fmt =
        fprintfnn (if tcConfigB.noFeedback then nullOut else outWriter) fmt

    member out.uprintnf fmt =
        out.uprintfn ""
        out.uprintf fmt

    member out.uprintnfn fmt =
        out.uprintfn ""
        out.uprintfn fmt

    member out.uprintnfnn fmt =
        out.uprintfn ""
        out.uprintfnn fmt

    /// clear screen
    member _.Clear() = System.Console.Clear()

    member _.Out = outWriter

    member _.Error = errorWriter

/// This DiagnosticsLogger reports all warnings, but raises StopProcessing on first error or early exit
type internal DiagnosticsLoggerThatStopsOnFirstError
    (
        tcConfigB: TcConfigBuilder,
        fsiStdinSyphon: FsiStdinSyphon,
        fsiConsoleOutput: FsiConsoleOutput
    ) =
    inherit DiagnosticsLogger("DiagnosticsLoggerThatStopsOnFirstError")
    let mutable errorCount = 0

    member _.SetError() = errorCount <- 1

    member _.ResetErrorCount() = errorCount <- 0

    override _.DiagnosticSink(diagnostic, severity) =
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)

        if diagnostic.ReportAsError(tcConfig.diagnosticsOptions, severity) then
            fsiStdinSyphon.PrintDiagnostic(tcConfig, diagnostic)
            errorCount <- errorCount + 1

            if tcConfigB.abortOnError then
                exit 1 (* non-zero exit code *)
            // STOP ON FIRST ERROR (AVOIDS PARSER ERROR RECOVERY)
            raise StopProcessing
        elif diagnostic.ReportAsWarning(tcConfig.diagnosticsOptions, severity) then
            DoWithDiagnosticColor FSharpDiagnosticSeverity.Warning (fun () ->
                fsiConsoleOutput.Error.WriteLine()
                diagnostic.WriteWithContext(fsiConsoleOutput.Error, "  ", fsiStdinSyphon.GetLine, tcConfig, severity)
                fsiConsoleOutput.Error.WriteLine()
                fsiConsoleOutput.Error.WriteLine()
                fsiConsoleOutput.Error.Flush())
        elif diagnostic.ReportAsInfo(tcConfig.diagnosticsOptions, severity) then
            DoWithDiagnosticColor FSharpDiagnosticSeverity.Info (fun () ->
                fsiConsoleOutput.Error.WriteLine()
                diagnostic.WriteWithContext(fsiConsoleOutput.Error, "  ", fsiStdinSyphon.GetLine, tcConfig, severity)
                fsiConsoleOutput.Error.WriteLine()
                fsiConsoleOutput.Error.WriteLine()
                fsiConsoleOutput.Error.Flush())

    override _.ErrorCount = errorCount

type DiagnosticsLogger with

    /// A helper function to check if its time to abort
    member x.AbortOnError(fsiConsoleOutput: FsiConsoleOutput) =
        if x.ErrorCount > 0 then
            fprintf fsiConsoleOutput.Error "%s" (FSIstrings.SR.stoppedDueToError ())
            fsiConsoleOutput.Error.Flush()
            raise StopProcessing

/// Get the directory name from a string, with some defaults if it doesn't have one
let internal directoryName (s: string) =
    if s = "" then
        "."
    else
        match Path.GetDirectoryName s with
        | null -> if FileSystem.IsPathRootedShim s then s else "."
        | res -> if res = "" then "." else res

//----------------------------------------------------------------------------
// cmd line - state for options
//----------------------------------------------------------------------------

/// Process the command line options
type internal FsiCommandLineOptions(fsi: FsiEvaluationSessionHostConfig, argv: string[], tcConfigB, fsiConsoleOutput: FsiConsoleOutput) =

    let mutable enableConsoleKeyProcessing = true

    let mutable gui = true // override via "--gui" on by default
#if DEBUG
    let mutable showILCode = false // show modul il code
#endif
    let mutable showTypes = true // show types after each interaction?
    let mutable fsiServerName = ""
    let mutable interact = true
    let mutable explicitArgs = []
    let mutable writeReferencesAndExit = None

    let mutable inputFilesAcc = []

    let mutable fsiServerInputCodePage = None
    let mutable fsiServerOutputCodePage = None
    let mutable fsiLCID = None

    // internal options
    let mutable probeToSeeIfConsoleWorks = true
    let mutable peekAheadOnConsoleToPermitTyping = true

    let isInteractiveServer () = fsiServerName <> ""
    let recordExplicitArg arg = explicitArgs <- explicitArgs @ [ arg ]

    let executableFileNameWithoutExtension =
        lazy
            let getFsiCommandLine () =
                let fileNameWithoutExtension path = Path.GetFileNameWithoutExtension(path)

                let currentProcess = Process.GetCurrentProcess()
                let processFileName = fileNameWithoutExtension currentProcess.MainModule.FileName

                let commandLineExecutableFileName =
                    try
                        fileNameWithoutExtension (Environment.GetCommandLineArgs().[0])
                    with _ ->
                        ""

                let stringComparison =
                    match Environment.OSVersion.Platform with
                    | PlatformID.MacOSX
                    | PlatformID.Unix -> StringComparison.Ordinal
                    | _ -> StringComparison.OrdinalIgnoreCase

                if String.Compare(processFileName, commandLineExecutableFileName, stringComparison) = 0 then
                    processFileName
                else
                    sprintf "%s %s" processFileName commandLineExecutableFileName

            tcConfigB.exename |> Option.defaultWith getFsiCommandLine

    // Additional fsi options are list below.
    // In the "--help", these options can be printed either before (fsiUsagePrefix) or after (fsiUsageSuffix) the core options.

    let displayHelpFsi tcConfigB (blocks: CompilerOptionBlock list) =
        Console.Write(GetBannerText tcConfigB)
        fprintfn fsiConsoleOutput.Out ""
        fprintfn fsiConsoleOutput.Out "%s" (FSIstrings.SR.fsiUsage (executableFileNameWithoutExtension.Value))
        Console.Write(GetCompilerOptionBlocks blocks tcConfigB.bufferWidth)
        exit 0

    // option tags
    let tagFile = "<file>"
    let tagNone = ""

    /// These options precede the FsiCoreCompilerOptions in the help blocks
    let fsiUsagePrefix tcConfigB =
        [
            PublicOptions(
                FSIstrings.SR.fsiInputFiles (),
                [
                    CompilerOption(
                        "use",
                        tagFile,
                        OptionString(fun s -> inputFilesAcc <- inputFilesAcc @ [ (s, true) ]),
                        None,
                        Some(FSIstrings.SR.fsiUse ())
                    )
                    CompilerOption(
                        "load",
                        tagFile,
                        OptionString(fun s -> inputFilesAcc <- inputFilesAcc @ [ (s, false) ]),
                        None,
                        Some(FSIstrings.SR.fsiLoad ())
                    )
                ]
            )
            PublicOptions(FSIstrings.SR.fsiCodeGeneration (), [])
            PublicOptions(FSIstrings.SR.fsiErrorsAndWarnings (), [])
            PublicOptions(FSIstrings.SR.fsiLanguage (), [])
            PublicOptions(FSIstrings.SR.fsiMiscellaneous (), [])
            PublicOptions(FSIstrings.SR.fsiAdvanced (), [])
            PrivateOptions(
                [ // Make internal fsi-server* options. Do not print in the help. They are used by VFSI.
                    CompilerOption("fsi-server-report-references", "", OptionString(fun s -> writeReferencesAndExit <- Some s), None, None)
                    CompilerOption("fsi-server", "", OptionString(fun s -> fsiServerName <- s), None, None) // "FSI server mode on given named channel");
                    CompilerOption("fsi-server-input-codepage", "", OptionInt(fun n -> fsiServerInputCodePage <- Some(n)), None, None) // " Set the input codepage for the console");
                    CompilerOption("fsi-server-output-codepage", "", OptionInt(fun n -> fsiServerOutputCodePage <- Some(n)), None, None) // " Set the output codepage for the console");
                    CompilerOption(
                        "fsi-server-no-unicode",
                        "",
                        OptionUnit(fun () ->
                            fsiServerOutputCodePage <- None
                            fsiServerInputCodePage <- None),
                        None,
                        None
                    ) // "Do not set the codepages for the console");
                    CompilerOption("fsi-server-lcid", "", OptionInt(fun n -> fsiLCID <- Some(n)), None, None) // "LCID from Visual Studio"

                    // We do not want to print the "script.fsx arg2..." as part of the options
                    CompilerOption(
                        "script.fsx arg1 arg2 ...",
                        "",
                        OptionGeneral(
                            (fun args -> args.Length > 0 && IsScript args[0]),
                            (fun args ->
                                let scriptFile = args[0]
                                let scriptArgs = List.tail args
                                inputFilesAcc <- inputFilesAcc @ [ (scriptFile, true) ] (* record script.fsx for evaluation *)
                                List.iter recordExplicitArg scriptArgs (* record rest of line as explicit arguments *)
                                tcConfigB.noFeedback <- true (* "quiet", no banners responses etc *)
                                interact <- false (* --exec, exit after eval *)
                                [] (* no arguments passed on, all consumed here *)

                                )
                        ),
                        None,
                        None
                    ) // "Run script.fsx with the follow command line arguments: arg1 arg2 ...");
                ]
            )
            PrivateOptions(
                [
                    // Private options, related to diagnostics around console probing
                    CompilerOption(
                        "probeconsole",
                        "",
                        OptionSwitch(fun flag -> probeToSeeIfConsoleWorks <- flag = OptionSwitch.On),
                        None,
                        None
                    ) // "Probe to see if Console looks functional");

                    CompilerOption(
                        "peekahead",
                        "",
                        OptionSwitch(fun flag -> peekAheadOnConsoleToPermitTyping <- flag = OptionSwitch.On),
                        None,
                        None
                    ) // "Probe to see if Console looks functional");

                    // Disables interaction (to be used by libraries embedding FSI only!)
                    CompilerOption("noninteractive", "", OptionUnit(fun () -> interact <- false), None, None) // "Deprecated, use --exec instead"

                ]
            )
        ]

    /// These options follow the FsiCoreCompilerOptions in the help blocks
    let fsiUsageSuffix tcConfigB =
        [
            PublicOptions(
                FSComp.SR.optsHelpBannerInputFiles (),
                [
                    CompilerOption("--", "", OptionRest recordExplicitArg, None, Some(FSIstrings.SR.fsiRemaining ()))
                ]
            )
            PublicOptions(
                FSComp.SR.optsHelpBannerMisc (),
                [
                    CompilerOption("help", tagNone, OptionConsoleOnly(displayHelpFsi tcConfigB), None, Some(FSIstrings.SR.fsiHelp ()))
                ]
            )
            PrivateOptions(
                [
                    CompilerOption("?", tagNone, OptionConsoleOnly(displayHelpFsi tcConfigB), None, None) // "Short form of --help");
                    CompilerOption("help", tagNone, OptionConsoleOnly(displayHelpFsi tcConfigB), None, None) // "Short form of --help");
                    CompilerOption("full-help", tagNone, OptionConsoleOnly(displayHelpFsi tcConfigB), None, None) // "Short form of --help");
                ]
            )
            PublicOptions(
                FSComp.SR.optsHelpBannerAdvanced (),
                [
                    CompilerOption("exec", "", OptionUnit(fun () -> interact <- false), None, Some(FSIstrings.SR.fsiExec ()))
                    CompilerOption(
                        "gui",
                        tagNone,
                        OptionSwitch(fun flag -> gui <- (flag = OptionSwitch.On)),
                        None,
                        Some(FSIstrings.SR.fsiGui ())
                    )
                    CompilerOption("quiet", "", OptionUnit(fun () -> tcConfigB.noFeedback <- true), None, Some(FSIstrings.SR.fsiQuiet ()))
                    CompilerOption(
                        "readline",
                        tagNone,
                        OptionSwitch(fun flag -> enableConsoleKeyProcessing <- (flag = OptionSwitch.On)),
                        None,
                        Some(FSIstrings.SR.fsiReadline ())
                    )
                    CompilerOption(
                        "quotations-debug",
                        tagNone,
                        OptionSwitch(fun switch -> tcConfigB.emitDebugInfoInQuotations <- switch = OptionSwitch.On),
                        None,
                        Some(FSIstrings.SR.fsiEmitDebugInfoInQuotations ())
                    )
                    CompilerOption(
                        "shadowcopyreferences",
                        tagNone,
                        OptionSwitch(fun flag -> tcConfigB.shadowCopyReferences <- flag = OptionSwitch.On),
                        None,
                        Some(FSIstrings.SR.shadowCopyReferences ())
                    )
                    CompilerOption(
                        "multiemit",
                        tagNone,
                        OptionSwitch(fun flag -> tcConfigB.fsiMultiAssemblyEmit <- flag = OptionSwitch.On),
                        None,
                        Some(FSIstrings.SR.fsiMultiAssemblyEmitOption ())
                    )
                ]
            )
        ]

    /// Process command line, flags and collect filenames.
    /// The ParseCompilerOptions function calls imperative function to process "real" args
    /// Rather than start processing, just collect names, then process them.
    let sourceFiles =
        let collect name =
            let fsx = IsScript name
            inputFilesAcc <- inputFilesAcc @ [ (name, fsx) ] // O(n^2), but n small...

        try
            let fsiCompilerOptions =
                fsiUsagePrefix tcConfigB
                @ GetCoreFsiCompilerOptions tcConfigB @ fsiUsageSuffix tcConfigB

            let abbrevArgs = GetAbbrevFlagSet tcConfigB false
            ParseCompilerOptions(collect, fsiCompilerOptions, List.tail (PostProcessCompilerArgs abbrevArgs argv))
        with e ->
            stopProcessingRecovery e range0
            failwithf "Error creating evaluation session: %A" e

        inputFilesAcc

    // We need a dependency provider with native resolution.  Managed resolution is handled by generated `#r`
    let dependencyProvider =
        new DependencyProvider(NativeResolutionProbe(tcConfigB.GetNativeProbingRoots))

    do
        if tcConfigB.clearResultsCache then
            dependencyProvider.ClearResultsCache(tcConfigB.compilerToolPaths, getOutputDir tcConfigB, reportError rangeCmdArgs)

        if tcConfigB.utf8output then
            let prev = Console.OutputEncoding
            Console.OutputEncoding <- Encoding.UTF8
            System.AppDomain.CurrentDomain.ProcessExit.Add(fun _ -> Console.OutputEncoding <- prev)

    do
        let firstArg =
            match sourceFiles with
            | [] -> argv[0]
            | _ -> fst (List.head (List.rev sourceFiles))

        let args = Array.ofList (firstArg :: explicitArgs)
        fsi.ReportUserCommandLineArgs args

    //----------------------------------------------------------------------------
    // Banner
    //----------------------------------------------------------------------------

    member _.ShowBanner() =
        fsiConsoleOutput.uprintnfn "%s" tcConfigB.productNameForBannerText
        fsiConsoleOutput.uprintfnn "%s" (FSComp.SR.optsCopyright ())
        fsiConsoleOutput.uprintfn "%s" (FSIstrings.SR.fsiBanner3 ())

    member _.ShowHelp(m) =
        let helpLine = sprintf "%s --help" executableFileNameWithoutExtension.Value

        fsiConsoleOutput.uprintfn ""
        fsiConsoleOutput.uprintfnn "%s" (FSIstrings.SR.fsiIntroTextHeader1directives ())
        fsiConsoleOutput.uprintfn """    #r "file.dll";;                               // %s""" (FSIstrings.SR.fsiIntroTextHashrInfo ())

        fsiConsoleOutput.uprintfn
            """    #i "package source uri";;                     // %s"""
            (FSIstrings.SR.fsiIntroPackageSourceUriInfo ())

        fsiConsoleOutput.uprintfn """    #I "path";;                                   // %s""" (FSIstrings.SR.fsiIntroTextHashIInfo ())
        fsiConsoleOutput.uprintfn """    #load "file.fs" ...;;                         // %s""" (FSIstrings.SR.fsiIntroTextHashloadInfo ())
        fsiConsoleOutput.uprintfn """    #time ["on"|"off"];;                          // %s""" (FSIstrings.SR.fsiIntroTextHashtimeInfo ())
        fsiConsoleOutput.uprintfn """    #help;;                                       // %s""" (FSIstrings.SR.fsiIntroTextHashhelpInfo ())

        if tcConfigB.langVersion.SupportsFeature(LanguageFeature.PackageManagement) then
            for msg in
                dependencyProvider.GetRegisteredDependencyManagerHelpText(
                    tcConfigB.compilerToolPaths,
                    getOutputDir tcConfigB,
                    reportError m
                ) do
                fsiConsoleOutput.uprintfn "%s" msg

        fsiConsoleOutput.uprintfn """    #clear;;                                      // %s""" (FSIstrings.SR.fsiIntroTextHashclearInfo ())
        fsiConsoleOutput.uprintfn """    #quit;;                                       // %s""" (FSIstrings.SR.fsiIntroTextHashquitInfo ())
        fsiConsoleOutput.uprintfn ""
        fsiConsoleOutput.uprintfnn "%s" (FSIstrings.SR.fsiIntroTextHeader2commandLine ())
        fsiConsoleOutput.uprintfn "%s" (FSIstrings.SR.fsiIntroTextHeader3 (helpLine))
        fsiConsoleOutput.uprintfn ""
        fsiConsoleOutput.uprintfn ""

    member _.ClearScreen() = fsiConsoleOutput.Clear()

#if DEBUG
    member _.ShowILCode
        with get () = showILCode
        and set v = showILCode <- v
#endif

    member _.ShowTypes
        with get () = showTypes
        and set v = showTypes <- v

    member _.FsiServerName = fsiServerName

    member _.FsiServerInputCodePage = fsiServerInputCodePage

    member _.FsiServerOutputCodePage = fsiServerOutputCodePage

    member _.FsiLCID
        with get () = fsiLCID
        and set v = fsiLCID <- v

    member _.UseServerPrompt = isInteractiveServer ()

    member _.IsInteractiveServer = isInteractiveServer ()

    member _.ProbeToSeeIfConsoleWorks = probeToSeeIfConsoleWorks

    member _.EnableConsoleKeyProcessing = enableConsoleKeyProcessing

    member _.Interact = interact

    member _.PeekAheadOnConsoleToPermitTyping = peekAheadOnConsoleToPermitTyping

    member _.SourceFiles = sourceFiles

    member _.Gui = gui

    member _.WriteReferencesAndExit = writeReferencesAndExit

    member _.DependencyProvider = dependencyProvider

    member _.FxResolver = tcConfigB.FxResolver

/// Set the current ui culture for the current thread.
let internal SetCurrentUICultureForThread (lcid: int option) =
    let culture = Thread.CurrentThread.CurrentUICulture

    match lcid with
    | Some n -> Thread.CurrentThread.CurrentUICulture <- CultureInfo(n)
    | None -> ()

    { new IDisposable with
        member _.Dispose() =
            Thread.CurrentThread.CurrentUICulture <- culture
    }

//----------------------------------------------------------------------------
// Reporting - warnings, errors
//----------------------------------------------------------------------------

let internal InstallErrorLoggingOnThisThread diagnosticsLogger =
    if progress then
        dprintfn "Installing logger on id=%d name=%s" Thread.CurrentThread.ManagedThreadId Thread.CurrentThread.Name

    SetThreadDiagnosticsLoggerNoUnwind(diagnosticsLogger)
    SetThreadBuildPhaseNoUnwind(BuildPhase.Interactive)

/// Set the input/output encoding. The use of a thread is due to a known bug on
/// on Vista where calls to Console.InputEncoding can block the process.
let internal SetServerCodePages (fsiOptions: FsiCommandLineOptions) =
    match fsiOptions.FsiServerInputCodePage, fsiOptions.FsiServerOutputCodePage with
    | None, None -> ()
    | inputCodePageOpt, outputCodePageOpt ->
        let mutable successful = false

        Async.Start(
            async {
                do
                    match inputCodePageOpt with
                    | None -> ()
                    | Some (n: int) ->
                        let encoding = Encoding.GetEncoding(n)
                        // Note this modifies the real honest-to-goodness settings for the current shell.
                        // and the modifications hang around even after the process has exited.
                        Console.InputEncoding <- encoding

                do
                    match outputCodePageOpt with
                    | None -> ()
                    | Some (n: int) ->
                        let encoding = Encoding.GetEncoding n
                        // Note this modifies the real honest-to-goodness settings for the current shell.
                        // and the modifications hang around even after the process has exited.
                        Console.OutputEncoding <- encoding

                do successful <- true
            }
        )

        for pause in [ 10; 50; 100; 1000; 2000; 10000 ] do
            if not successful then
                Thread.Sleep(pause)
#if LOGGING_GUI
        if not !successful then
            System.Windows.Forms.MessageBox.Show(FSIstrings.SR.fsiConsoleProblem ())
            |> ignore
#endif

//----------------------------------------------------------------------------
// Prompt printing
//----------------------------------------------------------------------------

type internal FsiConsolePrompt(fsiOptions: FsiCommandLineOptions, fsiConsoleOutput: FsiConsoleOutput) =

    // A prompt gets "printed ahead" at start up. Tells users to start type while initialisation completes.
    // A prompt can be skipped by "silent directives", e.g. ones sent to FSI by VS.
    let mutable dropPrompt = 0
    let mutable showPrompt = true

    // NOTE: SERVER-PROMPT is not user displayed, rather it's a prefix that code elsewhere
    // uses to identify the prompt, see service\FsPkgs\FSharp.VS.FSI\fsiSessionToolWindow.fs

    let prompt =
        if fsiOptions.UseServerPrompt then
            "SERVER-PROMPT>" + Environment.NewLine
        else
            "> "

    member _.Print() =
        if showPrompt then
            if dropPrompt = 0 then
                fsiConsoleOutput.uprintf "%s" prompt
            else
                dropPrompt <- dropPrompt - 1

    member _.PrintAhead() =
        if showPrompt then
            dropPrompt <- dropPrompt + 1
            fsiConsoleOutput.uprintf "%s" prompt

    // Can be turned off when executing blocks of code using:
    // # silentPrompt
    member _.ShowPrompt
        with get () = showPrompt
        and set (value) = showPrompt <- value

    member _.SkipNext() =
        if showPrompt then
            dropPrompt <- dropPrompt + 1

    member _.FsiOptions = fsiOptions

//----------------------------------------------------------------------------
// Startup processing
//----------------------------------------------------------------------------
type internal FsiConsoleInput
    (
        fsi: FsiEvaluationSessionHostConfig,
        fsiOptions: FsiCommandLineOptions,
        inReader: TextReader,
        outWriter: TextWriter
    ) =

    let consoleOpt =
        // The "console.fs" code does a limited form of "TAB-completion".
        // Currently, it turns on if it looks like we have a console.
        if fsiOptions.EnableConsoleKeyProcessing then
            fsi.GetOptionalConsoleReadLine(fsiOptions.ProbeToSeeIfConsoleWorks)
        else
            None

    // When VFSI is running, there should be no "console", and in particular the console.fs readline code should not to run.
    do
        if fsiOptions.IsInteractiveServer then
            assert consoleOpt.IsNone

    /// This threading event gets set after the first-line-reader has finished its work
    let consoleReaderStartupDone = new ManualResetEvent(false)

    /// When using a key-reading console this holds the first line after it is read
    let mutable firstLine = None

    // Peek on the standard input so that the user can type into it from a console window.
    do
        if fsiOptions.Interact then
            if fsiOptions.PeekAheadOnConsoleToPermitTyping then
                (Thread(fun () ->
                    match consoleOpt with
                    | Some console when fsiOptions.EnableConsoleKeyProcessing && not fsiOptions.UseServerPrompt ->
                        if List.isEmpty fsiOptions.SourceFiles then
                            if progress then
                                fprintfn outWriter "first-line-reader-thread reading first line..."

                            firstLine <- Some(console ())

                            if progress then
                                fprintfn outWriter "first-line-reader-thread got first line = %A..." firstLine

                        consoleReaderStartupDone.Set() |> ignore

                        if progress then
                            fprintfn outWriter "first-line-reader-thread has set signal and exited."
                    | _ ->
                        ignore (inReader.Peek())
                        consoleReaderStartupDone.Set() |> ignore))
                    .Start()
            else
                if progress then
                    fprintfn outWriter "first-line-reader-thread not in use."

                consoleReaderStartupDone.Set() |> ignore

    /// Try to get the first line, if we snarfed it while probing.
    member _.TryGetFirstLine() =
        let r = firstLine in
        firstLine <- None
        r

    /// Try to get the console, if it appears operational.
    member _.TryGetConsole() = consoleOpt

    member _.In = inReader

    member _.WaitForInitialConsoleInput() =
        WaitHandle.WaitAll [| consoleReaderStartupDone |] |> ignore

//----------------------------------------------------------------------------
// FsiDynamicCompilerState
//----------------------------------------------------------------------------

type FsiInteractionStepStatus =
    | CtrlC
    | EndOfFile
    | Completed of FsiValue option
    | CompletedWithAlreadyReportedError
    | CompletedWithReportedError of exn

[<AutoSerializable(false)>]
[<NoEquality; NoComparison>]
type FsiDynamicCompilerState =
    {
        optEnv: Optimizer.IncrementalOptimizationEnv
        emEnv: ILAssemblyEmitEnv
        tcGlobals: TcGlobals
        tcState: TcState
        tcImports: TcImports
        ilxGenerator: IlxAssemblyGenerator
        boundValues: NameMap<Val>
        // Why is this not in FsiOptions?
        timing: bool
        debugBreak: bool
    }

let WithImplicitHome (tcConfigB, dir) f =
    let old = tcConfigB.implicitIncludeDir
    tcConfigB.implicitIncludeDir <- dir

    try
        f ()
    finally
        tcConfigB.implicitIncludeDir <- old

let ConvReflectionTypeToILTypeRef (reflectionTy: Type) =
    if reflectionTy.Assembly.IsDynamic then
        raise (NotSupportedException(sprintf "Unable to import type, %A, from a dynamic assembly." reflectionTy))

    if not reflectionTy.IsPublic && not reflectionTy.IsNestedPublic then
        invalidOp (sprintf "Cannot import the non-public type, %A." reflectionTy)

    let aref = ILAssemblyRef.FromAssemblyName(reflectionTy.Assembly.GetName())
    let scoref = ILScopeRef.Assembly aref

    let fullName = reflectionTy.FullName
    let index = fullName.IndexOf("[")

    let fullName =
        if index = -1 then
            fullName
        else
            fullName.Substring(0, index)

    let isTop = reflectionTy.DeclaringType = null

    if isTop then
        ILTypeRef.Create(scoref, [], fullName)
    else
        let names = String.split StringSplitOptions.None [| "+"; "." |] fullName
        let enc = names[.. names.Length - 2]
        let nm = names[names.Length - 1]
        ILTypeRef.Create(scoref, List.ofArray enc, nm)

let rec ConvReflectionTypeToILType (reflectionTy: Type) =
    let arrayRank =
        if reflectionTy.IsArray then
            reflectionTy.GetArrayRank()
        else
            0

    let reflectionTy =
        // Special case functions.
        if FSharp.Reflection.FSharpType.IsFunction reflectionTy then
            let ctors =
                reflectionTy.GetConstructors(BindingFlags.Public ||| BindingFlags.NonPublic ||| BindingFlags.Instance)

            if
                ctors.Length = 1
                && ctors[ 0 ].GetCustomAttribute<CompilerGeneratedAttribute>() <> null
                && not ctors[0].IsPublic
                && IsCompilerGeneratedName reflectionTy.Name
            then
                let rec get (typ: Type) =
                    if FSharp.Reflection.FSharpType.IsFunction typ.BaseType then
                        get typ.BaseType
                    else
                        typ

                get reflectionTy
            else
                reflectionTy
        else
            reflectionTy

    let elementOrItemTref =
        if reflectionTy.HasElementType then
            reflectionTy.GetElementType()
        else
            reflectionTy
        |> ConvReflectionTypeToILTypeRef

    let genericArgs =
        reflectionTy.GenericTypeArguments
        |> Seq.map ConvReflectionTypeToILType
        |> Seq.map List.head
        |> List.ofSeq

    let boxity =
        if reflectionTy.IsValueType then
            ILBoxity.AsValue
        else
            ILBoxity.AsObject

    let tspec = ILTypeSpec.Create(elementOrItemTref, genericArgs)

    let ilType = mkILTy boxity tspec

    if arrayRank = 0 then
        [ ilType ]
    else
        let arrayShape = ILArrayShape.FromRank arrayRank
        let arrayIlType = mkILArrTy (ilType, arrayShape)
        [ arrayIlType; ilType ]

let internal mkBoundValueTypedImpl tcGlobals m moduleName name ty =
    let vis = Accessibility.TAccess([])
    let compPath = (CompilationPath.CompPath(ILScopeRef.Local, []))
    let mutable mty = Unchecked.defaultof<_>

    let entity =
        Construct.NewModuleOrNamespace (Some compPath) vis (Ident(moduleName, m)) XmlDoc.Empty [] (MaybeLazy.Lazy(lazy mty))

    let v =
        Construct.NewVal(
            name,
            m,
            None,
            ty,
            ValMutability.Immutable,
            false,
            Some(
                ValReprInfo(
                    [],
                    [],
                    {
                        Attribs = []
                        Name = None
                        OtherRange = None
                    }
                )
            ),
            vis,
            ValNotInRecScope,
            None,
            NormalVal,
            [],
            ValInline.Optional,
            XmlDoc.Empty,
            true,
            false,
            false,
            false,
            false,
            false,
            None,
            Parent(TypedTreeBasics.ERefLocal entity)
        )

    mty <- ModuleOrNamespaceType(ModuleOrNamespaceKind.ModuleOrType, QueueList.one v, QueueList.empty)

    let bindExpr = mkCallDefaultOf tcGlobals range0 ty
    let binding = Binding.TBind(v, bindExpr, DebugPointAtBinding.NoneAtLet)

    let mbinding =
        ModuleOrNamespaceBinding.Module(entity, TMDefs([ TMDefLet(binding, m) ]))

    let contents = TMDefs([ TMDefs[TMDefRec(false, [], [], [ mbinding ], m)] ])
    let qname = QualifiedNameOfFile.QualifiedNameOfFile(Ident(moduleName, m))
    entity, v, CheckedImplFile.CheckedImplFile(qname, [], mty, contents, false, false, StampMap.Empty, Map.empty)

let scriptingSymbolsPath =
    let createDirectory path =
        lazy
            try
                if not (Directory.Exists(path)) then
                    Directory.CreateDirectory(path) |> ignore

                path
            with _ ->
                path

    createDirectory (Path.Combine(Path.GetTempPath(), $"{DateTime.Now:s}-{Guid.NewGuid():n}".Replace(':', '-')))

let deleteScriptingSymbols () =
    try
#if !DEBUG
        if scriptingSymbolsPath.IsValueCreated then
            if Directory.Exists(scriptingSymbolsPath.Value) then
                Directory.Delete(scriptingSymbolsPath.Value, true)
#else
        ()
#endif
    with _ ->
        ()

AppDomain.CurrentDomain.ProcessExit
|> Event.add (fun _ -> deleteScriptingSymbols ())

let dynamicCcuName = "FSI-ASSEMBLY"

/// Encapsulates the coordination of the typechecking, optimization and code generation
/// components of the F# compiler for interactively executed fragments of code.
///
/// A single instance of this object is created per interactive session.
type internal FsiDynamicCompiler
    (
        fsi: FsiEvaluationSessionHostConfig,
        timeReporter: FsiTimeReporter,
        tcConfigB: TcConfigBuilder,
        tcLockObject: obj,
        outWriter: TextWriter,
        tcImports: TcImports,
        tcGlobals: TcGlobals,
        fsiOptions: FsiCommandLineOptions,
        fsiConsoleOutput: FsiConsoleOutput,
        fsiCollectible: bool,
        resolveAssemblyRef
    ) =

    let ilGlobals = tcGlobals.ilg

    let outfile = "TMPFSCI.exe"

    let valueBoundEvent = Control.Event<_>()

    let mutable fragmentId = 0

    static let mutable dynamicAssemblyId = 0

    static let maxVersion = int Int16.MaxValue

    let mutable prevIt: ValRef option = None

    let dynamicAssemblies = ResizeArray<Assembly>()

    let mutable hasDelayedDependencyManagerText = false

    let mutable delayedReferences = ResizeArray<_>()

    let generateDebugInfo = tcConfigB.debuginfo

    let valuePrinter = FsiValuePrinter(fsi, outWriter)

    let builders =
        if tcConfigB.fsiMultiAssemblyEmit then
            None
        else
            let assemBuilder, moduleBuilder =
                mkDynamicAssemblyAndModule (dynamicCcuName, tcConfigB.optSettings.LocalOptimizationsEnabled, fsiCollectible)

            dynamicAssemblies.Add(assemBuilder)
            Some(assemBuilder, moduleBuilder)

    let rangeStdin0 = rangeN stdinMockFileName 0

    let infoReader = InfoReader(tcGlobals, tcImports.GetImportMap())

    let reportedAssemblies = Dictionary<string, DateTime>()

    /// Add attributes
    let CreateModuleFragment (tcConfigB: TcConfigBuilder, dynamicCcuName, codegenResults) =
        if progress then
            fprintfn fsiConsoleOutput.Out "Creating main module..."

        let mainModule =
            mkILSimpleModule
                dynamicCcuName
                (GetGeneratedILModuleName tcConfigB.target dynamicCcuName)
                (tcConfigB.target = CompilerTarget.Dll)
                tcConfigB.subsystemVersion
                tcConfigB.useHighEntropyVA
                (mkILTypeDefs codegenResults.ilTypeDefs)
                None
                None
                0x0
                (mkILExportedTypes [])
                ""

        { mainModule with
            Manifest =
                (let man = mainModule.ManifestOfAssembly

                 Some
                     { man with
                         CustomAttrsStored = storeILCustomAttrs (mkILCustomAttrs codegenResults.ilAssemAttrs)
                     })
        }

    /// Generate one assembly using multi-assembly emit
    let EmitInMemoryAssembly (tcConfig: TcConfig, emEnv: ILMultiInMemoryAssemblyEmitEnv, ilxMainModule: ILModuleDef) =
        let embeddedTypes =
            tcGlobals.tryRemoveEmbeddedILTypeDefs ()
            |> List.filter (fun tdef -> not (emEnv.IsLocalInternalType(mkRefForNestedILTypeDef ILScopeRef.Local ([], tdef))))

        let ilxMainModule =
            { ilxMainModule with
                TypeDefs = mkILTypeDefs (ilxMainModule.TypeDefs.AsList() @ embeddedTypes)
            }

        let multiAssemblyName = ilxMainModule.ManifestOfAssembly.Name

        // Adjust the assembly name of this fragment, and add InternalsVisibleTo attributes to
        // allow internals access by all future assemblies with the same name (and only differing in version)
        let manifest =
            let manifest = ilxMainModule.Manifest.Value

            let attrs =
                [
                    tcGlobals.MakeInternalsVisibleToAttribute(dynamicCcuName)
                    yield! manifest.CustomAttrs.AsList()
                ]

            { manifest with
                Name = multiAssemblyName
                // Because the coreclr loader will not load a higher assembly make versions go downwards
                Version = Some(parseILVersion $"0.0.0.{maxVersion - dynamicAssemblyId}")
                CustomAttrsStored = storeILCustomAttrs (mkILCustomAttrs attrs)
            }

        // The name of the assembly is "FSI-ASSEMBLY" for all submissions. This number is used for the Version
        dynamicAssemblyId <- (dynamicAssemblyId + 1) % maxVersion

        let ilxMainModule =
            { ilxMainModule with
                Manifest = Some manifest
            }

        // Rewrite references to local types to their respective dynamic assemblies
        let ilxMainModule =
            ilxMainModule
            |> Morphs.morphILTypeRefsInILModuleMemoized TcGlobals.IsInEmbeddableKnownSet emEnv.MapTypeRef

        let opts =
            {
                ilg = tcGlobals.ilg
                outfile = $"{multiAssemblyName}-{dynamicAssemblyId}.dll"
                pdbfile = Some(Path.Combine(scriptingSymbolsPath.Value, $"{multiAssemblyName}-{dynamicAssemblyId}.pdb"))
                emitTailcalls = tcConfig.emitTailcalls
                deterministic = tcConfig.deterministic
                portablePDB = true
                embeddedPDB = false
                embedAllSource = false
                embedSourceList = []
                allGivenSources = []
                sourceLink = tcConfig.sourceLink
                checksumAlgorithm = tcConfig.checksumAlgorithm
                signer = None
                dumpDebugInfo = tcConfig.dumpDebugInfo
                referenceAssemblyOnly = false
                referenceAssemblyAttribOpt = None
                referenceAssemblySignatureHash = None
                pathMap = tcConfig.pathMap
            }

        let assemblyBytes, pdbBytes = WriteILBinaryInMemory(opts, ilxMainModule, id)

        let asm =
            match opts.pdbfile, pdbBytes with
            | (Some pdbfile), (Some pdbBytes) -> File.WriteAllBytes(pdbfile, pdbBytes)
            | _ -> ()

            match pdbBytes with
            | None -> Assembly.Load(assemblyBytes)
            | Some pdbBytes -> Assembly.Load(assemblyBytes, pdbBytes)

        // Force generated types to load
        for t in asm.GetTypes() do
            ignore t

        // remember this assembly
        dynamicAssemblies.Add(asm)

        let ilScopeRef = ILScopeRef.Assembly(ILAssemblyRef.FromAssemblyName(asm.GetName()))

        // Collect up the entry points for initialization
        let entries =
            let rec loop enc (tdef: ILTypeDef) =
                [
                    for mdef in tdef.Methods do
                        if mdef.IsEntryPoint then
                            yield mkRefForILMethod ilScopeRef (enc, tdef) mdef

                        for ntdef in tdef.NestedTypes do
                            yield! loop (enc @ [ tdef ]) ntdef
                ]

            [
                for tdef in ilxMainModule.TypeDefs do
                    yield! loop [] tdef
            ]

        let execs =
            [
                for edef in entries do
                    if edef.ArgCount = 0 then
                        yield
                            (fun () ->
                                let typ = asm.GetType(edef.DeclaringTypeRef.BasicQualifiedName)

                                try
                                    ignore (
                                        typ.InvokeMember(
                                            edef.Name,
                                            BindingFlags.InvokeMethod
                                            ||| BindingFlags.Public
                                            ||| BindingFlags.NonPublic
                                            ||| BindingFlags.Static,
                                            null,
                                            null,
                                            [||],
                                            Globalization.CultureInfo.InvariantCulture
                                        )
                                    )

                                    None
                                with :? TargetInvocationException as e ->
                                    Some e.InnerException)
            ]

        emEnv.AddModuleDef asm ilScopeRef ilxMainModule

        execs

    // Emit the codegen results using the assembly writer
    let ProcessCodegenResults
        (
            ctok,
            diagnosticsLogger: DiagnosticsLogger,
            istate,
            optEnv,
            tcState: TcState,
            tcConfig,
            prefixPath,
            showTypes: bool,
            isIncrementalFragment,
            fragName,
            declaredImpls,
            ilxGenerator: IlxAssemblyGenerator,
            codegenResults,
            m
        ) =
        let emEnv = istate.emEnv

        // Each input is like a small separately compiled extension to a single source file.
        // The incremental extension to the environment is dictated by the "signature" of the values as they come out
        // of the type checker. Hence we add the declaredImpls (unoptimized) to the environment, rather than the
        // optimizedImpls.
        ilxGenerator.AddIncrementalLocalAssemblyFragment(isIncrementalFragment, fragName, declaredImpls)

        ReportTime tcConfig "TAST -> ILX"
        diagnosticsLogger.AbortOnError(fsiConsoleOutput)

        ReportTime tcConfig "Linking"
        let ilxMainModule = CreateModuleFragment(tcConfigB, dynamicCcuName, codegenResults)

        diagnosticsLogger.AbortOnError(fsiConsoleOutput)

        ReportTime tcConfig "Assembly refs Normalised"

        let ilxMainModule =
            Morphs.morphILScopeRefsInILModuleMemoized
                TcGlobals.IsInEmbeddableKnownSet
                (NormalizeAssemblyRefs(ctok, ilGlobals, tcImports))
                ilxMainModule

        diagnosticsLogger.AbortOnError(fsiConsoleOutput)

#if DEBUG
        if fsiOptions.ShowILCode then
            fsiConsoleOutput.uprintnfn "--------------------"
            ILAsciiWriter.output_module outWriter ilGlobals ilxMainModule
            fsiConsoleOutput.uprintnfn "--------------------"
#else
        ignore (fsiOptions)
#endif

        ReportTime tcConfig "Reflection.Emit"

        let emEnv, execs =
            match emEnv with
            | SingleRefEmitAssembly (cenv, emEnv) ->

                let assemblyBuilder, moduleBuilder = builders.Value

                let emEnv, execs =
                    EmitDynamicAssemblyFragment(
                        ilGlobals,
                        tcConfig.emitTailcalls,
                        emEnv,
                        assemblyBuilder,
                        moduleBuilder,
                        ilxMainModule,
                        generateDebugInfo,
                        cenv.resolveAssemblyRef,
                        tcGlobals.TryFindSysILTypeRef
                    )

                SingleRefEmitAssembly(cenv, emEnv), execs

            | MultipleInMemoryAssemblies emEnv ->

                let execs = EmitInMemoryAssembly(tcConfig, emEnv, ilxMainModule)

                MultipleInMemoryAssemblies emEnv, execs

        diagnosticsLogger.AbortOnError(fsiConsoleOutput)

        // Explicitly register the resources with the QuotationPickler module
        match emEnv with
        | SingleRefEmitAssembly (cenv, emEnv) ->

            let assemblyBuilder, _moduleBuilder = builders.Value

            for referencedTypeDefs, bytes in codegenResults.quotationResourceInfo do
                let referencedTypes =
                    [|
                        for tref in referencedTypeDefs do
                            yield LookupTypeRef cenv emEnv tref
                    |]

                Quotations.Expr.RegisterReflectedDefinitions(assemblyBuilder, fragName, bytes, referencedTypes)

        | MultipleInMemoryAssemblies emEnv ->
            // Get the last assembly emitted
            let assembly = dynamicAssemblies[dynamicAssemblies.Count - 1]

            for referencedTypeDefs, bytes in codegenResults.quotationResourceInfo do
                let referencedTypes =
                    [|
                        for tref in referencedTypeDefs do
                            yield emEnv.LookupTypeRef tref
                    |]

                Quotations.Expr.RegisterReflectedDefinitions(assembly, fragName, bytes, referencedTypes)

        ReportTime tcConfig "Run Bindings"

        timeReporter.TimeOpIf istate.timing (fun () ->
            execs
            |> List.iter (fun exec ->
                match exec () with
                | Some err ->
                    match diagnosticsLogger with
                    | :? DiagnosticsLoggerThatStopsOnFirstError as diagnosticsLogger ->
                        fprintfn fsiConsoleOutput.Error "%s" (err.ToString())
                        diagnosticsLogger.SetError()
                        diagnosticsLogger.AbortOnError(fsiConsoleOutput)
                    | _ -> raise (StopProcessingExn(Some err))

                | None -> ()))

        diagnosticsLogger.AbortOnError(fsiConsoleOutput)

        // Echo the decls (reach inside wrapping)
        // This code occurs AFTER the execution of the declarations.
        // So stored values will have been initialised, modified etc.
        if showTypes && not tcConfig.noFeedback then
            let denv = tcState.TcEnvFromImpls.DisplayEnv

            let denv =
                if isIncrementalFragment then
                    // Extend denv with a (Val -> layout option) function for printing of val bindings.
                    { denv with
                        generatedValueLayout = (fun v -> valuePrinter.InvokeDeclLayout(emEnv, ilxGenerator, v))
                    }
                else
                    // With #load items, the vals in the inferred signature do not tie up with those generated. Disable printing.
                    denv

            let denv =
                { denv with
                    suppressInlineKeyword = false
                } // dont' suppress 'inline' in 'val inline f = ...'

            // 'Open' the path for the fragment we just compiled for any future printing.
            let denv = denv.AddOpenPath(pathOfLid prefixPath)

            for CheckedImplFile (contents = mexpr) in declaredImpls do
                let responseL =
                    NicePrint.layoutImpliedSignatureOfModuleOrNamespace false denv infoReader AccessibleFromSomewhere m mexpr

                if not (isEmptyL responseL) then
                    let opts = valuePrinter.GetFsiPrintOptions()
                    colorPrintL outWriter opts responseL

        // Build the new incremental state.
        let istate =
            { istate with
                optEnv = optEnv
                emEnv = emEnv
                ilxGenerator = ilxGenerator
                tcState = tcState
            }

        // Return the new state and the environment at the end of the last input, ready for further inputs.
        (istate, declaredImpls)

    let ProcessTypedImpl
        (
            diagnosticsLogger: DiagnosticsLogger,
            optEnv,
            tcState: TcState,
            tcConfig: TcConfig,
            isInteractiveItExpr,
            topCustomAttrs,
            prefixPath,
            isIncrementalFragment,
            declaredImpls,
            ilxGenerator: IlxAssemblyGenerator
        ) =
#if DEBUG
        // Logging/debugging
        if tcConfig.printAst then
            for input in declaredImpls do
                fprintfn fsiConsoleOutput.Out "AST:"
                fprintfn fsiConsoleOutput.Out "%+A" input
#endif

        diagnosticsLogger.AbortOnError(fsiConsoleOutput)

        let importMap = tcImports.GetImportMap()

        // optimize: note we collect the incremental optimization environment
        let optimizedImpls, _optData, optEnv =
            ApplyAllOptimizations(
                tcConfig,
                tcGlobals,
                LightweightTcValForUsingInBuildMethodCall tcGlobals,
                outfile,
                importMap,
                isIncrementalFragment,
                optEnv,
                tcState.Ccu,
                declaredImpls
            )

        diagnosticsLogger.AbortOnError(fsiConsoleOutput)

        let fragName = textOfLid prefixPath

        let codegenResults =
            GenerateIlxCode(IlReflectBackend, isInteractiveItExpr, tcConfig, topCustomAttrs, optimizedImpls, fragName, ilxGenerator)

        diagnosticsLogger.AbortOnError(fsiConsoleOutput)
        codegenResults, optEnv, fragName

    /// Check FSI entries for the presence of EntryPointAttribute and issue a warning if it's found
    let CheckEntryPoint (tcGlobals: TcGlobals) (declaredImpls: CheckedImplFile list) =
        let tryGetEntryPoint (TBind (var = value)) =
            TryFindFSharpAttribute tcGlobals tcGlobals.attrib_EntryPointAttribute value.Attribs
            |> Option.map (fun attrib -> value.DisplayName, attrib)

        let rec findEntryPointInContents =
            function
            | TMDefLet (binding = binding) -> tryGetEntryPoint binding
            | TMDefs defs -> defs |> List.tryPick findEntryPointInContents
            | TMDefRec (bindings = bindings) -> bindings |> List.tryPick findEntryPointInBinding
            | _ -> None

        and findEntryPointInBinding =
            function
            | ModuleOrNamespaceBinding.Binding binding -> tryGetEntryPoint binding
            | ModuleOrNamespaceBinding.Module (moduleOrNamespaceContents = contents) -> findEntryPointInContents contents

        let entryPointBindings =
            declaredImpls
            |> Seq.where (fun implFile -> implFile.HasExplicitEntryPoint)
            |> Seq.choose (fun implFile -> implFile.Contents |> findEntryPointInContents)

        for name, attrib in entryPointBindings do
            warning (Error(FSIstrings.SR.fsiEntryPointWontBeInvoked (name, name, name), attrib.Range))

    let ProcessInputs
        (
            ctok,
            diagnosticsLogger: DiagnosticsLogger,
            istate: FsiDynamicCompilerState,
            inputs: ParsedInput list,
            showTypes: bool,
            isIncrementalFragment: bool,
            isInteractiveItExpr: bool,
            prefixPath: LongIdent,
            m
        ) =
        let optEnv = istate.optEnv
        let tcState = istate.tcState
        let ilxGenerator = istate.ilxGenerator
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)

        let eagerFormat (diag: PhasedDiagnostic) = diag.EagerlyFormatCore true

        // Typecheck. The lock stops the type checker running at the same time as the
        // server intellisense implementation (which is currently incomplete and #if disabled)
        let tcState, topCustomAttrs, declaredImpls, tcEnvAtEndOfLastInput =
            lock tcLockObject (fun _ ->
                CheckClosedInputSet(
                    ctok,
                    diagnosticsLogger.CheckForErrors,
                    tcConfig,
                    tcImports,
                    tcGlobals,
                    Some prefixPath,
                    tcState,
                    eagerFormat,
                    inputs
                ))

        let codegenResults, optEnv, fragName =
            ProcessTypedImpl(
                diagnosticsLogger,
                optEnv,
                tcState,
                tcConfig,
                isInteractiveItExpr,
                topCustomAttrs,
                prefixPath,
                isIncrementalFragment,
                declaredImpls,
                ilxGenerator
            )

        let newState, declaredImpls =
            ProcessCodegenResults(
                ctok,
                diagnosticsLogger,
                istate,
                optEnv,
                tcState,
                tcConfig,
                prefixPath,
                showTypes,
                isIncrementalFragment,
                fragName,
                declaredImpls,
                ilxGenerator,
                codegenResults,
                m
            )

        CheckEntryPoint istate.tcGlobals declaredImpls

        (newState, tcEnvAtEndOfLastInput, declaredImpls)

    let tryGetGeneratedValue istate cenv v =
        match istate.ilxGenerator.LookupGeneratedValue(valuePrinter.GetEvaluationContext(istate.emEnv), v) with
        | Some (res, ty) -> Some(FsiValue(res, ty, FSharpType(cenv, v.Type)))
        | _ -> None

    let nextFragmentId () =
        fragmentId <- fragmentId + 1
        $"%04d{fragmentId}"

    let mkFragmentPath m fragmentId =
        [ mkSynId m (FsiDynamicModulePrefix + fragmentId ()) ]

    let processContents istate declaredImpls =
        let tcState = istate.tcState

        let mutable itValue = None
        let mutable boundValues = istate.boundValues

        try
            let contents =
                FSharpAssemblyContents(tcGlobals, tcState.Ccu, Some tcState.CcuSig, tcImports, declaredImpls)

            let contentFile = contents.ImplementationFiles[0]

            // Skip the "FSI_NNNN"
            match contentFile.Declarations with
            | [ FSharpImplementationFileDeclaration.Entity (_eFakeModule, modDecls) ] ->
                let cenv =
                    SymbolEnv(istate.tcGlobals, istate.tcState.Ccu, Some istate.tcState.CcuSig, istate.tcImports)

                for decl in modDecls do
                    match decl with
                    | FSharpImplementationFileDeclaration.MemberOrFunctionOrValue (v, _, _) ->
                        // Report a top-level function or value definition
                        if v.IsModuleValueOrMember && not v.IsMember then
                            let fsiValueOpt =
                                match v.Item with
                                | Item.Value vref ->
                                    let fsiValueOpt = tryGetGeneratedValue istate cenv vref.Deref

                                    if fsiValueOpt.IsSome then
                                        boundValues <- boundValues |> NameMap.add v.CompiledName vref.Deref

                                    fsiValueOpt
                                | _ -> None

                            if v.CompiledName = "it" then
                                itValue <- fsiValueOpt

                            match fsiValueOpt with
                            | Some fsiValue -> valueBoundEvent.Trigger(fsiValue.ReflectionValue, fsiValue.ReflectionType, v.CompiledName)
                            | None -> ()

                            let symbol = FSharpSymbol.Create(cenv, v.Item)

                            let symbolUse =
                                FSharpSymbolUse(
                                    istate.tcState.TcEnvFromImpls.DisplayEnv,
                                    symbol,
                                    [],
                                    ItemOccurence.Binding,
                                    v.DeclarationLocation
                                )

                            fsi.TriggerEvaluation(fsiValueOpt, symbolUse, decl)

                    | FSharpImplementationFileDeclaration.Entity (e, _) ->
                        // Report a top-level module or namespace definition
                        let symbol = FSharpSymbol.Create(cenv, e.Item)

                        let symbolUse =
                            FSharpSymbolUse(
                                istate.tcState.TcEnvFromImpls.DisplayEnv,
                                symbol,
                                [],
                                ItemOccurence.Binding,
                                e.DeclarationLocation
                            )

                        fsi.TriggerEvaluation(None, symbolUse, decl)

                    | FSharpImplementationFileDeclaration.InitAction _ ->
                        // Top level 'do' bindings are not reported as incremental declarations
                        ()
            | _ -> ()
        with _ ->
            ()

        { istate with
            boundValues = boundValues
        },
        Completed itValue

    let addCcusToIncrementalEnv istate ccuinfos =
        let optEnv =
            List.fold (AddExternalCcuToOptimizationEnv tcGlobals) istate.optEnv ccuinfos

        istate.ilxGenerator.AddExternalCcus(ccuinfos |> List.map (fun ccuinfo -> ccuinfo.FSharpViewOfMetadata))
        { istate with optEnv = optEnv }

    let importReflectionType istate reflectionTy =
        let tcImports = istate.tcImports
        let tcGlobals = istate.tcGlobals
        let amap = tcImports.GetImportMap()

        let prevCcuinfos = tcImports.GetImportedAssemblies()

        let rec import ccuinfos (ilTy: ILType) =
            let ccuinfos, tinst =
                (ilTy.GenericArgs, (ccuinfos, []))
                ||> List.foldBack (fun ilGenericArgTy (ccuInfos, tinst) ->
                    let ccuinfos2, ty = import ccuInfos ilGenericArgTy
                    (ccuinfos2 @ ccuinfos, ty :: tinst))

            let ty = Import.ImportILType amap range0 tinst ilTy

            let ccuinfos =
                match tryTcrefOfAppTy tcGlobals ty with
                | ValueSome tcref ->
                    match tcref.CompilationPath.ILScopeRef with
                    | ILScopeRef.Assembly aref ->
                        let ccuinfo =
                            tcImports.GetImportedAssemblies()
                            |> List.find (fun x -> x.FSharpViewOfMetadata.AssemblyName = aref.Name)

                        ccuinfo :: ccuinfos
                    | _ -> ccuinfos
                | _ -> ccuinfos

            ccuinfos, ty

        let addTypeToEnvironment state ilTy =
            if not (Import.CanImportILType amap range0 ilTy) then
                invalidOp (sprintf "Unable to import type, %A." reflectionTy)

            let ccuinfos, ty = import [] ilTy

            let ccuinfos =
                ccuinfos
                |> List.distinctBy (fun x -> x.FSharpViewOfMetadata.AssemblyName)
                |> List.filter (fun asm1 ->
                    not (
                        prevCcuinfos
                        |> List.exists (fun asm2 -> asm2.FSharpViewOfMetadata.AssemblyName = asm1.FSharpViewOfMetadata.AssemblyName)
                    ))
            // After we have successfully imported the type, then we can add newly resolved ccus to the env.
            addCcusToIncrementalEnv state ccuinfos, ty

        let ilTys = ConvReflectionTypeToILType reflectionTy

        // Rewrite references to dynamic .NET assemblies back to dynamicCcuName
        let ilTys =
            ilTys
            |> List.map (fun ilTy ->
                match istate.emEnv with
                | MultipleInMemoryAssemblies emEnv -> ilTy |> Morphs.morphILTypeRefsInILType emEnv.ReverseMapTypeRef
                | _ -> ilTy)

        ((istate, []), ilTys)
        ||> List.fold (fun (state, addedTys) ilTy ->
            let nextState, addedTy = addTypeToEnvironment state ilTy
            nextState, addedTys @ [ addedTy ])

    member _.DynamicAssemblies = dynamicAssemblies.ToArray()

    member _.FindDynamicAssembly(name, useFullName: bool) =
        let getName (assemblyName: AssemblyName) =
            if useFullName then
                assemblyName.FullName
            else
                assemblyName.Name

        dynamicAssemblies
        |> ResizeArray.tryFind (fun asm -> getName (asm.GetName()) = name)

    member _.EvalParsedSourceFiles(ctok, diagnosticsLogger, istate, inputs, m) =
        let prefix = mkFragmentPath m nextFragmentId
        // Ensure the path includes the qualifying name
        let inputs = inputs |> List.map (PrependPathToInput prefix)
        let isIncrementalFragment = false

        let istate, _, _ =
            ProcessInputs(ctok, diagnosticsLogger, istate, inputs, true, isIncrementalFragment, false, prefix, m)

        istate

    /// Evaluate the given definitions and produce a new interactive state.
    member _.EvalParsedDefinitions
        (
            ctok,
            diagnosticsLogger: DiagnosticsLogger,
            istate,
            showTypes,
            isInteractiveItExpr,
            defs: SynModuleDecl list
        ) =
        let fileName = stdinMockFileName

        let m =
            match defs with
            | [] -> rangeStdin0
            | _ -> List.reduce unionRanges [ for d in defs -> d.Range ]

        let prefix = mkFragmentPath m nextFragmentId
        let prefixPath = pathOfLid prefix

        let impl =
            SynModuleOrNamespace(
                prefix,
                false,
                SynModuleOrNamespaceKind.NamedModule,
                defs,
                PreXmlDoc.Empty,
                [],
                None,
                m,
                {
                    LeadingKeyword = SynModuleOrNamespaceLeadingKeyword.None
                }
            )

        let isLastCompiland = true
        let isExe = false

        let input =
            ParsedInput.ImplFile(
                ParsedImplFileInput(
                    fileName,
                    true,
                    ComputeQualifiedNameOfFileFromUniquePath(m, prefixPath),
                    [],
                    [],
                    [ impl ],
                    (isLastCompiland, isExe),
                    {
                        ConditionalDirectives = []
                        CodeComments = []
                    },
                    Set.empty
                )
            )

        let isIncrementalFragment = true

        let istate, tcEnvAtEndOfLastInput, declaredImpls =
            ProcessInputs(ctok, diagnosticsLogger, istate, [ input ], showTypes, isIncrementalFragment, isInteractiveItExpr, prefix, m)

        let tcState = istate.tcState

        let newState =
            { istate with
                tcState = tcState.NextStateAfterIncrementalFragment(tcEnvAtEndOfLastInput)
            }

        processContents newState declaredImpls

    /// Evaluate the given expression and produce a new interactive state.
    member fsiDynamicCompiler.EvalParsedExpression(ctok, diagnosticsLogger: DiagnosticsLogger, istate, expr: SynExpr) =
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)
        let itName = "it"

        // Construct the code that saves the 'it' value into the 'SaveIt' register.
        let defs = fsiDynamicCompiler.BuildItBinding expr

        // Evaluate the overall definitions.
        let istate =
            fsiDynamicCompiler.EvalParsedDefinitions(ctok, diagnosticsLogger, istate, false, true, defs)
            |> fst
        // Snarf the type for 'it' via the binding
        match istate.tcState.TcEnvFromImpls.NameEnv.FindUnqualifiedItem itName with
        | Item.Value vref ->
            if not tcConfig.noFeedback then
                let infoReader = InfoReader(istate.tcGlobals, istate.tcImports.GetImportMap())

                valuePrinter.InvokeExprPrinter(
                    istate.tcState.TcEnvFromImpls.DisplayEnv,
                    infoReader,
                    istate.emEnv,
                    istate.ilxGenerator,
                    vref
                )

            // Clear the value held in the previous "it" binding, if any, as long as it has never been referenced.
            match prevIt with
            | Some prevVal when not prevVal.Deref.HasBeenReferenced ->
                istate.ilxGenerator.ClearGeneratedValue(valuePrinter.GetEvaluationContext istate.emEnv, prevVal.Deref)
            | _ -> ()

            prevIt <- Some vref

            //
            let optValue =
                istate.ilxGenerator.LookupGeneratedValue(valuePrinter.GetEvaluationContext(istate.emEnv), vref.Deref)

            let fsiValue =
                match optValue with
                | Some (res, ty) ->
                    Some(FsiValue(res, ty, FSharpType(tcGlobals, istate.tcState.Ccu, istate.tcState.CcuSig, istate.tcImports, vref.Type)))
                | _ -> None

            istate, Completed fsiValue

        // Return the interactive state.
        | _ -> istate, Completed None

    // Construct the code that saves the 'it' value into the 'SaveIt' register.
    member _.BuildItBinding(expr: SynExpr) =
        let m = expr.Range
        let itName = "it"
        let itID = mkSynId m itName

        let mkBind pat expr =
            SynBinding(
                None,
                SynBindingKind.Do,
                false,
                false,
                [],
                PreXmlDoc.Empty,
                SynInfo.emptySynValData,
                pat,
                None,
                expr,
                m,
                DebugPointAtBinding.NoneAtInvisible,
                SynBindingTrivia.Zero
            )

        let bindingA = mkBind (mkSynPatVar None itID) expr
        let defA = SynModuleDecl.Let(false, [ bindingA ], m)
        [ defA ]

    // Construct an invisible call to Debugger.Break(), in the specified range
    member _.CreateDebuggerBreak(m: range) =
        let breakPath = [ "System"; "Diagnostics"; "Debugger"; "Break" ]
        let dots = List.replicate (breakPath.Length - 1) m

        let methCall =
            SynExpr.LongIdent(false, SynLongIdent(List.map (mkSynId m) breakPath, dots, List.replicate breakPath.Length None), None, m)

        let args = SynExpr.Const(SynConst.Unit, m)
        let breakStatement = SynExpr.App(ExprAtomicFlag.Atomic, false, methCall, args, m)
        SynModuleDecl.Expr(breakStatement, m)

    /// Resolve and register an assembly reference, delaying the actual addition of the reference
    /// to tcImports until a whole set of references has been collected.
    ///
    /// That is, references are collected across a group of #r declarations and only added to the
    /// tcImports state once all are collected.
    member _.AddDelayedReference(ctok, path, show, m) =

        // Check the file can be resolved
        if FileSystem.IsInvalidPathShim(path) then
            error (Error(FSIstrings.SR.fsiInvalidAssembly (path), m))

        // Do the resolution
        let resolutions =
            tcImports.ResolveAssemblyReference(ctok, AssemblyReference(m, path, None), ResolveAssemblyReferenceMode.ReportErrors)

        // Delay the addition of the assembly to the interactive state
        delayedReferences.Add((path, resolutions, show, m))

    /// Indicates if there are delayed assembly additions to be processed.
    member _.HasDelayedReferences = delayedReferences.Count > 0

    /// Process any delayed assembly additions.
    member _.ProcessDelayedReferences(ctok, istate) =

        // Grab the dealyed assembly reference additions
        let refs = delayedReferences |> Seq.toList
        delayedReferences.Clear()

        // Print the explicit assembly resolutions. Only for explicit '#r' in direct inputs, not those
        // in #load files. This means those resulting from nuget package resolution are not shown.
        for (_, resolutions, show, _) in refs do
            if show then
                for ar in resolutions do
                    let format =
                        if tcConfigB.shadowCopyReferences then
                            let resolvedPath = ar.resolvedPath.ToUpperInvariant()
                            let fileTime = FileSystem.GetLastWriteTimeShim(resolvedPath)

                            match reportedAssemblies.TryGetValue resolvedPath with
                            | false, _ ->
                                reportedAssemblies.Add(resolvedPath, fileTime)
                                FSIstrings.SR.fsiDidAHashr (ar.resolvedPath)
                            | true, time when time <> fileTime -> FSIstrings.SR.fsiDidAHashrWithStaleWarning (ar.resolvedPath)
                            | _ -> FSIstrings.SR.fsiDidAHashr (ar.resolvedPath)
                        else
                            FSIstrings.SR.fsiDidAHashrWithLockWarning (ar.resolvedPath)

                    fsiConsoleOutput.uprintnfnn "%s" format

        // Collect the overall resolutions
        let resolutions =
            [
                for (_, resolutions, _, _) in refs do
                    yield! resolutions
            ]

        // Add then to the config.
        for (path, _, _, m) in refs do
            tcConfigB.AddReferencedAssemblyByPath(m, path)

        let tcState = istate.tcState

        let tcEnv, asms =
            try
                RequireReferences(ctok, tcImports, tcState.TcEnvFromImpls, dynamicCcuName, resolutions)
            with _ ->
                for (path, _, _, m) in refs do
                    tcConfigB.RemoveReferencedAssemblyByPath(m, path)

                reraise ()

        let istate =
            { addCcusToIncrementalEnv istate asms with
                tcState = tcState.NextStateAfterIncrementalFragment(tcEnv)
            }

        istate

    // Dependency manager text is collected across a group of #r and #i declarations and
    // only actually processed once all are collected.
    member _.AddDelayedDependencyManagerText(packageManager: IDependencyManagerProvider, lt, m, path: string) =
        tcConfigB.packageManagerLines <- PackageManagerLine.AddLineWithKey packageManager.Key lt path m tcConfigB.packageManagerLines
        hasDelayedDependencyManagerText <- true

    member _.HasDelayedDependencyManagerText = hasDelayedDependencyManagerText

    member fsiDynamicCompiler.ProcessDelayedDependencyManagerText
        (
            ctok,
            istate: FsiDynamicCompilerState,
            lexResourceManager,
            diagnosticsLogger
        ) =
        if not hasDelayedDependencyManagerText then
            istate
        else
            hasDelayedDependencyManagerText <- false

            (istate, tcConfigB.packageManagerLines)
            ||> Seq.fold (fun istate kv ->
                let (KeyValue (packageManagerKey, packageManagerLines)) = kv

                match packageManagerLines with
                | [] -> istate
                | {
                      Directive = _
                      LineStatus = _
                      Line = _
                      Range = m
                  } :: _ ->
                    let outputDir = tcConfigB.outputDir |> Option.defaultValue ""

                    match
                        fsiOptions.DependencyProvider.TryFindDependencyManagerByKey(
                            tcConfigB.compilerToolPaths,
                            getOutputDir tcConfigB,
                            reportError m,
                            packageManagerKey
                        )
                    with
                    | Null ->
                        let err =
                            fsiOptions.DependencyProvider.CreatePackageManagerUnknownError(
                                tcConfigB.compilerToolPaths,
                                outputDir,
                                packageManagerKey,
                                reportError m
                            )

                        errorR (Error(err, m))
                        istate
                    | NonNull dependencyManager ->
                        let directive d =
                            match d with
                            | Directive.Resolution -> "r"
                            | Directive.Include -> "i"

                        let packageManagerTextLines =
                            packageManagerLines
                            |> List.map (fun line -> directive line.Directive, line.Line)

                        try
                            let tfm, rid = fsiOptions.FxResolver.GetTfmAndRid()

                            let result =
                                fsiOptions.DependencyProvider.Resolve(
                                    dependencyManager,
                                    ".fsx",
                                    packageManagerTextLines,
                                    reportError m,
                                    tfm,
                                    rid,
                                    tcConfigB.implicitIncludeDir,
                                    "stdin.fsx",
                                    "stdin.fsx"
                                )

                            if result.Success then

                                for line in result.StdOut do
                                    Console.Out.WriteLine(line)

                                for line in result.StdError do
                                    Console.Error.WriteLine(line)

                                tcConfigB.packageManagerLines <-
                                    PackageManagerLine.SetLinesAsProcessed packageManagerKey tcConfigB.packageManagerLines

                                for folder in result.Roots do
                                    tcConfigB.AddIncludePath(m, folder, "")

                                for resolution in result.Resolutions do
                                    tcConfigB.AddReferencedAssemblyByPath(m, resolution)

                                let scripts = result.SourceFiles |> Seq.toList

                                if not (isNil scripts) then
                                    fsiDynamicCompiler.EvalSourceFiles(ctok, istate, m, scripts, lexResourceManager, diagnosticsLogger)
                                else
                                    istate
                            else
                                // Send outputs via diagnostics
                                if result.StdOut.Length > 0 || result.StdError.Length > 0 then
                                    for line in Array.append result.StdOut result.StdError do
                                        errorR (Error(FSComp.SR.packageManagerError (line), m))

                                //Write outputs in F# Interactive and compiler
                                tcConfigB.packageManagerLines <-
                                    PackageManagerLine.RemoveUnprocessedLines packageManagerKey tcConfigB.packageManagerLines

                                istate // error already reported

                        with _ ->
                            // An exception occured during processing, so remove the lines causing the error from the package manager list.
                            tcConfigB.packageManagerLines <-
                                PackageManagerLine.RemoveUnprocessedLines packageManagerKey tcConfigB.packageManagerLines

                            reraise ())

    member fsiDynamicCompiler.PartiallyProcessReferenceOrPackageIncudePathDirective(ctok, istate, directiveKind, path, show, m) =
        let dm =
            fsiOptions.DependencyProvider.TryFindDependencyManagerInPath(
                tcConfigB.compilerToolPaths,
                getOutputDir tcConfigB,
                reportError m,
                path
            )

        match dm with
        | Null, Null ->
            // error already reported
            istate, CompletedWithAlreadyReportedError

        | _, NonNull dependencyManager ->
            if tcConfigB.langVersion.SupportsFeature(LanguageFeature.PackageManagement) then
                fsiDynamicCompiler.AddDelayedDependencyManagerText(dependencyManager, directiveKind, m, path)
                istate, Completed None
            else
                errorR (Error(FSComp.SR.packageManagementRequiresVFive (), m))
                istate, Completed None

        | _, _ when directiveKind = Directive.Include ->
            errorR (Error(FSComp.SR.poundiNotSupportedByRegisteredDependencyManagers (), m))
            istate, Completed None

        | NonNull p, Null ->
            let path = if String.IsNullOrWhiteSpace(p) then "" else p

            fsiDynamicCompiler.AddDelayedReference(ctok, path, show, m)

            istate, Completed None

    /// Scrape #r, #I and package manager commands from a #load
    member fsiDynamicCompiler.ProcessMetaCommandsFromParsedInputAsInteractiveCommands
        (
            ctok,
            istate: FsiDynamicCompilerState,
            sourceFile,
            input
        ) =
        WithImplicitHome (tcConfigB, directoryName sourceFile) (fun () ->
            ProcessMetaCommandsFromInput
                ((fun st (m, nm) ->
                    tcConfigB.TurnWarningOff(m, nm)
                    st),
                 (fun st (m, path, directive) ->
                     let st, _ =
                         fsiDynamicCompiler.PartiallyProcessReferenceOrPackageIncudePathDirective(ctok, st, directive, path, false, m)

                     st),
                 (fun _ _ -> ()))
                (tcConfigB, input, Path.GetDirectoryName sourceFile, istate))

    member fsiDynamicCompiler.EvalSourceFiles(ctok, istate, m, sourceFiles, lexResourceManager, diagnosticsLogger: DiagnosticsLogger) =
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)

        match sourceFiles with
        | [] -> istate
        | _ ->
            // use a set of source files as though they were command line inputs
            let sourceFiles =
                sourceFiles
                |> List.map (fun nm -> tcConfig.ResolveSourceFile(m, nm, tcConfig.implicitIncludeDir), m)

            // Close the #load graph on each file and gather the inputs from the scripts.
            let tcConfig = TcConfig.Create(tcConfigB, validate = false)

            let closure =
                LoadClosure.ComputeClosureOfScriptFiles(
                    tcConfig,
                    sourceFiles,
                    CodeContext.CompilationAndEvaluation,
                    lexResourceManager,
                    fsiOptions.DependencyProvider
                )

            // Intent "[Loading %s]\n" (String.concat "\n     and " sourceFiles)
            fsiConsoleOutput.uprintf "[%s " (FSIstrings.SR.fsiLoadingFilesPrefixText ())

            closure.Inputs
            |> List.iteri (fun i input ->
                if i = 0 then
                    fsiConsoleOutput.uprintf "%s" input.FileName
                else
                    fsiConsoleOutput.uprintnf " %s %s" (FSIstrings.SR.fsiLoadingFilesPrefixText ()) input.FileName)

            fsiConsoleOutput.uprintfn "]"

            for (warnNum, ranges) in closure.NoWarns do
                for m in ranges do
                    tcConfigB.TurnWarningOff(m, warnNum)

            // Play errors and warnings from resolution
            closure.ResolutionDiagnostics |> List.iter diagnosticSink

            // Non-scripts will not have been parsed during #load closure so parse them now
            let sourceFiles, inputs =
                closure.Inputs
                |> List.map (fun input ->
                    input.ParseDiagnostics |> List.iter diagnosticSink
                    input.MetaCommandDiagnostics |> List.iter diagnosticSink

                    let parsedInput =
                        match input.SyntaxTree with
                        | None -> ParseOneInputFile(tcConfig, lexResourceManager, input.FileName, (true, false), diagnosticsLogger, false)
                        | Some parseTree -> parseTree

                    input.FileName, parsedInput)
                |> List.unzip

            diagnosticsLogger.AbortOnError(fsiConsoleOutput)

            let istate =
                (istate, sourceFiles, inputs)
                |||> List.fold2 (fun istate sourceFile input ->
                    fsiDynamicCompiler.ProcessMetaCommandsFromParsedInputAsInteractiveCommands(ctok, istate, sourceFile, input))

            let istate = fsiDynamicCompiler.ProcessDelayedReferences(ctok, istate)

            fsiDynamicCompiler.EvalParsedSourceFiles(ctok, diagnosticsLogger, istate, inputs, m)

    member _.GetBoundValues istate =
        let cenv =
            SymbolEnv(istate.tcGlobals, istate.tcState.Ccu, Some istate.tcState.CcuSig, istate.tcImports)

        [
            for pair in istate.boundValues do
                let nm = pair.Key
                let v = pair.Value

                match tryGetGeneratedValue istate cenv v with
                | Some fsiValue -> FsiBoundValue(nm, fsiValue)
                | _ -> ()
        ]

    member _.TryFindBoundValue(istate, nm) =
        match istate.boundValues.TryFind nm with
        | Some v ->
            let cenv =
                SymbolEnv(istate.tcGlobals, istate.tcState.Ccu, Some istate.tcState.CcuSig, istate.tcImports)

            match tryGetGeneratedValue istate cenv v with
            | Some fsiValue -> Some(FsiBoundValue(nm, fsiValue))
            | _ -> None
        | _ -> None

    member _.AddBoundValue(ctok, diagnosticsLogger: DiagnosticsLogger, istate, name: string, value: obj) =
        try
            match value with
            | null -> nullArg "value"
            | _ -> ()

            if String.IsNullOrWhiteSpace name then
                invalidArg "name" "Name cannot be null or white-space."

            // Verify that the name is a valid identifier for a value.
            FSharpLexer.Tokenize(
                SourceText.ofString name,
                let mutable foundOne = false

                fun t ->
                    if not t.IsIdentifier || foundOne then
                        invalidArg "name" "Name is not a valid identifier."

                    foundOne <- true
            )

            if IsCompilerGeneratedName name then
                invalidArg "name" (FSComp.SR.lexhlpIdentifiersContainingAtSymbolReserved () |> snd)

            let istate, tys = importReflectionType istate (value.GetType())
            let ty = List.head tys
            let amap = istate.tcImports.GetImportMap()

            let m = rangeStdin0
            let prefix = mkFragmentPath m nextFragmentId
            let prefixPath = pathOfLid prefix
            let qualifiedName = ComputeQualifiedNameOfFileFromUniquePath(m, prefixPath)

            let tcConfig = TcConfig.Create(tcConfigB, validate = false)

            // Build a simple module with a single 'let' decl with a default value.
            let moduleEntity, v, impl =
                mkBoundValueTypedImpl istate.tcGlobals range0 qualifiedName.Text name ty

            let tcEnvAtEndOfLastInput =
                AddLocalSubModule tcGlobals amap range0 istate.tcState.TcEnvFromImpls moduleEntity
                |> AddLocalVal tcGlobals TcResultsSink.NoSink range0 v

            // Generate IL for the given typled impl and create new interactive state.
            let ilxGenerator = istate.ilxGenerator
            let isIncrementalFragment = true
            let showTypes = false
            let declaredImpls = [ impl ]

            let codegenResults, optEnv, fragName =
                ProcessTypedImpl(
                    diagnosticsLogger,
                    istate.optEnv,
                    istate.tcState,
                    tcConfig,
                    false,
                    EmptyTopAttrs,
                    prefix,
                    isIncrementalFragment,
                    declaredImpls,
                    ilxGenerator
                )

            let istate, declaredImpls =
                ProcessCodegenResults(
                    ctok,
                    diagnosticsLogger,
                    istate,
                    optEnv,
                    istate.tcState,
                    tcConfig,
                    prefix,
                    showTypes,
                    isIncrementalFragment,
                    fragName,
                    declaredImpls,
                    ilxGenerator,
                    codegenResults,
                    m
                )

            let newState =
                { istate with
                    tcState = istate.tcState.NextStateAfterIncrementalFragment tcEnvAtEndOfLastInput
                }

            // Force set the val with the given value obj.
            let ctxt = valuePrinter.GetEvaluationContext(newState.emEnv)
            ilxGenerator.ForceSetGeneratedValue(ctxt, v, value)

            processContents newState declaredImpls
        with ex ->
            istate, CompletedWithReportedError(StopProcessingExn(Some ex))

    member _.GetInitialInteractiveState() =
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)
        let optEnv0 = GetInitialOptimizationEnv(tcImports, tcGlobals)

        let emEnv0 =
            if tcConfigB.fsiMultiAssemblyEmit then
                let emEnv =
                    ILMultiInMemoryAssemblyEmitEnv(ilGlobals, resolveAssemblyRef, dynamicCcuName)

                MultipleInMemoryAssemblies emEnv
            else
                let cenv =
                    {
                        ilg = ilGlobals
                        emitTailcalls = tcConfig.emitTailcalls
                        generatePdb = generateDebugInfo
                        resolveAssemblyRef = resolveAssemblyRef
                        tryFindSysILTypeRef = tcGlobals.TryFindSysILTypeRef
                    }

                let emEnv = ILDynamicAssemblyWriter.emEnv0
                SingleRefEmitAssembly(cenv, emEnv)

        let tcEnv, openDecls0 =
            GetInitialTcEnv(dynamicCcuName, rangeStdin0, tcConfig, tcImports, tcGlobals)

        let ccuName = dynamicCcuName

        let tcState =
            GetInitialTcState(rangeStdin0, ccuName, tcConfig, tcGlobals, tcImports, tcEnv, openDecls0)

        let ilxGenerator =
            CreateIlxAssemblyGenerator(tcConfig, tcImports, tcGlobals, (LightweightTcValForUsingInBuildMethodCall tcGlobals), tcState.Ccu)

        {
            optEnv = optEnv0
            emEnv = emEnv0
            tcGlobals = tcGlobals
            tcState = tcState
            tcImports = tcImports
            ilxGenerator = ilxGenerator
            boundValues = NameMap.empty
            timing = false
            debugBreak = false
        }

    member _.CurrentPartialAssemblySignature(istate) =
        FSharpAssemblySignature(istate.tcGlobals, istate.tcState.Ccu, istate.tcState.CcuSig, istate.tcImports, None, istate.tcState.CcuSig)

    member _.FormatValue(obj: obj, objTy) = valuePrinter.FormatValue(obj, objTy)

    member _.ValueBound = valueBoundEvent.Publish

//----------------------------------------------------------------------------
// ctrl-c handling
//----------------------------------------------------------------------------

type ControlEventHandler = delegate of int -> bool

// One strange case: when a TAE happens a strange thing
// occurs the next read from stdin always returns
// 0 bytes, i.e. the channel will look as if it has been closed.  So we check
// for this condition explicitly.  We also recreate the lexbuf whenever CtrlC kicks.

type internal FsiInterruptStdinState =
    | StdinEOFPermittedBecauseCtrlCRecentlyPressed
    | StdinNormal

type internal FsiInterruptControllerState =
    | InterruptCanRaiseException
    | InterruptIgnored

type internal FsiInterruptControllerKillerThreadRequest =
    | ThreadAbortRequest
    | NoRequest
    | ExitRequest
    | PrintInterruptRequest

type internal FsiInterruptController
    (
        fsiOptions: FsiCommandLineOptions,
        controlledExecution: ControlledExecution,
        fsiConsoleOutput: FsiConsoleOutput
    ) =

    let mutable stdinInterruptState = StdinNormal
    let CTRL_C = 0
    let mutable interruptAllowed = InterruptIgnored
    let mutable killThreadRequest = NoRequest

    let mutable ctrlEventHandlers: ControlEventHandler list = []
    let mutable ctrlEventActions: (unit -> unit) list = []
    let mutable exitViaKillThread = false

    let mutable posixReinstate = (fun () -> ())

    member _.Exit() =
        if exitViaKillThread then
            killThreadRequest <- ExitRequest
            Thread.Sleep(1000)

        exit 0

    member _.FsiInterruptStdinState
        with get () = stdinInterruptState
        and set v = stdinInterruptState <- v

    member _.ClearInterruptRequest() = killThreadRequest <- NoRequest

    member _.InterruptAllowed
        with set v = interruptAllowed <- v

    member _.Interrupt() =
        ctrlEventActions |> List.iter (fun act -> act ())

    member _.EventHandlers = ctrlEventHandlers

    member _.ControlledExecution() = controlledExecution

    member controller.InstallKillThread() =
        // Compute how long to pause before a ThreadAbort is actually executed.
        // A somewhat arbitrary choice.
        let pauseMilliseconds = (if fsiOptions.Gui then 400 else 100)

        // Fsi Interrupt handler
        let raiseCtrlC () =
            use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID
            fprintf fsiConsoleOutput.Error "%s" (FSIstrings.SR.fsiInterrupt ())

            stdinInterruptState <- StdinEOFPermittedBecauseCtrlCRecentlyPressed

            if interruptAllowed = InterruptCanRaiseException then
                killThreadRequest <- ThreadAbortRequest

                let killerThread =
                    Thread(
                        ThreadStart(fun () ->
                            use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID
                            // sleep long enough to allow ControlEventHandler handler on main thread to return
                            // Also sleep to give computations a bit of time to terminate
                            Thread.Sleep(pauseMilliseconds)

                            if killThreadRequest = ThreadAbortRequest then
                                if progress then
                                    fsiConsoleOutput.uprintnfn "%s" (FSIstrings.SR.fsiAbortingMainThread ())

                                killThreadRequest <- NoRequest
                                controlledExecution.TryAbort()

                            ()),
                        Name = "ControlCAbortThread"
                    )

                killerThread.IsBackground <- true
                killerThread.Start()

        let fsiInterruptHandler (args: ConsoleCancelEventArgs) =
            args.Cancel <- true
            ctrlEventHandlers |> List.iter (fun handler -> handler.Invoke(CTRL_C) |> ignore)

        do Console.CancelKeyPress.Add(fsiInterruptHandler)

        // WINDOWS TECHNIQUE: .NET has more safe points, and you can do more when a safe point.
        // Hence we actually start up the killer thread within the handler.
        let ctrlEventHandler =
            ControlEventHandler(fun i ->
                if i = CTRL_C then
                    (raiseCtrlC ()
                     true)
                else
                    false)

        ctrlEventHandlers <- ctrlEventHandler :: ctrlEventHandlers
        ctrlEventActions <- raiseCtrlC :: ctrlEventActions
        exitViaKillThread <- false // don't exit via kill thread

    member _.PosixInvoke(n: int) =
        // we run this code once with n = -1 to make sure it is JITted before execution begins
        // since we are not allowed to JIT a signal handler.  This also ensures the "PosixInvoke"
        // method is not eliminated by dead-code elimination
        if n >= 0 then
            posixReinstate ()
            stdinInterruptState <- StdinEOFPermittedBecauseCtrlCRecentlyPressed

            killThreadRequest <-
                if (interruptAllowed = InterruptCanRaiseException) then
                    ThreadAbortRequest
                else
                    PrintInterruptRequest

//----------------------------------------------------------------------------
// assembly finder
//----------------------------------------------------------------------------

#nowarn "40"

// From http://msdn.microsoft.com/en-us/library/ff527268.aspx
// What the Event Handler Does
//
// The handler for the AssemblyResolve event receives the display name of the assembly to
// be loaded, in the ResolveEventArgs.Name property. If the handler does not recognize the
// assembly name, it returns null (Nothing in Visual Basic, nullptr in Visual C++).
//
// - If the handler recognizes the assembly name, it can load and return an assembly that
//   satisfies the request. The following list describes some sample scenarios.
//
// - If the handler knows the location of a version of the assembly, it can load the assembly by
//   using the Assembly.LoadFrom or Assembly.LoadFile method, and can return the loaded assembly if successful.
//
// - If the handler has access to a database of assemblies stored as byte arrays, it can load a byte array by
//   using one of the Assembly.Load method overloads that take a byte array.
//
// - The handler can generate a dynamic assembly and return it.
//
// It is the responsibility of the event handler to return a suitable assembly. The handler can parse the display
// name of the requested assembly by passing the ResolveEventArgs.Name property value to the AssemblyName(String)
// constructor. Beginning with the .NET Framework version 4, the handler can use the ResolveEventArgs.RequestingAssembly
// property to determine whether the current request is a dependency of another assembly. This information can help
// identify an assembly that will satisfy the dependency.
//
// The event handler can return a different version of the assembly than the version that was requested.
//
// In most cases, the assembly that is returned by the handler appears in the load context, regardless of the context
// the handler loads it into. For example, if the handler uses the Assembly.LoadFrom method to load an assembly into
// the load-from context, the assembly appears in the load context when the handler returns it. However, in the following
// case the assembly appears without context when the handler returns it:
//
// - The handler loads an assembly without context.
// - The ResolveEventArgs.RequestingAssembly property is not null.
// - The requesting assembly (that is, the assembly that is returned by the ResolveEventArgs.RequestingAssembly property)
//   was loaded without context.
//
// On the coreclr we add an UnmanagedDll Resoution handler to ensure that native dll's can be searched for,
// the desktop version of the Clr does not support this mechanism.
//
// For information about contexts, see the Assembly.LoadFrom(String) method overload.

type internal MagicAssemblyResolution() =

    // See bug 5501 for details on decision to use UnsafeLoadFrom here.
    // Summary:
    //  It is an explicit user trust decision to load an assembly with #r. Scripts are not run automatically (for example, by double-clicking in explorer).
    //  We considered setting loadFromRemoteSources in fsi.exe.config but this would transitively confer unsafe loading to the code in the referenced
    //  assemblies. Better to let those assemblies decide for themselves which is safer.
    static let assemblyLoadFrom (path: string) = Assembly.UnsafeLoadFrom(path)

    static member private ResolveAssemblyCore
        (
            ctok,
            m,
            tcConfigB,
            tcImports: TcImports,
            fsiDynamicCompiler: FsiDynamicCompiler,
            fsiConsoleOutput: FsiConsoleOutput,
            fullAssemName: string
        ) =

        try
            // Grab the name of the assembly
            let tcConfig = TcConfig.Create(tcConfigB, validate = false)
            let simpleAssemName = fullAssemName.Split([| ',' |]).[0]

            if progress then
                fsiConsoleOutput.uprintfn "ATTEMPT MAGIC LOAD ON ASSEMBLY, simpleAssemName = %s" simpleAssemName // "Attempting to load a dynamically required assembly in response to an AssemblyResolve event by using known static assembly references..."

            if
                simpleAssemName.EndsWith(".XmlSerializers", StringComparison.OrdinalIgnoreCase)
                || simpleAssemName = "UIAutomationWinforms"
            then
                null
            else
                // Check dynamic assemblies by exact version
                match fsiDynamicCompiler.FindDynamicAssembly(fullAssemName, true) with
                | Some asm -> asm
                | None ->
                    // Check dynamic assemblies by simple name
                    match fsiDynamicCompiler.FindDynamicAssembly(simpleAssemName, false) with
                    | Some asm when not (tcConfigB.fsiMultiAssemblyEmit) -> asm
                    | _ ->

                        // Otherwise continue
                        let assemblyReferenceTextDll = (simpleAssemName + ".dll")
                        let assemblyReferenceTextExe = (simpleAssemName + ".exe")

                        let overallSearchResult =

                            // OK, try to resolve as an existing DLL in the resolved reference set.  This does unification by assembly name
                            // once an assembly has been referenced.
                            let searchResult =
                                tcImports.TryFindExistingFullyQualifiedPathBySimpleAssemblyName simpleAssemName

                            match searchResult with
                            | Some r -> OkResult([], Choice1Of2 r)
                            | _ ->

                                // OK, try to resolve as a .dll
                                let searchResult =
                                    tcImports.TryResolveAssemblyReference(
                                        ctok,
                                        AssemblyReference(m, assemblyReferenceTextDll, None),
                                        ResolveAssemblyReferenceMode.Speculative
                                    )

                                match searchResult with
                                | OkResult (warns, [ r ]) -> OkResult(warns, Choice1Of2 r.resolvedPath)
                                | _ ->

                                    // OK, try to resolve as a .exe
                                    let searchResult =
                                        tcImports.TryResolveAssemblyReference(
                                            ctok,
                                            AssemblyReference(m, assemblyReferenceTextExe, None),
                                            ResolveAssemblyReferenceMode.Speculative
                                        )

                                    match searchResult with
                                    | OkResult (warns, [ r ]) -> OkResult(warns, Choice1Of2 r.resolvedPath)
                                    | _ ->

                                        if progress then
                                            fsiConsoleOutput.uprintfn "ATTEMPT LOAD, assemblyReferenceTextDll = %s" assemblyReferenceTextDll

                                        /// Take a look through the files quoted, perhaps with explicit paths
                                        let searchResult =
                                            tcConfig.referencedDLLs
                                            |> List.tryPick (fun assemblyReference ->
                                                if progress then
                                                    fsiConsoleOutput.uprintfn
                                                        "ATTEMPT MAGIC LOAD ON FILE, referencedDLL = %s"
                                                        assemblyReference.Text

                                                if
                                                    String.Compare(
                                                        FileSystemUtils.fileNameOfPath assemblyReference.Text,
                                                        assemblyReferenceTextDll,
                                                        StringComparison.OrdinalIgnoreCase
                                                    ) = 0
                                                    || String.Compare(
                                                        FileSystemUtils.fileNameOfPath assemblyReference.Text,
                                                        assemblyReferenceTextExe,
                                                        StringComparison.OrdinalIgnoreCase
                                                    ) = 0
                                                then
                                                    Some(
                                                        tcImports.TryResolveAssemblyReference(
                                                            ctok,
                                                            assemblyReference,
                                                            ResolveAssemblyReferenceMode.Speculative
                                                        )
                                                    )
                                                else
                                                    None)

                                        match searchResult with
                                        | Some (OkResult (warns, [ r ])) -> OkResult(warns, Choice1Of2 r.resolvedPath)
                                        | _ ->

#if !NO_TYPEPROVIDERS
                                            match tcImports.TryFindProviderGeneratedAssemblyByName(ctok, simpleAssemName) with
                                            | Some assembly -> OkResult([], Choice2Of2 assembly)
                                            | None ->
#endif

                                            // As a last resort, try to find the reference without an extension
                                            match
                                                tcImports.TryFindExistingFullyQualifiedPathByExactAssemblyRef(
                                                    ILAssemblyRef.Create(simpleAssemName, None, None, false, None, None)
                                                )
                                            with
                                            | Some resolvedPath -> OkResult([], Choice1Of2 resolvedPath)
                                            | None ->

                                                ErrorResult([], Failure(FSIstrings.SR.fsiFailedToResolveAssembly (simpleAssemName)))

                        match overallSearchResult with
                        | ErrorResult _ -> null
                        | OkResult _ ->
                            let res = CommitOperationResult overallSearchResult

                            match res with
                            | Choice1Of2 assemblyName ->
                                if simpleAssemName <> "Mono.Posix" && progress then
                                    fsiConsoleOutput.uprintfn "%s" (FSIstrings.SR.fsiBindingSessionTo (assemblyName))

                                if isRunningOnCoreClr then
                                    assemblyLoadFrom assemblyName
                                else
                                    try
                                        let an = AssemblyName.GetAssemblyName(assemblyName)
                                        an.CodeBase <- assemblyName
                                        Assembly.Load an
                                    with _ ->
                                        assemblyLoadFrom assemblyName
                            | Choice2Of2 assembly -> assembly

        with e ->
            stopProcessingRecovery e range0
            null

    [<ThreadStatic; DefaultValue>]
    static val mutable private resolving: bool

    static member private ResolveAssembly
        (
            ctok,
            m,
            tcConfigB,
            tcImports: TcImports,
            fsiDynamicCompiler: FsiDynamicCompiler,
            fsiConsoleOutput: FsiConsoleOutput,
            fullAssemName: string
        ) =

        //Eliminate recursive calls to Resolve which can happen via our callout to msbuild resolution
        if MagicAssemblyResolution.resolving then
            null
        else
            try
                MagicAssemblyResolution.resolving <- true

                MagicAssemblyResolution.ResolveAssemblyCore(
                    ctok,
                    m,
                    tcConfigB,
                    tcImports,
                    fsiDynamicCompiler,
                    fsiConsoleOutput,
                    fullAssemName
                )
            finally
                MagicAssemblyResolution.resolving <- false

    static member Install(tcConfigB, tcImports: TcImports, fsiDynamicCompiler: FsiDynamicCompiler, fsiConsoleOutput: FsiConsoleOutput) =

        let rangeStdin0 = rangeN stdinMockFileName 0

        let resolveAssembly =
            ResolveEventHandler(fun _ args ->
                // Explanation: our understanding is that magic assembly resolution happens
                // during compilation. So we recover the CompilationThreadToken here.
                let ctok = AssumeCompilationThreadWithoutEvidence()

                MagicAssemblyResolution.ResolveAssembly(
                    ctok,
                    rangeStdin0,
                    tcConfigB,
                    tcImports,
                    fsiDynamicCompiler,
                    fsiConsoleOutput,
                    args.Name
                ))

        AppDomain.CurrentDomain.add_AssemblyResolve (resolveAssembly)

        { new IDisposable with
            member _.Dispose() =
                AppDomain.CurrentDomain.remove_AssemblyResolve (resolveAssembly)
        }

//----------------------------------------------------------------------------
// Reading stdin
//----------------------------------------------------------------------------

type FsiStdinLexerProvider
    (
        tcConfigB,
        fsiStdinSyphon,
        fsiConsoleInput: FsiConsoleInput,
        fsiConsoleOutput: FsiConsoleOutput,
        fsiOptions: FsiCommandLineOptions,
        lexResourceManager: LexResourceManager
    ) =

    // #light is the default for FSI
    let indentationSyntaxStatus =
        let initialIndentationAwareSyntaxStatus =
            (tcConfigB.indentationAwareSyntax <> Some false)

        IndentationAwareSyntaxStatus(initialIndentationAwareSyntaxStatus, warn = false)

    let LexbufFromLineReader (fsiStdinSyphon: FsiStdinSyphon) (readF: unit -> string MaybeNull) =
        UnicodeLexing.FunctionAsLexbuf(
            true,
            tcConfigB.langVersion,
            tcConfigB.strictIndentation,
            (fun (buf: char[], start, len) ->
                //fprintf fsiConsoleOutput.Out "Calling ReadLine\n"
                let inputOption =
                    try
                        Some(readF ())
                    with :? EndOfStreamException ->
                        None

                inputOption
                |> Option.iter (fun t ->
                    match t with
                    | Null -> ()
                    | NonNull t -> fsiStdinSyphon.Add(t + "\n"))

                match inputOption with
                | Some null
                | None ->
                    if progress then
                        fprintfn fsiConsoleOutput.Out "End of file from TextReader.ReadLine"

                    0
                | Some (input: string) ->
                    let input = input + "\n"

                    if input.Length > len then
                        fprintf fsiConsoleOutput.Error "%s" (FSIstrings.SR.fsiLineTooLong ())

                    let numTrimmed = min len input.Length

                    for i = 0 to numTrimmed - 1 do
                        buf[i + start] <- input[i]

                    numTrimmed)
        )

    //----------------------------------------------------------------------------
    // Reading stdin as a lex stream
    //----------------------------------------------------------------------------

    let removeZeroCharsFromString (str: string MaybeNull) : string MaybeNull =
        match str with
        | Null -> str
        | NonNull str ->
            if str.Contains("\000") then
                String(str |> Seq.filter (fun c -> c <> '\000') |> Seq.toArray)
            else
                str

    let CreateLexerForLexBuffer (sourceFileName, lexbuf, diagnosticsLogger) =

        resetLexbufPos sourceFileName lexbuf
        let skip = true // don't report whitespace from lexer
        let applyLineDirectives = true

        let lexargs =
            mkLexargs (
                tcConfigB.conditionalDefines,
                indentationSyntaxStatus,
                lexResourceManager,
                [],
                diagnosticsLogger,
                PathMap.empty,
                applyLineDirectives
            )

        let tokenizer =
            LexFilter.LexFilter(
                indentationSyntaxStatus,
                tcConfigB.compilingFSharpCore,
                Lexer.token lexargs skip,
                lexbuf,
                tcConfigB.tokenize = TokenizeOption.Debug
            )

        tokenizer

    // Create a new lexer to read stdin
    member _.CreateStdinLexer diagnosticsLogger =
        let lexbuf =
            match fsiConsoleInput.TryGetConsole() with
            | Some console when fsiOptions.EnableConsoleKeyProcessing && not fsiOptions.UseServerPrompt ->
                LexbufFromLineReader fsiStdinSyphon (fun () ->
                    match fsiConsoleInput.TryGetFirstLine() with
                    | Some firstLine -> firstLine
                    | None -> console ())
            | _ -> LexbufFromLineReader fsiStdinSyphon (fun () -> fsiConsoleInput.In.ReadLine() |> removeZeroCharsFromString)

        fsiStdinSyphon.Reset()
        CreateLexerForLexBuffer(stdinMockFileName, lexbuf, diagnosticsLogger)

    // Create a new lexer to read an "included" script file
    member _.CreateIncludedScriptLexer(sourceFileName, reader, diagnosticsLogger) =
        let lexbuf =
            UnicodeLexing.StreamReaderAsLexbuf(true, tcConfigB.langVersion, tcConfigB.strictIndentation, reader)

        CreateLexerForLexBuffer(sourceFileName, lexbuf, diagnosticsLogger)

    // Create a new lexer to read a string
    member _.CreateStringLexer(sourceFileName, source, diagnosticsLogger) =
        let lexbuf =
            UnicodeLexing.StringAsLexbuf(true, tcConfigB.langVersion, tcConfigB.strictIndentation, source)

        CreateLexerForLexBuffer(sourceFileName, lexbuf, diagnosticsLogger)

    member _.ConsoleInput = fsiConsoleInput

    member _.CreateBufferLexer(sourceFileName, lexbuf, diagnosticsLogger) =
        CreateLexerForLexBuffer(sourceFileName, lexbuf, diagnosticsLogger)

[<RequireQualifiedAccess>]
type InteractionGroup =
    | Definitions of defns: SynModuleDecl list * range: range

    | HashDirectives of hashDirective: ParsedHashDirective list

//----------------------------------------------------------------------------
// Process one parsed interaction.  This runs on the GUI thread.
// It might be simpler if it ran on the parser thread.
//----------------------------------------------------------------------------

type FsiInteractionProcessor
    (
        fsi: FsiEvaluationSessionHostConfig,
        tcConfigB,
        fsiOptions: FsiCommandLineOptions,
        fsiDynamicCompiler: FsiDynamicCompiler,
        fsiConsolePrompt: FsiConsolePrompt,
        fsiConsoleOutput: FsiConsoleOutput,
        fsiInterruptController: FsiInterruptController,
        fsiStdinLexerProvider: FsiStdinLexerProvider,
        lexResourceManager: LexResourceManager,
        initialInteractiveState
    ) =

    let mutable currState = initialInteractiveState
    let event = Control.Event<unit>()

    let setCurrState s =
        currState <- s
        event.Trigger()

    let runCodeOnEventLoop diagnosticsLogger f istate =
        try
            fsi.EventLoopInvoke(fun () ->

                // Explanation: We assume the event loop on the 'fsi' object correctly transfers control to
                // a unique compilation thread.
                let ctok = AssumeCompilationThreadWithoutEvidence()

                // FSI error logging on switched to thread
                InstallErrorLoggingOnThisThread diagnosticsLogger
                use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID
                f ctok istate)
        with _ ->
            (istate, Completed None)

    let InteractiveCatch (diagnosticsLogger: DiagnosticsLogger) (f: _ -> _ * FsiInteractionStepStatus) istate =
        try
            // reset error count
            match diagnosticsLogger with
            | :? DiagnosticsLoggerThatStopsOnFirstError as diagnosticsLogger -> diagnosticsLogger.ResetErrorCount()
            | _ -> ()

            f istate
        with e ->
            stopProcessingRecovery e range0
            istate, CompletedWithReportedError e

    let rangeStdin0 = rangeN stdinMockFileName 0

    let ChangeDirectory (path: string) m =
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)
        let path = tcConfig.MakePathAbsolute path

        if FileSystem.DirectoryExistsShim(path) then
            tcConfigB.implicitIncludeDir <- path
        else
            error (Error(FSIstrings.SR.fsiDirectoryDoesNotExist (path), m))

    /// Parse one interaction. Called on the parser thread.
    let ParseInteraction (tokenizer: LexFilter.LexFilter) =
        let mutable lastToken = Parser.ELSE // Any token besides SEMICOLON_SEMICOLON will do for initial value

        try
            if progress then
                fprintfn fsiConsoleOutput.Out "In ParseInteraction..."

            let input =
                reusingLexbufForParsing tokenizer.LexBuffer (fun () ->
                    let lexerWhichSavesLastToken _lexbuf =
                        let tok = tokenizer.GetToken()
                        lastToken <- tok
                        tok

                    Parser.interaction lexerWhichSavesLastToken tokenizer.LexBuffer)

            Some input
        with e ->
            // On error, consume tokens until to ;; or EOF.
            // Caveat: Unless the error parse ended on ;; - so check the lastToken returned by the lexer function.
            // Caveat: What if this was a look-ahead? That's fine! Since we need to skip to the ;; anyway.
            if
                (match lastToken with
                 | Parser.SEMICOLON_SEMICOLON -> false
                 | _ -> true)
            then
                let mutable tok = Parser.ELSE (* <-- any token <> SEMICOLON_SEMICOLON will do *)

                while (match tok with
                       | Parser.SEMICOLON_SEMICOLON -> false
                       | _ -> true)
                      && not tokenizer.LexBuffer.IsPastEndOfStream do
                    tok <- tokenizer.GetToken()

            stopProcessingRecovery e range0
            None

    /// Partially process a hash directive, leaving state in packageManagerLines and required assemblies
    let PartiallyProcessHashDirective (ctok, istate, hash, diagnosticsLogger: DiagnosticsLogger) =
        match hash with
        | ParsedHashDirective ("load", ParsedHashDirectiveArguments sourceFiles, m) ->
            let istate =
                fsiDynamicCompiler.EvalSourceFiles(ctok, istate, m, sourceFiles, lexResourceManager, diagnosticsLogger)

            istate, Completed None

        | ParsedHashDirective (("reference" | "r"), ParsedHashDirectiveArguments [ path ], m) ->
            fsiDynamicCompiler.PartiallyProcessReferenceOrPackageIncudePathDirective(ctok, istate, Directive.Resolution, path, true, m)

        | ParsedHashDirective ("i", ParsedHashDirectiveArguments [ path ], m) ->
            fsiDynamicCompiler.PartiallyProcessReferenceOrPackageIncudePathDirective(ctok, istate, Directive.Include, path, true, m)

        | ParsedHashDirective ("I", ParsedHashDirectiveArguments [ path ], m) ->
            tcConfigB.AddIncludePath(m, path, tcConfigB.implicitIncludeDir)
            let tcConfig = TcConfig.Create(tcConfigB, validate = false)
            fsiConsoleOutput.uprintnfnn "%s" (FSIstrings.SR.fsiDidAHashI (tcConfig.MakePathAbsolute path))
            istate, Completed None

        | ParsedHashDirective ("cd", ParsedHashDirectiveArguments [ path ], m) ->
            ChangeDirectory path m
            istate, Completed None

        | ParsedHashDirective ("silentCd", ParsedHashDirectiveArguments [ path ], m) ->
            ChangeDirectory path m
            fsiConsolePrompt.SkipNext() (* "silent" directive *)
            istate, Completed None

        | ParsedHashDirective ("interactiveprompt", ParsedHashDirectiveArguments [ "show" | "hide" | "skip" as showPrompt ], m) ->
            match showPrompt with
            | "show" -> fsiConsolePrompt.ShowPrompt <- true
            | "hide" -> fsiConsolePrompt.ShowPrompt <- false
            | "skip" -> fsiConsolePrompt.SkipNext()
            | _ -> error (Error((FSComp.SR.fsiInvalidDirective ("prompt", String.concat " " [ showPrompt ])), m))

            istate, Completed None

        | ParsedHashDirective ("dbgbreak", [], _) ->
            let istate = { istate with debugBreak = true }
            istate, Completed None

        | ParsedHashDirective ("time", [], _) ->
            if istate.timing then
                fsiConsoleOutput.uprintnfnn "%s" (FSIstrings.SR.fsiTurnedTimingOff ())
            else
                fsiConsoleOutput.uprintnfnn "%s" (FSIstrings.SR.fsiTurnedTimingOn ())

            let istate =
                { istate with
                    timing = not istate.timing
                }

            istate, Completed None

        | ParsedHashDirective ("time", ParsedHashDirectiveArguments [ "on" | "off" as v ], _) ->
            if v <> "on" then
                fsiConsoleOutput.uprintnfnn "%s" (FSIstrings.SR.fsiTurnedTimingOff ())
            else
                fsiConsoleOutput.uprintnfnn "%s" (FSIstrings.SR.fsiTurnedTimingOn ())

            let istate = { istate with timing = (v = "on") }
            istate, Completed None

        | ParsedHashDirective ("nowarn", ParsedHashDirectiveArguments numbers, m) ->
            List.iter (fun (d: string) -> tcConfigB.TurnWarningOff(m, d)) numbers
            istate, Completed None

        | ParsedHashDirective ("terms", [], _) ->
            tcConfigB.showTerms <- not tcConfigB.showTerms
            istate, Completed None

        | ParsedHashDirective ("types", [], _) ->
            fsiOptions.ShowTypes <- not fsiOptions.ShowTypes
            istate, Completed None

#if DEBUG
        | ParsedHashDirective ("ilcode", [], _m) ->
            fsiOptions.ShowILCode <- not fsiOptions.ShowILCode
            istate, Completed None

        | ParsedHashDirective ("info", [], _m) ->
            PrintOptionInfo tcConfigB
            istate, Completed None
#endif
        | ParsedHashDirective (("clear"), [], _) ->
            fsiOptions.ClearScreen()
            istate, Completed None

        | ParsedHashDirective (("q" | "quit"), [], _) -> fsiInterruptController.Exit()

        | ParsedHashDirective ("help", [], m) ->
            fsiOptions.ShowHelp(m)
            istate, Completed None

        | ParsedHashDirective (c, ParsedHashDirectiveArguments arg, m) ->
            warning (Error((FSComp.SR.fsiInvalidDirective (c, String.concat " " arg)), m))
            istate, Completed None

    /// Most functions return a step status - this decides whether to continue and propogates the
    /// last value produced
    let ProcessStepStatus (istate, cont) lastResult f =
        match cont with
        | Completed newResult -> f newResult istate
        // stop on error
        | CompletedWithReportedError e -> istate, CompletedWithReportedError e
        // stop on error
        | CompletedWithAlreadyReportedError -> istate, CompletedWithAlreadyReportedError
        // stop on EOF
        | EndOfFile -> istate, Completed lastResult
        // stop on CtrlC
        | CtrlC -> istate, CtrlC

    /// Execute a group of interactions. Called on the GUI/execute/main thread.
    /// The action is either a group of definitions or a group of hash-references.
    let ExecuteInteractionGroup (ctok, istate, action: InteractionGroup, diagnosticsLogger: DiagnosticsLogger) =
        istate
        |> InteractiveCatch diagnosticsLogger (fun istate ->
            let rec loop istate action =
                // These following actions terminate a dependency manager and/or references group
                // - nothing left to do
                // - a group of non-hash definitions
                // - a #load
                match action with
                | InteractionGroup.Definitions _
                | InteractionGroup.HashDirectives []
                | InteractionGroup.HashDirectives (ParsedHashDirective ("load", _, _) :: _) ->
                    if fsiDynamicCompiler.HasDelayedDependencyManagerText then
                        let istate =
                            fsiDynamicCompiler.ProcessDelayedDependencyManagerText(ctok, istate, lexResourceManager, diagnosticsLogger)

                        loop istate action
                    elif fsiDynamicCompiler.HasDelayedReferences then
                        let istate = fsiDynamicCompiler.ProcessDelayedReferences(ctok, istate)
                        loop istate action
                    else
                        match action with
                        | InteractionGroup.Definitions ([], _)
                        | InteractionGroup.HashDirectives [] -> istate, Completed None

                        | InteractionGroup.Definitions ([ SynModuleDecl.Expr (expr, _) ], _) ->
                            fsiDynamicCompiler.EvalParsedExpression(ctok, diagnosticsLogger, istate, expr)

                        | InteractionGroup.Definitions (defs, _) ->
                            fsiDynamicCompiler.EvalParsedDefinitions(ctok, diagnosticsLogger, istate, true, false, defs)

                        | InteractionGroup.HashDirectives (hash :: rest) ->
                            let status = PartiallyProcessHashDirective(ctok, istate, hash, diagnosticsLogger)
                            ProcessStepStatus status None (fun _ istate -> loop istate (InteractionGroup.HashDirectives rest))

                // Other hash directives do not terminate a dependency manager and/or references group
                | InteractionGroup.HashDirectives (hash :: rest) ->
                    let status = PartiallyProcessHashDirective(ctok, istate, hash, diagnosticsLogger)
                    ProcessStepStatus status None (fun _ istate -> loop istate (InteractionGroup.HashDirectives rest))

            loop istate action)

    let isDefHash =
        function
        | SynModuleDecl.HashDirective _ -> true
        | _ -> false

    // Only add automatic debugger breaks before 'let' or 'do' expressions with sequence points
    let isBreakable def =
        match def with
        | SynModuleDecl.Let(bindings = SynBinding(debugPoint = DebugPointAtBinding.Yes _) :: _) -> true
        | _ -> false

    /// Execute a single parsed interaction which may contain multiple items to be executed
    /// independently, because some are #directives. Called on the GUI/execute/main thread.
    ///
    /// #directive comes through with other definitions as a SynModuleDecl.HashDirective.
    /// We split these out for individual processing.
    let rec ExecuteParsedInteractionInGroups
        (
            ctok,
            istate,
            synInteraction,
            diagnosticsLogger: DiagnosticsLogger,
            lastResult: FsiValue option,
            cancellationToken: CancellationToken
        ) =
        cancellationToken.ThrowIfCancellationRequested()

        let group, others, istate =
            match synInteraction with
            | None -> None, None, istate

            | Some (ParsedScriptInteraction.Definitions (defs, m)) ->
                match defs with
                | [] -> None, None, istate

                | SynModuleDecl.HashDirective _ :: _ ->
                    let hashes =
                        List.takeWhile isDefHash defs
                        |> List.choose (function
                            | (SynModuleDecl.HashDirective (hash, _)) -> Some(hash)
                            | _ -> None)

                    let defsB = List.skipWhile isDefHash defs

                    let group = InteractionGroup.HashDirectives(hashes)
                    let others = ParsedScriptInteraction.Definitions(defsB, m)
                    Some group, Some others, istate

                | _ ->

                    let defsA = Seq.takeWhile (isDefHash >> not) defs |> Seq.toList
                    let defsB = Seq.skipWhile (isDefHash >> not) defs |> Seq.toList

                    // If user is debugging their script interactively, inject call
                    // to Debugger.Break() at the first "breakable" line.
                    // Update istate so that more Break() calls aren't injected when recursing
                    let defsA, istate =
                        if istate.debugBreak then
                            let preBreak = Seq.takeWhile (isBreakable >> not) defsA |> Seq.toList
                            let postBreak = Seq.skipWhile (isBreakable >> not) defsA |> Seq.toList

                            match postBreak with
                            | h :: _ ->
                                preBreak @ (fsiDynamicCompiler.CreateDebuggerBreak(h.Range) :: postBreak),
                                { istate with debugBreak = false }
                            | _ -> defsA, istate
                        else
                            defsA, istate

                    // When the last declaration has a shape of DoExp (i.e., non-binding),
                    // transform it to a shape of "let it = <exp>", so we can refer it.
                    let defsA =
                        if not (isNil defsB) then
                            defsA
                        else
                            match defsA with
                            | [] -> defsA
                            | [ _ ] -> defsA
                            | _ ->
                                match List.rev defsA with
                                | SynModuleDecl.Expr (expr, _) :: rest -> (rest |> List.rev) @ (fsiDynamicCompiler.BuildItBinding expr)
                                | _ -> defsA

                    let group = InteractionGroup.Definitions(defsA, m)
                    let others = ParsedScriptInteraction.Definitions(defsB, m)
                    Some group, Some others, istate

        match group with
        | None -> istate, Completed lastResult
        | Some group ->
            let status = ExecuteInteractionGroup(ctok, istate, group, diagnosticsLogger)

            ProcessStepStatus status lastResult (fun lastResult istate ->
                ExecuteParsedInteractionInGroups(ctok, istate, others, diagnosticsLogger, lastResult, cancellationToken))

    /// Execute a single parsed interaction which may contain multiple items to be executed
    /// independently
    let ExecuteParsedInteraction
        (
            ctok,
            istate,
            synInteraction,
            diagnosticsLogger: DiagnosticsLogger,
            lastResult: FsiValue option,
            cancellationToken: CancellationToken
        ) =
        let status =
            ExecuteParsedInteractionInGroups(ctok, istate, synInteraction, diagnosticsLogger, lastResult, cancellationToken)

        ProcessStepStatus status lastResult (fun lastResult istate ->
            let rec loop istate =
                if fsiDynamicCompiler.HasDelayedDependencyManagerText then
                    let istate =
                        fsiDynamicCompiler.ProcessDelayedDependencyManagerText(ctok, istate, lexResourceManager, diagnosticsLogger)

                    loop istate
                elif fsiDynamicCompiler.HasDelayedReferences then
                    let istate = fsiDynamicCompiler.ProcessDelayedReferences(ctok, istate)
                    loop istate
                else
                    istate, Completed lastResult

            loop istate)

    /// Execute a single parsed interaction on the parser/execute thread.
    let mainThreadProcessAction ctok action istate =
        try
            let mutable result = Unchecked.defaultof<'a * FsiInteractionStepStatus>

            fsiInterruptController
                .ControlledExecution()
                .Run(fun () ->
                    if progress then
                        fprintfn fsiConsoleOutput.Out "In mainThreadProcessAction..."

                    fsiInterruptController.InterruptAllowed <- InterruptCanRaiseException
                    let res = action ctok istate
                    fsiInterruptController.ClearInterruptRequest()
                    fsiInterruptController.InterruptAllowed <- InterruptIgnored
                    result <- res)

            result
        with
        | :? ThreadAbortException ->
            fsiInterruptController.ClearInterruptRequest()
            fsiInterruptController.InterruptAllowed <- InterruptIgnored
            fsiInterruptController.ControlledExecution().ResetAbort()
            (istate, CtrlC)

        | :? TargetInvocationException as e when
            (ControlledExecution.StripTargetInvocationException(e)).GetType().Name = "ThreadAbortException"
            || (ControlledExecution.StripTargetInvocationException(e)).GetType().Name = "OperationCanceledException"
            ->
            fsiInterruptController.ClearInterruptRequest()
            fsiInterruptController.InterruptAllowed <- InterruptIgnored
            fsiInterruptController.ControlledExecution().ResetAbort()
            (istate, CtrlC)

        | e ->
            fsiInterruptController.ClearInterruptRequest()
            fsiInterruptController.InterruptAllowed <- InterruptIgnored
            stopProcessingRecovery e range0
            istate, CompletedWithReportedError e

    let ExecuteParsedInteractionOnMainThread (ctok, diagnosticsLogger, synInteraction, istate, cancellationToken) =
        istate
        |> mainThreadProcessAction ctok (fun ctok istate ->
            ExecuteParsedInteraction(ctok, istate, synInteraction, diagnosticsLogger, None, cancellationToken))

    let ParseExpression (tokenizer: LexFilter.LexFilter) =
        reusingLexbufForParsing tokenizer.LexBuffer (fun () ->
            Parser.typedSequentialExprEOF (fun _ -> tokenizer.GetToken()) tokenizer.LexBuffer)

    let ExecuteParsedExpressionOnMainThread (ctok, diagnosticsLogger, expr, istate) =
        istate
        |> InteractiveCatch diagnosticsLogger (fun istate ->
            istate
            |> mainThreadProcessAction ctok (fun ctok istate ->
                fsiDynamicCompiler.EvalParsedExpression(ctok, diagnosticsLogger, istate, expr)))

    let commitResult (istate, result) =
        match result with
        | FsiInteractionStepStatus.CtrlC -> Choice2Of2(Some(OperationCanceledException() :> exn))
        | FsiInteractionStepStatus.EndOfFile -> Choice2Of2(Some(System.Exception "End of input"))
        | FsiInteractionStepStatus.Completed res ->
            setCurrState istate
            Choice1Of2 res
        | FsiInteractionStepStatus.CompletedWithReportedError (StopProcessingExn userExnOpt) -> Choice2Of2 userExnOpt
        | FsiInteractionStepStatus.CompletedWithReportedError _
        | FsiInteractionStepStatus.CompletedWithAlreadyReportedError -> Choice2Of2 None

    /// Parse then process one parsed interaction.
    ///
    /// During normal execution, this initially runs on the parser
    /// thread, then calls runCodeOnMainThread when it has completed
    /// parsing and needs to typecheck and execute a definition. This blocks the parser thread
    /// until execution has competed on the GUI thread.
    ///
    /// During processing of startup scripts, this runs on the main thread.
    ///
    /// This is blocking: it reads until one chunk of input have been received, unless IsPastEndOfStream is true
    member _.ParseAndExecuteInteractionFromLexbuf
        (
            runCodeOnMainThread,
            istate: FsiDynamicCompilerState,
            tokenizer: LexFilter.LexFilter,
            diagnosticsLogger,
            ?cancellationToken: CancellationToken
        ) =
        let cancellationToken = defaultArg cancellationToken CancellationToken.None

        if tokenizer.LexBuffer.IsPastEndOfStream then
            let stepStatus =
                if fsiInterruptController.FsiInterruptStdinState = StdinEOFPermittedBecauseCtrlCRecentlyPressed then
                    fsiInterruptController.FsiInterruptStdinState <- StdinNormal
                    CtrlC
                else
                    EndOfFile

            istate, stepStatus

        else

            fsiConsolePrompt.Print()

            istate
            |> InteractiveCatch diagnosticsLogger (fun istate ->
                if progress then
                    fprintfn fsiConsoleOutput.Out "entering ParseInteraction..."

                // Parse the interaction. When FSI.EXE is waiting for input from the console the
                // parser thread is blocked somewhere deep this call.
                let action = ParseInteraction tokenizer

                if progress then
                    fprintfn fsiConsoleOutput.Out "returned from ParseInteraction...calling runCodeOnMainThread..."

                // After we've unblocked and got something to run we switch
                // over to the run-thread (e.g. the GUI thread)
                let res =
                    istate
                    |> runCodeOnMainThread (fun ctok istate ->
                        ExecuteParsedInteractionOnMainThread(ctok, diagnosticsLogger, action, istate, cancellationToken))

                if progress then
                    fprintfn fsiConsoleOutput.Out "Just called runCodeOnMainThread, res = %O..." res

                res)

    member _.CurrentState = currState

    /// Perform an "include" on a script file (i.e. a script file specified on the command line)
    member processor.EvalIncludedScript(ctok, istate, sourceFile, m, diagnosticsLogger) =
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)
        // Resolve the file name to an absolute file name
        let sourceFile =
            tcConfig.ResolveSourceFile(m, sourceFile, tcConfig.implicitIncludeDir)
        // During the processing of the file, further filenames are
        // resolved relative to the home directory of the loaded file.
        WithImplicitHome (tcConfigB, directoryName sourceFile) (fun () ->
            // An included script file may parse several interaction blocks.
            // We repeatedly parse and process these, until an error occurs.
            use fileStream = FileSystem.OpenFileForReadShim(sourceFile)
            use reader = fileStream.GetReader(tcConfigB.inputCodePage, false)

            let tokenizer =
                fsiStdinLexerProvider.CreateIncludedScriptLexer(sourceFile, reader, diagnosticsLogger)

            let rec run istate =
                let status =
                    processor.ParseAndExecuteInteractionFromLexbuf((fun f istate -> f ctok istate), istate, tokenizer, diagnosticsLogger)

                ProcessStepStatus status None (fun _ istate -> run istate)

            run istate)

    /// Load the source files, one by one. Called on the main thread.
    member processor.EvalIncludedScripts(ctok, istate, sourceFiles, diagnosticsLogger) =
        match sourceFiles with
        | [] -> istate, Completed None
        | sourceFile :: moreSourceFiles ->
            // Catch errors on a per-file basis, so results/bindings from pre-error files can be kept.
            let status =
                InteractiveCatch
                    diagnosticsLogger
                    (fun istate -> processor.EvalIncludedScript(ctok, istate, sourceFile, rangeStdin0, diagnosticsLogger))
                    istate

            ProcessStepStatus status None (fun _ istate -> processor.EvalIncludedScripts(ctok, istate, moreSourceFiles, diagnosticsLogger))

    member processor.LoadInitialFiles(ctok, diagnosticsLogger) =
        /// Consume initial source files in chunks of scripts or non-scripts
        let rec consume istate sourceFiles =
            match sourceFiles with
            | [] -> istate
            | (_, isScript1) :: _ ->
                let sourceFiles, rest =
                    List.takeUntil (fun (_, isScript2) -> isScript1 <> isScript2) sourceFiles

                let sourceFiles = List.map fst sourceFiles

                let istate, _ =
                    if isScript1 then
                        processor.EvalIncludedScripts(ctok, istate, sourceFiles, diagnosticsLogger)
                    else
                        istate
                        |> InteractiveCatch diagnosticsLogger (fun istate ->
                            fsiDynamicCompiler.EvalSourceFiles(
                                ctok,
                                istate,
                                rangeStdin0,
                                sourceFiles,
                                lexResourceManager,
                                diagnosticsLogger
                            ),
                            Completed None)

                consume istate rest

        setCurrState (consume currState fsiOptions.SourceFiles)

        if not (List.isEmpty fsiOptions.SourceFiles) then
            fsiConsolePrompt.PrintAhead() // Seems required. I expected this could be deleted. Why not?

    /// Send a dummy interaction through F# Interactive, to ensure all the most common code generation paths are
    /// JIT'ed and ready for use.
    member _.LoadDummyInteraction(ctok, diagnosticsLogger) =
        setCurrState (
            currState
            |> InteractiveCatch diagnosticsLogger (fun istate ->
                fsiDynamicCompiler.EvalParsedDefinitions(ctok, diagnosticsLogger, istate, true, false, [])
                |> fst,
                Completed None)
            |> fst
        )

    member _.EvalInteraction(ctok, sourceText, scriptFileName, diagnosticsLogger, ?cancellationToken) =
        let cancellationToken = defaultArg cancellationToken CancellationToken.None
        use _ = UseBuildPhase BuildPhase.Interactive
        use _ = UseDiagnosticsLogger diagnosticsLogger
        use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID

        let lexbuf =
            UnicodeLexing.StringAsLexbuf(true, tcConfigB.langVersion, tcConfigB.strictIndentation, sourceText)

        let tokenizer =
            fsiStdinLexerProvider.CreateBufferLexer(scriptFileName, lexbuf, diagnosticsLogger)

        currState
        |> InteractiveCatch diagnosticsLogger (fun istate ->
            let expr = ParseInteraction tokenizer
            ExecuteParsedInteractionOnMainThread(ctok, diagnosticsLogger, expr, istate, cancellationToken))
        |> commitResult

    member this.EvalScript(ctok, scriptPath, diagnosticsLogger) =
        // Todo: this runs the script as expected but errors are displayed one line to far in debugger
        let sourceText = sprintf "#load @\"%s\" " scriptPath
        this.EvalInteraction(ctok, sourceText, scriptPath, diagnosticsLogger)

    member _.EvalExpression(ctok, sourceText, scriptFileName, diagnosticsLogger) =
        use _unwind1 = UseBuildPhase BuildPhase.Interactive
        use _unwind2 = UseDiagnosticsLogger diagnosticsLogger
        use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID

        let lexbuf =
            UnicodeLexing.StringAsLexbuf(true, tcConfigB.langVersion, tcConfigB.strictIndentation, sourceText)

        let tokenizer =
            fsiStdinLexerProvider.CreateBufferLexer(scriptFileName, lexbuf, diagnosticsLogger)

        currState
        |> InteractiveCatch diagnosticsLogger (fun istate ->
            let expr = ParseExpression tokenizer
            let m = expr.Range
            // Make this into "(); expr" to suppress generalization and compilation-as-function
            let exprWithSeq =
                SynExpr.Sequential(DebugPointAtSequential.SuppressExpr, true, SynExpr.Const(SynConst.Unit, m.StartRange), expr, m)

            ExecuteParsedExpressionOnMainThread(ctok, diagnosticsLogger, exprWithSeq, istate))
        |> commitResult

    member _.AddBoundValue(ctok, diagnosticsLogger, name, value: obj) =
        currState
        |> InteractiveCatch diagnosticsLogger (fun istate -> fsiDynamicCompiler.AddBoundValue(ctok, diagnosticsLogger, istate, name, value))
        |> commitResult

    member _.PartialAssemblySignatureUpdated = event.Publish

    /// Start the background thread used to read the input reader and/or console
    ///
    /// This is the main stdin loop, running on the stdinReaderThread.
    ///
    // We run the actual computations for each action on the main GUI thread by using
    // mainForm.Invoke to pipe a message back through the form's main event loop. (The message
    // is a delegate to execute on the main Thread)
    //
    member processor.StartStdinReadAndProcessThread diagnosticsLogger =

        if progress then
            fprintfn fsiConsoleOutput.Out "creating stdinReaderThread"

        let stdinReaderThread =
            Thread(
                ThreadStart(fun () ->
                    InstallErrorLoggingOnThisThread diagnosticsLogger // FSI error logging on stdinReaderThread, e.g. parse errors.
                    use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID

                    try
                        try
                            let initialTokenizer = fsiStdinLexerProvider.CreateStdinLexer(diagnosticsLogger)

                            if progress then
                                fprintfn fsiConsoleOutput.Out "READER: stdin thread started..."

                            // Delay until we've peeked the input or read the entire first line
                            fsiStdinLexerProvider.ConsoleInput.WaitForInitialConsoleInput()

                            if progress then
                                fprintfn fsiConsoleOutput.Out "READER: stdin thread got first line..."

                            let runCodeOnMainThread = runCodeOnEventLoop diagnosticsLogger

                            // Keep going until EndOfFile on the inReader or console
                            let rec loop currTokenizer =

                                let istateNew, cont =
                                    processor.ParseAndExecuteInteractionFromLexbuf(
                                        runCodeOnMainThread,
                                        currState,
                                        currTokenizer,
                                        diagnosticsLogger
                                    )

                                setCurrState istateNew

                                match cont with
                                | EndOfFile -> ()
                                | CtrlC -> loop (fsiStdinLexerProvider.CreateStdinLexer(diagnosticsLogger)) // After each interrupt, restart to a brand new tokenizer
                                | CompletedWithAlreadyReportedError
                                | CompletedWithReportedError _
                                | Completed _ -> loop currTokenizer

                            loop initialTokenizer

                            if progress then
                                fprintfn fsiConsoleOutput.Out "- READER: Exiting stdinReaderThread"

                        with e ->
                            stopProcessingRecovery e range0

                    finally
                        exit 1

                ),
                Name = "StdinReaderThread"
            )

        if progress then
            fprintfn fsiConsoleOutput.Out "MAIN: starting stdin thread..."

        stdinReaderThread.Start()

    member _.CompletionsForPartialLID(istate, prefix: string) =
        let lid, stem =
            if prefix.IndexOf(".", StringComparison.Ordinal) >= 0 then
                let parts = prefix.Split('.')
                let n = parts.Length
                Array.sub parts 0 (n - 1) |> Array.toList, parts[n - 1]
            else
                [], prefix

        let tcState = istate.tcState
        let amap = istate.tcImports.GetImportMap()
        let infoReader = InfoReader(istate.tcGlobals, amap)

        let ncenv =
            NameResolver(istate.tcGlobals, amap, infoReader, FakeInstantiationGenerator)

        let ad = tcState.TcEnvFromImpls.AccessRights
        let nenv = tcState.TcEnvFromImpls.NameEnv

        let nItems =
            ResolvePartialLongIdent
                ncenv
                nenv
                (ConstraintSolver.IsApplicableMethApprox istate.tcGlobals amap rangeStdin0)
                rangeStdin0
                ad
                lid
                false

        let names = nItems |> List.map (fun d -> d.DisplayName)
        let names = names |> List.filter (fun name -> name.StartsWithOrdinal(stem))
        names

    member _.ParseAndCheckInteraction(legacyReferenceResolver, istate, text: string) =
        let tcConfig = TcConfig.Create(tcConfigB, validate = false)

        let fsiInteractiveChecker =
            FsiInteractiveChecker(legacyReferenceResolver, tcConfig, istate.tcGlobals, istate.tcImports, istate.tcState)

        fsiInteractiveChecker.ParseAndCheckInteraction(SourceText.ofString text)

//----------------------------------------------------------------------------
// Server mode:
//----------------------------------------------------------------------------

let internal SpawnThread name f =
    let th = Thread(ThreadStart(f), Name = name)
    th.IsBackground <- true
    th.Start()

let internal SpawnInteractiveServer
    (
        fsi: FsiEvaluationSessionHostConfig,
        fsiOptions: FsiCommandLineOptions,
        fsiConsoleOutput: FsiConsoleOutput
    ) =
    //printf "Spawning fsi server on channel '%s'" !fsiServerName;
    SpawnThread "ServerThread" (fun () ->
        use _scope = SetCurrentUICultureForThread fsiOptions.FsiLCID

        try
            fsi.StartServer(fsiOptions.FsiServerName)
        with e ->
            fprintfn fsiConsoleOutput.Error "%s" (FSIstrings.SR.fsiExceptionRaisedStartingServer (e.ToString())))

/// Repeatedly drive the event loop (e.g. Application.Run()) but catching ThreadAbortException and re-running.
///
/// This gives us a last chance to catch an abort on the main execution thread.
let internal DriveFsiEventLoop
    (
        fsi: FsiEvaluationSessionHostConfig,
        fsiInterruptController: FsiInterruptController,
        fsiConsoleOutput: FsiConsoleOutput
    ) =

    if progress then
        fprintfn fsiConsoleOutput.Out "GUI thread runLoop"

    fsiInterruptController.InstallKillThread()

    let rec runLoop () =

        let restart =
            try
                fsi.EventLoopRun()
            with
            | :? TargetInvocationException as e when
                (ControlledExecution.StripTargetInvocationException(e)).GetType().Name = "ThreadAbortException"
                ->
                // If this TAE handler kicks it's almost certainly too late to save the
                // state of the process - the state of the message loop may have been corrupted
                fsiInterruptController.ControlledExecution().ResetAbort()
                true
            | :? ThreadAbortException ->
                // If this TAE handler kicks it's almost certainly too late to save the
                // state of the process - the state of the message loop may have been corrupted
                fsiInterruptController.ControlledExecution().ResetAbort()
                true
            | e ->
                stopProcessingRecovery e range0
                true
        // Try again, just case we can restart
        if progress then
            fprintfn fsiConsoleOutput.Out "MAIN:  exited event loop..."

        if restart then
            runLoop ()

    runLoop ()

/// Thrown when there was an error compiling the given code in FSI.
type FsiCompilationException(message: string, errorInfos: FSharpDiagnostic[] option) =
    inherit System.Exception(message)
    member _.ErrorInfos = errorInfos

/// The primary type, representing a full F# Interactive session, reading from the given
/// text input, writing to the given text output and error writers.
type FsiEvaluationSession
    (
        fsi: FsiEvaluationSessionHostConfig,
        argv: string[],
        inReader: TextReader,
        outWriter: TextWriter,
        errorWriter: TextWriter,
        fsiCollectible: bool,
        legacyReferenceResolver: LegacyReferenceResolver option
    ) =

    // Explanation: When FsiEvaluationSession.Create is called we do a bunch of processing. For fsi.exe
    // and fsiAnyCpu.exe there are no other active threads at this point, so we can assume this is the
    // unique compilation thread.  For other users of FsiEvaluationSession it is reasonable to assume that
    // the object is not accessed concurrently during startup preparation.
    //
    // We later switch to doing interaction-by-interaction processing on the "event loop" thread.
    let ctokStartup = AssumeCompilationThreadWithoutEvidence()

    let timeReporter = FsiTimeReporter(outWriter)

    //----------------------------------------------------------------------------
    // tcConfig - build the initial config
    //----------------------------------------------------------------------------

    let currentDirectory = Directory.GetCurrentDirectory()
    let tryGetMetadataSnapshot = (fun _ -> None)

    let defaultFSharpBinariesDir = BinFolderOfDefaultFSharpCompiler(None).Value

    let legacyReferenceResolver =
        match legacyReferenceResolver with
        | None -> SimulatedMSBuildReferenceResolver.getResolver ()
        | Some rr -> rr

    let tcConfigB =
        TcConfigBuilder.CreateNew(
            legacyReferenceResolver,
            defaultFSharpBinariesDir = defaultFSharpBinariesDir,
            reduceMemoryUsage = ReduceMemoryFlag.Yes,
            implicitIncludeDir = currentDirectory,
            isInteractive = true,
            isInvalidationSupported = false,
            defaultCopyFSharpCore = CopyFSharpCoreFlag.No,
            tryGetMetadataSnapshot = tryGetMetadataSnapshot,
            sdkDirOverride = None,
            rangeForErrors = range0
        )

    let tcConfigP = TcConfigProvider.BasedOnMutableBuilder(tcConfigB)
    do tcConfigB.resolutionEnvironment <- LegacyResolutionEnvironment.CompilationAndEvaluation // See Bug 3608
    do tcConfigB.useFsiAuxLib <- fsi.UseFsiAuxLib
    do tcConfigB.conditionalDefines <- "INTERACTIVE" :: tcConfigB.conditionalDefines

    do tcConfigB.SetUseSdkRefs true
    do tcConfigB.useSimpleResolution <- true

    do
        if isRunningOnCoreClr then
            SetTargetProfile tcConfigB "netcore" // always assume System.Runtime codegen

    // Preset: --optimize+ -g --tailcalls+ (see 4505)
    do SetOptimizeSwitch tcConfigB OptionSwitch.On
    do SetDebugSwitch tcConfigB (Some "pdbonly") OptionSwitch.On
    do SetTailcallSwitch tcConfigB OptionSwitch.On

    // set platform depending on whether the current process is a 64-bit process.
    // BUG 429882 : FsiAnyCPU.exe issues warnings (x64 v MSIL) when referencing 64-bit assemblies
    do tcConfigB.platform <- if IntPtr.Size = 8 then Some AMD64 else Some X86

    let fsiStdinSyphon = FsiStdinSyphon(errorWriter)
    let fsiConsoleOutput = FsiConsoleOutput(tcConfigB, outWriter, errorWriter)

    let diagnosticsLogger =
        DiagnosticsLoggerThatStopsOnFirstError(tcConfigB, fsiStdinSyphon, fsiConsoleOutput)

    do InstallErrorLoggingOnThisThread diagnosticsLogger // FSI error logging on main thread.

    let updateBannerText () =
        tcConfigB.productNameForBannerText <- FSIstrings.SR.fsiProductName (FSharpBannerVersion)

    do updateBannerText () // setting the correct banner so that 'fsi -?' display the right thing

    let fsiOptions = FsiCommandLineOptions(fsi, argv, tcConfigB, fsiConsoleOutput)

    do
        match fsiOptions.WriteReferencesAndExit with
        | Some outFile ->
            let tcConfig = tcConfigP.Get(ctokStartup)

            let references, _unresolvedReferences =
                TcAssemblyResolutions.GetAssemblyResolutionInformation(tcConfig)

            let lines = [ for r in references -> r.resolvedPath ]
            FileSystem.OpenFileForWriteShim(outFile).WriteAllLines(lines)
            exit 0
        | _ -> ()

    let fsiConsolePrompt = FsiConsolePrompt(fsiOptions, fsiConsoleOutput)

    do
        match tcConfigB.preferredUiLang with
        | Some s -> Thread.CurrentThread.CurrentUICulture <- CultureInfo(s)
        | None -> ()

    do
        try
            SetServerCodePages fsiOptions
        with e ->
            warning (e)

    do
        updateBannerText () // resetting banner text after parsing options

        if tcConfigB.showBanner then
            fsiOptions.ShowBanner()

    do fsiConsoleOutput.uprintfn ""

    // When no source files to load, print ahead prompt here
    do
        if List.isEmpty fsiOptions.SourceFiles then
            fsiConsolePrompt.PrintAhead()

    let fsiConsoleInput = FsiConsoleInput(fsi, fsiOptions, inReader, outWriter)

    /// The single, global interactive checker that can be safely used in conjunction with other operations
    /// on the FsiEvaluationSession.
    let checker =
        FSharpChecker.Create(legacyReferenceResolver = legacyReferenceResolver)

    let tcGlobals, frameworkTcImports, nonFrameworkResolutions, unresolvedReferences =
        try
            let tcConfig = tcConfigP.Get(ctokStartup)

            checker.FrameworkImportsCache.Get tcConfig
            |> NodeCode.RunImmediateWithoutCancellation
        with e ->
            stopProcessingRecovery e range0
            failwithf "Error creating evaluation session: %A" e

    let tcImports =
        try
            TcImports.BuildNonFrameworkTcImports(
                tcConfigP,
                frameworkTcImports,
                nonFrameworkResolutions,
                unresolvedReferences,
                fsiOptions.DependencyProvider
            )
            |> NodeCode.RunImmediateWithoutCancellation
        with e ->
            stopProcessingRecovery e range0
            failwithf "Error creating evaluation session: %A" e

    // Share intern'd strings across all lexing/parsing
    let lexResourceManager = LexResourceManager()

    /// The lock stops the type checker running at the same time as the server intellisense implementation.
    let tcLockObject = box 7 // any new object will do

    let resolveAssemblyRef (aref: ILAssemblyRef) =
        // Explanation: This callback is invoked during compilation to resolve assembly references
        // We don't yet propagate the ctok through these calls (though it looks plausible to do so).
#if !NO_TYPEPROVIDERS
        let ctok = AssumeCompilationThreadWithoutEvidence()

        match tcImports.TryFindProviderGeneratedAssemblyByName(ctok, aref.Name) with
        | Some assembly -> Some(Choice2Of2 assembly)
        | None ->
#endif
        match tcImports.TryFindExistingFullyQualifiedPathByExactAssemblyRef aref with
        | Some resolvedPath -> Some(Choice1Of2 resolvedPath)
        | None -> None

    let fsiDynamicCompiler =
        FsiDynamicCompiler(
            fsi,
            timeReporter,
            tcConfigB,
            tcLockObject,
            outWriter,
            tcImports,
            tcGlobals,
            fsiOptions,
            fsiConsoleOutput,
            fsiCollectible,
            resolveAssemblyRef
        )

    let controlledExecution = ControlledExecution(fsiOptions.Interact)

    let fsiInterruptController =
        FsiInterruptController(fsiOptions, controlledExecution, fsiConsoleOutput)

    let uninstallMagicAssemblyResolution =
        MagicAssemblyResolution.Install(tcConfigB, tcImports, fsiDynamicCompiler, fsiConsoleOutput)

    /// This reference cell holds the most recent interactive state
    let initialInteractiveState = fsiDynamicCompiler.GetInitialInteractiveState()

    let fsiStdinLexerProvider =
        FsiStdinLexerProvider(tcConfigB, fsiStdinSyphon, fsiConsoleInput, fsiConsoleOutput, fsiOptions, lexResourceManager)

    let fsiInteractionProcessor =
        FsiInteractionProcessor(
            fsi,
            tcConfigB,
            fsiOptions,
            fsiDynamicCompiler,
            fsiConsolePrompt,
            fsiConsoleOutput,
            fsiInterruptController,
            fsiStdinLexerProvider,
            lexResourceManager,
            initialInteractiveState
        )

    // Raising an exception throws away the exception stack making diagnosis hard
    // this wraps the existing exception as the inner exception
    let makeNestedException (userExn: #Exception) =
        // clone userExn -- make userExn the inner exception, to retain the stacktrace on raise
        let arguments = [| userExn.Message :> obj; userExn :> obj |]
        Activator.CreateInstance(userExn.GetType(), arguments) :?> Exception

    let commitResult res =
        match res with
        | Choice1Of2 r -> r
        | Choice2Of2 None -> raise (FsiCompilationException(FSIstrings.SR.fsiOperationFailed (), None))
        | Choice2Of2 (Some userExn) -> raise (makeNestedException userExn)

    let commitResultNonThrowing errorOptions scriptFile (diagnosticsLogger: CompilationDiagnosticLogger) res =
        let errs = diagnosticsLogger.GetDiagnostics()

        let errorInfos =
            DiagnosticHelpers.CreateDiagnostics(errorOptions, true, scriptFile, errs, true, tcConfigB.flatErrors, None)

        let userRes =
            match res with
            | Choice1Of2 r -> Choice1Of2 r
            | Choice2Of2 None ->
                Choice2Of2(FsiCompilationException(FSIstrings.SR.fsiOperationCouldNotBeCompleted (), Some errorInfos) :> exn)
            | Choice2Of2 (Some userExn) -> Choice2Of2 userExn

        // 'true' is passed for "suggestNames" because we want the FSI session to suggest names for misspellings and it won't affect IDE perf much
        userRes, errorInfos

    let dummyScriptFileName = "input.fsx"

    let eagerFormat (diag: PhasedDiagnostic) = diag.EagerlyFormatCore true

    interface IDisposable with
        member _.Dispose() =
            (tcImports :> IDisposable).Dispose()
            uninstallMagicAssemblyResolution.Dispose()

    /// Load the dummy interaction, load the initial files, and,
    /// if interacting, start the background thread to read the standard input.
    member _.Interrupt() = fsiInterruptController.Interrupt()

    /// A host calls this to get the completions for a long identifier, e.g. in the console
    member _.GetCompletions(longIdent) =
        fsiInteractionProcessor.CompletionsForPartialLID(fsiInteractionProcessor.CurrentState, longIdent)
        |> Seq.ofList

    member _.ParseAndCheckInteraction(code) =
        fsiInteractionProcessor.ParseAndCheckInteraction(legacyReferenceResolver, fsiInteractionProcessor.CurrentState, code)
        |> Cancellable.runWithoutCancellation

    member _.InteractiveChecker = checker

    member _.CurrentPartialAssemblySignature =
        fsiDynamicCompiler.CurrentPartialAssemblySignature fsiInteractionProcessor.CurrentState

    member _.DynamicAssemblies = fsiDynamicCompiler.DynamicAssemblies

    /// A host calls this to determine if the --gui parameter is active
    member _.IsGui = fsiOptions.Gui

    /// A host calls this to get the active language ID if provided by fsi-server-lcid
    member _.LCID = fsiOptions.FsiLCID

    /// A host calls this to report an unhandled exception in a standard way, e.g. an exception on the GUI thread gets printed to stderr
    member x.ReportUnhandledException exn = x.ReportUnhandledExceptionSafe true exn

    member _.ReportUnhandledExceptionSafe _isFromThreadException (exn: exn) =
        fsi.EventLoopInvoke(fun () ->
            fprintfn fsiConsoleOutput.Error "%s" (exn.ToString())
            diagnosticsLogger.SetError()
            diagnosticsLogger.AbortOnError(fsiConsoleOutput))

    member _.PartialAssemblySignatureUpdated =
        fsiInteractionProcessor.PartialAssemblySignatureUpdated

    member _.FormatValue(reflectionValue: obj, reflectionType) =
        fsiDynamicCompiler.FormatValue(reflectionValue, reflectionType)

    member this.EvalExpression(code) =
        this.EvalExpression(code, dummyScriptFileName)

    member _.EvalExpression(code, scriptFileName) =

        // Explanation: When the user of the FsiInteractiveSession object calls this method, the
        // code is parsed, checked and evaluated on the calling thread. This means EvalExpression
        // is not safe to call concurrently.
        let ctok = AssumeCompilationThreadWithoutEvidence()

        fsiInteractionProcessor.EvalExpression(ctok, code, scriptFileName, diagnosticsLogger)
        |> commitResult

    member this.EvalExpressionNonThrowing(code) =
        this.EvalExpressionNonThrowing(code, dummyScriptFileName)

    member _.EvalExpressionNonThrowing(code, scriptFileName) =
        // Explanation: When the user of the FsiInteractiveSession object calls this method, the
        // code is parsed, checked and evaluated on the calling thread. This means EvalExpression
        // is not safe to call concurrently.
        let ctok = AssumeCompilationThreadWithoutEvidence()

        let errorOptions = TcConfig.Create(tcConfigB, validate = false).diagnosticsOptions

        let diagnosticsLogger =
            CompilationDiagnosticLogger("EvalInteraction", errorOptions, eagerFormat)

        fsiInteractionProcessor.EvalExpression(ctok, code, scriptFileName, diagnosticsLogger)
        |> commitResultNonThrowing errorOptions scriptFileName diagnosticsLogger

    member this.EvalInteraction(code, ?cancellationToken) : unit =
        let cancellationToken = defaultArg cancellationToken CancellationToken.None
        this.EvalInteraction(code, dummyScriptFileName, cancellationToken)

    member _.EvalInteraction(code, scriptFileName, ?cancellationToken) : unit =
        // Explanation: When the user of the FsiInteractiveSession object calls this method, the
        // code is parsed, checked and evaluated on the calling thread. This means EvalExpression
        // is not safe to call concurrently.
        let ctok = AssumeCompilationThreadWithoutEvidence()
        let cancellationToken = defaultArg cancellationToken CancellationToken.None

        fsiInteractionProcessor.EvalInteraction(ctok, code, scriptFileName, diagnosticsLogger, cancellationToken)
        |> commitResult
        |> ignore

    member this.EvalInteractionNonThrowing(code, ?cancellationToken) =
        let cancellationToken = defaultArg cancellationToken CancellationToken.None
        this.EvalInteractionNonThrowing(code, dummyScriptFileName, cancellationToken)

    member this.EvalInteractionNonThrowing(code, scriptFileName, ?cancellationToken) =
        // Explanation: When the user of the FsiInteractiveSession object calls this method, the
        // code is parsed, checked and evaluated on the calling thread. This means EvalExpression
        // is not safe to call concurrently.
        let ctok = AssumeCompilationThreadWithoutEvidence()
        let cancellationToken = defaultArg cancellationToken CancellationToken.None

        let errorOptions = TcConfig.Create(tcConfigB, validate = false).diagnosticsOptions

        let diagnosticsLogger =
            CompilationDiagnosticLogger("EvalInteraction", errorOptions, eagerFormat)

        fsiInteractionProcessor.EvalInteraction(ctok, code, scriptFileName, diagnosticsLogger, cancellationToken)
        |> commitResultNonThrowing errorOptions scriptFileName diagnosticsLogger

    member _.EvalScript(filePath) : unit =
        // Explanation: When the user of the FsiInteractiveSession object calls this method, the
        // code is parsed, checked and evaluated on the calling thread. This means EvalExpression
        // is not safe to call concurrently.
        let ctok = AssumeCompilationThreadWithoutEvidence()

        fsiInteractionProcessor.EvalScript(ctok, filePath, diagnosticsLogger)
        |> commitResult
        |> ignore

    member _.EvalScriptNonThrowing(filePath) =
        // Explanation: When the user of the FsiInteractiveSession object calls this method, the
        // code is parsed, checked and evaluated on the calling thread. This means EvalExpression
        // is not safe to call concurrently.
        let ctok = AssumeCompilationThreadWithoutEvidence()

        let errorOptions = TcConfig.Create(tcConfigB, validate = false).diagnosticsOptions

        let diagnosticsLogger =
            CompilationDiagnosticLogger("EvalInteraction", errorOptions, eagerFormat)

        fsiInteractionProcessor.EvalScript(ctok, filePath, diagnosticsLogger)
        |> commitResultNonThrowing errorOptions filePath diagnosticsLogger
        |> function
            | Choice1Of2 _, errs -> Choice1Of2(), errs
            | Choice2Of2 exn, errs -> Choice2Of2 exn, errs

    /// Event fires when a root-level value is bound to an identifier, e.g., via `let x = ...`.
    member _.ValueBound = fsiDynamicCompiler.ValueBound

    member _.GetBoundValues() =
        fsiDynamicCompiler.GetBoundValues fsiInteractionProcessor.CurrentState

    member _.TryFindBoundValue(name: string) =
        fsiDynamicCompiler.TryFindBoundValue(fsiInteractionProcessor.CurrentState, name)

    member _.AddBoundValue(name: string, value: obj) =
        // Explanation: When the user of the FsiInteractiveSession object calls this method, the
        // code is parsed, checked and evaluated on the calling thread. This means EvalExpression
        // is not safe to call concurrently.
        let ctok = AssumeCompilationThreadWithoutEvidence()

        fsiInteractionProcessor.AddBoundValue(ctok, diagnosticsLogger, name, value)
        |> commitResult
        |> ignore

    /// Performs these steps:
    ///    - Load the dummy interaction, if any
    ///    - Set up exception handling, if any
    ///    - Load the initial files, if any
    ///    - Start the background thread to read the standard input, if any
    ///    - Sit in the GUI event loop indefinitely, if needed
    ///
    /// This method only returns after "exit". The method repeatedly calls the event loop and
    /// the thread may be subject to Thread.Abort() signals if Interrupt() is used, giving rise
    /// to internal ThreadAbortExceptions.
    ///
    /// A background thread is started by this thread to read from the inReader and/or console reader.

    member x.Run() =
        progress <- isEnvVarSet "FSHARP_INTERACTIVE_PROGRESS"

        // Explanation: When Run is called we do a bunch of processing. For fsi.exe
        // and fsiAnyCpu.exe there are no other active threads at this point, so we can assume this is the
        // unique compilation thread.  For other users of FsiEvaluationSession it is reasonable to assume that
        // the object is not accessed concurrently during startup preparation.
        //
        // We later switch to doing interaction-by-interaction processing on the "event loop" thread
        let ctokRun = AssumeCompilationThreadWithoutEvidence()

        if fsiOptions.IsInteractiveServer then
            SpawnInteractiveServer(fsi, fsiOptions, fsiConsoleOutput)

        use _ = UseBuildPhase BuildPhase.Interactive

        if fsiOptions.Interact then
            // page in the type check env
            fsiInteractionProcessor.LoadDummyInteraction(ctokStartup, diagnosticsLogger)

            if progress then
                fprintfn fsiConsoleOutput.Out "MAIN: got initial state, creating form"

            // Route background exceptions to the exception handlers
            AppDomain.CurrentDomain.UnhandledException.Add(fun args ->
                match args.ExceptionObject with
                | :? System.Exception as err -> x.ReportUnhandledExceptionSafe false err
                | _ -> ())

            fsiInteractionProcessor.LoadInitialFiles(ctokRun, diagnosticsLogger)
            fsiInteractionProcessor.StartStdinReadAndProcessThread(diagnosticsLogger)

            DriveFsiEventLoop(fsi, fsiInterruptController, fsiConsoleOutput)

        else // not interact
            if progress then
                fprintfn fsiConsoleOutput.Out "Run: not interact, loading initial files..."

            fsiInteractionProcessor.LoadInitialFiles(ctokRun, diagnosticsLogger)

            if progress then
                fprintfn fsiConsoleOutput.Out "Run: done..."

            exit (min diagnosticsLogger.ErrorCount 1)

        // The Ctrl-C exception handler that we've passed to native code has
        // to be explicitly kept alive.
        GC.KeepAlive fsiInterruptController.EventHandlers

    static member Create(fsiConfig, argv, inReader, outWriter, errorWriter, ?collectible, ?legacyReferenceResolver) =
        new FsiEvaluationSession(fsiConfig, argv, inReader, outWriter, errorWriter, defaultArg collectible false, legacyReferenceResolver)

    static member GetDefaultConfiguration(fsiObj: obj) =
        FsiEvaluationSession.GetDefaultConfiguration(fsiObj, true)

    static member GetDefaultConfiguration(fsiObj: obj, useFsiAuxLib: bool) =
        // We want to avoid modifying FSharp.Compiler.Interactive.Settings to avoid republishing that DLL.
        // So we access these via reflection
        { new FsiEvaluationSessionHostConfig() with
            member _.FormatProvider = getInstanceProperty fsiObj "FormatProvider"
            member _.FloatingPointFormat = getInstanceProperty fsiObj "FloatingPointFormat"
            member _.AddedPrinters = getInstanceProperty fsiObj "AddedPrinters"
            member _.ShowDeclarationValues = getInstanceProperty fsiObj "ShowDeclarationValues"
            member _.ShowIEnumerable = getInstanceProperty fsiObj "ShowIEnumerable"
            member _.ShowProperties = getInstanceProperty fsiObj "ShowProperties"
            member _.PrintSize = getInstanceProperty fsiObj "PrintSize"
            member _.PrintDepth = getInstanceProperty fsiObj "PrintDepth"
            member _.PrintWidth = getInstanceProperty fsiObj "PrintWidth"
            member _.PrintLength = getInstanceProperty fsiObj "PrintLength"

            member _.ReportUserCommandLineArgs args =
                setInstanceProperty fsiObj "CommandLineArgs" args

            member _.StartServer(fsiServerName) =
                failwith "--fsi-server not implemented in the default configuration"

            member _.EventLoopRun() =
                callInstanceMethod0 (getInstanceProperty fsiObj "EventLoop") [||] "Run"

            member _.EventLoopInvoke(f: unit -> 'T) =
                callInstanceMethod1 (getInstanceProperty fsiObj "EventLoop") [| typeof<'T> |] "Invoke" f

            member _.EventLoopScheduleRestart() =
                callInstanceMethod0 (getInstanceProperty fsiObj "EventLoop") [||] "ScheduleRestart"

            member _.UseFsiAuxLib = useFsiAuxLib
            member _.GetOptionalConsoleReadLine(_probe) = None
        }
//-------------------------------------------------------------------------------
// If no "fsi" object for the configuration is specified, make the default
// configuration one which stores the settings in-process

module Settings =
    type IEventLoop =
        abstract Run: unit -> bool
        abstract Invoke: (unit -> 'T) -> 'T
        abstract ScheduleRestart: unit -> unit

    // fsi.fs in FSHarp.Compiler.Service.dll avoids a hard dependency on FSharp.Compiler.Interactive.Settings.dll
    // by providing an optional reimplementation of the functionality

    // An implementation of IEventLoop suitable for the command-line console
    [<AutoSerializable(false)>]
    type internal SimpleEventLoop() =
        let runSignal = new AutoResetEvent(false)
        let exitSignal = new AutoResetEvent(false)
        let doneSignal = new AutoResetEvent(false)
        let mutable queue = ([]: (unit -> obj) list)
        let mutable result = (None: obj option)

        let setSignal (signal: AutoResetEvent) =
            while not (signal.Set()) do
                Thread.Sleep(1)

        let waitSignal signal =
            WaitHandle.WaitAll([| (signal :> WaitHandle) |]) |> ignore

        let waitSignal2 signal1 signal2 =
            WaitHandle.WaitAny([| (signal1 :> WaitHandle); (signal2 :> WaitHandle) |])

        let mutable running = false
        let mutable restart = false

        interface IEventLoop with
            member x.Run() =
                running <- true

                let rec run () =
                    match waitSignal2 runSignal exitSignal with
                    | 0 ->
                        queue
                        |> List.iter (fun f ->
                            result <-
                                try
                                    Some(f ())
                                with _ ->
                                    None)

                        setSignal doneSignal
                        run ()
                    | 1 ->
                        running <- false
                        restart
                    | _ -> run ()

                run ()

            member _.Invoke(f: unit -> 'T) : 'T =
                queue <- [ f >> box ]
                setSignal runSignal
                waitSignal doneSignal
                result.Value |> unbox

            member _.ScheduleRestart() =
                if running then
                    restart <- true
                    setSignal exitSignal

        interface IDisposable with
            member _.Dispose() =
                runSignal.Dispose()
                exitSignal.Dispose()
                doneSignal.Dispose()

    [<Sealed>]
    type InteractiveSettings() =
        let mutable evLoop = (new SimpleEventLoop() :> IEventLoop)
        let mutable showIDictionary = true
        let mutable showDeclarationValues = true
        let mutable args = Environment.GetCommandLineArgs()
        let mutable fpfmt = "g10"
        let mutable fp = (CultureInfo.InvariantCulture :> IFormatProvider)
        let mutable printWidth = 78
        let mutable printDepth = 100
        let mutable printLength = 100
        let mutable printSize = 10000
        let mutable showIEnumerable = true
        let mutable showProperties = true
        let mutable addedPrinters = []

        member _.FloatingPointFormat
            with get () = fpfmt
            and set v = fpfmt <- v

        member _.FormatProvider
            with get () = fp
            and set v = fp <- v

        member _.PrintWidth
            with get () = printWidth
            and set v = printWidth <- v

        member _.PrintDepth
            with get () = printDepth
            and set v = printDepth <- v

        member _.PrintLength
            with get () = printLength
            and set v = printLength <- v

        member _.PrintSize
            with get () = printSize
            and set v = printSize <- v

        member _.ShowDeclarationValues
            with get () = showDeclarationValues
            and set v = showDeclarationValues <- v

        member _.ShowProperties
            with get () = showProperties
            and set v = showProperties <- v

        member _.ShowIEnumerable
            with get () = showIEnumerable
            and set v = showIEnumerable <- v

        member _.ShowIDictionary
            with get () = showIDictionary
            and set v = showIDictionary <- v

        member _.AddedPrinters
            with get () = addedPrinters
            and set v = addedPrinters <- v

        member _.CommandLineArgs
            with get () = args
            and set v = args <- v

        member _.AddPrinter(printer: 'T -> string) =
            addedPrinters <- Choice1Of2(typeof<'T>, (fun (x: obj) -> printer (unbox x))) :: addedPrinters

        member _.EventLoop
            with get () = evLoop
            and set (x: IEventLoop) =
                evLoop.ScheduleRestart()
                evLoop <- x

        member _.AddPrintTransformer(printer: 'T -> obj) =
            addedPrinters <- Choice2Of2(typeof<'T>, (fun (x: obj) -> printer (unbox x))) :: addedPrinters

    let fsi = InteractiveSettings()

type FsiEvaluationSession with

    static member GetDefaultConfiguration() =
        FsiEvaluationSession.GetDefaultConfiguration(Settings.fsi, false)

/// Defines a read-only input stream used to feed content to the hosted F# Interactive dynamic compiler.
[<AllowNullLiteral>]
type CompilerInputStream() =
    inherit Stream()
    // Duration (in milliseconds) of the pause in the loop of waitForAtLeastOneByte.
    let pauseDuration = 100

    // Queue of characters waiting to be read.
    let readQueue = Queue<byte>()

    let waitForAtLeastOneByte (count: int) =
        let rec loop () =
            let attempt =
                lock readQueue (fun () ->
                    let n = readQueue.Count

                    if (n >= 1) then
                        let lengthToRead = if (n < count) then n else count
                        let ret = Array.zeroCreate lengthToRead

                        for i in 0 .. lengthToRead - 1 do
                            ret[i] <- readQueue.Dequeue()

                        Some ret
                    else
                        None)

            match attempt with
            | None ->
                Thread.Sleep(pauseDuration)
                loop ()
            | Some res -> res

        loop ()

    override x.CanRead = true
    override x.CanWrite = false
    override x.CanSeek = false

    override x.Position
        with get () = raise (NotSupportedException())
        and set _v = raise (NotSupportedException())

    override x.Length = raise (NotSupportedException())
    override x.Flush() = ()
    override x.Seek(_offset, _origin) = raise (NotSupportedException())
    override x.SetLength(_value) = raise (NotSupportedException())

    override x.Write(_buffer, _offset, _count) =
        raise (NotSupportedException("Cannot write to input stream"))

    override x.Read(buffer, offset, count) =
        let bytes = waitForAtLeastOneByte count
        Array.Copy(bytes, 0, buffer, offset, bytes.Length)
        bytes.Length

    /// Feeds content into the stream.
    member _.Add(str: string) =
        if (String.IsNullOrEmpty(str)) then
            ()
        else

            lock readQueue (fun () ->
                let bytes = Encoding.UTF8.GetBytes(str)

                for i in 0 .. bytes.Length - 1 do
                    readQueue.Enqueue(bytes[i]))

/// Defines a write-only stream used to capture output of the hosted F# Interactive dynamic compiler.
[<AllowNullLiteral>]
type CompilerOutputStream() =
    inherit Stream()
    // Queue of characters waiting to be read.
    let contentQueue = Queue<byte>()
    let nyi () = raise (NotSupportedException())

    override x.CanRead = false
    override x.CanWrite = true
    override x.CanSeek = false

    override x.Position
        with get () = nyi ()
        and set _v = nyi ()

    override x.Length = nyi ()
    override x.Flush() = ()
    override x.Seek(_offset, _origin) = nyi ()
    override x.SetLength(_value) = nyi ()

    override x.Read(_buffer, _offset, _count) =
        raise (NotSupportedException("Cannot write to input stream"))

    override x.Write(buffer, offset, count) =
        let stop = offset + count

        if (stop > buffer.Length) then
            raise (ArgumentException("offset,count"))

        lock contentQueue (fun () ->
            for i in offset .. stop - 1 do
                contentQueue.Enqueue(buffer[i]))

    member _.Read() =
        lock contentQueue (fun () ->
            let n = contentQueue.Count

            if (n > 0) then
                let bytes = Array.zeroCreate n

                for i in 0 .. n - 1 do
                    bytes[i] <- contentQueue.Dequeue()

                Encoding.UTF8.GetString(bytes, 0, n)
            else
                "")
