Compiler Services: Virtualized File System

#r "FSharp.Compiler.Service.dll"

open System.IO
open System.Text
open FSharp.Compiler.CodeAnalysis
open FSharp.Compiler.IO

let defaultFileSystem = FileSystem

let fileName1 = @"c:\mycode\test1.fs" // note, the path doesn't exist
let fileName2 = @"c:\mycode\test2.fs" // note, the path doesn't exist

type MyFileSystem() =
    let file1 =
        """
module File1

let A = 1"""

    let file2 =
        """
module File2
let B = File1.A + File1.A"""

    let files =
        dict [ (fileName1, file1)
               (fileName2, file2) ]

    interface IFileSystem with
        // Implement the service to open files for reading and writing
        member _.OpenFileForReadShim(fileName, ?useMemoryMappedFile: bool, ?shouldShadowCopy: bool) =
            match files.TryGetValue fileName with
            | true, text -> new MemoryStream(Encoding.UTF8.GetBytes(text)) :> Stream
            | _ ->
                defaultFileSystem.OpenFileForReadShim(
                    fileName,
                    ?useMemoryMappedFile = useMemoryMappedFile,
                    ?shouldShadowCopy = shouldShadowCopy
                )

        member _.OpenFileForWriteShim(fileName, ?fileMode: FileMode, ?fileAccess: FileAccess, ?fileShare: FileShare) =
            defaultFileSystem.OpenFileForWriteShim(
                fileName,
                ?fileMode = fileMode,
                ?fileAccess = fileAccess,
                ?fileShare = fileShare
            )

        // Implement the service related to file existence and deletion
        member _.FileExistsShim(fileName) =
            files.ContainsKey(fileName)
            || defaultFileSystem.FileExistsShim(fileName)

        // Implement the service related to temporary paths and file time stamps
        member _.GetTempPathShim() = defaultFileSystem.GetTempPathShim()

        member _.GetLastWriteTimeShim(fileName) =
            defaultFileSystem.GetLastWriteTimeShim(fileName)

        member _.GetFullPathShim(fileName) =
            defaultFileSystem.GetFullPathShim(fileName)

        member _.IsInvalidPathShim(fileName) =
            defaultFileSystem.IsInvalidPathShim(fileName)

        member _.IsPathRootedShim(fileName) =
            defaultFileSystem.IsPathRootedShim(fileName)

        member _.FileDeleteShim(fileName) =
            defaultFileSystem.FileDeleteShim(fileName)

        member _.AssemblyLoader = defaultFileSystem.AssemblyLoader

        member _.GetFullFilePathInDirectoryShim dir fileName =
            defaultFileSystem.GetFullFilePathInDirectoryShim dir fileName

        member _.NormalizePathShim(path) =
            defaultFileSystem.NormalizePathShim(path)

        member _.GetDirectoryNameShim(path) =
            defaultFileSystem.GetDirectoryNameShim(path)

        member _.GetCreationTimeShim(path) =
            defaultFileSystem.GetCreationTimeShim(path)

        member _.CopyShim(src, dest, overwrite) =
            defaultFileSystem.CopyShim(src, dest, overwrite)

        member _.DirectoryCreateShim(path) =
            defaultFileSystem.DirectoryCreateShim(path)

        member _.DirectoryExistsShim(path) =
            defaultFileSystem.DirectoryExistsShim(path)

        member _.DirectoryDeleteShim(path) =
            defaultFileSystem.DirectoryDeleteShim(path)

        member _.EnumerateFilesShim(path, pattern) =
            defaultFileSystem.EnumerateFilesShim(path, pattern)

        member _.EnumerateDirectoriesShim(path) =
            defaultFileSystem.EnumerateDirectoriesShim(path)

        member _.IsStableFileHeuristic(path) =
            defaultFileSystem.IsStableFileHeuristic(path)

        member this.ChangeExtensionShim(path, extension) =
            defaultFileSystem.ChangeExtensionShim(path, extension)

let myFileSystem = MyFileSystem()
FileSystem <- MyFileSystem()

let checker = FSharpChecker.Create()

let projectOptions =
    let sysLib nm =
        if System.Environment.OSVersion.Platform = System.PlatformID.Win32NT then // file references only valid on Windows
            System.Environment.GetFolderPath(System.Environment.SpecialFolder.ProgramFilesX86)
            + @"\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\"
            + nm
            + ".dll"
        else
            let sysDir =
                System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory()

            let (++) a b = System.IO.Path.Combine(a, b)
            sysDir ++ nm + ".dll"

    let fsCore4300 () =
        if System.Environment.OSVersion.Platform = System.PlatformID.Win32NT then // file references only valid on Windows
            System.Environment.GetFolderPath(System.Environment.SpecialFolder.ProgramFilesX86)
            + @"\Reference Assemblies\Microsoft\FSharp\.NETFramework\v4.0\4.3.0.0\FSharp.Core.dll"
        else
            sysLib "FSharp.Core"

    let allFlags =
        [| "--simpleresolution"
           "--noframework"
           "--debug:full"
           "--define:DEBUG"
           "--optimize-"
           "--doc:test.xml"
           "--warn:3"
           "--fullpaths"
           "--flaterrors"
           "--target:library"
           let references =
               [ sysLib "mscorlib"
                 sysLib "System"
                 sysLib "System.Core"
                 fsCore4300 () ]

           for r in references do
               "-r:" + r |]

    { ProjectFileName = @"c:\mycode\compilation.fsproj" // Make a name that is unique in this directory.
      ProjectId = None
      SourceFiles = [| fileName1; fileName2 |]
      OriginalLoadReferences = []
      Stamp = None
      OtherOptions = allFlags
      ReferencedProjects = [||]
      IsIncompleteTypeCheckEnvironment = false
      UseScriptResolutionRules = true
      LoadTime = System.DateTime.Now // Note using 'Now' forces reloading
      UnresolvedReferences = None }

let results =
    checker.ParseAndCheckProject(projectOptions)
    |> Async.RunSynchronously

results.Diagnostics
results.AssemblySignature.Entities.Count //2

results.AssemblySignature.Entities.[0]
    .MembersFunctionsAndValues
    .Count

results.AssemblySignature.Entities.[0]
    .MembersFunctionsAndValues.[0]
    .DisplayName