[Fable Compiler] AST endpoint

src/Fable.Cli/Fable.Cli.fsproj

@@ -33,7 +33,6 @@
     <Compile Include="FileWatchers.fsi" />
     <Compile Include="FileWatchers.fs" />
     <Compile Include="Pipeline.fs" />
-    <Compile Include="MSBuildCrackerResolver.fs" />
     <Compile Include="BuildalyzerCrackerResolver.fs" />
     <Compile Include="Main.fs" />
     <Compile Include="CustomLogging.fs" />

src/Fable.Cli/Main.fs

@@ -14,7 +14,6 @@ open Fable.Transforms
 open Fable.Transforms.State
 open Fable.Compiler.ProjectCracker
 open Fable.Compiler.Util
-open Fable.Cli.MSBuildCrackerResolver
 
 module private Util =
     type PathResolver with
@@ -376,7 +375,7 @@ type ProjectCracked(cliArgs: CliArgs, crackerResponse: CrackerResponse, sourceFi
             <| fun () ->
                 let resolver: ProjectCrackerResolver =
                     if useMSBuildForCracking then
-                        MSBuildCrackerResolver()
+                        Fable.Compiler.MSBuildCrackerResolver()
                     else
                         BuildalyzerCrackerResolver()
 

src/Fable.Compiler/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+* [GH-3758](https://github.com/fable-compiler/Fable/pull/3758) Endpoint to get Fable.AST for a file. (by @nojaf)
+
 ## 4.0.0-alpha-006 - 2024-02-12
 
 ### Changed

src/Fable.Compiler/Fable.Compiler.fsproj

@@ -23,6 +23,7 @@
         <Compile Include="File.fs" />
         <Compile Include="ProjectCracker.fsi" />
         <Compile Include="ProjectCracker.fs" />
+        <Compile Include="MSBuildCrackerResolver.fs" />
         <Compile Include="Library.fsi"/>
         <Compile Include="Library.fs"/>
     </ItemGroup>

src/Fable.Compiler/Library.fs

@@ -117,7 +117,6 @@ module CodeServices =
             return output
         }
 
-
     let typeCheckProject
         (sourceReader: SourceReader)
         (checker: InteractiveChecker)
@@ -142,6 +141,58 @@ module CodeServices =
                 }
         }
 
+    let compileFileToFableAST
+        (sourceReader: SourceReader)
+        (checker: InteractiveChecker)
+        (cliArgs: CliArgs)
+        (crackerResponse: CrackerResponse)
+        (currentFile: string)
+        : Async<AST.Fable.File>
+        =
+        async {
+            let! assemblies = checker.GetImportedAssemblies()
+
+            // Type-check the project up until the current file.
+            let! checkProjectResult =
+                checker.ParseAndCheckProject(
+                    cliArgs.ProjectFile,
+                    crackerResponse.ProjectOptions.SourceFiles,
+                    sourceReader,
+                    lastFile = currentFile
+                )
+
+            let fableProj =
+                Project.From(
+                    cliArgs.ProjectFile,
+                    crackerResponse.ProjectOptions.SourceFiles,
+                    checkProjectResult.AssemblyContents.ImplementationFiles,
+                    assemblies,
+                    Log.log,
+                    getPlugin = Reflection.loadType cliArgs
+                )
+
+            let opts = cliArgs.CompilerOptions
+
+            let fableLibDir = Path.getRelativePath currentFile crackerResponse.FableLibDir
+
+            let compiler: Compiler =
+                CompilerImpl(
+                    currentFile,
+                    fableProj,
+                    opts,
+                    fableLibDir,
+                    crackerResponse.OutputType,
+                    ?outDir = cliArgs.OutDir
+                )
+
+            // TODO: make it configurable if FableTransforms.transformFile is applied?
+            let fableAST =
+                FSharp2Fable.Compiler.transformFile compiler
+                |> FableTransforms.transformFile compiler
+
+            return fableAST
+        }
+
     let compileMultipleFilesToJavaScript
         (pathResolver: PathResolver)
         (cliArgs: CliArgs)

src/Fable.Compiler/Library.fsi

@@ -32,6 +32,15 @@ module CodeServices =
         crackerResponse: CrackerResponse ->
             Async<TypeCheckProjectResult>
 
+    /// Transform a file in a project to Fable.AST
+    val compileFileToFableAST:
+        sourceReader: SourceReader ->
+        checker: InteractiveChecker ->
+        cliArgs: CliArgs ->
+        crackerResponse: CrackerResponse ->
+        currentFile: string ->
+            Async<AST.Fable.File>
+
     /// And compile multiple files of a project to JavaScript.
     /// The expected usage of this function is either every file in the project or only the user files.
     val compileMultipleFilesToJavaScript: