Code action: Extract module to file (#983)

* code action for extracting a module to a new file

* make sure comments are retained

* fix broken serialization

* changelog

Author: zth

Diff for: CHANGELOG.md

@@ -31,6 +31,7 @@
 - Statically linked Linux binaries
 - Emit `%todo` instead of `failwith("TODO")` when we can (ReScript >= v11.1). https://github.com/rescript-lang/rescript-vscode/pull/981
 - Complete `%todo`. https://github.com/rescript-lang/rescript-vscode/pull/981
+- Add code action for extracting a locally defined module into its own file. https://github.com/rescript-lang/rescript-vscode/pull/983
 
 ## 1.50.0
 

Diff for: analysis/src/CodeActions.ml

@@ -13,6 +13,15 @@ let make ~title ~kind ~uri ~newText ~range =
     edit =
       {
         documentChanges =
-          [{textDocument = {version = None; uri}; edits = [{newText; range}]}];
+          [
+            TextDocumentEdit
+              {
+                Protocol.textDocument = {version = None; uri};
+                edits = [{newText; range}];
+              };
+          ];
       };
   }
+
+let makeWithDocumentChanges ~title ~kind ~documentChanges =
+  {Protocol.title; codeActionKind = kind; edit = {documentChanges}}

Diff for: analysis/src/Codemod.ml

@@ -6,7 +6,7 @@ let rec collectPatterns p =
   | _ -> [p]
 
 let transform ~path ~pos ~debug ~typ ~hint =
-  let structure, printExpr, _ = Xform.parseImplementation ~filename:path in
+  let structure, printExpr, _, _ = Xform.parseImplementation ~filename:path in
   match typ with
   | AddMissingCases -> (
     let source = "let " ^ hint ^ " = ()" in

Diff for: analysis/src/Commands.ml

@@ -453,15 +453,23 @@ let test ~path =
             |> List.iter (fun {Protocol.title; edit = {documentChanges}} ->
                    Printf.printf "Hit: %s\n" title;
                    documentChanges
-                   |> List.iter (fun {Protocol.edits} ->
-                          edits
-                          |> List.iter (fun {Protocol.range; newText} ->
-                                 let indent =
-                                   String.make range.start.character ' '
-                                 in
-                                 Printf.printf "%s\nnewText:\n%s<--here\n%s%s\n"
-                                   (Protocol.stringifyRange range)
-                                   indent indent newText)))
+                   |> List.iter (fun dc ->
+                          match dc with
+                          | Protocol.TextDocumentEdit tde ->
+                            Printf.printf "\nTextDocumentEdit: %s\n"
+                              tde.textDocument.uri;
+
+                            tde.edits
+                            |> List.iter (fun {Protocol.range; newText} ->
+                                   let indent =
+                                     String.make range.start.character ' '
+                                   in
+                                   Printf.printf
+                                     "%s\nnewText:\n%s<--here\n%s%s\n"
+                                     (Protocol.stringifyRange range)
+                                     indent indent newText)
+                          | CreateFile cf ->
+                            Printf.printf "\nCreateFile: %s\n" cf.uri))
           | "c-a" ->
             let hint = String.sub rest 3 (String.length rest - 3) in
             print_endline

Diff for: analysis/src/Protocol.ml

@@ -75,7 +75,14 @@ type textDocumentEdit = {
   edits: textEdit list;
 }
 
-type codeActionEdit = {documentChanges: textDocumentEdit list}
+type createFileOptions = {overwrite: bool option; ignoreIfExists: bool option}
+type createFile = {uri: string; options: createFileOptions option}
+
+type documentChange =
+  | TextDocumentEdit of textDocumentEdit
+  | CreateFile of createFile
+
+type codeActionEdit = {documentChanges: documentChange list}
 type codeActionKind = RefactorRewrite
 
 type codeAction = {
@@ -232,13 +239,41 @@ let stringifyTextDocumentEdit tde =
     (stringifyoptionalVersionedTextDocumentIdentifier tde.textDocument)
     (tde.edits |> List.map stringifyTextEdit |> array)
 
+let stringifyCreateFile cf =
+  stringifyObject
+    [
+      ("kind", Some (wrapInQuotes "create"));
+      ("uri", Some (wrapInQuotes cf.uri));
+      ( "options",
+        match cf.options with
+        | None -> None
+        | Some options ->
+          Some
+            (stringifyObject
+               [
+                 ( "overwrite",
+                   match options.overwrite with
+                   | None -> None
+                   | Some ov -> Some (string_of_bool ov) );
+                 ( "ignoreIfExists",
+                   match options.ignoreIfExists with
+                   | None -> None
+                   | Some i -> Some (string_of_bool i) );
+               ]) );
+    ]
+
+let stringifyDocumentChange dc =
+  match dc with
+  | TextDocumentEdit tde -> stringifyTextDocumentEdit tde
+  | CreateFile cf -> stringifyCreateFile cf
+
 let codeActionKindToString kind =
   match kind with
   | RefactorRewrite -> "refactor.rewrite"
 
 let stringifyCodeActionEdit cae =
   Printf.sprintf {|{"documentChanges": %s}|}
-    (cae.documentChanges |> List.map stringifyTextDocumentEdit |> array)
+    (cae.documentChanges |> List.map stringifyDocumentChange |> array)
 
 let stringifyCodeAction ca =
   Printf.sprintf {|{"title": "%s", "kind": "%s", "edit": %s}|} ca.title

Diff for: analysis/src/Xform.ml

@@ -117,6 +117,75 @@ module IfThenElse = struct
       codeActions := codeAction :: !codeActions
 end
 
+module ModuleToFile = struct
+  let mkIterator ~pos ~changed ~path ~printStandaloneStructure =
+    let structure_item (iterator : Ast_iterator.iterator)
+        (structure_item : Parsetree.structure_item) =
+      (match structure_item.pstr_desc with
+      | Pstr_module
+          {pmb_loc; pmb_name; pmb_expr = {pmod_desc = Pmod_structure structure}}
+        when structure_item.pstr_loc |> Loc.hasPos ~pos ->
+        let range = rangeOfLoc structure_item.pstr_loc in
+        let newTextInCurrentFile = "" in
+        let textForExtractedFile =
+          printStandaloneStructure ~loc:pmb_loc structure
+        in
+        let moduleName = pmb_name.txt in
+        let newFilePath =
+          Uri.fromPath
+            (Filename.concat (Filename.dirname path) moduleName ^ ".res")
+        in
+        changed :=
+          Some
+            (CodeActions.makeWithDocumentChanges ~title:"Extract module as file"
+               ~kind:RefactorRewrite
+               ~documentChanges:
+                 [
+                   Protocol.CreateFile
+                     {
+                       uri = newFilePath |> Uri.toString;
+                       options =
+                         Some
+                           {overwrite = Some false; ignoreIfExists = Some true};
+                     };
+                   TextDocumentEdit
+                     {
+                       textDocument =
+                         {uri = newFilePath |> Uri.toString; version = None};
+                       edits =
+                         [
+                           {
+                             newText = textForExtractedFile;
+                             range =
+                               {
+                                 start = {line = 0; character = 0};
+                                 end_ = {line = 0; character = 0};
+                               };
+                           };
+                         ];
+                     };
+                   TextDocumentEdit
+                     {
+                       textDocument = {uri = path; version = None};
+                       edits = [{newText = newTextInCurrentFile; range}];
+                     };
+                 ]);
+        ()
+      | _ -> ());
+      Ast_iterator.default_iterator.structure_item iterator structure_item
+    in
+
+    {Ast_iterator.default_iterator with structure_item}
+
+  let xform ~pos ~codeActions ~path ~printStandaloneStructure structure =
+    let changed = ref None in
+    let iterator = mkIterator ~pos ~path ~changed ~printStandaloneStructure in
+    iterator.structure iterator structure;
+    match !changed with
+    | None -> ()
+    | Some codeAction -> codeActions := codeAction :: !codeActions
+end
+
 module AddBracesToFn = struct
   (* Add braces to fn without braces *)
 
@@ -626,7 +695,12 @@ let parseImplementation ~filename =
          ~comments:(comments |> filterComments ~loc:item.pstr_loc)
     |> Utils.indent range.start.character
   in
-  (structure, printExpr, printStructureItem)
+  let printStandaloneStructure ~(loc : Location.t) structure =
+    structure
+    |> Res_printer.printImplementation ~width:!Res_cli.ResClflags.width
+         ~comments:(comments |> filterComments ~loc)
+  in
+  (structure, printExpr, printStructureItem, printStandaloneStructure)
 
 let parseInterface ~filename =
   let {Res_driver.parsetree = structure; comments} =
@@ -654,10 +728,12 @@ let extractCodeActions ~path ~startPos ~endPos ~currentFile ~debug =
   let codeActions = ref [] in
   match Files.classifySourceFile currentFile with
   | Res ->
-    let structure, printExpr, printStructureItem =
+    let structure, printExpr, printStructureItem, printStandaloneStructure =
       parseImplementation ~filename:currentFile
     in
     IfThenElse.xform ~pos ~codeActions ~printExpr ~path structure;
+    ModuleToFile.xform ~pos ~codeActions ~path ~printStandaloneStructure
+      structure;
     AddBracesToFn.xform ~pos ~codeActions ~path ~printStructureItem structure;
     AddDocTemplate.Implementation.xform ~pos ~codeActions ~path
       ~printStructureItem ~structure;

Diff for: analysis/tests/not_compiled/expected/DocTemplate.res.txt

@@ -1,6 +1,8 @@
 Xform not_compiled/DocTemplate.res 3:3
 can't find module DocTemplate
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.res
 {"start": {"line": 3, "character": 0}, "end": {"line": 5, "character": 9}}
 newText:
 <--here
@@ -14,6 +16,8 @@ and e = C
 Xform not_compiled/DocTemplate.res 6:15
 can't find module DocTemplate
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.res
 {"start": {"line": 6, "character": 0}, "end": {"line": 6, "character": 33}}
 newText:
 <--here
@@ -26,6 +30,8 @@ type name = Name(string)
 Xform not_compiled/DocTemplate.res 8:4
 can't find module DocTemplate
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.res
 {"start": {"line": 8, "character": 0}, "end": {"line": 8, "character": 9}}
 newText:
 <--here
@@ -37,6 +43,8 @@ let a = 1
 Xform not_compiled/DocTemplate.res 10:4
 can't find module DocTemplate
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.res
 {"start": {"line": 10, "character": 0}, "end": {"line": 10, "character": 20}}
 newText:
 <--here
@@ -48,6 +56,8 @@ let inc = x => x + 1
 Xform not_compiled/DocTemplate.res 12:7
 can't find module DocTemplate
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.res
 {"start": {"line": 12, "character": 0}, "end": {"line": 16, "character": 1}}
 newText:
 <--here
@@ -59,21 +69,61 @@ module T = {
   let b = 1
   //  ^xfm
 }
+Hit: Extract module as file
+
+CreateFile: T.res
+
+TextDocumentEdit: T.res
+{"start": {"line": 0, "character": 0}, "end": {"line": 0, "character": 0}}
+newText:
+<--here
+//   ^xfm
+let b = 1
+//  ^xfm
+
+
+TextDocumentEdit: not_compiled/DocTemplate.res
+{"start": {"line": 12, "character": 0}, "end": {"line": 16, "character": 1}}
+newText:
+<--here
+
 
 Xform not_compiled/DocTemplate.res 14:6
 can't find module DocTemplate
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.res
 {"start": {"line": 14, "character": 2}, "end": {"line": 14, "character": 11}}
 newText:
   <--here
   /**
 
   */
   let b = 1
+Hit: Extract module as file
+
+CreateFile: T.res
+
+TextDocumentEdit: T.res
+{"start": {"line": 0, "character": 0}, "end": {"line": 0, "character": 0}}
+newText:
+<--here
+//   ^xfm
+let b = 1
+//  ^xfm
+
+
+TextDocumentEdit: not_compiled/DocTemplate.res
+{"start": {"line": 12, "character": 0}, "end": {"line": 16, "character": 1}}
+newText:
+<--here
+
 
 Xform not_compiled/DocTemplate.res 18:2
 can't find module DocTemplate
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.res
 {"start": {"line": 17, "character": 0}, "end": {"line": 18, "character": 46}}
 newText:
 <--here

Diff for: analysis/tests/not_compiled/expected/DocTemplate.resi.txt

@@ -1,5 +1,7 @@
 Xform not_compiled/DocTemplate.resi 3:3
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.resi
 {"start": {"line": 3, "character": 0}, "end": {"line": 5, "character": 9}}
 newText:
 <--here
@@ -12,6 +14,8 @@ and e = C
 
 Xform not_compiled/DocTemplate.resi 6:15
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.resi
 {"start": {"line": 6, "character": 0}, "end": {"line": 6, "character": 33}}
 newText:
 <--here
@@ -23,6 +27,8 @@ type name = Name(string)
 
 Xform not_compiled/DocTemplate.resi 8:4
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.resi
 {"start": {"line": 8, "character": 0}, "end": {"line": 8, "character": 10}}
 newText:
 <--here
@@ -33,6 +39,8 @@ let a: int
 
 Xform not_compiled/DocTemplate.resi 10:4
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.resi
 {"start": {"line": 10, "character": 0}, "end": {"line": 10, "character": 19}}
 newText:
 <--here
@@ -43,6 +51,8 @@ let inc: int => int
 
 Xform not_compiled/DocTemplate.resi 12:7
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.resi
 {"start": {"line": 12, "character": 0}, "end": {"line": 16, "character": 1}}
 newText:
 <--here
@@ -57,6 +67,8 @@ module T: {
 
 Xform not_compiled/DocTemplate.resi 14:6
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.resi
 {"start": {"line": 14, "character": 2}, "end": {"line": 14, "character": 12}}
 newText:
   <--here
@@ -67,6 +79,8 @@ newText:
 
 Xform not_compiled/DocTemplate.resi 18:2
 Hit: Add Documentation template
+
+TextDocumentEdit: DocTemplate.resi
 {"start": {"line": 17, "character": 0}, "end": {"line": 18, "character": 46}}
 newText:
 <--here