Sourcemap tab

Author: fhammerschmidt

compiler/core/js_source_map.ml

@@ -41,6 +41,7 @@ type t = {
   generated_dir: string;
   source_root: string;
   sources_content: bool;
+  provided_source_contents: (string, string) Hashtbl.t;
   sources: (string, int) Hashtbl.t;
   mutable source_list: source list;
   mutable mappings: mapping list;
@@ -109,20 +110,27 @@ let relative_path ~from_dir ~to_file =
     let parts = repeat ".." (List.length from_rest) @ to_rest in
     if parts = [] then Filename.basename to_file else String.concat "/" parts
 
-let make ~generated_file ~source_root ~sources_content =
+let make ~source_contents ~generated_file ~source_root ~sources_content =
+  let provided_source_contents = Hashtbl.create (List.length source_contents) in
+  source_contents
+  |> List.iter (fun (filename, content) ->
+      Hashtbl.replace provided_source_contents (absolute_path filename) content);
   {
     generated_file = Filename.basename generated_file;
     generated_dir = Filename.dirname generated_file;
     source_root;
     sources_content;
+    provided_source_contents;
     sources = Hashtbl.create 4;
     source_list = [];
     mappings = [];
     last_generated = None;
   }
 
-let load_content filename =
-  try Some (Ext_io.load_file filename) with _ -> None
+let load_content builder filename =
+  match Hashtbl.find_opt builder.provided_source_contents filename with
+  | Some content -> Some content
+  | None -> (try Some (Ext_io.load_file filename) with _ -> None)
 
 let add_source builder filename =
   let filename =
@@ -138,7 +146,7 @@ let add_source builder filename =
       {
         relative_path =
           relative_path ~from_dir:builder.generated_dir ~to_file:filename;
-        content = load_content filename;
+        content = load_content builder filename;
       }
     in
     let index = List.length builder.source_list in

compiler/core/js_source_map.mli

@@ -1,7 +1,11 @@
 type t
 
 val make :
-  generated_file:string -> source_root:string -> sources_content:bool -> t
+  source_contents:(string * string) list ->
+  generated_file:string ->
+  source_root:string ->
+  sources_content:bool ->
+  t
 
 val with_builder : t -> (unit -> 'a) -> 'a
 

compiler/core/lam_compile_main.ml

@@ -434,7 +434,7 @@ let remove_stale_source_map ?(remove_stale_map = true) target_file =
 let dump_deps_program_with_source_map ?(remove_stale_map = true) ~target_file
     ~output_prefix module_system lambda_output chan =
   let builder =
-    Js_source_map.make ~generated_file:target_file
+    Js_source_map.make ~source_contents:[] ~generated_file:target_file
       ~source_root:!Js_config.source_map_root
       ~sources_content:!Js_config.source_map_sources_content
   in

compiler/jsoo/jsoo_playground_main.ml

@@ -52,7 +52,7 @@
  * v5: Removed .ml support.
  * v6: Added `config.experimental_features` and `config.jsx_preserve_mode` to the BundleConfig.
  * v7: Added debug dump output APIs for developer playground tooling,
- * including gentype output.
+ * including gentype and source map output.
  * *)
 let api_version = "7"
 
@@ -80,6 +80,9 @@ module Bundle_config = struct
     mutable experimental_features: string list;
     mutable jsx_preserve_mode: bool;
     mutable gentype_enabled: bool;
+    mutable source_map_mode: Js_config.source_map;
+    mutable source_map_sources_content: bool;
+    mutable source_map_root: string;
   }
 
   let make () =
@@ -91,6 +94,9 @@ module Bundle_config = struct
       experimental_features = [];
       jsx_preserve_mode = false;
       gentype_enabled = false;
+      source_map_mode = No_source_map;
+      source_map_sources_content = false;
+      source_map_root = "";
     }
 
   let default_filename (lang : Lang.t) = "playground." ^ Lang.to_string lang
@@ -99,6 +105,21 @@ module Bundle_config = struct
     match m with
     | Ext_module_system.Commonjs -> "commonjs"
     | Esmodule -> "esmodule"
+
+  let source_map_of_string value =
+    match String.lowercase_ascii value with
+    | "linked" -> Some Js_config.Linked
+    | "inline" -> Some Inline
+    | "hidden" -> Some Hidden
+    | "false" | "none" | "disabled" -> Some No_source_map
+    | _ -> None
+
+  let string_of_source_map mode =
+    match mode with
+    | Js_config.Linked -> "linked"
+    | Inline -> "inline"
+    | Hidden -> "hidden"
+    | No_source_map -> "false"
 end
 
 type loc_err_info = {
@@ -542,6 +563,47 @@ module Compile = struct
       ^ "\n" ^ code_text ^ "\n"
     else "No @gentype annotations found."
 
+  let render_javascript ~module_system ~filename ~source ~source_map_mode
+      ~source_map_sources_content ~source_map_root lambda_output =
+    let buffer = Buffer.create 1000 in
+    let generated_file =
+      Filename.concat (Sys.getcwd ())
+        (Filename.remove_extension (Filename.basename filename)
+        ^ Literals.suffix_js)
+    in
+    let source_map_builder =
+      match source_map_mode with
+      | Js_config.No_source_map -> None
+      | Linked | Inline | Hidden ->
+        Some
+          (Js_source_map.make ~source_contents:[(filename, source)] ~generated_file
+             ~source_root:source_map_root
+             ~sources_content:source_map_sources_content)
+    in
+    let print_javascript () =
+      Js_dump_program.pp_deps_program ~output_prefix:"" module_system
+        lambda_output (Ext_pp.from_buffer buffer)
+    in
+    (match source_map_builder with
+    | None -> print_javascript ()
+    | Some builder -> Js_source_map.with_builder builder print_javascript);
+    let source_map =
+      match source_map_builder with
+      | None -> None
+      | Some builder ->
+        let json = Js_source_map.json builder in
+        (match source_map_mode with
+        | Linked ->
+          Buffer.add_string buffer
+            (Js_source_map.linked_comment ~map_file:(generated_file ^ ".map"))
+        | Inline ->
+          Buffer.add_string buffer (Js_source_map.inline_comment ~json)
+        | Hidden -> ()
+        | No_source_map -> assert false);
+        Some json
+    in
+    (Buffer.contents buffer, source_map)
+
   let implementation ?(include_debug_outputs = false)
       ~(config : Bundle_config.t) ~lang str =
     let {
@@ -551,6 +613,9 @@ module Compile = struct
       experimental_features;
       jsx_preserve_mode;
       gentype_enabled;
+      source_map_mode;
+      source_map_sources_content;
+      source_map_root;
     } =
       config
     in
@@ -572,6 +637,9 @@ module Compile = struct
       let types_signature = ref [] in
       Js_config.jsx_version := Some Js_config.Jsx_v4;
       Js_config.jsx_preserve := jsx_preserve_mode;
+      Js_config.source_map := source_map_mode;
+      Js_config.source_map_sources_content := source_map_sources_content;
+      Js_config.source_map_root := source_map_root;
       experimental_features
       |> List.iter Experimental_features.enable_from_string;
       (* default *)
@@ -589,19 +657,18 @@ module Compile = struct
       let {Translmod.lambda; exports; hoisted_functions} =
         Translmod.transl_implementation modulename typed_tree
       in
-      let buffer = Buffer.create 1000 in
-      let () =
-        Js_dump_program.pp_deps_program ~output_prefix:""
-          (* does not matter here *) module_system
-          (Lam_compile_main.compile "" exports hoisted_functions lambda)
-          (Ext_pp.from_buffer buffer)
+      let lambda_output =
+        Lam_compile_main.compile "" exports hoisted_functions lambda
+      in
+      let js_code, source_map =
+        render_javascript ~module_system ~filename ~source:str ~source_map_mode
+          ~source_map_sources_content ~source_map_root lambda_output
       in
-      let v = Buffer.contents buffer in
       let type_hints = collect_type_hints typed_tree in
       let attrs =
         Js.Unsafe.
           [|
-            ("js_code", inject @@ Js.string v);
+            ("js_code", inject @@ Js.string js_code);
             ( "warnings",
               inject
               @@ (!warning_infos
@@ -633,13 +700,12 @@ module Compile = struct
               |]
           else [||]
         in
-        (* TODO(sourcemap PR): The developer playground already knows how to
-           show an optional "source_map" debug tab. Add optional instance
-           setters named "setSourceMapMode", "setSourceMapSourcesContent",
-           and "setSourceMapRoot", matching getConfig fields named
-           "source_map_mode", "source_map_sources_content", and
-           "source_map_root", plus a compileWithDebug output field named
-           "source_map". *)
+        let source_map_attrs =
+          match source_map with
+          | None -> [||]
+          | Some source_map ->
+            Js.Unsafe.[|("source_map", inject @@ Js.string source_map)|]
+        in
         let debug_attrs =
           Js.Unsafe.
             [|
@@ -649,7 +715,8 @@ module Compile = struct
               ("lam", inject @@ Js.string lam);
             |]
         in
-        Js.Unsafe.obj (Array.concat [attrs; debug_attrs; gentype_attrs])
+        Js.Unsafe.obj
+          (Array.concat [attrs; debug_attrs; gentype_attrs; source_map_attrs])
       else Js.Unsafe.obj attrs
     with e -> (
       match e with
@@ -754,6 +821,21 @@ module Export = struct
       config.gentype_enabled <- value;
       true
     in
+    let set_source_map_mode value =
+      match Bundle_config.source_map_of_string value with
+      | Some source_map_mode ->
+        config.source_map_mode <- source_map_mode;
+        true
+      | None -> false
+    in
+    let set_source_map_sources_content value =
+      config.source_map_sources_content <- value;
+      true
+    in
+    let set_source_map_root value =
+      config.source_map_root <- value;
+      true
+    in
     let convert_syntax ~(from_lang : string) ~(to_lang : string) (src : string)
         =
       let open Lang in
@@ -816,6 +898,19 @@ module Export = struct
             inject
             @@ Js.wrap_meth_callback (fun _ value ->
                    Js.bool (set_gentype_enabled (Js.to_bool value))) );
+          ( "setSourceMapMode",
+            inject
+            @@ Js.wrap_meth_callback (fun _ value ->
+                   Js.bool (set_source_map_mode (Js.to_string value))) );
+          ( "setSourceMapSourcesContent",
+            inject
+            @@ Js.wrap_meth_callback (fun _ value ->
+                   Js.bool
+                     (set_source_map_sources_content (Js.to_bool value))) );
+          ( "setSourceMapRoot",
+            inject
+            @@ Js.wrap_meth_callback (fun _ value ->
+                   Js.bool (set_source_map_root (Js.to_string value))) );
           ( "getConfig",
             inject
             @@ Js.wrap_meth_callback (fun _ ->
@@ -832,6 +927,16 @@ module Export = struct
                            inject @@ (config.jsx_preserve_mode |> Js.bool) );
                          ( "gentype_enabled",
                            inject @@ (config.gentype_enabled |> Js.bool) );
+                         ( "source_map_mode",
+                           inject
+                           @@ (config.source_map_mode
+                             |> Bundle_config.string_of_source_map |> Js.string)
+                         );
+                         ( "source_map_sources_content",
+                           inject
+                           @@ (config.source_map_sources_content |> Js.bool) );
+                         ( "source_map_root",
+                           inject @@ Js.string config.source_map_root );
                          ( "experimental_features",
                            inject
                            @@ (config.experimental_features |> Array.of_list

packages/dev-playground/package.json

@@ -9,11 +9,13 @@
     "prepare-pages-site": "node scripts/prepare-pages-site.mjs",
     "res:build": "rescript",
     "res:watch": "rescript -w",
+    "test": "rescript && node --test scripts/source-map-navigation.test.mjs",
     "dev": "vite --host 127.0.0.1",
     "build": "rescript && vite build",
     "preview": "vite preview --host 127.0.0.1"
   },
   "dependencies": {
+    "@jridgewell/trace-mapping": "^0.3.31",
     "@rescript/runtime": "12.3.0",
     "rescript": "12.3.0",
     "vite": "^8.0.14",

packages/dev-playground/scripts/source-map-navigation.test.mjs

@@ -0,0 +1,50 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  decode,
+  generatedForOriginal,
+} from "../src/SourceMapNavigation.res.mjs";
+
+const sourceMap = JSON.stringify({
+  version: 3,
+  file: "Playground.js",
+  sources: ["Playground.res"],
+  names: [],
+  mappings: "AAAA;AACA",
+});
+
+test("decodes source map positions", () => {
+  assert.deepEqual(decode(sourceMap), [
+    {
+      generated: { line: 1, col: 0 },
+      original: {
+        source: "Playground.res",
+        position: { line: 1, col: 0 },
+      },
+    },
+    {
+      generated: { line: 2, col: 0 },
+      original: {
+        source: "Playground.res",
+        position: { line: 2, col: 0 },
+      },
+    },
+  ]);
+});
+
+test("finds the closest generated position for a source position", () => {
+  const mapping = generatedForOriginal(decode(sourceMap), { line: 2, col: 5 });
+
+  assert.deepEqual(mapping?.generated, { line: 2, col: 0 });
+});
+
+test("does not carry a generated position onto an unmapped source line", () => {
+  const mapping = generatedForOriginal(decode(sourceMap), { line: 3, col: 0 });
+
+  assert.equal(mapping, undefined);
+});
+
+test("handles invalid source maps", () => {
+  assert.deepEqual(decode("not a source map"), []);
+});