[WIP] feat: Add native SourceMap support

bar.js

@@ -0,0 +1,6 @@
+"use strict";
+
+throw new Error("Hello world!");
+//# sourceMappingURL=bar.js.map
+
+asd;

core/Cargo.toml

@@ -24,6 +24,7 @@ snapshot_flags_eager_parse = []
 
 [dependencies]
 anyhow.workspace = true
+base64 = "0.22.1"
 bincode.workspace = true
 bit-set.workspace = true
 bit-vec.workspace = true

core/error.rs

@@ -249,7 +249,7 @@ impl JsStackFrame {
     let c = message.get_start_column() as u32 + 1;
     let state = JsRuntime::state_from(scope);
     let mut source_mapper = state.source_mapper.borrow_mut();
-    match source_mapper.apply_source_map(&f, l, c) {
+    match source_mapper.apply_source_map(scope, &f, l, c) {
       SourceMapApplication::Unchanged => Some(JsStackFrame::from_location(
         Some(f),
         Some(l.into()),
@@ -354,15 +354,12 @@ impl JsError {
     {
       let state = JsRuntime::state_from(scope);
       let mut source_mapper = state.source_mapper.borrow_mut();
-      for (i, frame) in frames.iter().enumerate() {
+      if let Some(frame) = frames.first() {
         if let (Some(file_name), Some(line_number)) =
           (&frame.file_name, frame.line_number)
         {
-          if !file_name.trim_start_matches('[').starts_with("ext:") {
-            source_line = source_mapper.get_source_line(file_name, line_number);
-            source_line_frame_index = Some(i);
-            break;
-          }
+          source_line = source_mapper.get_source_line(file_name, line_number);
+          source_line_frame_index = Some(0);
         }
       }
     }
@@ -475,16 +472,12 @@ impl JsError {
       {
         let state = JsRuntime::state_from(scope);
         let mut source_mapper = state.source_mapper.borrow_mut();
-        for (i, frame) in frames.iter().enumerate() {
+        if let Some(frame) = frames.first() {
           if let (Some(file_name), Some(line_number)) =
             (&frame.file_name, frame.line_number)
           {
-            if !file_name.trim_start_matches('[').starts_with("ext:") {
-              source_line =
-                source_mapper.get_source_line(file_name, line_number);
-              source_line_frame_index = Some(i);
-              break;
-            }
+            source_line = source_mapper.get_source_line(file_name, line_number);
+            source_line_frame_index = Some(0);
           }
         }
       }

core/ops_builtin_v8.rs

@@ -1047,9 +1047,10 @@ fn write_line_and_col_to_ret_buf(
 // 2: mapped line, column, and file name. new line, column, and file name are in
 //    ret_buf. retrieve file name by calling `op_apply_source_map_filename`
 //    immediately after this op returns.
-#[op2(fast)]
+#[op2]
 #[smi]
 pub fn op_apply_source_map(
+  scope: &mut v8::HandleScope,
   state: &JsRuntimeState,
   #[string] file_name: &str,
   #[smi] line_number: u32,
@@ -1060,8 +1061,12 @@ pub fn op_apply_source_map(
     return Err(type_error("retBuf must be 8 bytes"));
   }
   let mut source_mapper = state.source_mapper.borrow_mut();
-  let application =
-    source_mapper.apply_source_map(file_name, line_number, column_number);
+  let application = source_mapper.apply_source_map(
+    scope,
+    file_name,
+    line_number,
+    column_number,
+  );
   match application {
     SourceMapApplication::Unchanged => Ok(0),
     SourceMapApplication::LineAndColumn {
@@ -1137,7 +1142,7 @@ pub fn op_current_user_call_site(
     let application = js_runtime_state
       .source_mapper
       .borrow_mut()
-      .apply_source_map(&file_name, line_number, column_number);
+      .apply_source_map(scope, &file_name, line_number, column_number);
 
     match application {
       SourceMapApplication::Unchanged => {

core/source_map.rs

@@ -5,9 +5,15 @@
 // TODO(bartlomieju): remove once `SourceMapGetter` is removed.
 #![allow(deprecated)]
 
+use crate::module_specifier::ModuleResolutionError;
+use crate::resolve_import;
 use crate::resolve_url;
+use crate::runtime::JsRealm;
 use crate::ModuleLoader;
 use crate::ModuleName;
+use crate::RequestedModuleType;
+use base64::prelude::BASE64_STANDARD;
+use base64::Engine;
 pub use sourcemap::SourceMap;
 use std::borrow::Cow;
 use std::collections::HashMap;
@@ -89,13 +95,93 @@ impl SourceMapper {
     std::mem::take(&mut self.ext_source_maps)
   }
 
+  pub fn apply_source_map_from_module_map(
+    &mut self,
+    scope: &mut v8::HandleScope,
+    file_name: &str,
+    line_number: u32,
+    column_number: u32,
+  ) -> Option<SourceMapApplication> {
+    let module_map_rc = JsRealm::module_map_from(scope);
+    let id = module_map_rc.get_id(file_name, RequestedModuleType::None)?;
+
+    let module_handle = module_map_rc.get_handle(id).unwrap();
+    let module = v8::Local::new(scope, module_handle);
+    let unbound_module_script = module.get_unbound_module_script(scope);
+    let maybe_source_mapping_url =
+      unbound_module_script.get_source_mapping_url(scope);
+
+    // TODO(bartlomieju): This should be the last fallback and it's only useful
+    // for eval - probably for `Deno.core.evalContext()`.
+    // let maybe_source_url = unbound_module_script
+    //   .get_source_url(scope)
+    //   .to_rust_string_lossy(scope);
+    // eprintln!("maybe source url {}", maybe_source_url);
+
+    if !maybe_source_mapping_url.is_string() {
+      return None;
+    }
+
+    let source_map_string =
+      maybe_source_mapping_url.to_rust_string_lossy(scope);
+    // eprintln!("maybe source mapping url {}", source_map_string);
+
+    // TODO(bartlomieju): this is a fast path - if it fails, we should try to parse
+    // the URL (or resolve it from the current file being mapped) and fallback to
+    // acquiring a source map from that URL. In Deno we might want to apply permissions
+    // checks for fetching the map.
+    let source_map = if let Some(b64) =
+      source_map_string.strip_prefix("data:application/json;base64,")
+    {
+      let decoded_b64 = BASE64_STANDARD.decode(b64).ok()?;
+      // eprintln!(
+      //   "source map {:?}",
+      //   String::from_utf8(decoded_b64.clone()).unwrap()
+      // );
+      SourceMap::from_slice(&decoded_b64).ok()?
+    } else {
+      let url = match resolve_import(&source_map_string, file_name) {
+        Ok(url) => Some(url),
+        Err(err) => match err {
+          ModuleResolutionError::ImportPrefixMissing(_, _) => {
+            resolve_import(&format!("./{}", source_map_string), file_name).ok()
+          }
+          _ => None,
+        },
+      };
+      // eprintln!(
+      //   "source map url sourceMappingURL={} file_name={} url={}",
+      //   source_map_string,
+      //   file_name,
+      //   url.as_ref().map(|s| s.as_str()).unwrap_or_default()
+      // );
+      let url = url?;
+      if url.scheme() != "file" {
+        return None;
+      }
+      let contents = module_map_rc
+        .loader
+        .borrow()
+        .get_source_map(url.to_file_path().ok()?.to_str()?)?;
+      SourceMap::from_slice(&contents).ok()?
+    };
+
+    Some(Self::compute_application(
+      &source_map,
+      file_name,
+      line_number,
+      column_number,
+    ))
+  }
+
   /// Apply a source map to the passed location. If there is no source map for
   /// this location, or if the location remains unchanged after mapping, the
   /// changed values are returned.
   ///
   /// Line and column numbers are 1-based.
   pub fn apply_source_map(
     &mut self,
+    scope: &mut v8::HandleScope,
     file_name: &str,
     line_number: u32,
     column_number: u32,
@@ -104,6 +190,17 @@ impl SourceMapper {
     let line_number = line_number - 1;
     let column_number = column_number - 1;
 
+    // TODO(bartlomieju): requires scope and should only be called in a fallback op,
+    // that will access scope if the fast op doesn't return anything.
+    if let Some(app) = self.apply_source_map_from_module_map(
+      scope,
+      file_name,
+      line_number,
+      column_number,
+    ) {
+      return app;
+    }
+
     let getter = self.getter.as_ref();
     let maybe_source_map =
       self.maps.entry(file_name.to_owned()).or_insert_with(|| {
@@ -123,6 +220,15 @@ impl SourceMapper {
       return SourceMapApplication::Unchanged;
     };
 
+    Self::compute_application(source_map, file_name, line_number, column_number)
+  }
+
+  fn compute_application(
+    source_map: &SourceMap,
+    file_name: &str,
+    line_number: u32,
+    column_number: u32,
+  ) -> SourceMapApplication {
     let Some(token) = source_map.lookup_token(line_number, column_number)
     else {
       return SourceMapApplication::Unchanged;
@@ -212,11 +318,13 @@ mod tests {
 
   use super::*;
   use crate::ascii_str;
+  use crate::JsRuntime;
   use crate::ModuleCodeString;
   use crate::ModuleLoadResponse;
   use crate::ModuleSpecifier;
   use crate::RequestedModuleType;
   use crate::ResolutionKind;
+  use crate::RuntimeOptions;
 
   struct SourceMapLoaderContent {
     source_map: Option<ModuleCodeString>,
@@ -279,19 +387,29 @@ mod tests {
       },
     );
 
-    let mut source_mapper = SourceMapper::new(Rc::new(loader), None);
+    let loader = Rc::new(loader);
+
+    let mut js_runtime = JsRuntime::new(RuntimeOptions {
+      module_loader: Some(loader.clone()),
+      ..Default::default()
+    });
+    let state = JsRuntime::state_from(js_runtime.v8_isolate());
+    let scope = &mut js_runtime.handle_scope();
+    let mut source_mapper = state.source_mapper.borrow_mut();
 
     // Non-existent file
     let application =
-      source_mapper.apply_source_map("file:///doesnt_exist.js", 1, 1);
+      source_mapper.apply_source_map(scope, "file:///doesnt_exist.js", 1, 1);
     assert_eq!(application, SourceMapApplication::Unchanged);
 
     // File with no source map
-    let application = source_mapper.apply_source_map("file:///b.js", 1, 1);
+    let application =
+      source_mapper.apply_source_map(scope, "file:///b.js", 1, 1);
     assert_eq!(application, SourceMapApplication::Unchanged);
 
     // File with a source map
-    let application = source_mapper.apply_source_map("file:///a.ts", 1, 21);
+    let application =
+      source_mapper.apply_source_map(scope, "file:///a.ts", 1, 21);
     assert_eq!(
       application,
       SourceMapApplication::LineAndColumn {

foo.js

@@ -0,0 +1,6 @@
+"use strict";
+
+throw new Error("Hello world!");
+//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoiIiwic291cmNlUm9vdCI6IiIsInNvdXJjZXMiOlsiaHR0cDovL2xvY2FsaG9zdDo0NTQ1L3J1bi9pbmxpbmVfanNfc291cmNlX21hcF8yLnRzIl0sInNvdXJjZXNDb250ZW50IjpbIjErMTtcbmludGVyZmFjZSBUZXN0IHtcbiAgaGVsbG86IHN0cmluZztcbn1cblxudGhyb3cgbmV3IEVycm9yKFwiSGVsbG8gd29ybGQhXCIgYXMgdW5rbm93biBhcyBzdHJpbmcpO1xuIl0sIm5hbWVzIjpbXSwibWFwcGluZ3MiOiI7QUFBQSxDQUFDLEdBQUMsQ0FBQyxDQUFDO0FBS0osTUFBTSxJQUFJLEtBQUssQ0FBQyxjQUErQixDQUFDLENBQUMifQ==
+
+asd;