commit bf3e8e923ae30426c20e7cc0c20ba6cfea9d3bfe
author Stephen Adams <sra@google.com> Fri Oct 17 12:01:43 2025 -0700
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Oct 17 12:01:43 2025 -0700
tree 539410f61c2c58af20533efbe486e3553b2267bd
parent b243e6aae5420cd3fb5e7093c1b071971ce74343

[wasm_builder] Add method to deserialize just the sourceMapUrl

It is useful to be able to extract the sourceMapUrl without parsing
the rest of the module.

Change-Id: I595b615b07015597fc1b082aa320887d86f16204
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/455542
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Stephen Adams <sra@google.com>

pkg/wasm_builder/lib/src/ir/module.dart

diff --git a/pkg/wasm_builder/lib/src/ir/module.dart b/pkg/wasm_builder/lib/src/ir/module.dart
index 112e514..000e3d9 100644
--- a/pkg/wasm_builder/lib/src/ir/module.dart
+++ b/pkg/wasm_builder/lib/src/ir/module.dart
@@ -119,7 +119,8 @@
     SourceMapSection(sourceMapUrl).serialize(s);
   }
 
-  static Module deserialize(Deserializer d) {
+  static (Map<int, List<Deserializer>>, Map<String, List<Deserializer>>)
+      _deserializeTopLevel(Deserializer d) {
     final preamble = d.readBytes(8);
     if (preamble[0] != 0x00 ||
         preamble[1] != 0x61 ||
@@ -151,6 +152,12 @@
       }
     }
 
+    return (sections, customSections);
+  }
+
+  static Module deserialize(Deserializer d) {
+    final (sections, customSections) = _deserializeTopLevel(d);
+
     final Module module = Module.uninitialized();
 
     // We read the sections in the order they should be in the binary.
@@ -235,6 +242,14 @@
       );
   }
 
+  /// Deserialize just the `sourceMapUrl` section of a module as a [Uri].
+  static Uri? deserializeSourceMapUrl(Deserializer d) {
+    final (sections, customSections) = _deserializeTopLevel(d);
+    final sourceMapUrl = SourceMapSection.deserialize(
+        customSections[SourceMapSection.customSectionName]?.single);
+    return sourceMapUrl;
+  }
+
   String printAsWat() {
     final mp = ModulePrinter(this);