Add Module::script_id() (#497)

src/binding.cc

@@ -1909,6 +1909,14 @@ int v8__Module__GetIdentityHash(const v8::Module& self) {
   return self.GetIdentityHash();
 }
 
+int v8__Module__ScriptId(const v8::Module& self) {
+  // Module::ScriptId() isn't marked const but its implementation is
+  // so this const_cast is sound.
+  // TODO(bnoordhuis) Open V8 CL to mark Module::ScriptId() and
+  // UnboundScript::GetId() const.
+  return const_cast<v8::Module&>(self).ScriptId();
+}
+
 MaybeBool v8__Module__InstantiateModule(const v8::Module& self,
                                         const v8::Context& context,
                                         v8::Module::ResolveCallback cb) {

src/module.rs

@@ -138,6 +138,7 @@ extern "C" {
   ) -> Location;
   fn v8__Module__GetModuleNamespace(this: *const Module) -> *const Value;
   fn v8__Module__GetIdentityHash(this: *const Module) -> int;
+  fn v8__Module__ScriptId(this: *const Module) -> int;
   fn v8__Module__InstantiateModule(
     this: *const Module,
     context: *const Context,
@@ -248,6 +249,19 @@ impl Module {
     unsafe { v8__Module__GetIdentityHash(self) }
   }
 
+  /// Returns the underlying script's id.
+  ///
+  /// The module must be a SourceTextModule and must not have an Errored status.
+  pub fn script_id(&self) -> Option<int> {
+    if !self.is_source_text_module() {
+      return None;
+    }
+    if self.get_status() == ModuleStatus::Errored {
+      return None;
+    }
+    Some(unsafe { v8__Module__ScriptId(self) })
+  }
+
   /// Returns the namespace object of this module.
   ///
   /// The module's status must be at least kInstantiated.

tests/test_api.rs

@@ -1856,6 +1856,7 @@ fn module_instantiation_failures1() {
     let module = v8::script_compiler::compile_module(scope, source).unwrap();
     assert_eq!(v8::ModuleStatus::Uninstantiated, module.get_status());
     assert_eq!(2, module.get_module_requests_length());
+    assert!(module.script_id().is_some());
 
     assert_eq!(
       "./foo.js",
@@ -1930,6 +1931,7 @@ fn module_evaluation() {
     let source = v8::script_compiler::Source::new(source_text, &origin);
 
     let module = v8::script_compiler::compile_module(scope, source).unwrap();
+    assert!(module.script_id().is_some());
     assert!(module.is_source_text_module());
     assert!(!module.is_synthetic_module());
     assert_eq!(v8::ModuleStatus::Uninstantiated, module.get_status());
@@ -3530,16 +3532,21 @@ fn module_snapshot() {
       let module = v8::script_compiler::compile_module(scope, source).unwrap();
       assert_eq!(v8::ModuleStatus::Uninstantiated, module.get_status());
 
+      let script_id = module.script_id();
+      assert!(script_id.is_some());
+
       let result = module.instantiate_module(
         scope,
         compile_specifier_as_module_resolve_callback,
       );
       assert!(result.unwrap());
       assert_eq!(v8::ModuleStatus::Instantiated, module.get_status());
+      assert_eq!(script_id, module.script_id());
 
       let result = module.evaluate(scope);
       assert!(result.is_some());
       assert_eq!(v8::ModuleStatus::Evaluated, module.get_status());
+      assert_eq!(script_id, module.script_id());
 
       snapshot_creator.set_default_context(context);
     }
@@ -3722,6 +3729,7 @@ fn synthetic_module() {
   );
   assert!(!module.is_source_text_module());
   assert!(module.is_synthetic_module());
+  assert!(module.script_id().is_none());
   assert_eq!(module.get_status(), v8::ModuleStatus::Uninstantiated);
 
   module