Collect list of requested modules in ModuleDescriptor while parsing

BUG=v8:1569
LOG=n

Review URL: https://codereview.chromium.org/1078903002

Cr-Commit-Position: refs/heads/master@{#27724}

src/modules.cc

@@ -35,6 +35,15 @@ void ModuleDescriptor::AddLocalExport(const AstRawString* export_name,
 }
 
 
+void ModuleDescriptor::AddModuleRequest(const AstRawString* module_specifier,
+                                        Zone* zone) {
+  // TODO(adamk): Avoid this O(N) operation on each insert by storing
+  // a HashMap, or by de-duping after parsing.
+  if (requested_modules_.Contains(module_specifier)) return;
+  requested_modules_.Add(module_specifier, zone);
+}
+
+
 const AstRawString* ModuleDescriptor::LookupLocalExport(
     const AstRawString* export_name, Zone* zone) {
   if (exports_ == nullptr) return nullptr;

src/modules.h

@@ -20,7 +20,7 @@ class ModuleDescriptor : public ZoneObject {
   // Factory methods.
 
   static ModuleDescriptor* New(Zone* zone) {
-    return new (zone) ModuleDescriptor();
+    return new (zone) ModuleDescriptor(zone);
   }
 
   // ---------------------------------------------------------------------------
@@ -31,6 +31,10 @@ class ModuleDescriptor : public ZoneObject {
   void AddLocalExport(const AstRawString* export_name,
                       const AstRawString* local_name, Zone* zone, bool* ok);
 
+  // Add module_specifier to the list of requested modules,
+  // if not already present.
+  void AddModuleRequest(const AstRawString* module_specifier, Zone* zone);
+
   // Do not allow any further refinements, directly or through unification.
   void Freeze() { frozen_ = true; }
 
@@ -61,6 +65,10 @@ class ModuleDescriptor : public ZoneObject {
   const AstRawString* LookupLocalExport(const AstRawString* export_name,
                                         Zone* zone);
 
+  const ZoneList<const AstRawString*>& requested_modules() const {
+    return requested_modules_;
+  }
+
   // ---------------------------------------------------------------------------
   // Iterators.
 
@@ -95,11 +103,16 @@ class ModuleDescriptor : public ZoneObject {
   // ---------------------------------------------------------------------------
   // Implementation.
  private:
+  explicit ModuleDescriptor(Zone* zone)
+      : frozen_(false),
+        exports_(NULL),
+        requested_modules_(1, zone),
+        index_(-1) {}
+
   bool frozen_;
   ZoneHashMap* exports_;   // Module exports and their types (allocated lazily)
+  ZoneList<const AstRawString*> requested_modules_;
   int index_;
-
-  ModuleDescriptor() : frozen_(false), exports_(NULL), index_(-1) {}
 };
 
 } }  // namespace v8::internal

src/parser.cc

@@ -1560,6 +1560,8 @@ Statement* Parser::ParseImportDeclaration(bool* ok) {
   const AstRawString* module_specifier = ParseModuleSpecifier(CHECK_OK);
   ExpectSemicolon(CHECK_OK);
 
+  scope_->module()->AddModuleRequest(module_specifier, zone());
+
   if (module_instance_binding != NULL) {
     // TODO(ES6): Set the module specifier for the module namespace binding.
   }
@@ -1697,6 +1699,8 @@ Statement* Parser::ParseExportDeclaration(bool* ok) {
           }
         }
       } else {
+        scope_->module()->AddModuleRequest(indirect_export_module_specifier,
+                                           zone());
         for (int i = 0; i < length; ++i) {
           // TODO(ES6): scope_->module()->AddIndirectExport(...);(
         }

test/cctest/test-parsing.cc

@@ -5445,7 +5445,8 @@ TEST(ModuleParsingInternals) {
       "let x = 5;"
       "export { x as y };"
       "import { q as z } from 'm.js';"
-      "import n from 'n.js'";
+      "import n from 'n.js';"
+      "export { a as b } from 'm.js';";
   i::Handle<i::String> source = factory->NewStringFromAsciiChecked(kSource);
   i::Handle<i::Script> script = factory->NewScript(source);
   i::Zone zone;
@@ -5485,6 +5486,12 @@ TEST(ModuleParsingInternals) {
   CHECK(import_decl->import_name()->IsOneByteEqualTo("default"));
   CHECK(import_decl->proxy()->raw_name()->IsOneByteEqualTo("n"));
   CHECK(import_decl->module_specifier()->IsOneByteEqualTo("n.js"));
+  // TODO(adamk): Add test for indirect exports once they're fully implemented.
+  const i::ZoneList<const i::AstRawString*>& requested_modules =
+      descriptor->requested_modules();
+  CHECK_EQ(2, requested_modules.length());
+  CHECK(requested_modules[0]->IsOneByteEqualTo("m.js"));
+  CHECK(requested_modules[1]->IsOneByteEqualTo("n.js"));
 }