[es7] Implement async functions parsing

src/parser.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/parser.h"
 
 #include "src/api.h"
 #include "src/ast.h"
 #include "src/ast-literal-reindexer.h"
 #include "src/bailout-reason.h"
@@ skipping 909 matching lines @@
   set_allow_harmony_sloppy_let(FLAG_harmony_sloppy_let);
   set_allow_harmony_rest_parameters(FLAG_harmony_rest_parameters);
   set_allow_harmony_default_parameters(FLAG_harmony_default_parameters);
   set_allow_harmony_spread_calls(FLAG_harmony_spread_calls);
   set_allow_harmony_destructuring(FLAG_harmony_destructuring);
   set_allow_harmony_spread_arrays(FLAG_harmony_spread_arrays);
   set_allow_harmony_new_target(FLAG_harmony_new_target);
   set_allow_strong_mode(FLAG_strong_mode);
   set_allow_legacy_const(FLAG_legacy_const);
   set_allow_harmony_do_expressions(FLAG_harmony_do_expressions);
+  set_allow_harmony_async_await(FLAG_harmony_async_await);
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {
     use_counts_[feature] = 0;
   }
   if (info->ast_value_factory() == NULL) {
     // info takes ownership of AstValueFactory.
     info->set_ast_value_factory(new AstValueFactory(zone(), info->hash_seed()));
     info->set_ast_value_factory_owned();
     ast_value_factory_ = info->ast_value_factory();
   }
@@ skipping 461 matching lines @@
   //    Statement
   //    Declaration
 
   if (peek() != Token::CLASS) {
     // No more classes follow; reset the start position for the consecutive
     // class declaration group.
     scope_->set_class_declaration_group_start(-1);
   }
 
   switch (peek()) {
+    case Token::ASYNC:
+      if (allow_harmony_async_await() && IsNextAsyncFunctionKeyword()) {
+        return ParseFunctionDeclaration(NULL, ok);
+      }
+      break;
     case Token::FUNCTION:
       return ParseFunctionDeclaration(NULL, ok);
     case Token::CLASS:
       if (scope_->class_declaration_group_start() < 0) {
         scope_->set_class_declaration_group_start(
             scanner()->peek_location().beg_pos);
       }
       return ParseClassDeclaration(NULL, ok);
     case Token::CONST:
       if (allow_const()) {
@@ skipping 801 matching lines @@
       factory()->NewAssignment(
           Token::INIT_VAR, proxy, lit, RelocInfo::kNoPosition),
       pos);
 }
 
 
 Statement* Parser::ParseFunctionDeclaration(
     ZoneList<const AstRawString*>* names, bool* ok) {
   // FunctionDeclaration ::
   //   'function' Identifier '(' FormalParameterListopt ')' '{' FunctionBody '}'
+  // AsyncFunctionDeclaration ::
+  //   'async' 'function' Identifier '(' FormalParameterListopt ')'
+  //      '{' FunctionBody '}'
   // GeneratorDeclaration ::
   //   'function' '*' Identifier '(' FormalParameterListopt ')'
   //      '{' FunctionBody '}'
+  bool is_async = allow_harmony_async_await() ? Check(Token::ASYNC) : false;
   Expect(Token::FUNCTION, CHECK_OK);
   int pos = position();
-  bool is_generator = Check(Token::MUL);
+  bool is_generator = is_async ? false : Check(Token::MUL);
   bool is_strict_reserved = false;
   const AstRawString* name = ParseIdentifierOrStrictReservedWord(
       &is_strict_reserved, CHECK_OK);
 
   if (fni_ != NULL) {
     fni_->Enter();
     fni_->PushEnclosingName(name);
   }
+
+  FunctionKind kind = FunctionKind::kNormalFunction;
+  if (is_generator) {
+    kind = FunctionKind::kGeneratorFunction;
+  } else if (is_async) {
+    kind = FunctionKind::kAsyncFunction;
+  }
+
   FunctionLiteral* fun = ParseFunctionLiteral(
       name, scanner()->location(),
       is_strict_reserved ? kFunctionNameIsStrictReserved
                          : kFunctionNameValidityUnknown,
-      is_generator ? FunctionKind::kGeneratorFunction
-                   : FunctionKind::kNormalFunction,
-      pos, FunctionLiteral::DECLARATION, FunctionLiteral::NORMAL_ARITY,
+      kind, pos, FunctionLiteral::DECLARATION, FunctionLiteral::NORMAL_ARITY,
       language_mode(), CHECK_OK);
   if (fni_ != NULL) fni_->Leave();
 
   // Even if we're not at the top-level of the global or a function
   // scope, we treat it as such and introduce the function with its
   // initial value upon entering the corresponding scope.
   // In ES6, a function behaves as a lexical binding, except in
   // a script scope, or the initial scope of eval or another function.
   VariableMode mode =
       is_strong(language_mode())
@@ skipping 2548 matching lines @@
     SET_ALLOW(harmony_sloppy);
     SET_ALLOW(harmony_sloppy_let);
     SET_ALLOW(harmony_rest_parameters);
     SET_ALLOW(harmony_default_parameters);
     SET_ALLOW(harmony_spread_calls);
     SET_ALLOW(harmony_destructuring);
     SET_ALLOW(harmony_spread_arrays);
     SET_ALLOW(harmony_new_target);
     SET_ALLOW(strong_mode);
     SET_ALLOW(harmony_do_expressions);
+    SET_ALLOW(harmony_async_await);
 #undef SET_ALLOW
   }
   PreParser::PreParseResult result = reusable_preparser_->PreParseLazyFunction(
       language_mode(), function_state_->kind(), scope_->has_simple_parameters(),
       logger, bookmark);
   if (pre_parse_timer_ != NULL) {
     pre_parse_timer_->Stop();
   }
   return result;
 }
@@ skipping 1556 matching lines @@
 
 Expression* Parser::SpreadCallNew(Expression* function,
                                   ZoneList<v8::internal::Expression*>* args,
                                   int pos) {
   args->InsertAt(0, function, zone());
 
   return factory()->NewCallRuntime(Context::REFLECT_CONSTRUCT_INDEX, args, pos);
 }
 }  // namespace internal
 }  // namespace v8