Fix scope/context behavior in await transformer.

runtime/vm/parser.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/parser.h"
 
 #include "lib/invocation_mirror.h"
 #include "platform/utils.h"
 #include "vm/ast_transformer.h"
 #include "vm/bootstrap.h"
@@ skipping 268 matching lines @@
 
 // For parsing a compilation unit.
 Parser::Parser(const Script& script, const Library& library, intptr_t token_pos)
     : isolate_(Isolate::Current()),
       script_(Script::Handle(isolate_, script.raw())),
       tokens_iterator_(TokenStream::Handle(isolate_, script.tokens()),
                        token_pos),
       token_kind_(Token::kILLEGAL),
       current_block_(NULL),
       is_top_level_(false),
+      await_is_keyword_(false),
       current_member_(NULL),
       allow_function_literals_(true),
       parsed_function_(NULL),
       innermost_function_(Function::Handle(isolate_)),
       literal_token_(LiteralToken::Handle(isolate_)),
       current_class_(Class::Handle(isolate_)),
       library_(Library::Handle(isolate_, library.raw())),
       try_blocks_list_(NULL),
       last_used_try_index_(0),
       unregister_pending_function_(false) {
   ASSERT(tokens_iterator_.IsValid());
   ASSERT(!library.IsNull());
 }
 
 
 // For parsing a function.
 Parser::Parser(const Script& script,
                ParsedFunction* parsed_function,
                intptr_t token_position)
     : isolate_(Isolate::Current()),
       script_(Script::Handle(isolate_, script.raw())),
       tokens_iterator_(TokenStream::Handle(isolate_, script.tokens()),
                        token_position),
       token_kind_(Token::kILLEGAL),
       current_block_(NULL),
       is_top_level_(false),
+      await_is_keyword_(false),
       current_member_(NULL),
       allow_function_literals_(true),
       parsed_function_(parsed_function),
       innermost_function_(Function::Handle(isolate_,
                                            parsed_function->function().raw())),
       literal_token_(LiteralToken::Handle(isolate_)),
       current_class_(Class::Handle(isolate_,
                                    parsed_function->function().Owner())),
       library_(Library::Handle(isolate_, Class::Handle(
           isolate_,
@@ skipping 2625 matching lines @@
 
   OpenBlock();  // Open a nested scope for the outermost function block.
 
   Function& async_closure = Function::ZoneHandle(I);
   if (func.IsAsyncFunction() && !func.is_async_closure()) {
     async_closure = OpenAsyncFunction(formal_params_pos);
   } else if (func.is_async_closure()) {
     OpenAsyncClosure();
   }
 
+  // For async functions and their inner closures parse "await" as a keyword.
+  if (func.IsAsyncFunction() || func.is_async_closure()) {
+    await_is_keyword_ = true;
+  }
+
   intptr_t end_token_pos = 0;
   if (CurrentToken() == Token::kLBRACE) {
     ConsumeToken();
     if (String::Handle(I, func.name()).Equals(
         Symbols::EqualOperator())) {
       const Class& owner = Class::Handle(I, func.Owner());
       if (!owner.IsObjectClass()) {
         AddEqualityNullCheck();
       }
     }
@@ skipping 48 matching lines @@
   func.set_end_token_pos(end_token_pos);
   SequenceNode* body = CloseBlock();
   if (func.IsAsyncFunction() && !func.is_async_closure()) {
     body = CloseAsyncFunction(async_closure, body);
   } else if (func.is_async_closure()) {
     CloseAsyncClosure(body);
   }
   current_block_->statements->Add(body);
   innermost_function_ = saved_innermost_function.raw();
   last_used_try_index_ = saved_try_index;
+  await_is_keyword_ = false;

[hausner, 2014/08/26 22:48:06]

Interesting. Why are you setting this flag to false here?

[Michael Lippautz (Google), 2014/08/26 23:01:44]

As discussed offline: Need for parsing nested functions. Example:

foo() {
  bar() async {};
  // We need to have await_is_keyword_ set to false here.
}

   return CloseBlock();
 }
 
 
 void Parser::AddEqualityNullCheck() {
   AstNode* argument =
       new LoadLocalNode(Scanner::kNoSourcePos,
                         current_block_->scope->parent()->VariableAt(1));
   LiteralNode* null_operand =
       new LiteralNode(Scanner::kNoSourcePos, Instance::ZoneHandle(I));
@@ skipping 3210 matching lines @@
     *value = Bool::True().raw();
     return true;
   } else if (CurrentToken() == Token::kFALSE) {
     *value = Bool::False().raw();
     return true;
   }
   return false;
 }
 
 
-// Returns true if the current token is kIDENT or a pseudo-keyword.
+// Returns true if the current token is
+// * kIDENT,
+// * or a pseudo-keyword,
+// * or is not the literal "await" in an async function.
 bool Parser::IsIdentifier() {
-  return Token::IsIdentifier(CurrentToken());
+  return Token::IsIdentifier(CurrentToken()) &&
+         (!await_is_keyword_ ||
+          (CurrentLiteral()->raw() != Symbols::Await().raw()));
 }
 
 
 // Returns true if the next tokens can be parsed as a an optionally
 // qualified identifier: [ident '.'] ident.
 // Current token position is not restored.
 bool Parser::TryParseQualIdent() {
   if (CurrentToken() != Token::kIDENT) {
     return false;
   }
@@ skipping 2176 matching lines @@
   parsed_function()->reset_have_seen_await();
   AstNode* expr = ParseExpr(require_compiletime_const, consume_cascades);
   if (parsed_function()->have_seen_await()) {
     if (!current_block_->scope->LookupVariable(
           Symbols::AsyncOperation(), true)) {
       // Async operations are always encapsulated into a local function. We only
       // need to transform the expression when generating code for this inner
       // function.
       return expr;
     }
-    SequenceNode* intermediates_block = new(I) SequenceNode(
-        Scanner::kNoSourcePos, current_block_->scope);
-    AwaitTransformer at(intermediates_block, library_, parsed_function());
+    OpenBlock();
+    AwaitTransformer at(current_block_->statements,
+                        library_,
+                        parsed_function());
     AstNode* result = at.Transform(expr);
-    current_block_->statements->Add(intermediates_block);
+    current_block_->statements->Add(CloseBlock());
     parsed_function()->reset_have_seen_await();
     return result;
   }
   return expr;
 }
 
 
 AstNode* Parser::ParseExpr(bool require_compiletime_const,
                            bool consume_cascades) {
   TRACE_PARSER("ParseExpr");
@@ skipping 2364 matching lines @@
   TRACE_PARSER("ParsePrimary");
   ASSERT(!is_top_level_);
   AstNode* primary = NULL;
   const Token::Kind token = CurrentToken();
   if (IsFunctionLiteral()) {
     // The name of a literal function is visible from inside the function, but
     // must not collide with names in the scope declaring the literal.
     OpenBlock();
     primary = ParseFunctionStatement(true);
     CloseBlock();
-  } else if (IsLiteral("await") &&
+  } else if ((CurrentLiteral()->raw() == Symbols::Await().raw()) &&
              (parsed_function()->function().IsAsyncFunction() ||
               parsed_function()->function().is_async_closure())) {
     // The body of an async function is parsed multiple times. The first time
     // when setting up an AsyncFunction() for generating relevant scope
     // information. The second time the body is parsed for actually generating
     // code.
     TRACE_PARSER("ParseAwaitExpr");
     ConsumeToken();
     parsed_function()->record_await();
     primary = new(I) AwaitNode(
@@ skipping 530 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart