[es6] parse destructuring assignment

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/v8.h"
 
 #include "src/api.h"
 #include "src/ast.h"
 #include "src/bailout-reason.h"
 #include "src/base/platform/platform.h"
@@ skipping 2576 matching lines @@
       break;
 
     // TODO(arv): Handle `let [`
     // https://code.google.com/p/v8/issues/detail?id=3847
 
     default:
       break;
   }
 
   bool starts_with_idenfifier = peek_any_identifier();
+
   Expression* expr = ParseExpression(true, CHECK_OK);
   if (peek() == Token::COLON && starts_with_idenfifier && expr != NULL &&
       expr->AsVariableProxy() != NULL &&
       !expr->AsVariableProxy()->is_this()) {
     // Expression is a single identifier, and not, e.g., a parenthesized
     // identifier.
     VariableProxy* var = expr->AsVariableProxy();
     const AstRawString* label = var->raw_name();
     // TODO(1240780): We don't check for redeclaration of labels
     // during preparsing since keeping track of the set of active
@@ skipping 816 matching lines @@
 
   inner_scope->set_end_position(scanner()->location().end_pos);
   inner_block->set_scope(inner_scope);
   scope_ = for_scope;
 
   outer_loop->Initialize(NULL, NULL, NULL, inner_block);
   return outer_block;
 }
 
 
+Expression* Parser::DesugarDestructuringAssignment(Expression* expr) {
+  // TODO(caitp): implement the desugaring
+  DCHECK(expr->IsAssignment());
+  Assignment* assign = expr->AsAssignment();
+  while (assign->value()->IsAssignment()) {
+    assign = assign->value()->AsAssignment();
+  }
+  return assign->value();
+}
+
+
 Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
                                      bool* ok) {
   // ForStatement ::
   //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
 
   int stmt_pos = peek_position();
   bool is_const = false;
   Statement* init = NULL;
   ZoneList<const AstRawString*> lexical_bindings(1, zone());
 
@@ skipping 2375 matching lines @@
 Expression* Parser::SpreadCallNew(Expression* function,
                                   ZoneList<v8::internal::Expression*>* args,
                                   int pos) {
   args->InsertAt(0, function, zone());
 
   return factory()->NewCallRuntime(
       ast_value_factory()->reflect_construct_string(), NULL, args, pos);
 }
 }  // namespace internal
 }  // namespace v8