[es6] implement destructuring assignment [clean diff]

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 3589 matching lines @@
 
   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();
+  Expression* value = assign->value();
+  Expression* target = assign->target();
+  Variable* result = nullptr;
+  if (value->IsAssignment()) {

[caitp (gmail), 2015/10/19 11:17:39]

I'll make all of this completion-value-saving code much simpler, shortly

+    value = DesugarDestructuringAssignment(value);
+    if (value->IsDoExpression()) {
+      result = value->AsDoExpression()->result()->var();
+    }
   }
-  return assign->value();
+  if (target->IsObjectLiteral() || target->IsArrayLiteral()) {
+    Block* block = factory()->NewBlock(nullptr, 8, false, expr->position());
+    bool ok = true;
+    result = PatternRewriter::RewriteDestructuringAssignment(
+        this, block, target, value, result, &ok);
+    DCHECK_EQ(ok, true);
+    DCHECK_NOT_NULL(result);
+    return factory()->NewDoExpression(block, result, expr->position());
+  }
+
+  return expr;
 }
 
 
 Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
                                      bool* ok) {
   // ForStatement ::
   //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
 
   int stmt_pos = peek_position();
   bool is_const = false;
@@ skipping 2774 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