[es6] implement destructuring assignment [clean diff]

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index dac59b7d4437ee5fd406740cf7023277dfecd0f6..f043c23fbdd30725327fa787be568d640562ba68 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -3603,14 +3603,33 @@ Statement* Parser::DesugarLexicalBindingsInForStatement(
 }
 
 
-Expression* Parser::DesugarDestructuringAssignment(Expression* expr) {
-  // TODO(caitp): implement the desugaring
-  DCHECK(expr->IsAssignment());
+Expression* Parser::DesugarDestructuringAssignmentInternal(Expression* expr,
+                                                           Variable** result) {
   Assignment* assign = expr->AsAssignment();
-  while (assign->value()->IsAssignment()) {
-    assign = assign->value()->AsAssignment();
+  Expression* value = assign->value();
+  Expression* target = assign->target();
+  if (value->IsAssignment()) {
+    value = DesugarDestructuringAssignmentInternal(value, result);
+  }
+  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 assign->value();
+
+  return expr;
+}
+
+
+Expression* Parser::DesugarDestructuringAssignment(Expression* expr) {
+  DCHECK(expr->IsAssignment());
+  Variable* result = nullptr;
+
+  return DesugarDestructuringAssignmentInternal(expr, &result);
 }