[es6] implement destructuring assignment

src/ast.h

Index: src/ast.h
diff --git a/src/ast.h b/src/ast.h
index e81c02c40a8936b36d6fb91878255a81505cfd73..1f5d72684c2a60a449f75cc49f5a4bac025e8525 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -2334,6 +2334,9 @@ class Assignment final : public Expression {
   Token::Value op() const { return TokenField::decode(bit_field_); }
   Expression* target() const { return target_; }
   Expression* value() const { return value_; }
+  Expression* destructuring_assignment() const {
+    return destructuring_assignment_;
+  }
   BinaryOperation* binary_operation() const { return binary_operation_; }
 
   // This check relies on the definition order of token in token.h.
@@ -2367,6 +2370,17 @@ class Assignment final : public Expression {
   void set_store_mode(KeyedAccessStoreMode mode) {
     bit_field_ = StoreModeField::update(bit_field_, mode);
   }
+  bool is_destructuring_assignment() const {
+    return DestructuringAssignmentField::decode(bit_field_);
+  }
+  void set_is_destructuring_assignment() {
+    bit_field_ |= DestructuringAssignmentField::encode(true);
+  }
+  Expression* destructuring_assignment() { return destructuring_assignment_; }

[adamk, 2015/11/25 21:05:28]

Looks like this is a non-const dup of the above accessor, I don't think you need
it.

[caitp (gmail), 2015/11/25 21:41:51]

Acknowledged. 

+
+  void set_destructuring_assignment(Expression* expression) {
+    destructuring_assignment_ = expression;
+  }
 
   void AssignFeedbackVectorSlots(Isolate* isolate, FeedbackVectorSpec* spec,
                                  FeedbackVectorSlotCache* cache) override;
@@ -2384,12 +2398,15 @@ class Assignment final : public Expression {
   class KeyTypeField : public BitField16<IcCheckType, 1, 1> {};
   class StoreModeField : public BitField16<KeyedAccessStoreMode, 2, 3> {};
   class TokenField : public BitField16<Token::Value, 5, 8> {};
+  class DestructuringAssignmentField
+      : public BitField16<bool, TokenField::kNext, 1> {};

[adamk, 2015/11/25 21:05:28]

Can you use kNext for the above lines while you're at it?

[caitp (gmail), 2015/11/25 21:41:51]

Acknowledged.

 
   // Starts with 16-bit field, which should get packed together with
   // Expression's trailing 16-bit field.
   uint16_t bit_field_;
   Expression* target_;
   Expression* value_;
+  Expression* destructuring_assignment_;
   BinaryOperation* binary_operation_;
   SmallMapList receiver_types_;
   FeedbackVectorSlot slot_;
@@ -3196,6 +3213,15 @@ class AstVisitor BASE_EMBEDDED {
 #undef DEF_VISIT
 };
 
+// Pattern used in some AST visitors
+#define RETURN_IF_VISIT_NODE(node) \
+  do {                             \
+    AstNode* tmp = node;           \
+    if (tmp != nullptr) {          \
+      Visit(tmp);                  \
+      return;                      \
+    }                              \
+  } while (false)
 
 #define DEFINE_AST_VISITOR_SUBCLASS_MEMBERS()               \
  public:                                                    \