[destructuring] Implement spread binding patterns.

src/preparser.h

Index: src/preparser.h
diff --git a/src/preparser.h b/src/preparser.h
index 116a8eac9b891721e208bea92d9f3b7e4ad30528..129f7b1d00a0c1777e98d07d1a58f77f8d194807 100644
--- a/src/preparser.h
+++ b/src/preparser.h
@@ -1485,7 +1485,8 @@ class PreParserFactory {
     return PreParserExpression::Default();
   }
 
-  PreParserExpression NewSpread(PreParserExpression expression, int pos) {
+  PreParserExpression NewSpread(PreParserExpression expression,
+                                int literal_index, int pos) {
     return PreParserExpression::Spread(expression);
   }
 
@@ -2497,6 +2498,7 @@ typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParseArrayLiteral(
       this->NewExpressionList(4, zone_);
   Expect(Token::LBRACK, CHECK_OK);
   while (peek() != Token::RBRACK) {
+    bool seen_spread = false;
     ExpressionT elem = this->EmptyExpression();
     if (peek() == Token::COMMA) {
       if (is_strong(language_mode())) {
@@ -2506,11 +2508,24 @@ typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParseArrayLiteral(
         return this->EmptyExpression();
       }
       elem = this->GetLiteralTheHole(peek_position(), factory());
+    } else if (peek() == Token::ELLIPSIS) {
+      ExpressionUnexpectedToken(classifier);
+      int start_pos = peek_position();
+      Consume(Token::ELLIPSIS);
+      ExpressionT argument =
+          this->ParseAssignmentExpression(true, classifier, CHECK_OK);
+
+      int literal_index = function_state_->NextMaterializedLiteralIndex();

[arv (Not doing code reviews), 2015/05/20 13:52:25]

Is this going to be a problem in the case of array spread?

[Dmitry Lomov (no reviews), 2015/05/20 14:07:19]

I don't think so - we will just have an unused literal index.

[Dmitry Lomov (no reviews), 2015/05/20 14:22:03]

Scratch that - I have One Weird Trick in mind here ;)

+      elem = factory()->NewSpread(argument, literal_index, start_pos);
+      seen_spread = true;
     } else {
       elem = this->ParseAssignmentExpression(true, classifier, CHECK_OK);
     }
     values->Add(elem, zone_);
     if (peek() != Token::RBRACK) {
+      if (seen_spread) {
+        BindingPatternUnexpectedToken(classifier);
+      }
       Expect(Token::COMMA, CHECK_OK);
     }
   }
@@ -2822,7 +2837,7 @@ typename Traits::Type::ExpressionList ParserBase<Traits>::ParseArguments(
         spread_arg.beg_pos = start_pos;
         spread_arg.end_pos = peek_position();
       }
-      argument = factory()->NewSpread(argument, start_pos);
+      argument = factory()->NewSpread(argument, -1, start_pos);
     }
     result->Add(argument, zone_);