[destructuring] Implement spread binding patterns.

src/preparser.h

 // 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.
 
 #ifndef V8_PREPARSER_H
 #define V8_PREPARSER_H
 
 #include "src/v8.h"
 
 #include "src/bailout-reason.h"
@@ skipping 1467 matching lines @@
       Scope* scope, PreParserStatementList body, int materialized_literal_count,
       int expected_property_count, int handler_count, int parameter_count,
       FunctionLiteral::ParameterFlag has_duplicate_parameters,
       FunctionLiteral::FunctionType function_type,
       FunctionLiteral::IsFunctionFlag is_function,
       FunctionLiteral::EagerCompileHint eager_compile_hint, FunctionKind kind,
       int position) {
     return PreParserExpression::Default();
   }
 
-  PreParserExpression NewSpread(PreParserExpression expression, int pos) {
+  PreParserExpression NewSpread(PreParserExpression expression,
+                                int literal_index, int pos) {
     return PreParserExpression::Spread(expression);
   }
 
   // Return the object itself as AstVisitor and implement the needed
   // dummy method right in this class.
   PreParserFactory* visitor() { return this; }
   int* ast_properties() {
     static int dummy = 42;
     return &dummy;
   }
@@ skipping 991 matching lines @@
 typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParseArrayLiteral(
     ExpressionClassifier* classifier, bool* ok) {
   // ArrayLiteral ::
   //   '[' Expression? (',' Expression?)* ']'
 
   int pos = peek_position();
   typename Traits::Type::ExpressionList values =
       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())) {
         ReportMessageAt(scanner()->peek_location(),
                         MessageTemplate::kStrongEllision);
         *ok = false;
         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);
     }
   }
   Expect(Token::RBRACK, CHECK_OK);
 
   // Update the scope information before the pre-parsing bailout.
   int literal_index = function_state_->NextMaterializedLiteralIndex();
 
   return factory()->NewArrayLiteral(values, literal_index,
                                     is_strong(language_mode()), pos);
@@ skipping 291 matching lines @@
     int start_pos = peek_position();
     if (is_spread) Consume(Token::ELLIPSIS);
 
     ExpressionT argument = this->ParseAssignmentExpression(
         true, classifier, CHECK_OK_CUSTOM(NullExpressionList));
     if (is_spread) {
       if (!spread_arg.IsValid()) {
         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_);
 
     // unspread_sequences_count is the number of sequences of parameters which
     // are not prefixed with a spread '...' operator.
     if (is_spread) {
       was_unspread = false;
     } else if (!was_unspread) {
       was_unspread = true;
       unspread_sequences_count++;
@@ skipping 1171 matching lines @@
       *ok = false;
       return;
     }
     has_seen_constructor_ = true;
     return;
   }
 }
 } }  // v8::internal
 
 #endif  // V8_PREPARSER_H