[es6] Initial support for let/const bindings in sloppy mode

src/preparser.cc

 // Copyright 2011 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 <cmath>
 
 #include "src/allocation.h"
 #include "src/base/logging.h"
 #include "src/conversions-inl.h"
 #include "src/conversions.h"
@@ skipping 179 matching lines @@
     case Token::FUNCTION:
       return ParseFunctionDeclaration(ok);
     case Token::CLASS:
       return ParseClassDeclaration(ok);
     case Token::CONST:
       if (allow_const()) {
         return ParseVariableStatement(kStatementListItem, ok);
       }
       break;
     case Token::LET:
-      if (is_strict(language_mode())) {
+      if (allow_let()) {
         return ParseVariableStatement(kStatementListItem, ok);
       }
       break;
     default:
       break;
   }
   return ParseStatement(ok);
 }
 
 
@@ skipping 238 matching lines @@
 PreParser::Statement PreParser::ParseBlock(bool* ok) {
   // Block ::
   //   '{' Statement* '}'
 
   // Note that a Block does not introduce a new execution scope!
   // (ECMA-262, 3rd, 12.2)
   //
   Expect(Token::LBRACE, CHECK_OK);
   Statement final = Statement::Default();
   while (peek() != Token::RBRACE) {
-    if (is_strict(language_mode())) {
+    if (is_strict(language_mode()) || allow_harmony_sloppy()) {
       final = ParseStatementListItem(CHECK_OK);
     } else {
       final = ParseStatement(CHECK_OK);
     }
   }
   Expect(Token::RBRACE, ok);
   return final;
 }
 
 
@@ skipping 47 matching lines @@
     //
     // ConstDeclaration : const ConstBinding (',' ConstBinding)* ';'
     //
     // * It is a Syntax Error if the code that matches this production is not
     //   contained in extended code.
     //
     // However disallowing const in sloppy mode will break compatibility with
     // existing pages. Therefore we keep allowing const with the old
     // non-harmony semantics in sloppy mode.
     Consume(Token::CONST);
-    if (is_strict(language_mode())) {
+    if (is_strict(language_mode()) ||
+        (allow_harmony_sloppy() && !allow_legacy_const())) {
       DCHECK(var_context != kStatement);
       is_strict_const = true;
       require_initializer = var_context != kForStatement;
     }
-  } else if (peek() == Token::LET && is_strict(language_mode())) {
+  } else if (peek() == Token::LET && allow_let()) {
     Consume(Token::LET);
     DCHECK(var_context != kStatement);
   } else {
     *ok = false;
     return Statement::Default();
   }
 
   // The scope of a var/const declared variable anywhere inside a function
   // is the entire function (ECMA-262, 3rd, 10.1.3, and 12.2). The scope
   // of a let declared variable is the scope of the immediately enclosing
@@ skipping 319 matching lines @@
 PreParser::Statement PreParser::ParseForStatement(bool* ok) {
   // ForStatement ::
   //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
 
   Expect(Token::FOR, CHECK_OK);
   Expect(Token::LPAREN, CHECK_OK);
   bool is_let_identifier_expression = false;
   if (peek() != Token::SEMICOLON) {
     ForEachStatement::VisitMode mode;
     if (peek() == Token::VAR || (peek() == Token::CONST && allow_const()) ||
-        (peek() == Token::LET && is_strict(language_mode()))) {
+        (peek() == Token::LET && allow_let())) {
       int decl_count;
       Scanner::Location first_initializer_loc = Scanner::Location::invalid();
       Scanner::Location bindings_loc = Scanner::Location::invalid();
       ParseVariableDeclarations(kForStatement, &decl_count,
                                 &first_initializer_loc, &bindings_loc,
                                 CHECK_OK);
       bool accept_IN = decl_count >= 1;
       bool accept_OF = true;
       if (accept_IN && CheckInOrOf(accept_OF, &mode, ok)) {
         if (!*ok) return Statement::Default();
@@ skipping 309 matching lines @@
 
   DCHECK(!spread_pos.IsValid());
 
   return Expression::Default();
 }
 
 #undef CHECK_OK
 
 
 } }  // v8::internal