tools/gn: don't allow trailing junk or non-literals in "value" conversion

tools/gn/parser.h

 // Copyright (c) 2013 The Chromium 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 TOOLS_GN_PARSER_H_
 #define TOOLS_GN_PARSER_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 22 matching lines @@
 class Parser {
  public:
   // Will return a null pointer and set the err on error.
   static scoped_ptr<ParseNode> Parse(const std::vector<Token>& tokens,
                                      Err* err);
 
   // Alternative to parsing that assumes the input is an expression.
   static scoped_ptr<ParseNode> ParseExpression(const std::vector<Token>& tokens,
                                                Err* err);
 
-  scoped_ptr<ParseNode> ParseExpression();
+  // Alternative to parsing that assumes the input is a literal value.
+  static scoped_ptr<ParseNode> ParseValue(const std::vector<Token>& tokens,
+                                          Err* err);
 
  private:
   // Vector must be valid for lifetime of call.
   Parser(const std::vector<Token>& tokens, Err* err);
   ~Parser();
 
+  scoped_ptr<ParseNode> ParseExpression();
+
   // Parses an expression with the given precedence or higher.
   scoped_ptr<ParseNode> ParseExpression(int precedence);
 
   // |PrefixFunc|s used in parsing expressions.
   scoped_ptr<ParseNode> Literal(Token token);
   scoped_ptr<ParseNode> Name(Token token);
   scoped_ptr<ParseNode> Group(Token token);
   scoped_ptr<ParseNode> Not(Token token);
   scoped_ptr<ParseNode> List(Token token);
   scoped_ptr<ParseNode> BlockComment(Token token);
@@ skipping 59 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(Parser, Expression);
   FRIEND_TEST_ALL_PREFIXES(Parser, FunctionCall);
   FRIEND_TEST_ALL_PREFIXES(Parser, List);
   FRIEND_TEST_ALL_PREFIXES(Parser, ParenExpression);
   FRIEND_TEST_ALL_PREFIXES(Parser, UnaryOp);
 
   DISALLOW_COPY_AND_ASSIGN(Parser);
 };
 
 #endif  // TOOLS_GN_PARSER_H_