tools/gn: move the implementation of IsIdentifierXXX functions to the source file

tools/gn/tokenizer.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_TOKENIZER_H_
 #define TOOLS_GN_TOKENIZER_H_
 
 #include <vector>
 
 #include "base/macros.h"
 #include "base/strings/string_piece.h"
-#include "base/strings/string_util.h"
 #include "tools/gn/err.h"
 #include "tools/gn/token.h"
 
 class InputFile;
 
 class Tokenizer {
  public:
   static std::vector<Token> Tokenize(const InputFile* input_file, Err* err);
 
   // Counts lines in the given buffer (the first line is "1") and returns
   // the byte offset of the beginning of that line, or (size_t)-1 if there
   // aren't that many lines in the file. Note that this will return the byte
   // one past the end of the input if the last character is a newline.
   //
   // This is a helper function for error output so that the tokenizer's
   // notion of lines can be used elsewhere.
   static size_t ByteOffsetOfNthLine(const base::StringPiece& buf, int n);
 
   // Returns true if the given offset of the string piece counts as a newline.
   // The offset must be in the buffer.
   static bool IsNewline(const base::StringPiece& buffer, size_t offset);
 
-  static bool IsIdentifierFirstChar(char c) {
-    return base::IsAsciiAlpha(c) || c == '_';
-  }
+  static bool IsIdentifierFirstChar(char c);
 
-  static bool IsIdentifierContinuingChar(char c) {
-    // Also allow digits after the first char.
-    return IsIdentifierFirstChar(c) || base::IsAsciiDigit(c);
-  }
+  static bool IsIdentifierContinuingChar(char c);
 
  private:
   // InputFile must outlive the tokenizer and all generated tokens.
   Tokenizer(const InputFile* input_file, Err* err);
   ~Tokenizer();
 
   std::vector<Token> Run();
 
   void AdvanceToNextToken();
   Token::Type ClassifyCurrent() const;
@@ skipping 32 matching lines @@
   Err* err_;
   size_t cur_;  // Byte offset into input buffer.
 
   int line_number_;
   int char_in_line_;
 
   DISALLOW_COPY_AND_ASSIGN(Tokenizer);
 };
 
 #endif  // TOOLS_GN_TOKENIZER_H_