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

tools/gn/tokenizer.cc

 // 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.
 
 #include "tools/gn/tokenizer.h"
 
 #include "base/logging.h"
 #include "base/strings/string_util.h"
 #include "tools/gn/input_file.h"
 
@@ skipping 162 matching lines @@
   return static_cast<size_t>(-1);
 }
 
 // static
 bool Tokenizer::IsNewline(const base::StringPiece& buffer, size_t offset) {
   DCHECK(offset < buffer.size());
   // We may need more logic here to handle different line ending styles.
   return buffer[offset] == '\n';
 }
 
+// static
+bool Tokenizer::IsIdentifierFirstChar(char c) {
+  return base::IsAsciiAlpha(c) || c == '_';
+}
+
+// static
+bool Tokenizer::IsIdentifierContinuingChar(char c) {
+  // Also allow digits after the first char.
+  return IsIdentifierFirstChar(c) || base::IsAsciiDigit(c);
+}
 
 void Tokenizer::AdvanceToNextToken() {
   while (!at_end() && IsCurrentWhitespace())
     Advance();
 }
 
 Token::Type Tokenizer::ClassifyCurrent() const {
   DCHECK(!at_end());
   char next_char = cur_char();
   if (base::IsAsciiDigit(next_char))
@@ skipping 197 matching lines @@
     // Different types of comments.
     help = "Comments should start with # instead";
   } else if (cur_char() == '\'') {
     help = "Strings are delimited by \" characters, not apostrophes.";
   } else {
     help = "I have no idea what this is.";
   }
 
   return Err(location, "Invalid token.", help);
 }