base/json: Make ReadHexDigits easier to read by using IsHexDigit() function.

base/json/json_reader.cc

 // Copyright (c) 2011 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 "base/json/json_reader.h"
 
 #include "base/float_util.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stringprintf.h"
@@ skipping 35 matching lines @@
 }
 
 // A helper method for ParseStringToken.  It reads |digits| hex digits from the
 // token. If the sequence if digits is not valid (contains other characters),
 // the method returns false.
 bool ReadHexDigits(base::JSONReader::Token& token, int digits) {
   for (int i = 1; i <= digits; ++i) {
     wchar_t c = *(token.begin + token.length + i);
     if ('\0' == c)
       return false;
-    if (!(('0' <= c && c <= '9') || ('a' <= c && c <= 'f') ||
-          ('A' <= c && c <= 'F'))) {
+    if (!IsHexDigit(c))
       return false;
-    }
   }
 
   token.length += digits;
   return true;
 }
 
 }  // namespace
 
 namespace base {
 
@@ skipping 591 matching lines @@
       ++column_number;
     }
   }
 
   error_line_ = line_number;
   error_col_ = column_number;
   error_code_ = error;
 }
 
 }  // namespace base