Minor clean-up to getValueName (i.e. CSSValueID -> string conversion)

Source/build/scripts/make_css_value_keywords.py

 #!/usr/bin/env python
 
 import os.path
 import re
 import subprocess
 import sys
 
 from in_file import InFile
 from name_utilities import upper_first_letter
 import in_generator
@@ skipping 11 matching lines @@
 
 namespace blink {
 
 enum CSSValueID {
 %(value_keyword_enums)s
 };
 
 const int numCSSValueKeywords = %(value_keywords_count)d;
 const size_t maxCSSValueKeywordLength = %(max_value_keyword_length)d;
 
-const char* getValueName(unsigned short id);
+const char* getValueName(CSSValueID);
 bool isValueAllowedInMode(unsigned short id, CSSParserMode mode);
 
 } // namespace blink
 
 #endif // %(class_name)s_h
 """
 
 GPERF_TEMPLATE = """
 %%{
 %(license)s
 
 #include "config.h"
 #include "%(class_name)s.h"
 #include "core/css/HashTools.h"
 #include <string.h>
 
 namespace blink {
 static const char valueListStringPool[] = {
-"\\0"
 %(value_keyword_strings)s
 };
 
 static const unsigned short valueListStringOffsets[] = {
 %(value_keyword_offsets)s
 };
 
 %%}
 %%struct-type
 struct Value;
 %%omit-struct-type
 %%language=C++
 %%readonly-tables
 %%compare-strncmp
 %%define class-name %(class_name)sHash
 %%define lookup-function-name findValueImpl
 %%define hash-function-name value_hash_function
 %%define slot-name nameOffset
 %%define word-array-name value_word_list
 %%pic
 %%enum
 %%%%
 %(value_keyword_to_enum_map)s
 %%%%
 const Value* findValue(register const char* str, register unsigned int len)
 {
     return CSSValueKeywordsHash::findValueImpl(str, len);
 }
 
-const char* getValueName(unsigned short id)
+const char* getValueName(CSSValueID id)
 {
-    if (id >= numCSSValueKeywords || id <= 0)
-        return 0;
-    return valueListStringPool + valueListStringOffsets[id];
+    ASSERT(id > 0 && id < numCSSValueKeywords);
+    return valueListStringPool + valueListStringOffsets[id - 1];
 }
 
 bool isValueAllowedInMode(unsigned short id, CSSParserMode mode)
 {
     switch (id) {
         %(ua_sheet_mode_values_keywords)s
             return isUASheetBehavior(mode);
         %(quirks_mode_or_ua_sheet_mode_values_keywords)s
             return isUASheetBehavior(mode) || isQuirksModeBehavior(mode);
         default:
@@ skipping 45 matching lines @@
             'class_name': self.class_name,
             'value_keyword_enums': "\n".join(enum_enties),
             'value_keywords_count': len(enum_enties),
             'max_value_keyword_length': reduce(max, map(len, map(lambda property: property['name'], self._value_keywords))),
         }
 
     def _value_keywords_with_mode(self, mode):
         return filter(lambda property: property['mode'] == mode, self._value_keywords)
 
     def generate_implementation(self):
-        keyword_offsets = [0]
-        current_offset = 1
+        keyword_offsets = []
+        current_offset = 0
         for keyword in self._value_keywords:
             keyword_offsets.append(current_offset)
             current_offset += len(keyword["name"]) + 1
 
         gperf_input = GPERF_TEMPLATE % {
             'license': license.license_for_generated_cpp(),
             'class_name': self.class_name,
             'value_keyword_strings': '\n'.join(map(lambda property: '    "%(name)s\\0"' % property, self._value_keywords)),
             'value_keyword_offsets': '\n'.join(map(lambda offset: '  %d,' % offset, keyword_offsets)),
             'value_keyword_to_enum_map': '\n'.join('%(lower_name)s, %(enum_name)s' % keyword for keyword in self._value_keywords),
             'ua_sheet_mode_values_keywords': '\n        '.join(map(self._case_value_keyword, self._value_keywords_with_mode('UASheet'))),
             'quirks_mode_or_ua_sheet_mode_values_keywords': '\n    '.join(map(self._case_value_keyword, self._value_keywords_with_mode('QuirksOrUASheet'))),
         }
         # FIXME: If we could depend on Python 2.7, we would use subprocess.check_output
         gperf_args = [self.gperf_path, '--key-positions=*', '-P', '-n']
         gperf_args.extend(['-m', '50'])  # Pick best of 50 attempts.
         gperf_args.append('-D')  # Allow duplicate hashes -> More compact code.
         gperf = subprocess.Popen(gperf_args, stdin=subprocess.PIPE, stdout=subprocess.PIPE, universal_newlines=True)
         return gperf.communicate(gperf_input)[0]
 
 
 if __name__ == "__main__":
     in_generator.Maker(CSSValueKeywordsWriter).main(sys.argv)