WTF: Add comments and tests for Unicode aware case-insensitive string operations.

third_party/WebKit/Source/wtf/text/StringBuilder.h

 /*
  * Copyright (C) 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 229 matching lines @@
                        unsigned length) {
   if (s.length() != length)
     return false;
 
   if (s.is8Bit())
     return equalIgnoringCase(s.characters8(), buffer, length);
 
   return equalIgnoringCase(s.characters16(), buffer, length);
 }
 
+// Unicode aware case insensitive string matching. Non-ASCII characters might
+// match to ASCII characters. This function is rarely used to implement web
+// platform features.
 inline bool equalIgnoringCase(const StringBuilder& s, const char* string) {
   return equalIgnoringCase(s, reinterpret_cast<const LChar*>(string),
                            strlen(string));
 }
 
 template <typename StringType>
 bool equal(const StringBuilder& a, const StringType& b) {
   if (a.length() != b.length())
     return false;
 
   if (!a.length())
     return true;
 
   if (a.is8Bit()) {
     if (b.is8Bit())
       return equal(a.characters8(), b.characters8(), a.length());
     return equal(a.characters8(), b.characters16(), a.length());
   }
 
   if (b.is8Bit())
     return equal(a.characters16(), b.characters8(), a.length());
   return equal(a.characters16(), b.characters16(), a.length());
 }
 
-template <typename StringType>
-bool equalIgnoringCase(const StringBuilder& a, const StringType& b) {
-  if (a.length() != b.length())
-    return false;
-
-  if (!a.length())
-    return true;
-
-  if (a.is8Bit()) {
-    if (b.is8Bit())
-      return equalIgnoringCase(a.characters8(), b.characters8(), a.length());
-    return equalIgnoringCase(a.characters8(), b.characters16(), a.length());
-  }
-
-  if (b.is8Bit())
-    return equalIgnoringCase(a.characters16(), b.characters8(), a.length());
-  return equalIgnoringCase(a.characters16(), b.characters16(), a.length());
-}
-
 inline bool operator==(const StringBuilder& a, const StringBuilder& b) {
   return equal(a, b);
 }
 inline bool operator!=(const StringBuilder& a, const StringBuilder& b) {
   return !equal(a, b);
 }
 inline bool operator==(const StringBuilder& a, const String& b) {
   return equal(a, b);
 }
 inline bool operator!=(const StringBuilder& a, const String& b) {
   return !equal(a, b);
 }
 inline bool operator==(const String& a, const StringBuilder& b) {
   return equal(b, a);
 }
 inline bool operator!=(const String& a, const StringBuilder& b) {
   return !equal(b, a);
 }
 
 }  // namespace WTF
 
 using WTF::StringBuilder;
 
 #endif  // StringBuilder_h