Faster WTF::toASCIILower() implementation for 8-bit strings

Source/wtf/ASCIICType.h

 /*
  * Copyright (C) 2007, 2008, 2009, 2011 Apple 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 12 matching lines @@
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WTF_ASCIICType_h
 #define WTF_ASCIICType_h
 
 #include "wtf/Assertions.h"
+#include "wtf/unicode/Unicode.h"
 
 // The behavior of many of the functions in the <ctype.h> header is dependent
 // on the current locale. But in the WebKit project, all uses of those functions
 // are in code processing something that's not locale-specific. These equivalents
 // for some of the <ctype.h> functions are named more explicitly, not dependent
 // on the C library locale, and we should also optimize them as needed.
 
 // All functions return false or leave the character unchanged if passed a character
 // that is outside the range 0-7F. So they can be used on Unicode strings or
 // characters if the intent is to do processing only if the character is ASCII.
@@ skipping 56 matching lines @@
 template<typename CharType> inline bool isASCIISpace(CharType c)
 {
     return c <= ' ' && (c == ' ' || (c <= 0xD && c >= 0x9));
 }
 
 template<typename CharType> inline bool isASCIIUpper(CharType c)
 {
     return c >= 'A' && c <= 'Z';
 }
 
+const LChar ASCIICaseFoldTable[256] = {
+    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
+    0x40, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
+    0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
+    0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
+    0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
+    0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
+    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
+    0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
+    0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
+    0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
+    0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
+    0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
+    0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
+};
+
 template<typename CharType> inline CharType toASCIILower(CharType c)
 {
 #if defined(_MSC_FULL_VER) && _MSC_FULL_VER == 170060610
     // Make a workaround for VS2012 update 3 optimizer bug, remove once VS2012 fix it.
     return (c >= 'A' && c <= 'Z') ? c + 0x20 : c;
 #else
     return c | ((c >= 'A' && c <= 'Z') << 5);
 #endif
 }
 
+inline LChar toASCIILower(LChar c)
+{
+    return ASCIICaseFoldTable[c];
+}
+
+inline char toASCIILower(char c)
+{
+    return static_cast<char>(ASCIICaseFoldTable[static_cast<LChar>(c)]);
+}
+
 template<typename CharType> inline CharType toASCIILowerUnchecked(CharType character)
 {
     // This function can be used for comparing any input character
     // to a lowercase English character. The isASCIIAlphaCaselessEqual
     // below should be used for regular comparison of ASCII alpha
     // characters, but switch statements in CSS tokenizer require
     // direct use of this function.
     return character | 0x20;
 }
 
@@ skipping 48 matching lines @@
 using WTF::isASCIIUpper;
 using WTF::toASCIIHexValue;
 using WTF::toASCIILower;
 using WTF::toASCIILowerUnchecked;
 using WTF::toASCIIUpper;
 using WTF::lowerNibbleToASCIIHexDigit;
 using WTF::upperNibbleToASCIIHexDigit;
 using WTF::isASCIIAlphaCaselessEqual;
 
 #endif