Changeset 52776 in webkit for trunk/JavaScriptCore/runtime/UStringImpl.cpp

Timestamp:

Jan 4, 2010, 5:24:48 PM (15 years ago)

Author:

[email protected]

Message:

JavaScriptCore: ​https://bugs.webkit.org/show_bug.cgi?id=33163
Add string hashing functions to WTF.
Use WTF's string hashing functions from UStringImpl.

Reviewed by Sam Weinig, additional coding by Mark Rowe.

• GNUmakefile.am:
• JavaScriptCore.exp:
• JavaScriptCore.gypi:
• JavaScriptCore.vcproj/JavaScriptCore/JavaScriptCore.def:
• JavaScriptCore.xcodeproj/project.pbxproj:
• runtime/UStringImpl.cpp:
• runtime/UStringImpl.h:

(JSC::UStringImpl::computeHash):

• wtf/HashFunctions.h:
• wtf/StringHashFunctions.h: Added.

(WTF::stringHash):

JavaScriptGlue: Add a forwarding header so that StringHashFunctions.h can be found.

Reviewed by Sam Weinig.

• ForwardingHeaders/wtf/StringHashFunctions.h: Added.

WebCore: ​https://bugs.webkit.org/show_bug.cgi?id=33163
Use WTF's string hashing functions from StringImpl.

Patch by Mark Rowe <​[email protected]> on 2010-01-04
Reviewed by Sam Weinig.

• ForwardingHeaders/wtf/StringHashFunctions.h: Added.
• platform/text/StringHash.h:
• platform/text/StringImpl.h:

(WebCore::StringImpl::computeHash):

File:

• trunk/JavaScriptCore/runtime/UStringImpl.cpp (modified) (1 diff)

trunk/JavaScriptCore/runtime/UStringImpl.cpp

@@ -82 +82 @@
 }
 
-// Golden ratio - arbitrary start value to avoid mapping all 0's to all 0's
-// or anything like that.
-const unsigned PHI = 0x9e3779b9U;
-
-// Paul Hsieh's SuperFastHash
-// http://www.azillionmonkeys.com/qed/hash.html
-unsigned UStringImpl::computeHash(const UChar* s, int len)
-{
-    unsigned l = len;
-    uint32_t hash = PHI;
-    uint32_t tmp;
-
-    int rem = l & 1;
-    l >>= 1;
-
-    // Main loop
-    for (; l > 0; l--) {
-        hash += s[0];
-        tmp = (s[1] << 11) ^ hash;
-        hash = (hash << 16) ^ tmp;
-        s += 2;
-        hash += hash >> 11;
-    }
-
-    // Handle end case
-    if (rem) {
-        hash += s[0];
-        hash ^= hash << 11;
-        hash += hash >> 17;
-    }
-
-    // Force "avalanching" of final 127 bits
-    hash ^= hash << 3;
-    hash += hash >> 5;
-    hash ^= hash << 2;
-    hash += hash >> 15;
-    hash ^= hash << 10;
-
-    // this avoids ever returning a hash code of 0, since that is used to
-    // signal "hash not computed yet", using a value that is likely to be
-    // effectively the same as 0 when the low bits are masked
-    if (hash == 0)
-        hash = 0x80000000;
-
-    return hash;
 }
-
-// Paul Hsieh's SuperFastHash
-// http://www.azillionmonkeys.com/qed/hash.html
-unsigned UStringImpl::computeHash(const char* s, int l)
-{
-    // This hash is designed to work on 16-bit chunks at a time. But since the normal case
-    // (above) is to hash UTF-16 characters, we just treat the 8-bit chars as if they
-    // were 16-bit chunks, which should give matching results
-
-    uint32_t hash = PHI;
-    uint32_t tmp;
-
-    size_t rem = l & 1;
-    l >>= 1;
-
-    // Main loop
-    for (; l > 0; l--) {
-        hash += static_cast<unsigned char>(s[0]);
-        tmp = (static_cast<unsigned char>(s[1]) << 11) ^ hash;
-        hash = (hash << 16) ^ tmp;
-        s += 2;
-        hash += hash >> 11;
-    }
-
-    // Handle end case
-    if (rem) {
-        hash += static_cast<unsigned char>(s[0]);
-        hash ^= hash << 11;
-        hash += hash >> 17;
-    }
-
-    // Force "avalanching" of final 127 bits
-    hash ^= hash << 3;
-    hash += hash >> 5;
-    hash ^= hash << 2;
-    hash += hash >> 15;
-    hash ^= hash << 10;
-
-    // this avoids ever returning a hash code of 0, since that is used to
-    // signal "hash not computed yet", using a value that is likely to be
-    // effectively the same as 0 when the low bits are masked
-    if (hash == 0)
-        hash = 0x80000000;
-
-    return hash;
-}
-
-}