Page Speed Optimization Libraries  1.5.27.2
net/instaweb/util/public/string_hash.h
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00001 /*
00002  * Copyright 2010 Google Inc.
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *      http:///www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00018 
00019 #ifndef NET_INSTAWEB_UTIL_PUBLIC_STRING_HASH_H_
00020 #define NET_INSTAWEB_UTIL_PUBLIC_STRING_HASH_H_
00021 
00022 #include <cstddef>
00023 
00024 #include "net/instaweb/util/public/string.h"
00025 #include "net/instaweb/util/public/string_util.h"
00026 
00027 namespace net_instaweb {
00028 
00031 template<class CharTransform, typename IntType>
00032 inline IntType HashString(const char* s, size_t len) {
00035   IntType result = 0;
00036   for (size_t i = 0; i < len; ++i, ++s) {
00037     result = (result * 131) + CharTransform::Normalize(*s);
00038   }
00039   return result;
00040 }
00041 
00044 inline size_t JoinHash(size_t a, size_t b) {
00045   return (a + 56) * 137 + b * 151; 
00046 }
00047 
00049 struct CasePreserve {
00057   static unsigned char Normalize(char c) {
00058     return c;
00059   }
00060 
00061   static bool Compare(const StringPiece& a, const StringPiece& b) {
00062     return a < b;
00063   }
00064 };
00065 
00067 struct CaseFold {
00068   static unsigned char Normalize(char c) {
00069     return LowerChar(c);
00070   }
00071 
00072   static bool Compare(const StringPiece& a, const StringPiece& b) {
00073     return StringCaseCompare(a, b) < 0;
00074   }
00075 };
00076 
00078 struct CasePreserveStringHash {
00079   size_t operator()(const GoogleString& str) const {
00080     return HashString<CasePreserve, size_t>(str.data(), str.size());
00081   }
00082 };
00083 
00084 struct CaseFoldStringHash {
00085   size_t operator()(const GoogleString& str) const {
00086     return HashString<CaseFold, size_t>(str.data(), str.size());
00087   }
00088 };
00089 
00090 struct CaseFoldStringEqual {
00091   bool operator()(const GoogleString& a, const GoogleString& b) const {
00092     return MemCaseEqual(a.data(), a.size(), b.data(), b.size());
00093   }
00094 };
00095 
00096 }  
00097 
00098 #endif  ///< NET_INSTAWEB_UTIL_PUBLIC_STRING_HASH_H_
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