Page Speed Optimization Libraries  1.2.24.1
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_util.h"
00025 
00026 namespace net_instaweb {
00027 
00030 template<class CharTransform, typename IntType>
00031 inline IntType HashString(const char* s, size_t len) {
00034   IntType result = 0;
00035   for (size_t i = 0; i < len; ++i, ++s) {
00036     result = (result * 131) + CharTransform::Normalize(*s);
00037   }
00038   return result;
00039 }
00040 
00043 inline size_t JoinHash(size_t a, size_t b) {
00044   return (a + 56) * 137 + b * 151; 
00045 }
00046 
00048 struct CasePreserve {
00056   static unsigned char Normalize(char c) {
00057     return c;
00058   }
00059 
00060   static bool Compare(const StringPiece& a, const StringPiece& b) {
00061     return a < b;
00062   }
00063 };
00064 
00066 struct CaseFold {
00067   static unsigned char Normalize(char c) {
00068     return LowerChar(c);
00069   }
00070 
00071   static bool Compare(const StringPiece& a, const StringPiece& b) {
00072     return StringCaseCompare(a, b) < 0;
00073   }
00074 };
00075 
00076 }  
00077 
00078 #endif  ///< NET_INSTAWEB_UTIL_PUBLIC_STRING_HASH_H_
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