string_hash.h

Go to the documentation of this file.

/*
 * Copyright 2010 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http:///www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#ifndef PAGESPEED_KERNEL_BASE_STRING_HASH_H_
#define PAGESPEED_KERNEL_BASE_STRING_HASH_H_

#include <cstddef>

#include "pagespeed/kernel/base/string.h"
#include "pagespeed/kernel/base/string_util.h"

namespace net_instaweb {

template<class CharTransform, typename IntType>
inline IntType HashString(const char* s, size_t len) {
  IntType result = 0;
  for (const char* end = s + len; s != end; ++s) {
    result = (result * 131) + CharTransform::Normalize(*s);
  }
  return result;
}

inline size_t JoinHash(size_t a, size_t b) {
  return (a + 56) * 137 + b * 151; 
}

struct CasePreserve {
  static unsigned char Normalize(char c) {
    return c;
  }

  static bool Compare(const StringPiece& a, const StringPiece& b) {
    return a < b;
  }
};

struct CaseFold {
  static unsigned char Normalize(char c) {
    return LowerChar(c);
  }

  static bool Compare(const StringPiece& a, const StringPiece& b) {
    return StringCaseCompare(a, b) < 0;
  }
};

struct CasePreserveStringHash {
  size_t operator()(const GoogleString& str) const {
    return HashString<CasePreserve, size_t>(str.data(), str.size());
  }
};

struct CaseFoldStringHash {
  size_t operator()(const GoogleString& str) const {
    return HashString<CaseFold, size_t>(str.data(), str.size());
  }
};

struct CaseFoldStringEqual {
  bool operator()(const GoogleString& a, const GoogleString& b) const {
    return MemCaseEqual(a.data(), a.size(), b.data(), b.size());
  }
};

struct CasePreserveStringPieceHash {
  size_t operator()(StringPiece str) const {
    return HashString<CasePreserve, size_t>(str.data(), str.size());
  }
};

struct CaseFoldStringPieceHash {
  size_t operator()(StringPiece str) const {
    return HashString<CaseFold, size_t>(str.data(), str.size());
  }
};
struct CaseFoldStringPieceEqual {
  bool operator()(StringPiece a, StringPiece b) const {
    return MemCaseEqual(a.data(), a.size(), b.data(), b.size());
  }
};

}  

#endif