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// Copyright 2011 Google Inc. All Rights Reserved.
//
// 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 NINJA_MAP_H_
#define NINJA_MAP_H_
#include "string_piece.h"
// MurmurHash2, by Austin Appleby
static inline
unsigned int MurmurHash2(const void* key, size_t len) {
static const unsigned int seed = 0xDECAFBAD;
const unsigned int m = 0x5bd1e995;
const int r = 24;
unsigned int h = seed ^ len;
const unsigned char * data = (const unsigned char *)key;
while (len >= 4) {
unsigned int k = *(unsigned int *)data;
k *= m;
k ^= k >> r;
k *= m;
h *= m;
h ^= k;
data += 4;
len -= 4;
}
switch (len) {
case 3: h ^= data[2] << 16;
case 2: h ^= data[1] << 8;
case 1: h ^= data[0];
h *= m;
};
h ^= h >> 13;
h *= m;
h ^= h >> 15;
return h;
}
#ifdef _MSC_VER
#include <hash_map>
using stdext::hash_map;
using stdext::hash_compare;
struct StringPieceCmp : public hash_compare<StringPiece> {
size_t operator()(const StringPiece& key) const {
return MurmurHash2(key.str_, key.len_);
}
bool operator()(const StringPiece& a, const StringPiece& b) const {
int cmp = strncmp(a.str_, b.str_, min(a.len_, b.len_));
if (cmp < 0) {
return true;
} else if (cmp > 0) {
return false;
} else {
return a.len_ < b.len_;
}
}
};
#else
#include <ext/hash_map>
using __gnu_cxx::hash_map;
namespace __gnu_cxx {
template<>
struct hash<std::string> {
size_t operator()(const std::string& s) const {
return hash<const char*>()(s.c_str());
}
};
template<>
struct hash<StringPiece> {
size_t operator()(StringPiece key) const {
return MurmurHash2(key.str_, key.len_);
}
};
}
#endif
/// A template for hash_maps keyed by a StringPiece whose string is
/// owned externally (typically by the values). Use like:
/// ExternalStringHash<Foo*>::Type foos; to make foos into a hash
/// mapping StringPiece => Foo*.
template<typename V>
struct ExternalStringHashMap {
#ifdef _MSC_VER
typedef hash_map<StringPiece, V, StringPieceCmp> Type;
#else
typedef hash_map<StringPiece, V> Type;
#endif
};
#endif // NINJA_MAP_H_
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