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//===- StringHash.h ---------------------------------------------------------===//
//
// The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef MCLD_STRING_HASH_FUNCTION_H
#define MCLD_STRING_HASH_FUNCTION_H
#ifdef ENABLE_UNITTEST
#include <gtest.h>
#endif
#include <llvm/ADT/StringRef.h>
#include <llvm/Support/ErrorHandling.h>
#include <functional>
namespace mcld
{
enum StringHashType
{
RS,
JS,
PJW,
ELF,
BKDR,
SDBM,
DJB,
DEK,
BP,
FNV,
AP
};
/** \class template<size_t TYPE> StringHash
* \brief the template StringHash class, for specification
*/
template<size_t TYPE>
struct StringHash : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
llvm::report_fatal_error("Undefined StringHash function.\n");
}
};
/** \class StringHash<RSHash>
* \brief RS StringHash funciton
*/
template<>
struct StringHash<RS> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
const unsigned int b = 378551;
size_t a = 63689;
size_t hash_val = 0;
for(unsigned int i = 0; i < pKey.size(); ++i) {
hash_val = hash_val * a + pKey[i];
a = a * b;
}
return hash_val;
}
};
/** \class StringHash<JSHash>
* \brief JS hash funciton
*/
template<>
struct StringHash<JS> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
size_t hash_val = 1315423911;
for(unsigned int i = 0; i < pKey.size(); ++i) {
hash_val ^= ((hash_val << 5) + pKey[i] + (hash_val >> 2));
}
return hash_val;
}
};
/** \class StringHash<PJW>
* \brief P.J. Weinberger hash function
*/
template<>
struct StringHash<PJW> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
const unsigned int BitsInUnsignedInt = (unsigned int)(sizeof(unsigned int) * 8);
const unsigned int ThreeQuarters = (unsigned int)((BitsInUnsignedInt * 3) / 4);
const unsigned int OneEighth = (unsigned int)(BitsInUnsignedInt / 8);
const unsigned int HighBits = (unsigned int)(0xFFFFFFFF) << (BitsInUnsignedInt - OneEighth);
size_t hash_val = 0;
size_t test = 0;
for(unsigned int i = 0; i < pKey.size(); ++i) {
hash_val = (hash_val << OneEighth) + pKey[i];
if((test = hash_val & HighBits) != 0) {
hash_val = (( hash_val ^ (test >> ThreeQuarters)) & (~HighBits));
}
}
return hash_val;
}
};
/** \class StringHash<ELF>
* \brief ELF hash function.
*/
template<>
struct StringHash<ELF> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
size_t hash_val = 0;
size_t x = 0;
for (unsigned int i = 0; i < pKey.size(); ++i) {
hash_val = (hash_val << 4) + pKey[i];
if((x = hash_val & 0xF0000000L) != 0)
hash_val ^= (x >> 24);
hash_val &= ~x;
}
return hash_val;
}
};
/** \class StringHash<BKDR>
* \brief BKDR hash function
*/
template<>
struct StringHash<BKDR> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
const size_t seed = 131;
size_t hash_val = 0;
for(size_t i = 0; i < pKey.size(); ++i)
hash_val = (hash_val * seed) + pKey[i];
return hash_val;
}
};
/** \class StringHash<SDBM>
* \brief SDBM hash function
* 0.049s in 100000 test
*/
template<>
struct StringHash<SDBM> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
size_t hash_val = 0;
for(size_t i = 0; i < pKey.size(); ++i)
hash_val = pKey[i] + (hash_val << 6) + (hash_val << 16) - hash_val;
return hash_val;
}
};
/** \class StringHash<DJB>
* \brief DJB hash function
* 0.057s in 100000 test
*/
template<>
struct StringHash<DJB> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
size_t hash_val = 5381;
for(size_t i = 0; i < pKey.size(); ++i)
hash_val = ((hash_val << 5) + hash_val) + pKey[i];
return hash_val;
}
};
/** \class StringHash<DEK>
* \brief DEK hash function
* 0.60s
*/
template<>
struct StringHash<DEK> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
size_t hash_val = pKey.size();
for(size_t i = 0; i < pKey.size(); ++i)
hash_val = ((hash_val << 5) ^ (hash_val >> 27)) ^ pKey[i];
return hash_val;
}
};
/** \class StringHash<BP>
* \brief BP hash function
* 0.057s
*/
template<>
struct StringHash<BP> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
size_t hash_val = 0;
for(size_t i = 0; i < pKey.size(); ++i)
hash_val = hash_val << 7 ^ pKey[i];
return hash_val;
}
};
/** \class StringHash<FNV>
* \brief FNV hash function
* 0.058s
*/
template<>
struct StringHash<FNV> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
const size_t fnv_prime = 0x811C9DC5;
size_t hash_val = 0;
for(size_t i = 0; i < pKey.size(); ++i) {
hash_val *= fnv_prime;
hash_val ^= pKey[i];
}
return hash_val;
}
};
/** \class StringHash<AP>
* \brief AP hash function
* 0.060s
*/
template<>
struct StringHash<AP> : public std::unary_function<const llvm::StringRef&, size_t>
{
size_t operator()(const llvm::StringRef& pKey) const
{
unsigned int hash_val = 0xAAAAAAAA;
for(size_t i = 0; i < pKey.size(); ++i) {
hash_val ^= ((i & 1) == 0)?
((hash_val << 7) ^ pKey[i] * (hash_val >> 3)):
(~((hash_val << 11) + (pKey[i] ^ (hash_val >> 5))));
}
return hash_val;
}
};
/** \class template<size_t TYPE> StringCompare
* \brief the template StringCompare class, for specification
*/
template<typename STRING_TYPE>
struct StringCompare : public std::binary_function<const STRING_TYPE&, const STRING_TYPE&, bool>
{
bool operator()(const STRING_TYPE& X, const STRING_TYPE& Y) const
{ return X == Y; }
};
template<>
struct StringCompare<const char*> : public std::binary_function<const char*, const char*, bool>
{
bool operator()(const char* X, const char* Y) const
{ return (0 == std::strcmp(X, Y)); }
};
template<>
struct StringCompare<char*> : public std::binary_function<const char*, const char*, bool>
{
bool operator()(const char* X, const char* Y) const
{ return (0 == std::strcmp(X, Y)); }
};
} // namespace of mcld
#endif
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