113 lines
3.2 KiB
C++
113 lines
3.2 KiB
C++
/*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version 2
|
|
* of the License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*/
|
|
|
|
#ifndef __BLI_HASH_CXX_H__
|
|
#define __BLI_HASH_CXX_H__
|
|
|
|
/** \file
|
|
* \ingroup bli
|
|
*
|
|
* This file provides default hash functions for some primitive types. The hash functions can be
|
|
* used by containers such as Map and Set.
|
|
*/
|
|
|
|
#include <functional>
|
|
#include <string>
|
|
#include <utility>
|
|
#include <memory>
|
|
|
|
#include "BLI_utildefines.h"
|
|
#include "BLI_math_base.h"
|
|
|
|
namespace BLI {
|
|
|
|
template<typename T> struct DefaultHash {
|
|
};
|
|
|
|
#define TRIVIAL_DEFAULT_INT_HASH(TYPE) \
|
|
template<> struct DefaultHash<TYPE> { \
|
|
uint32_t operator()(TYPE value) const \
|
|
{ \
|
|
return (uint32_t)value; \
|
|
} \
|
|
}
|
|
|
|
/**
|
|
* Cannot make any assumptions about the distribution of keys, so use a trivial hash function by
|
|
* default. The hash table implementations are designed to take all bits of the hash into account
|
|
* to avoid really bad behavior when the lower bits are all zero. Special hash functions can be
|
|
* implemented when more knowledge about a specific key distribution is available.
|
|
*/
|
|
TRIVIAL_DEFAULT_INT_HASH(int8_t);
|
|
TRIVIAL_DEFAULT_INT_HASH(uint8_t);
|
|
TRIVIAL_DEFAULT_INT_HASH(int16_t);
|
|
TRIVIAL_DEFAULT_INT_HASH(uint16_t);
|
|
TRIVIAL_DEFAULT_INT_HASH(int32_t);
|
|
TRIVIAL_DEFAULT_INT_HASH(uint32_t);
|
|
TRIVIAL_DEFAULT_INT_HASH(int64_t);
|
|
TRIVIAL_DEFAULT_INT_HASH(uint64_t);
|
|
|
|
template<> struct DefaultHash<float> {
|
|
uint32_t operator()(float value) const
|
|
{
|
|
return *(uint32_t *)&value;
|
|
}
|
|
};
|
|
|
|
template<> struct DefaultHash<std::string> {
|
|
uint32_t operator()(const std::string &value) const
|
|
{
|
|
uint32_t hash = 5381;
|
|
for (char c : value) {
|
|
hash = hash * 33 + c;
|
|
}
|
|
return hash;
|
|
}
|
|
};
|
|
|
|
/**
|
|
* While we cannot guarantee that the lower 3 bits or a pointer are zero, it is safe to assume
|
|
* this in the general case. MEM_malloc only returns 8 byte aligned addresses on 64-bit systems.
|
|
*/
|
|
template<typename T> struct DefaultHash<T *> {
|
|
uint32_t operator()(const T *value) const
|
|
{
|
|
uintptr_t ptr = POINTER_AS_UINT(value);
|
|
uint32_t hash = (uint32_t)(ptr >> 3);
|
|
return hash;
|
|
}
|
|
};
|
|
|
|
template<typename T> struct DefaultHash<std::unique_ptr<T>> {
|
|
uint32_t operator()(const std::unique_ptr<T> &value) const
|
|
{
|
|
return DefaultHash<T *>{}(value.get());
|
|
}
|
|
};
|
|
|
|
template<typename T1, typename T2> struct DefaultHash<std::pair<T1, T2>> {
|
|
uint32_t operator()(const std::pair<T1, T2> &value) const
|
|
{
|
|
uint32_t hash1 = DefaultHash<T1>{}(value.first);
|
|
uint32_t hash2 = DefaultHash<T2>{}(value.second);
|
|
return hash1 ^ (hash2 * 33);
|
|
}
|
|
};
|
|
|
|
} // namespace BLI
|
|
|
|
#endif /* __BLI_HASH_CXX_H__ */
|