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godot/core/templates/hashfuncs.h
reduz 8b7c7f5a75 Add a new HashMap implementation 
Adds a new, cleaned up, HashMap implementation.

* Uses Robin Hood Hashing (https://en.wikipedia.org/wiki/Hash_table#Robin_Hood_hashing).
* Keeps elements in a double linked list for simpler, ordered, iteration.
* Allows keeping iterators for later use in removal (Unlike Map<>, it does not do much
  for performance vs keeping the key, but helps replace old code).
* Uses a more modern C++ iterator API, deprecates the old one.
* Supports custom allocator (in case there is a wish to use a paged one).

This class aims to unify all the associative template usage and replace it by this one:
* Map<> (whereas key order does not matter, which is 99% of cases)
* HashMap<>
* OrderedHashMap<>
* OAHashMap<>
2022-05-12 11:21:29 +02:00

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/*************************************************************************/
/* hashfuncs.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md). */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#ifndef HASHFUNCS_H
#define HASHFUNCS_H
#include "core/math/aabb.h"
#include "core/math/math_defs.h"
#include "core/math/math_funcs.h"
#include "core/math/rect2.h"
#include "core/math/rect2i.h"
#include "core/math/vector2.h"
#include "core/math/vector2i.h"
#include "core/math/vector3.h"
#include "core/math/vector3i.h"
#include "core/object/object_id.h"
#include "core/string/node_path.h"
#include "core/string/string_name.h"
#include "core/string/ustring.h"
#include "core/templates/rid.h"
#include "core/typedefs.h"
/**
* Hashing functions
*/
/**
* DJB2 Hash function
* @param C String
* @return 32-bits hashcode
*/
static inline uint32_t hash_djb2(const char *p_cstr) {
const unsigned char *chr = (const unsigned char *)p_cstr;
uint32_t hash = 5381;
uint32_t c;
while ((c = *chr++)) {
hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
}
return hash;
}
static inline uint32_t hash_djb2_buffer(const uint8_t *p_buff, int p_len, uint32_t p_prev = 5381) {
uint32_t hash = p_prev;
for (int i = 0; i < p_len; i++) {
hash = ((hash << 5) + hash) + p_buff[i]; /* hash * 33 + c */
}
return hash;
}
static inline uint32_t hash_djb2_one_32(uint32_t p_in, uint32_t p_prev = 5381) {
return ((p_prev << 5) + p_prev) + p_in;
}
/**
* Thomas Wang's 64-bit to 32-bit Hash function:
* https://web.archive.org/web/20071223173210/https:/www.concentric.net/~Ttwang/tech/inthash.htm
*
* @param p_int - 64-bit unsigned integer key to be hashed
* @return unsigned 32-bit value representing hashcode
*/
static inline uint32_t hash_one_uint64(const uint64_t p_int) {
uint64_t v = p_int;
v = (~v) + (v << 18); // v = (v << 18) - v - 1;
v = v ^ (v >> 31);
v = v * 21; // v = (v + (v << 2)) + (v << 4);
v = v ^ (v >> 11);
v = v + (v << 6);
v = v ^ (v >> 22);
return uint32_t(v);
}
static inline uint32_t hash_djb2_one_float(double p_in, uint32_t p_prev = 5381) {
union {
double d;
uint64_t i;
} u;
// Normalize +/- 0.0 and NaN values so they hash the same.
if (p_in == 0.0f) {
u.d = 0.0;
} else if (Math::is_nan(p_in)) {
u.d = NAN;
} else {
u.d = p_in;
}
return ((p_prev << 5) + p_prev) + hash_one_uint64(u.i);
}
template <class T>
static inline uint32_t make_uint32_t(T p_in) {
union {
T t;
uint32_t _u32;
} _u;
_u._u32 = 0;
_u.t = p_in;
return _u._u32;
}
static inline uint64_t hash_djb2_one_float_64(double p_in, uint64_t p_prev = 5381) {
union {
double d;
uint64_t i;
} u;
// Normalize +/- 0.0 and NaN values so they hash the same.
if (p_in == 0.0f) {
u.d = 0.0;
} else if (Math::is_nan(p_in)) {
u.d = NAN;
} else {
u.d = p_in;
}
return ((p_prev << 5) + p_prev) + u.i;
}
static inline uint64_t hash_djb2_one_64(uint64_t p_in, uint64_t p_prev = 5381) {
return ((p_prev << 5) + p_prev) + p_in;
}
template <class T>
static inline uint64_t make_uint64_t(T p_in) {
union {
T t;
uint64_t _u64;
} _u;
_u._u64 = 0; // in case p_in is smaller
_u.t = p_in;
return _u._u64;
}
struct HashMapHasherDefault {
static _FORCE_INLINE_ uint32_t hash(const String &p_string) { return p_string.hash(); }
static _FORCE_INLINE_ uint32_t hash(const char *p_cstr) { return hash_djb2(p_cstr); }
static _FORCE_INLINE_ uint32_t hash(const uint64_t p_int) { return hash_one_uint64(p_int); }
static _FORCE_INLINE_ uint32_t hash(const ObjectID &p_id) { return hash_one_uint64(p_id); }
static _FORCE_INLINE_ uint32_t hash(const int64_t p_int) { return hash(uint64_t(p_int)); }
static _FORCE_INLINE_ uint32_t hash(const float p_float) { return hash_djb2_one_float(p_float); }
static _FORCE_INLINE_ uint32_t hash(const double p_double) { return hash_djb2_one_float(p_double); }
static _FORCE_INLINE_ uint32_t hash(const uint32_t p_int) { return p_int; }
static _FORCE_INLINE_ uint32_t hash(const int32_t p_int) { return (uint32_t)p_int; }
static _FORCE_INLINE_ uint32_t hash(const uint16_t p_int) { return p_int; }
static _FORCE_INLINE_ uint32_t hash(const int16_t p_int) { return (uint32_t)p_int; }
static _FORCE_INLINE_ uint32_t hash(const uint8_t p_int) { return p_int; }
static _FORCE_INLINE_ uint32_t hash(const int8_t p_int) { return (uint32_t)p_int; }
static _FORCE_INLINE_ uint32_t hash(const wchar_t p_wchar) { return (uint32_t)p_wchar; }
static _FORCE_INLINE_ uint32_t hash(const char16_t p_uchar) { return (uint32_t)p_uchar; }
static _FORCE_INLINE_ uint32_t hash(const char32_t p_uchar) { return (uint32_t)p_uchar; }
static _FORCE_INLINE_ uint32_t hash(const RID &p_rid) { return hash_one_uint64(p_rid.get_id()); }
static _FORCE_INLINE_ uint32_t hash(const StringName &p_string_name) { return p_string_name.hash(); }
static _FORCE_INLINE_ uint32_t hash(const NodePath &p_path) { return p_path.hash(); }
static _FORCE_INLINE_ uint32_t hash(const Vector2i &p_vec) {
uint32_t h = hash_djb2_one_32(p_vec.x);
return hash_djb2_one_32(p_vec.y, h);
}
static _FORCE_INLINE_ uint32_t hash(const Vector3i &p_vec) {
uint32_t h = hash_djb2_one_32(p_vec.x);
h = hash_djb2_one_32(p_vec.y, h);
return hash_djb2_one_32(p_vec.z, h);
}
static _FORCE_INLINE_ uint32_t hash(const Vector2 &p_vec) {
uint32_t h = hash_djb2_one_float(p_vec.x);
return hash_djb2_one_float(p_vec.y, h);
}
static _FORCE_INLINE_ uint32_t hash(const Vector3 &p_vec) {
uint32_t h = hash_djb2_one_float(p_vec.x);
h = hash_djb2_one_float(p_vec.y, h);
return hash_djb2_one_float(p_vec.z, h);
}
static _FORCE_INLINE_ uint32_t hash(const Rect2i &p_rect) {
uint32_t h = hash_djb2_one_32(p_rect.position.x);
h = hash_djb2_one_32(p_rect.position.y, h);
h = hash_djb2_one_32(p_rect.size.x, h);
return hash_djb2_one_32(p_rect.size.y, h);
}
static _FORCE_INLINE_ uint32_t hash(const Rect2 &p_rect) {
uint32_t h = hash_djb2_one_float(p_rect.position.x);
h = hash_djb2_one_float(p_rect.position.y, h);
h = hash_djb2_one_float(p_rect.size.x, h);
return hash_djb2_one_float(p_rect.size.y, h);
}
static _FORCE_INLINE_ uint32_t hash(const AABB &p_aabb) {
uint32_t h = hash_djb2_one_float(p_aabb.position.x);
h = hash_djb2_one_float(p_aabb.position.y, h);
h = hash_djb2_one_float(p_aabb.position.z, h);
h = hash_djb2_one_float(p_aabb.size.x, h);
h = hash_djb2_one_float(p_aabb.size.y, h);
return hash_djb2_one_float(p_aabb.size.z, h);
}
//static _FORCE_INLINE_ uint32_t hash(const void* p_ptr) { return uint32_t(uint64_t(p_ptr))*(0x9e3779b1L); }
};
template <typename T>
struct HashMapComparatorDefault {
static bool compare(const T &p_lhs, const T &p_rhs) {
return p_lhs == p_rhs;
}
bool compare(const float &p_lhs, const float &p_rhs) {
return (p_lhs == p_rhs) || (Math::is_nan(p_lhs) && Math::is_nan(p_rhs));
}
bool compare(const double &p_lhs, const double &p_rhs) {
return (p_lhs == p_rhs) || (Math::is_nan(p_lhs) && Math::is_nan(p_rhs));
}
};
constexpr uint32_t HASH_TABLE_SIZE_MAX = 29;
const uint32_t hash_table_size_primes[HASH_TABLE_SIZE_MAX] = {
5,
13,
23,
47,
97,
193,
389,
769,
1543,
3079,
6151,
12289,
24593,
49157,
98317,
196613,
393241,
786433,
1572869,
3145739,
6291469,
12582917,
25165843,
50331653,
100663319,
201326611,
402653189,
805306457,
1610612741,
};
#endif // HASHFUNCS_H
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