594 lines
16 KiB
C++
594 lines
16 KiB
C++
/*************************************************************************/
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/* oa_hash_map.h */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* https://godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2018 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2018 Godot Engine contributors (cf. AUTHORS.md) */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#ifndef OA_HASH_MAP_H
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#define OA_HASH_MAP_H
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#include "hashfuncs.h"
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#include "math_funcs.h"
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#include "os/copymem.h"
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#include "os/memory.h"
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// uncomment this to disable intial local storage.
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#define OA_HASH_MAP_INITIAL_LOCAL_STORAGE
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/**
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* This class implements a hash map datastructure that uses open addressing with
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* local probing.
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*
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* It can give huge performance improvements over a chained HashMap because of
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* the increased data locality.
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*
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* Because of that locality property it's important to not use "large" value
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* types as the "TData" type. If TData values are too big it can cause more
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* cache misses then chaining. If larger values are needed then storing those
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* in a separate array and using pointers or indices to reference them is the
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* better solution.
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*
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* This hash map also implements real-time incremental rehashing.
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*
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*/
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template <class TKey, class TData,
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uint16_t INITIAL_NUM_ELEMENTS = 64,
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class Hasher = HashMapHasherDefault,
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class Comparator = HashMapComparatorDefault<TKey> >
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class OAHashMap {
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private:
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#ifdef OA_HASH_MAP_INITIAL_LOCAL_STORAGE
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TData local_data[INITIAL_NUM_ELEMENTS];
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TKey local_keys[INITIAL_NUM_ELEMENTS];
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uint32_t local_hashes[INITIAL_NUM_ELEMENTS];
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uint8_t local_flags[INITIAL_NUM_ELEMENTS / 4 + (INITIAL_NUM_ELEMENTS % 4 != 0 ? 1 : 0)];
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#endif
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struct {
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TData *data;
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TKey *keys;
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uint32_t *hashes;
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// This is actually an array of bits, 4 bit pairs per octet.
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// | ba ba ba ba | ba ba ba ba | ....
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//
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// if a is set it means that there is an element present.
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// if b is set it means that an element was deleted. This is needed for
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// the local probing to work without relocating any succeeding and
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// colliding entries.
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uint8_t *flags;
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uint32_t capacity;
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} table, old_table;
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bool is_rehashing;
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uint32_t rehash_position;
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uint32_t rehash_amount;
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uint32_t elements;
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/* Methods */
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// returns true if the value already existed, false if it's a new entry
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bool _raw_set_with_hash(uint32_t p_hash, const TKey &p_key, const TData &p_data) {
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for (int i = 0; i < table.capacity; i++) {
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int pos = (p_hash + i) % table.capacity;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = table.flags[flags_pos] & (1 << (2 * flags_pos_offset));
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bool is_deleted_flag = table.flags[flags_pos] & (1 << (2 * flags_pos_offset + 1));
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if (is_filled_flag) {
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if (table.hashes[pos] == p_hash && Comparator::compare(table.keys[pos], p_key)) {
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table.data[pos] = p_data;
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return true;
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}
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continue;
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}
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table.keys[pos] = p_key;
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table.data[pos] = p_data;
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table.hashes[pos] = p_hash;
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table.flags[flags_pos] |= (1 << (2 * flags_pos_offset));
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table.flags[flags_pos] &= ~(1 << (2 * flags_pos_offset + 1));
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return false;
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}
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return false;
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}
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public:
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_FORCE_INLINE_ uint32_t get_capacity() const { return table.capacity; }
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_FORCE_INLINE_ uint32_t get_num_elements() const { return elements; }
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void set(const TKey &p_key, const TData &p_data) {
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uint32_t hash = Hasher::hash(p_key);
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// We don't progress the rehashing if the table just got resized
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// to keep the cost of this function low.
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if (is_rehashing) {
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// rehash progress
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for (int i = 0; i <= rehash_amount && rehash_position < old_table.capacity; rehash_position++) {
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int flags_pos = rehash_position / 4;
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int flags_pos_offset = rehash_position % 4;
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bool is_filled_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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bool is_deleted_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset + 1))) > 0;
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if (is_filled_flag) {
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_raw_set_with_hash(old_table.hashes[rehash_position], old_table.keys[rehash_position], old_table.data[rehash_position]);
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old_table.keys[rehash_position].~TKey();
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old_table.data[rehash_position].~TData();
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memnew_placement(&old_table.keys[rehash_position], TKey);
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memnew_placement(&old_table.data[rehash_position], TData);
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old_table.flags[flags_pos] &= ~(1 << (2 * flags_pos_offset));
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old_table.flags[flags_pos] |= (1 << (2 * flags_pos_offset + 1));
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}
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}
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if (rehash_position >= old_table.capacity) {
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// wohooo, we can get rid of the old table.
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is_rehashing = false;
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#ifdef OA_HASH_MAP_INITIAL_LOCAL_STORAGE
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if (old_table.data == local_data) {
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// Everything is local, so no cleanup :P
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} else
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#endif
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{
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memdelete_arr(old_table.data);
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memdelete_arr(old_table.keys);
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memdelete_arr(old_table.hashes);
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memdelete_arr(old_table.flags);
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}
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}
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}
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// Table is almost full, resize and start rehashing process.
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if (elements >= table.capacity * 0.7) {
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old_table.capacity = table.capacity;
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old_table.data = table.data;
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old_table.flags = table.flags;
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old_table.hashes = table.hashes;
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old_table.keys = table.keys;
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table.capacity = old_table.capacity * 2;
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table.data = memnew_arr(TData, table.capacity);
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table.flags = memnew_arr(uint8_t, table.capacity / 4 + (table.capacity % 4 != 0 ? 1 : 0));
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table.hashes = memnew_arr(uint32_t, table.capacity);
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table.keys = memnew_arr(TKey, table.capacity);
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zeromem(table.flags, table.capacity / 4 + (table.capacity % 4 != 0 ? 1 : 0));
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is_rehashing = true;
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rehash_position = 0;
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rehash_amount = (elements * 2) / (table.capacity * 0.7 - old_table.capacity);
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}
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if (!_raw_set_with_hash(hash, p_key, p_data))
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elements++;
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}
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/**
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* returns true if the value was found, false otherwise.
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*
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* if r_data is not NULL then the value will be written to the object
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* it points to.
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*/
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bool lookup(const TKey &p_key, TData *r_data) {
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uint32_t hash = Hasher::hash(p_key);
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bool check_old_table = is_rehashing;
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bool check_new_table = true;
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// search for the key and return the value associated with it
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//
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// if we're rehashing we need to check both the old and the
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// current table. If we find a value in the old table we still
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// need to continue searching in the new table as it might have
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// been added after
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TData *value = NULL;
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for (int i = 0; i < table.capacity; i++) {
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if (!check_new_table && !check_old_table) {
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break;
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}
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// if we're rehashing check the old table
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if (check_old_table && i < old_table.capacity) {
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int pos = (hash + i) % old_table.capacity;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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bool is_deleted_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset + 1))) > 0;
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if (is_filled_flag) {
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// found our entry?
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if (old_table.hashes[pos] == hash && Comparator::compare(old_table.keys[pos], p_key)) {
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value = &old_table.data[pos];
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check_old_table = false;
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}
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} else if (!is_deleted_flag) {
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// we hit an empty field here, we don't
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// need to further check this old table
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// because we know it's not in here.
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check_old_table = false;
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}
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}
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if (check_new_table) {
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int pos = (hash + i) % table.capacity;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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bool is_deleted_flag = (table.flags[flags_pos] & (1 << (2 * flags_pos_offset + 1))) > 0;
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if (is_filled_flag) {
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// found our entry?
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if (table.hashes[pos] == hash && Comparator::compare(table.keys[pos], p_key)) {
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if (r_data != NULL)
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*r_data = table.data[pos];
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return true;
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}
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continue;
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} else if (is_deleted_flag) {
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continue;
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} else if (value != NULL) {
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// We found a value in the old table
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if (r_data != NULL)
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*r_data = *value;
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return true;
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} else {
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check_new_table = false;
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}
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}
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}
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if (value != NULL) {
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if (r_data != NULL)
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*r_data = *value;
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return true;
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}
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return false;
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}
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_FORCE_INLINE_ bool has(const TKey &p_key) {
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return lookup(p_key, NULL);
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}
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void remove(const TKey &p_key) {
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uint32_t hash = Hasher::hash(p_key);
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bool check_old_table = is_rehashing;
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bool check_new_table = true;
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for (int i = 0; i < table.capacity; i++) {
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if (!check_new_table && !check_old_table) {
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return;
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}
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// if we're rehashing check the old table
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if (check_old_table && i < old_table.capacity) {
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int pos = (hash + i) % old_table.capacity;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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bool is_deleted_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset + 1))) > 0;
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if (is_filled_flag) {
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// found our entry?
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if (old_table.hashes[pos] == hash && Comparator::compare(old_table.keys[pos], p_key)) {
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old_table.keys[pos].~TKey();
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old_table.data[pos].~TData();
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memnew_placement(&old_table.keys[pos], TKey);
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memnew_placement(&old_table.data[pos], TData);
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old_table.flags[flags_pos] &= ~(1 << (2 * flags_pos_offset));
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old_table.flags[flags_pos] |= (1 << (2 * flags_pos_offset + 1));
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elements--;
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return;
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}
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} else if (!is_deleted_flag) {
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// we hit an empty field here, we don't
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// need to further check this old table
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// because we know it's not in here.
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check_old_table = false;
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}
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}
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if (check_new_table) {
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int pos = (hash + i) % table.capacity;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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bool is_deleted_flag = (table.flags[flags_pos] & (1 << (2 * flags_pos_offset + 1))) > 0;
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if (is_filled_flag) {
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// found our entry?
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if (table.hashes[pos] == hash && Comparator::compare(table.keys[pos], p_key)) {
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table.keys[pos].~TKey();
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table.data[pos].~TData();
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memnew_placement(&table.keys[pos], TKey);
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memnew_placement(&table.data[pos], TData);
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table.flags[flags_pos] &= ~(1 << (2 * flags_pos_offset));
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table.flags[flags_pos] |= (1 << (2 * flags_pos_offset + 1));
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// don't return here, this value might still be in the old table
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// if it was already relocated.
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elements--;
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return;
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}
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continue;
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} else if (is_deleted_flag) {
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continue;
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} else {
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check_new_table = false;
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}
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}
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}
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}
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struct Iterator {
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bool valid;
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uint32_t hash;
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const TKey *key;
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const TData *data;
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private:
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friend class OAHashMap;
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bool was_from_old_table;
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};
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Iterator iter() const {
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Iterator it;
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it.valid = false;
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it.was_from_old_table = false;
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bool check_old_table = is_rehashing;
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for (int i = 0; i < table.capacity; i++) {
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// if we're rehashing check the old table first
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if (check_old_table && i < old_table.capacity) {
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int pos = i;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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if (is_filled_flag) {
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it.valid = true;
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it.hash = old_table.hashes[pos];
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it.data = &old_table.data[pos];
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it.key = &old_table.keys[pos];
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it.was_from_old_table = true;
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return it;
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}
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}
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{
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int pos = i;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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if (is_filled_flag) {
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it.valid = true;
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it.hash = table.hashes[pos];
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it.data = &table.data[pos];
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it.key = &table.keys[pos];
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return it;
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}
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}
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}
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return it;
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}
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Iterator next_iter(const Iterator &p_iter) const {
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if (!p_iter.valid) {
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return p_iter;
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}
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Iterator it;
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it.valid = false;
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it.was_from_old_table = false;
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bool check_old_table = is_rehashing;
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// we use this to skip the first check or not
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bool was_from_old_table = p_iter.was_from_old_table;
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int prev_index = (p_iter.data - (p_iter.was_from_old_table ? old_table.data : table.data));
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if (!was_from_old_table) {
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prev_index++;
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}
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for (int i = prev_index; i < table.capacity; i++) {
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// if we're rehashing check the old table first
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if (check_old_table && i < old_table.capacity && !was_from_old_table) {
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int pos = i;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (old_table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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if (is_filled_flag) {
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it.valid = true;
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it.hash = old_table.hashes[pos];
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it.data = &old_table.data[pos];
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it.key = &old_table.keys[pos];
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it.was_from_old_table = true;
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return it;
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}
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}
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was_from_old_table = false;
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{
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int pos = i;
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int flags_pos = pos / 4;
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int flags_pos_offset = pos % 4;
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bool is_filled_flag = (table.flags[flags_pos] & (1 << (2 * flags_pos_offset))) > 0;
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if (is_filled_flag) {
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it.valid = true;
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it.hash = table.hashes[pos];
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it.data = &table.data[pos];
|
|
it.key = &table.keys[pos];
|
|
|
|
return it;
|
|
}
|
|
}
|
|
}
|
|
|
|
return it;
|
|
}
|
|
|
|
OAHashMap(uint32_t p_initial_capacity = INITIAL_NUM_ELEMENTS) {
|
|
|
|
#ifdef OA_HASH_MAP_INITIAL_LOCAL_STORAGE
|
|
|
|
if (p_initial_capacity <= INITIAL_NUM_ELEMENTS) {
|
|
table.data = local_data;
|
|
table.keys = local_keys;
|
|
table.hashes = local_hashes;
|
|
table.flags = local_flags;
|
|
|
|
zeromem(table.flags, INITIAL_NUM_ELEMENTS / 4 + (INITIAL_NUM_ELEMENTS % 4 != 0 ? 1 : 0));
|
|
|
|
table.capacity = INITIAL_NUM_ELEMENTS;
|
|
elements = 0;
|
|
} else
|
|
#endif
|
|
{
|
|
table.data = memnew_arr(TData, p_initial_capacity);
|
|
table.keys = memnew_arr(TKey, p_initial_capacity);
|
|
table.hashes = memnew_arr(uint32_t, p_initial_capacity);
|
|
table.flags = memnew_arr(uint8_t, p_initial_capacity / 4 + (p_initial_capacity % 4 != 0 ? 1 : 0));
|
|
|
|
zeromem(table.flags, p_initial_capacity / 4 + (p_initial_capacity % 4 != 0 ? 1 : 0));
|
|
|
|
table.capacity = p_initial_capacity;
|
|
elements = 0;
|
|
}
|
|
|
|
is_rehashing = false;
|
|
rehash_position = 0;
|
|
}
|
|
|
|
~OAHashMap() {
|
|
#ifdef OA_HASH_MAP_INITIAL_LOCAL_STORAGE
|
|
if (table.capacity <= INITIAL_NUM_ELEMENTS) {
|
|
return; // Everything is local, so no cleanup :P
|
|
}
|
|
#endif
|
|
if (is_rehashing) {
|
|
|
|
#ifdef OA_HASH_MAP_INITIAL_LOCAL_STORAGE
|
|
if (old_table.data == local_data) {
|
|
// Everything is local, so no cleanup :P
|
|
} else
|
|
#endif
|
|
{
|
|
memdelete_arr(old_table.data);
|
|
memdelete_arr(old_table.keys);
|
|
memdelete_arr(old_table.hashes);
|
|
memdelete_arr(old_table.flags);
|
|
}
|
|
}
|
|
|
|
memdelete_arr(table.data);
|
|
memdelete_arr(table.keys);
|
|
memdelete_arr(table.hashes);
|
|
memdelete_arr(table.flags);
|
|
}
|
|
};
|
|
|
|
#endif
|