7da392bcc5
We prefer to prevent using chained assignment (`T a = b = c = T();`) as this can lead to confusing code and subtle bugs. According to https://en.wikipedia.org/wiki/Assignment_operator_(C%2B%2B), C++ allows any arbitrary return type, so this is standard compliant. This could be re-assessed if/when we have an actual need for a behavior more akin to that of the C++ STL, for now this PR simply changes a handful of cases which were inconsistent with the rest of the codebase (`void` return type was already the most common case prior to this commit).
301 lines
8.7 KiB
C++
301 lines
8.7 KiB
C++
/*************************************************************************/
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/* ordered_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) 2007-2021 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2021 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 ORDERED_HASH_MAP_H
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#define ORDERED_HASH_MAP_H
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#include "core/templates/hash_map.h"
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#include "core/templates/list.h"
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#include "core/templates/pair.h"
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/**
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* A hash map which allows to iterate elements in insertion order.
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* Insertion, lookup, deletion have O(1) complexity.
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* The API aims to be consistent with Map rather than HashMap, because the
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* former is more frequently used and is more coherent with the rest of the
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* codebase.
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* Deletion during iteration is safe and will preserve the order.
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*/
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template <class K, class V, class Hasher = HashMapHasherDefault, class Comparator = HashMapComparatorDefault<K>, uint8_t MIN_HASH_TABLE_POWER = 3, uint8_t RELATIONSHIP = 8>
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class OrderedHashMap {
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typedef List<Pair<const K *, V>> InternalList;
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typedef HashMap<K, typename InternalList::Element *, Hasher, Comparator, MIN_HASH_TABLE_POWER, RELATIONSHIP> InternalMap;
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InternalList list;
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InternalMap map;
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public:
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class Element {
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friend class OrderedHashMap<K, V, Hasher, Comparator, MIN_HASH_TABLE_POWER, RELATIONSHIP>;
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typename InternalList::Element *list_element = nullptr;
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typename InternalList::Element *prev_element = nullptr;
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typename InternalList::Element *next_element = nullptr;
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Element(typename InternalList::Element *p_element) {
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list_element = p_element;
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if (list_element) {
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next_element = list_element->next();
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prev_element = list_element->prev();
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}
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}
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public:
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_FORCE_INLINE_ Element() {}
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Element next() const {
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return Element(next_element);
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}
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Element prev() const {
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return Element(prev_element);
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}
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Element(const Element &other) :
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list_element(other.list_element),
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prev_element(other.prev_element),
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next_element(other.next_element) {
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}
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void operator=(const Element &other) {
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list_element = other.list_element;
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next_element = other.next_element;
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prev_element = other.prev_element;
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}
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_FORCE_INLINE_ bool operator==(const Element &p_other) const {
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return this->list_element == p_other.list_element;
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}
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_FORCE_INLINE_ bool operator!=(const Element &p_other) const {
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return this->list_element != p_other.list_element;
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}
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operator bool() const {
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return (list_element != nullptr);
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}
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const K &key() const {
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CRASH_COND(!list_element);
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return *(list_element->get().first);
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}
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V &value() {
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CRASH_COND(!list_element);
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return list_element->get().second;
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}
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const V &value() const {
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CRASH_COND(!list_element);
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return list_element->get().second;
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}
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V &get() {
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CRASH_COND(!list_element);
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return list_element->get().second;
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}
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const V &get() const {
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CRASH_COND(!list_element);
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return list_element->get().second;
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}
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};
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class ConstElement {
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friend class OrderedHashMap<K, V, Hasher, Comparator, MIN_HASH_TABLE_POWER, RELATIONSHIP>;
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const typename InternalList::Element *list_element = nullptr;
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ConstElement(const typename InternalList::Element *p_element) :
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list_element(p_element) {
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}
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public:
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_FORCE_INLINE_ ConstElement() {}
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ConstElement(const ConstElement &other) :
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list_element(other.list_element) {
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}
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void operator=(const ConstElement &other) {
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list_element = other.list_element;
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}
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ConstElement next() const {
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return ConstElement(list_element ? list_element->next() : nullptr);
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}
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ConstElement prev() const {
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return ConstElement(list_element ? list_element->prev() : nullptr);
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}
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_FORCE_INLINE_ bool operator==(const ConstElement &p_other) const {
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return this->list_element == p_other.list_element;
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}
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_FORCE_INLINE_ bool operator!=(const ConstElement &p_other) const {
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return this->list_element != p_other.list_element;
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}
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operator bool() const {
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return (list_element != nullptr);
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}
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const K &key() const {
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CRASH_COND(!list_element);
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return *(list_element->get().first);
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}
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const V &value() const {
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CRASH_COND(!list_element);
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return list_element->get().second;
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}
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const V &get() const {
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CRASH_COND(!list_element);
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return list_element->get().second;
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}
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};
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ConstElement find(const K &p_key) const {
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typename InternalList::Element *const *list_element = map.getptr(p_key);
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if (list_element) {
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return ConstElement(*list_element);
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}
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return ConstElement(nullptr);
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}
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Element find(const K &p_key) {
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typename InternalList::Element **list_element = map.getptr(p_key);
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if (list_element) {
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return Element(*list_element);
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}
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return Element(nullptr);
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}
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Element insert(const K &p_key, const V &p_value) {
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typename InternalList::Element **list_element = map.getptr(p_key);
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if (list_element) {
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(*list_element)->get().second = p_value;
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return Element(*list_element);
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}
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// Incorrectly set the first value of the pair with a value that will
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// be invalid as soon as we leave this function...
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typename InternalList::Element *new_element = list.push_back(Pair<const K *, V>(&p_key, p_value));
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// ...this is needed here in case the hashmap recursively reference itself...
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typename InternalMap::Element *e = map.set(p_key, new_element);
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// ...now we can set the right value !
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new_element->get().first = &e->key();
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return Element(new_element);
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}
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void erase(Element &p_element) {
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map.erase(p_element.key());
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list.erase(p_element.list_element);
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p_element.list_element = nullptr;
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}
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bool erase(const K &p_key) {
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typename InternalList::Element **list_element = map.getptr(p_key);
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if (list_element) {
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list.erase(*list_element);
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map.erase(p_key);
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return true;
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}
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return false;
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}
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inline bool has(const K &p_key) const {
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return map.has(p_key);
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}
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const V &operator[](const K &p_key) const {
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ConstElement e = find(p_key);
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CRASH_COND(!e);
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return e.value();
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}
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V &operator[](const K &p_key) {
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Element e = find(p_key);
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if (!e) {
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// consistent with Map behaviour
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e = insert(p_key, V());
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}
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return e.value();
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}
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inline Element front() {
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return Element(list.front());
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}
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inline Element back() {
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return Element(list.back());
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}
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inline ConstElement front() const {
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return ConstElement(list.front());
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}
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inline ConstElement back() const {
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return ConstElement(list.back());
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}
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inline bool is_empty() const { return list.is_empty(); }
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inline int size() const { return list.size(); }
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const void *id() const {
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return list.id();
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}
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void clear() {
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map.clear();
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list.clear();
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}
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private:
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void _copy_from(const OrderedHashMap &p_map) {
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for (ConstElement E = p_map.front(); E; E = E.next()) {
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insert(E.key(), E.value());
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}
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}
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public:
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void operator=(const OrderedHashMap &p_map) {
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_copy_from(p_map);
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}
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OrderedHashMap(const OrderedHashMap &p_map) {
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_copy_from(p_map);
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}
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_FORCE_INLINE_ OrderedHashMap() {}
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};
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#endif // ORDERED_HASH_MAP_H
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