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| /* Copyright (c) 2018 The node-webrtc project authors. All rights reserved. | ||
| * | ||
| * Use of this source code is governed by a BSD-style license that can be found | ||
| * in the LICENSE.md file in the root of the source tree. All contributing | ||
| * project authors may be found in the AUTHORS file in the root of the source | ||
| * tree. | ||
| */ | ||
| #ifndef SRC_BIDIMAP_H_ | ||
| #define SRC_BIDIMAP_H_ | ||
|
|
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| #include <functional> | ||
| #include <map> | ||
| #include <utility> | ||
|
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| #include "src/functional/maybe.h" | ||
| #include "src/functional/operators.h" | ||
|
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| namespace node_webrtc { | ||
|
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| /** | ||
| * A BidiMap is a "bidirectional map" supporting get and set operations on both | ||
| * keys and values. | ||
| * @tparam K the type of keys | ||
| * @tparam V the type of values | ||
| */ | ||
| template <typename K, typename V> | ||
| class BidiMap { | ||
| public: | ||
| /** | ||
| * Construct an empty BidiMap. | ||
| */ | ||
| BidiMap() = default; | ||
|
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| /** | ||
| * Remove all keys and values from the BidiMap. | ||
| */ | ||
| void clear() { | ||
| _keyToValue.clear(); | ||
| _valueToKey.clear(); | ||
| } | ||
|
|
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| /** | ||
| * Compute, set, and return a key's value if it's absent; otherwise, return | ||
| * the key's value. | ||
| * @param key | ||
| * @param computeValue | ||
| * @return the existing or newly set value | ||
| */ | ||
| V computeIfAbsent(K key, std::function<V()> computeValue) { | ||
| return get(key).Or([this, key, computeValue]() { | ||
| auto value = computeValue(); | ||
| this->set(key, value); | ||
| return value; | ||
| }); | ||
| } | ||
|
|
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| /** | ||
| * Get the key's value from the BidiMap. | ||
| * @param key | ||
| * @return Nothing if the key was not present | ||
| */ | ||
| Maybe<V> get(K key) const { | ||
| return has(key) | ||
| ? Maybe<V>::Just(_keyToValue.at(key)) | ||
| : Maybe<V>::Nothing(); | ||
| } | ||
|
|
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| /** | ||
| * Check if the BidiMap contains a value for the key. | ||
| * @param key | ||
| * @return true if the BidiMap contains a value for the key | ||
| */ | ||
| bool has(K key) const { | ||
| return _keyToValue.count(key) > 0; | ||
| } | ||
|
|
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| /** | ||
| * Remove the key and its value from the BidiMap. | ||
| * @param key | ||
| * @return Nothing if the key was not present | ||
| */ | ||
| Maybe<V> remove(K key) { | ||
| return [this, key](V value) { | ||
| this->_keyToValue.erase(key); | ||
| this->_valueToKey.erase(value); | ||
| return value; | ||
| } % get(key); | ||
| } | ||
|
|
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| /** | ||
| * Return a BidiMap with its keys and values swapped. | ||
| * @return a BidiMap with its keys and values swapped | ||
| */ | ||
| BidiMap<V, K> reverse() const { | ||
| return BidiMap<V, K>(_valueToKey, _keyToValue); | ||
| } | ||
|
|
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| /** | ||
| * Compute, set, and return a value's key if it's absent; otherwise, return | ||
| * the value's key. | ||
| * @param value | ||
| * @param computeKey | ||
| * @return the existing or newly set key | ||
| */ | ||
| K reverseComputeIfAbsent(V value, std::function<K()> computeKey) { | ||
| return reverseGet(value).Or([this, value, computeKey]() { | ||
| auto key = computeKey(); | ||
| this->reverseSet(value, key); | ||
| return key; | ||
| }); | ||
| } | ||
|
|
||
| /** | ||
| * Get the value's key from the BidiMap. | ||
| * @param value | ||
| * @return Nothing if the value was not present | ||
| */ | ||
| Maybe<K> reverseGet(V value) const { | ||
| return reverseHas(value) | ||
| ? Maybe<K>::Just(_valueToKey.at(value)) | ||
| : Maybe<K>::Nothing(); | ||
| } | ||
|
|
||
| /** | ||
| * Check if the BidiMap contains a key for the value. | ||
| * @param value | ||
| * @return true if the BidiMap contains a key for the value | ||
| */ | ||
| bool reverseHas(V value) const { | ||
| return _valueToKey.count(value) > 0; | ||
| } | ||
|
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| /** | ||
| * Remove a value and its key from the BidiMap. | ||
| * @param value | ||
| * @return Nothing if the value was not present | ||
| */ | ||
| Maybe<K> reverseRemove(V value) { | ||
| return [this, value](K key) { | ||
| this->_keyToValue.erase(key); | ||
| this->_valueToKey.erase(value); | ||
| return key; | ||
| } % reverseGet(value); | ||
| } | ||
|
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| /** | ||
| * Set a value and its key in the BidiMap. | ||
| * @param value | ||
| * @param key | ||
| * @return a pair of the previously set key (if any) and the previously set | ||
| * value (if any) | ||
| */ | ||
| std::pair<Maybe<K>, Maybe<V>> reverseSet(V value, K key) { | ||
| auto pair = std::make_pair(reverseGet(value), get(key)); | ||
| remove(key); | ||
| _valueToKey[value] = key; | ||
| _keyToValue[key] = value; | ||
| return pair; | ||
| } | ||
|
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| /** | ||
| * Set a key and its value in the BidiMap. | ||
| * @param key | ||
| * @param value | ||
| * @return a pair of the previously set value (if any) and the previously set | ||
| * key (if any) | ||
| */ | ||
| std::pair<Maybe<V>, Maybe<K>> set(K key, V value) { | ||
| auto pair = std::make_pair(get(key), reverseGet(value)); | ||
| reverseRemove(value); | ||
| _keyToValue[key] = value; | ||
| _valueToKey[value] = key; | ||
| return pair; | ||
| } | ||
|
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| /** | ||
| * Construct a BidiMap from a map. | ||
| * @param map | ||
| * @return Nothing if the map contains duplicate values | ||
| */ | ||
| static Maybe<BidiMap<K, V>> FromMap(std::map<K, V> map) { | ||
| BidiMap<K, V> bidiMap; | ||
| for (auto pair : map) { | ||
| auto previousKey = bidiMap.reverseSet(pair.second, pair.first); | ||
| if (previousKey.IsJust()) { | ||
| return Maybe<BidiMap<K, V>>::Nothing(); | ||
| } | ||
| } | ||
| return Maybe<BidiMap<K, V>>::Just(bidiMap); | ||
| } | ||
|
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| private: | ||
| BidiMap(const std::map<K, V>& keyToValue, const std::map<V, K>& valueToKey) | ||
| : _keyToValue(keyToValue), _valueToKey(valueToKey) {} | ||
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| std::map<K, V> _keyToValue; | ||
| std::map<V, K> _valueToKey; | ||
| }; | ||
|
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| } // namespace node_webrtc | ||
|
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| #endif // SRC_BIDIMAP_H_ |
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