szaszm commented on a change in pull request #839: URL: https://github.com/apache/nifi-minifi-cpp/pull/839#discussion_r492879152
########## File path: libminifi/include/utils/FlatMap.h ########## @@ -0,0 +1,270 @@ +/** + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#pragma once + +#include <tuple> +#include <functional> +#include <vector> +#include <utility> + +namespace org { +namespace apache { +namespace nifi { +namespace minifi { +namespace utils { + +template<typename K, typename V> +class FlatMap{ + using Container = std::vector<std::pair<K, V>>; + + public: + using value_type = std::pair<K, V>; + using reference = value_type&; + using const_reference = const value_type&; + using difference_type = typename Container::difference_type; + using size_type = typename Container::size_type; + + class iterator{ + friend class const_iterator; + friend class FlatMap; + explicit iterator(typename Container::iterator it) noexcept : it_(it) {} + + public: + using difference_type = typename Container::iterator::difference_type; + using value_type = FlatMap::value_type; + using pointer = value_type*; + using reference = value_type&; + using iterator_category = std::forward_iterator_tag; + + iterator() = default; + + value_type* operator->() const {return &(*it_);} + value_type& operator*() const {return *it_;} + + bool operator==(const iterator& other) const { + return it_ == other.it_; + } + + bool operator!=(const iterator& other) const { + return !(*this == other); + } + + iterator& operator++() { + ++it_; + return *this; + } + + iterator operator++(int) { + auto tmp = *this; + ++(*this); + return tmp; + } + + private: + typename Container::iterator it_; + }; + + class const_iterator{ + friend class FlatMap; + explicit const_iterator(typename Container::const_iterator it) noexcept : it_(it) {} + + public: + const_iterator(iterator it) noexcept : it_(it.it_) {} // NOLINT + const_iterator() = default; + + using difference_type = typename Container::const_iterator::difference_type; + using value_type = const FlatMap::value_type; + using pointer = value_type*; + using reference = value_type&; + using iterator_category = std::forward_iterator_tag; + + value_type* operator->() const {return &(*it_);} + value_type& operator*() const {return *it_;} + + bool operator==(const const_iterator& other) const { + return it_ == other.it_; + } + + bool operator!=(const const_iterator& other) const { + return !(*this == other); + } + + const_iterator& operator++() { + ++it_; + return *this; + } + + const_iterator operator++(int) { + auto tmp = *this; + ++(*this); + return tmp; + } + + private: + typename Container::const_iterator it_; + }; + + FlatMap() = default; + FlatMap(const FlatMap&) = default; + FlatMap(FlatMap&&) noexcept = default; + FlatMap(std::initializer_list<value_type> items) : data_(items) {} + template<class InputIterator> + FlatMap(InputIterator begin, InputIterator end) : data_(begin, end) {} + + FlatMap& operator=(const FlatMap& source) = default; + FlatMap& operator=(FlatMap&& source) = default; + FlatMap& operator=(std::initializer_list<value_type> items) { + data_ = items; + return *this; + } + + size_type size() const noexcept { + return data_.size(); + } + + V& operator[](const K& key) { + auto it = find(key); + if (it != end()) { + return it->second; + } + data_.emplace_back(key, V{}); + return data_.rbegin()->second; + } + + iterator erase(const_iterator pos) { + auto offset = pos.it_ - data_.begin(); + std::swap(*data_.rbegin(), *(data_.begin() + offset)); + data_.pop_back(); + return iterator{data_.begin() + offset}; + } + + std::size_t erase(const K& key) { + for (auto it = data_.begin(); it != data_.end(); ++it) { + if (it->first == key) { + std::swap(*data_.rbegin(), *it); + data_.pop_back(); + return 1; + } + } + return 0; + } + + std::pair<iterator, bool> insert(const value_type& value) { + auto it = find(value.first); + if (it != end()) { + return {it, false}; + } + data_.push_back(value); + return {iterator{data_.begin() + data_.size() - 1}, true}; + } + + template<typename M> + std::pair<iterator, bool> insert_or_assign(const K& key, M&& value) { + auto it = find(key); + if (it != end()) { + it->second = std::forward<M>(value); + return {it, false}; + } + data_.emplace_back(key, std::forward<M>(value)); + return {iterator{data_.begin() + data_.size() - 1}, true}; + } + + iterator find(const K& key) { + for (auto it = data_.begin(); it != data_.end(); ++it) { + if (it->first == key) return iterator{it}; + } + return end(); + } + + const_iterator find(const K& key) const { + for (auto it = data_.begin(); it != data_.end(); ++it) { + if (it->first == key) return const_iterator{it}; + } + return end(); + } + + iterator begin() noexcept { + return iterator{data_.begin()}; + } + + iterator end() noexcept { + return iterator{data_.end()}; + } + + const_iterator begin() const noexcept { + return const_iterator{data_.begin()}; + } + + const_iterator end() const noexcept { + return const_iterator{data_.end()}; + } + + const_iterator cbegin() const noexcept { + return const_iterator{data_.begin()}; + } + + const_iterator cend() const noexcept { + return const_iterator{data_.end()}; + } + + bool operator==(const FlatMap& other) const { + if (size() != other.size()) { + return false; + } + // no linearity can be guaranteed unless we + // sort the underlying storage Review comment: Boost flat_map provides this guarantee by keeping the underlying vector sorted. Just FYI, not a change request. https://www.boost.org/doc/libs/1_74_0/doc/html/boost/container/flat_map.html ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
