mirror of
https://github.com/OpenTTD/OpenTTD
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103 lines
3.4 KiB
C++
103 lines
3.4 KiB
C++
/*
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* This file is part of OpenTTD.
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* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
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* OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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* See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file string_inplace.hpp Inplace-replacement of textual and binary data.
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*/
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#ifndef STRING_INPLACE_HPP
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#define STRING_INPLACE_HPP
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#include "string_builder.hpp"
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#include "string_consumer.hpp"
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/**
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* Builder implementation for InPlaceReplacement.
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*/
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class InPlaceBuilder final : public BaseStringBuilder {
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std::span<char> dest;
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size_type position = 0;
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const StringConsumer &consumer;
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friend class InPlaceReplacement;
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explicit InPlaceBuilder(std::span<char> dest, const StringConsumer &consumer) : dest(dest), consumer(consumer) {}
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InPlaceBuilder(const InPlaceBuilder &src, const StringConsumer &consumer) : dest(src.dest), position(src.position), consumer(consumer) {}
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void AssignBuffer(const InPlaceBuilder &src) { this->dest = src.dest; this->position = src.position; }
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public:
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InPlaceBuilder(const InPlaceBuilder &) = delete;
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InPlaceBuilder& operator=(const InPlaceBuilder &) = delete;
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/**
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* Check whether any bytes have been written.
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*/
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[[nodiscard]] bool AnyBytesWritten() const noexcept { return this->position != 0; }
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/**
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* Get number of already written bytes.
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*/
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[[nodiscard]] size_type GetBytesWritten() const noexcept { return this->position; }
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/**
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* Get already written data.
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*/
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[[nodiscard]] std::string_view GetWrittenData() const noexcept { return {this->dest.data(), this->position}; }
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[[nodiscard]] bool AnyBytesUnused() const noexcept;
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[[nodiscard]] size_type GetBytesUnused() const noexcept;
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void PutBuffer(std::span<const char> str) override;
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/**
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* Implementation of std::back_insert_iterator for non-growing destination buffer.
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*/
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class back_insert_iterator {
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InPlaceBuilder *parent = nullptr;
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public:
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using value_type = void;
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using difference_type = void;
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using iterator_category = std::output_iterator_tag;
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using pointer = void;
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using reference = void;
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back_insert_iterator(InPlaceBuilder &parent) : parent(&parent) {}
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back_insert_iterator &operator++() { return *this; }
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back_insert_iterator operator++(int) { return *this; }
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back_insert_iterator &operator*() { return *this; }
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back_insert_iterator &operator=(char value)
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{
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this->parent->PutChar(value);
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return *this;
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}
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};
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/**
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* Create a back-insert-iterator.
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*/
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back_insert_iterator back_inserter()
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{
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return back_insert_iterator(*this);
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}
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};
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/**
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* Compose data into a fixed size buffer, which is consumed at the same time.
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* - The Consumer reads data from a buffer.
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* - The Builder writes data to the buffer, replacing already consumed data.
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* - The Builder asserts, if it overtakes the consumer.
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*/
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class InPlaceReplacement {
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public:
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StringConsumer consumer; ///< Consumer from shared buffer
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InPlaceBuilder builder; ///< Builder into shared buffer
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public:
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InPlaceReplacement(std::span<char> buffer);
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InPlaceReplacement(const InPlaceReplacement &src);
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InPlaceReplacement& operator=(const InPlaceReplacement &src);
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};
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#endif /* STRING_INPLACE_HPP */
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