98 lines
2.4 KiB
C++
98 lines
2.4 KiB
C++
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#pragma once
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/**
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* @file linebuffer.hpp
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* @author Eric Mertens <emertens@gmail.com>
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* @brief A line buffering class
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* @version 0.1
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* @date 2023-08-22
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*
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* @copyright Copyright (c) 2023
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*
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*/
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#include <boost/asio/buffer.hpp>
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#include <algorithm>
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#include <concepts>
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#include <vector>
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/**
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* @brief Fixed-size buffer with line-oriented dispatch
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*
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*/
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class LineBuffer
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{
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std::vector<char> buffer;
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// [buffer.begin(), end_) contains buffered data
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// [end_, buffer.end()) is available buffer space
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std::vector<char>::iterator end_;
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public:
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/**
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* @brief Construct a new Line Buffer object
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*
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* @param n Buffer size
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*/
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LineBuffer(std::size_t n) : buffer(n), end_{buffer.begin()} {}
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/**
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* @brief Get the available buffer space
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*
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* @return boost::asio::mutable_buffer
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*/
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auto get_buffer() -> boost::asio::mutable_buffer
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{
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return boost::asio::buffer(&*end_, std::distance(end_, buffer.end()));
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}
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/**
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* @brief Commit new buffer bytes and dispatch line callback
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*
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* The first n bytes of the buffer will be considered to be
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* populated. The line callback function will be called once
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* per completed line. Those lines are removed from the buffer
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* and the is ready for additional calls to get_buffer and
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* add_bytes.
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*
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* @param n Bytes written to the last call of get_buffer
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* @param line_cb Callback function to run on each completed line
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*/
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auto add_bytes(std::size_t n, std::invocable<char *> auto line_cb) -> void
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{
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auto const start = end_;
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std::advance(end_, n);
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// new data is now located in [start, end_)
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// cursor marks the beginning of the current line
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auto cursor = buffer.begin();
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for (auto nl = std::find(start, end_, '\n');
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nl != end_;
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nl = std::find(cursor, end_, '\n'))
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{
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// Null-terminate the line. Support both \n and \r\n
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if (cursor < nl && *std::prev(nl) == '\r')
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{
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*std::prev(nl) = '\0';
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}
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else
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{
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*nl = '\0';
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}
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line_cb(&*cursor);
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cursor = std::next(nl);
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}
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// If any lines were processed, move all processed lines to
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// the front of the buffer
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if (cursor != buffer.begin())
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{
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end_ = std::move(cursor, end_, buffer.begin());
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}
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}
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};
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