71 lines
1.7 KiB
C++
71 lines
1.7 KiB
C++
// somebar - dwl bar
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// See LICENSE file for copyright and license details.
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#pragma once
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#include <array>
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#include <algorithm>
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#include <sys/types.h>
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// reads data from Reader, and passes complete lines to Consumer.
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template<size_t BufSize>
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class LineBuffer {
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using Iterator = typename std::array<char, BufSize>::iterator;
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std::array<char, BufSize> _buffer;
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Iterator _bufferedTo;
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Iterator _consumedTo;
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bool _discardLine {false};
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public:
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LineBuffer()
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: _bufferedTo {_buffer.begin()}
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, _consumedTo {_buffer.begin()}
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{
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}
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template<typename Reader, typename Consumer>
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ssize_t readLines(const Reader& reader, const Consumer& consumer)
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{
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while (true) {
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auto bytesRead = reader(_bufferedTo, _buffer.end() - _bufferedTo);
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if (bytesRead <= 0) {
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return bytesRead;
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}
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_bufferedTo += bytesRead;
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dispatchLines(consumer);
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resetBuffer();
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}
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}
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private:
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template<typename Consumer>
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void dispatchLines(const Consumer& consumer)
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{
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while (true) {
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auto separator = std::find(_consumedTo, _bufferedTo, '\n');
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if (separator == _bufferedTo) {
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break;
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}
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size_t lineLength = separator - _consumedTo;
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if (!_discardLine) {
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consumer(_consumedTo, lineLength);
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}
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_consumedTo = separator + 1;
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_discardLine = false;
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}
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}
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void resetBuffer()
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{
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size_t bytesRemaining = _bufferedTo - _consumedTo;
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if (bytesRemaining == _buffer.size()) {
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// line too long
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_discardLine = true;
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_consumedTo = _buffer.begin();
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_bufferedTo = _buffer.begin();
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} else {
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// move the last partial message to the front of the buffer, so a full-sized
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// message will fit
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std::copy(_consumedTo, _bufferedTo, _buffer.begin());
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_consumedTo = _buffer.begin();
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_bufferedTo = _consumedTo + bytesRemaining;
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}
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}
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};
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