61 lines
2 KiB
C++
61 lines
2 KiB
C++
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// 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 <string.h>
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// reads data from Reader, and passes complete lines to Handler.
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template<size_t N>
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class LineBuffer {
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std::array<char, N> _buffer;
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size_t _bytesBuffered {0};
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size_t _bytesConsumed {0};
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bool _discardLine {0};
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public:
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template<typename Reader, typename Handler>
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size_t readLines(const Reader& reader, const Handler& handler)
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{
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auto d = _buffer.data();
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while (true) {
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auto bytesRead = reader(d + _bytesBuffered, _buffer.size() - _bytesBuffered);
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if (bytesRead <= 0) {
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return bytesRead;
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}
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_bytesBuffered += bytesRead;
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char* linePosition = nullptr;
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do {
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char* lineStart = d + _bytesConsumed;
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linePosition = static_cast<char*>(memchr(
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lineStart,
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'\n',
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_bytesBuffered - _bytesConsumed));
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if (linePosition) {
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int lineLength = linePosition - lineStart;
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if (!_discardLine) {
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handler(lineStart, lineLength);
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}
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_bytesConsumed += lineLength + 1;
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_discardLine = false;
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}
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} while (linePosition);
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size_t bytesRemaining = _bytesBuffered - _bytesConsumed;
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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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_bytesBuffered = 0;
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_bytesConsumed = 0;
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} else if (bytesRemaining > 0 && _bytesConsumed > 0) {
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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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memmove(d, d+_bytesConsumed, bytesRemaining);
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_bytesBuffered = bytesRemaining;
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_bytesConsumed = 0;
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}
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}
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}
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};
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