mpd/src/io/BufferedReader.hxx

101 lines
2.7 KiB
C++

/*
* Copyright 2014-2022 Max Kellermann <max.kellermann@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "util/DynamicFifoBuffer.hxx"
#include <cstddef>
#include <span>
class Reader;
class BufferedReader {
static constexpr std::size_t MAX_SIZE = 512 * 1024;
Reader &reader;
DynamicFifoBuffer<char> buffer;
bool eof = false;
unsigned line_number = 0;
public:
explicit BufferedReader(Reader &_reader) noexcept
:reader(_reader), buffer(16384) {}
/**
* Reset the internal state. Should be called after rewinding
* the underlying #Reader.
*/
void Reset() noexcept {
buffer.Clear();
eof = false;
line_number = 0;
}
bool Fill(bool need_more);
[[gnu::pure]]
std::span<std::byte> Read() const noexcept {
return std::as_writable_bytes(buffer.Read());
}
/**
* Read a buffer of exactly the given size (without consuming
* it). Throws std::runtime_error if not enough data is
* available.
*/
void *ReadFull(std::size_t size);
void Consume(std::size_t n) noexcept {
buffer.Consume(n);
}
/**
* Read (and consume) data from the input buffer into the
* given buffer. Does not attempt to refill the buffer.
*/
std::size_t ReadFromBuffer(std::span<std::byte> dest) noexcept;
/**
* Read data into the given buffer and consume it from our
* buffer. Throw an exception if the request cannot be
* forfilled.
*/
void ReadFull(std::span<std::byte> dest);
char *ReadLine();
unsigned GetLineNumber() const noexcept {
return line_number;
}
};