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6de63782c7
The streaming operator doesn't short-circuit, consider the following
snippet:
void foo(InputStream& stream) {
int a, b;
stream >> a >> b;
}
If the first read fails, the second is called regardless. It should be
well defined what happens in this case: nothing.
124 lines
3.4 KiB
C++
124 lines
3.4 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/Optional.h>
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#include <AK/Stream.h>
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namespace AK {
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class InputBitStream final : public InputStream {
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public:
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explicit InputBitStream(InputStream& stream)
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: m_stream(stream)
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{
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}
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size_t read(Bytes bytes) override
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{
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if (has_any_error())
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return 0;
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size_t nread = 0;
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if (bytes.size() >= 1) {
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if (m_next_byte.has_value()) {
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bytes[0] = m_next_byte.value();
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m_next_byte.clear();
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++nread;
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}
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}
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return nread + m_stream.read(bytes.slice(nread));
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}
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bool read_or_error(Bytes bytes) override
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{
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if (read(bytes) != bytes.size()) {
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set_fatal_error();
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return false;
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}
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return true;
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}
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bool eof() const override { return !m_next_byte.has_value() && m_stream.eof(); }
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bool discard_or_error(size_t count) override
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{
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if (count >= 1) {
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if (m_next_byte.has_value()) {
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m_next_byte.clear();
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--count;
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}
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}
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return discard_or_error(count);
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}
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u32 read_bits(size_t count)
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{
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u32 result = 0;
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size_t nread = 0;
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while (nread < count) {
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if (m_next_byte.has_value()) {
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const auto bit = (m_next_byte.value() >> m_bit_offset) & 1;
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result |= bit << nread;
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++nread;
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if (m_bit_offset++ == 7)
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m_next_byte.clear();
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} else if (m_stream.eof()) {
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set_fatal_error();
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return 0;
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} else {
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m_stream >> m_next_byte;
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m_bit_offset = 0;
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}
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}
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return result;
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}
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bool read_bit() { return static_cast<bool>(read_bits(1)); }
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void align_to_byte_boundary()
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{
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if (m_next_byte.has_value())
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m_next_byte.clear();
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}
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private:
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Optional<u8> m_next_byte;
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size_t m_bit_offset { 0 };
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InputStream& m_stream;
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};
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}
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using AK::InputBitStream;
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