js/external/utils/streaming/ConstBuffer.cpp

/*
 * This file is part of the Flowee project
 * Copyright (C) 2016-2019 Tom Zander <tom@flowee.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include "ConstBuffer.h"

#include <cassert>
#include <cstdint>

Streaming::ConstBuffer Streaming::ConstBuffer::create(const char *start, size_t size)
{
    auto buf = std::shared_ptr<char>(new char[size], std::default_delete<char[]>());
    memcpy(buf.get(), start, size);
    return Streaming::ConstBuffer(buf, buf.get(), buf.get() + size);
}

Streaming::ConstBuffer Streaming::ConstBuffer::create(const std::vector<unsigned char> &vector)
{
    auto buf = std::shared_ptr<char>(new char[vector.size()], std::default_delete<char[]>());
    memcpy(buf.get(), &vector[0], vector.size());
    return Streaming::ConstBuffer(buf, buf.get(), buf.get() + vector.size());
}

Streaming::ConstBuffer::ConstBuffer()
    : m_buffer(nullptr),
    m_start(nullptr),
    m_stop(nullptr)
{
}

Streaming::ConstBuffer::ConstBuffer(std::shared_ptr<char> buffer, char const *start, char const *stop)
    : m_buffer(buffer),
    m_start(start),
    m_stop(stop)
{
    assert(stop >= start);
    assert(start >= buffer.get());
    assert(stop >= buffer.get());
}

char const* Streaming::ConstBuffer::begin() const
{
    return m_start;
}

char const* Streaming::ConstBuffer::constData() const
{
    return m_start;
}

char const* Streaming::ConstBuffer::end() const
{
    return m_stop;
}

int Streaming::ConstBuffer::size() const
{
    return m_stop - m_start;
}

Streaming::ConstBuffer::operator boost::asio::const_buffer() const
{
    return boost::asio::const_buffer(constData(), size());
}

std::shared_ptr<char> Streaming::ConstBuffer::internal_buffer() const
{
    return m_buffer;
}

Streaming::ConstBuffer Streaming::ConstBuffer::mid(int offset, int length) const
{
    if (length > 0) {
        assert(m_start + offset + length <= m_stop);
        return ConstBuffer(m_buffer, m_start + offset, m_start + offset + length);
    }
    assert(m_start + offset <= m_stop);
    return ConstBuffer(m_buffer, m_start + offset, m_stop);
}

char Streaming::ConstBuffer::operator[](size_t idx) const
{
    assert(begin() + idx < end());
    return *(begin() + idx);
}

bool Streaming::ConstBuffer::startsWith(const Streaming::ConstBuffer &other) const
{
    if (!other.isValid()) return false;
    if (other.size() > size()) return false;

    const char *s1 = m_start;
    const char *s2 = other.begin();
    while (s2 != other.end()) {
        const uint8_t a = static_cast<uint8_t>(*s1);
        const uint8_t b = static_cast<uint8_t>(*s2);
        if (a != b)
            return false;
        s1++; s2++;
    }
    return true;
}

bool Streaming::ConstBuffer::operator==(const Streaming::ConstBuffer &other) const
{
    if (!other.isValid())
        return !isValid();
    if (!isValid())
        return false;
    if (size() != other.size())
        return false;
    const char *me = begin();
    const char *them = other.begin();
    while (me != end()) {
        if (*me != *them)
            return false;
        ++them;
        ++me;
    }
    return true;
}