Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards


// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at
// Official repository:

// This is a derivative work based on Zlib, copyright below:
    Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler

    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any damages
    arising from the use of this software.

    Permission is granted to anyone to use this software for any purpose,
    including commercial applications, and to alter it and redistribute it
    freely, subject to the following restrictions:

    1. The origin of this software must not be misrepresented; you must not
       claim that you wrote the original software. If you use this software
       in a product, an acknowledgment in the product documentation would be
       appreciated but is not required.
    2. Altered source versions must be plainly marked as such, and must not be
       misrepresented as being the original software.
    3. This notice may not be removed or altered from any source distribution.

    Jean-loup Gailly        Mark Adler

    The data format used by the zlib library is described by RFCs (Request for
    Comments) 1950 to 1952 in the files
    (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).


#include <boost/beast/zlib/error.hpp>
#include <type_traits>

namespace boost {
namespace beast {
namespace zlib {
namespace detail {

class error_codes : public error_category
    const char*
    name() const noexcept override
        return "boost.beast.zlib";

    message(int ev) const override
        case error::need_buffers: return "need buffers";
        case error::end_of_stream: return "unexpected end of deflate stream";
        case error::need_dict: return "need dict";
        case error::stream_error: return "stream error";

        case error::invalid_block_type: return "invalid block type";
        case error::invalid_stored_length: return "invalid stored block length";
        case error::too_many_symbols: return "too many symbols";
        case error::invalid_code_lengths: return "invalid code lengths";
        case error::invalid_bit_length_repeat: return "invalid bit length repeat";
        case error::missing_eob: return "missing end of block code";
        case error::invalid_literal_length: return "invalid literal/length code";
        case error::invalid_distance_code: return "invalid distance code";
        case error::invalid_distance: return "invalid distance";

        case error::over_subscribed_length: return "over-subscribed length";
        case error::incomplete_length_set: return "incomplete length set";

        case error::general:
            return "beast.zlib error";

    default_error_condition(int ev) const noexcept override
        return error_condition{ev, *this};

    equivalent(int ev,
        error_condition const& condition
            ) const noexcept override
        return condition.value() == ev &&
            &condition.category() == this;

    equivalent(error_code const& error, int ev) const noexcept override
        return error.value() == ev &&
            &error.category() == this;

} // detail

make_error_code(error ev)
    static detail::error_codes const cat{};
    return error_code{static_cast<
        std::underlying_type<error>::type>(ev), cat};

} // zlib
} // beast
} // boost