Program Listing for File format.hpp

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/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 NKI/AVL, Netherlands Cancer Institute
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer
 * 2. 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 COPYRIGHT OWNER 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 <string>

namespace cif
{

namespace detail
{
    template <typename T>
    struct to_varg
    {
        using type = T;

        to_varg(const T &v)
            : m_value(v)
        {
        }

        type operator*() { return m_value; }

        T m_value;
    };

    template <>
    struct to_varg<const char *>
    {
        using type = const char *;

        to_varg(const char *v)
            : m_value(v)
        {
        }

        type operator*() { return m_value.c_str(); }

        std::string m_value;
    };

    template <>
    struct to_varg<std::string>
    {
        using type = const char *;

        to_varg(const std::string &v)
            : m_value(v)
        {
        }

        type operator*() { return m_value.c_str(); }

        std::string m_value;
    };

} // namespace

template <typename... Args>
class format_plus_arg
{
  public:
    using args_vector_type = std::tuple<detail::to_varg<Args>...>;
    using vargs_vector_type = std::tuple<typename detail::to_varg<Args>::type...>;

    format_plus_arg(const format_plus_arg &) = delete;
    format_plus_arg &operator=(const format_plus_arg &) = delete;


    format_plus_arg(std::string_view fmt, Args... args)
        : m_fmt(fmt)
        , m_args(std::forward<Args>(args)...)
    {
        auto ix = std::make_index_sequence<sizeof...(Args)>();
        copy_vargs(ix);
    }

    std::string str()
    {
        char buffer[1024];
        std::string::size_type r = std::apply(snprintf, std::tuple_cat(std::make_tuple(buffer, sizeof(buffer), m_fmt.c_str()), m_vargs));
        return { buffer, r };
    }

    friend std::ostream &operator<<(std::ostream &os, const format_plus_arg &f)
    {
        char buffer[1024];
        std::string::size_type r = std::apply(snprintf, std::tuple_cat(std::make_tuple(buffer, sizeof(buffer), f.m_fmt.c_str()), f.m_vargs));
        os.write(buffer, r);
        return os;
    }

  private:

    template <std::size_t... I>
    void copy_vargs(std::index_sequence<I...>)
    {
        ((std::get<I>(m_vargs) = *std::get<I>(m_args)), ...);
    }

    std::string m_fmt;
    args_vector_type m_args;
    vargs_vector_type m_vargs;
};

template <typename... Args>
constexpr auto format(std::string_view fmt, Args... args)
{
    return format_plus_arg(fmt, std::forward<Args>(args)...);
}

// --------------------------------------------------------------------

class fill_out_streambuf : public std::streambuf
{
  public:

    using base_type = std::streambuf;
    using int_type = base_type::int_type;
    using char_type = base_type::char_type;
    using traits_type = base_type::traits_type;

    fill_out_streambuf(std::ostream &os, int width = 80)
        : m_os(os)
        , m_upstream(os.rdbuf())
        , m_width(width)
    {
    }

    ~fill_out_streambuf()
    {
        m_os.rdbuf(m_upstream);
    }

    virtual int_type
    overflow(int_type ic = traits_type::eof())
    {
        char ch = traits_type::to_char_type(ic);

        int_type result = ic;

        if (ch == '\n')
        {
            for (int i = m_column_count; result != traits_type::eof() and i < m_width; ++i)
                result = m_upstream->sputc(' ');
        }

        if (result != traits_type::eof())
            result = m_upstream->sputc(ch);

        if (result != traits_type::eof())
        {
            if (ch == '\n')
            {
                m_column_count = 0;
                ++m_line_count;
            }
            else
                ++m_column_count;
        }

        return result;
    }

    std::streambuf *get_upstream() const { return m_upstream; }

    int get_line_count() const { return m_line_count; }

  private:
    std::ostream &m_os;
    std::streambuf *m_upstream;
    int m_width;
    int m_line_count = 0;
    int m_column_count = 0;
};

} // namespace pdbx