ostream.h

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// Formatting library for C++ - std::ostream support
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
//
// For the license information refer to format.h.
 
#ifndef FMT_OSTREAM_H_
#define FMT_OSTREAM_H_
 
#include <fstream>
#include <ostream>
#if defined(_WIN32) && defined(__GLIBCXX__)
#include <ext/stdio_filebuf.h>
#include <ext/stdio_sync_filebuf.h>
#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
#include <__std_stream>
#endif
 
#include "format.h"
 
FMT_BEGIN_NAMESPACE
 
template <typename OutputIt, typename Char>
class basic_printf_context;
 
namespace detail
{
 
    // Checks if T has a user-defined operator<<.
    template <typename T, typename Char, typename Enable = void>
    class is_streamable
    {
    private:
        template <typename U>
        static auto test(int)
            -> bool_constant<sizeof(std::declval<std::basic_ostream<Char>&>()
                                    << std::declval<U>()) != 0>;
 
        template <typename>
        static auto test(...) -> std::false_type;
 
        using result = decltype(test<T>(0));
 
    public:
        is_streamable() = default;
 
        static const bool value = result::value;
    };
 
    // Formatting of built-in types and arrays is intentionally disabled because
    // it's handled by standard (non-ostream) formatters.
    template <typename T, typename Char>
    struct is_streamable<
        T,
        Char,
        enable_if_t<
            std::is_arithmetic<T>::value || std::is_array<T>::value ||
            std::is_pointer<T>::value || std::is_same<T, char8_type>::value ||
            std::is_convertible<T, fmt::basic_string_view<Char>>::value ||
            std::is_same<T, std_string_view<Char>>::value ||
            (std::is_convertible<T, int>::value && !std::is_enum<T>::value)>>
        : std::false_type
    {
    };
 
    // Generate a unique explicit instantion in every translation unit using a tag
    // type in an anonymous namespace.
    namespace
    {
        struct file_access_tag
        {
        };
    } // namespace
    template <class Tag, class BufType, FILE* BufType::*FileMemberPtr>
    class file_access
    {
        friend auto get_file(BufType& obj) -> FILE*
        {
            return obj.*FileMemberPtr;
        }
    };
 
#if FMT_MSC_VERSION
    template class file_access<file_access_tag, std::filebuf, &std::filebuf::_Myfile>;
    auto get_file(std::filebuf&) -> FILE*;
#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
    template class file_access<file_access_tag, std::__stdoutbuf<char>, &std::__stdoutbuf<char>::__file_>;
    auto get_file(std::__stdoutbuf<char>&) -> FILE*;
#endif
 
    inline bool write_ostream_unicode(std::ostream& os, fmt::string_view data)
    {
#if FMT_MSC_VERSION
        if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
            if (FILE* f = get_file(*buf))
                return write_console(f, data);
#elif defined(_WIN32) && defined(__GLIBCXX__)
        auto* rdbuf = os.rdbuf();
        FILE* c_file;
        if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
            c_file = fbuf->file();
        else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
            c_file = fbuf->file();
        else
            return false;
        if (c_file)
            return write_console(c_file, data);
#elif defined(_WIN32) && defined(_LIBCPP_VERSION)
        if (auto* buf = dynamic_cast<std::__stdoutbuf<char>*>(os.rdbuf()))
            if (FILE* f = get_file(*buf))
                return write_console(f, data);
#else
        ignore_unused(os, data);
#endif
        return false;
    }
    inline bool write_ostream_unicode(std::wostream&,
                                      fmt::basic_string_view<wchar_t>)
    {
        return false;
    }
 
    // Write the content of buf to os.
    // It is a separate function rather than a part of vprint to simplify testing.
    template <typename Char>
    void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf)
    {
        const Char* buf_data         = buf.data();
        using unsigned_streamsize    = std::make_unsigned<std::streamsize>::type;
        unsigned_streamsize size     = buf.size();
        unsigned_streamsize max_size = to_unsigned(max_value<std::streamsize>());
        do
        {
            unsigned_streamsize n = size <= max_size ? size : max_size;
            os.write(buf_data, static_cast<std::streamsize>(n));
            buf_data += n;
            size -= n;
        } while (size != 0);
    }
 
    template <typename Char, typename T>
    void format_value(buffer<Char>& buf, const T& value, locale_ref loc = locale_ref())
    {
        auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
        auto&& output     = std::basic_ostream<Char>(&format_buf);
#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
        if (loc)
            output.imbue(loc.get<std::locale>());
#endif
        output << value;
        output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
    }
 
    template <typename T>
    struct streamed_view
    {
        const T& value;
    };
 
} // namespace detail
 
// Formats an object of type T that has an overloaded ostream operator<<.
template <typename Char>
struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char>
{
    void set_debug_format() = delete;
 
    template <typename T, typename OutputIt>
    auto format(const T& value, basic_format_context<OutputIt, Char>& ctx) const
        -> OutputIt
    {
        auto buffer = basic_memory_buffer<Char>();
        format_value(buffer, value, ctx.locale());
        return formatter<basic_string_view<Char>, Char>::format(
            {buffer.data(), buffer.size()}, ctx);
    }
};
 
using ostream_formatter = basic_ostream_formatter<char>;
 
template <typename T, typename Char>
struct formatter<detail::streamed_view<T>, Char>
    : basic_ostream_formatter<Char>
{
    template <typename OutputIt>
    auto format(detail::streamed_view<T>              view,
                basic_format_context<OutputIt, Char>& ctx) const -> OutputIt
    {
        return basic_ostream_formatter<Char>::format(view.value, ctx);
    }
};
 
template <typename T>
auto streamed(const T& value) -> detail::streamed_view<T>
{
    return {value};
}
 
namespace detail
{
 
    // Formats an object of type T that has an overloaded ostream operator<<.
    template <typename T, typename Char>
    struct fallback_formatter<T, Char, enable_if_t<is_streamable<T, Char>::value>>
        : basic_ostream_formatter<Char>
    {
        using basic_ostream_formatter<Char>::format;
    };
 
    inline void vprint_directly(std::ostream& os, string_view format_str, format_args args)
    {
        auto buffer = memory_buffer();
        detail::vformat_to(buffer, format_str, args);
        detail::write_buffer(os, buffer);
    }
 
} // namespace detail
 
FMT_MODULE_EXPORT template <typename Char>
void vprint(std::basic_ostream<Char>&                                os,
            basic_string_view<type_identity_t<Char>>                 format_str,
            basic_format_args<buffer_context<type_identity_t<Char>>> args)
{
    auto buffer = basic_memory_buffer<Char>();
    detail::vformat_to(buffer, format_str, args);
    if (detail::write_ostream_unicode(os, {buffer.data(), buffer.size()}))
        return;
    detail::write_buffer(os, buffer);
}
 
FMT_MODULE_EXPORT template <typename... T>
void print(std::ostream& os, format_string<T...> fmt, T&&... args)
{
    const auto& vargs = fmt::make_format_args(args...);
    if (detail::is_utf8())
        vprint(os, fmt, vargs);
    else
        detail::vprint_directly(os, fmt, vargs);
}
 
FMT_MODULE_EXPORT
template <typename... Args>
void print(std::wostream&                                         os,
           basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
           Args&&... args)
{
    vprint(os, fmt, fmt::make_format_args<buffer_context<wchar_t>>(args...));
}
 
FMT_END_NAMESPACE
 
#endif // FMT_OSTREAM_H_