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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>
#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 {};
template <typename Char> FILE* get_file(std::basic_filebuf<Char>&) {
return nullptr;
}
struct dummy_filebuf {
FILE* _Myfile;
};
template <typename T, typename U = int> struct ms_filebuf {
using type = dummy_filebuf;
};
template <typename T> struct ms_filebuf<T, decltype(T::_Myfile, 0)> {
using type = T;
};
using filebuf_type = ms_filebuf<std::filebuf>::type;
FILE* get_file(filebuf_type& buf);
// Generate a unique explicit instantion in every translation unit using a tag
// type in an anonymous namespace.
namespace {
struct filebuf_access_tag {};
} // namespace
template <typename Tag, typename FileMemberPtr, FileMemberPtr file>
class filebuf_access {
friend FILE* get_file(filebuf_type& buf) { return buf.*file; }
};
template class filebuf_access<filebuf_access_tag,
decltype(&filebuf_type::_Myfile),
&filebuf_type::_Myfile>;
inline bool write(std::filebuf& buf, fmt::string_view data) {
FILE* f = get_file(buf);
if (!f) return false;
print(f, data);
return true;
}
inline bool write(std::wfilebuf&, 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) {
if (const_check(FMT_MSC_VERSION)) {
auto filebuf = dynamic_cast<std::basic_filebuf<Char>*>(os.rdbuf());
if (filebuf && write(*filebuf, {buf.data(), buf.size()})) return;
}
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> {
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>
struct formatter<detail::streamed_view<T>> : ostream_formatter {
template <typename OutputIt>
auto format(detail::streamed_view<T> view,
basic_format_context<OutputIt, char>& ctx) const -> OutputIt {
return ostream_formatter::format(view.value, ctx);
}
};
/**
\rst
Returns a view that formats `value` via an ostream ``operator<<``.
**Example**::
fmt::print("Current thread id: {}\n",
fmt::streamed(std::this_thread::get_id()));
\endrst
*/
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;
};
} // 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);
detail::write_buffer(os, buffer);
}
/**
\rst
Prints formatted data to the stream *os*.
**Example**::
fmt::print(cerr, "Don't {}!", "panic");
\endrst
*/
FMT_MODULE_EXPORT template <typename... T>
void print(std::ostream& os, format_string<T...> fmt, T&&... args) {
vprint(os, fmt, fmt::make_format_args(args...));
}
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_
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