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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 <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_same<T, std::basic_string<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 {};
- // 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);
- buf.try_resize(buf.size());
- }
- // 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>>
- : private formatter<basic_string_view<Char>, Char> {
- using formatter<basic_string_view<Char>, Char>::parse;
- template <typename OutputIt>
- auto format(const T& value, basic_format_context<OutputIt, Char>& ctx)
- -> 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);
- }
- // DEPRECATED!
- template <typename OutputIt>
- auto format(const T& value, basic_printf_context<OutputIt, Char>& ctx)
- -> OutputIt {
- auto buffer = basic_memory_buffer<Char>();
- format_value(buffer, value, ctx.locale());
- return std::copy(buffer.begin(), buffer.end(), ctx.out());
- }
- };
- } // namespace detail
- FMT_MODULE_EXPORT
- template <typename Char>
- void vprint(std::basic_ostream<Char>& os, basic_string_view<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 S, typename... Args,
- typename Char = enable_if_t<detail::is_string<S>::value, char_t<S>>>
- void print(std::basic_ostream<Char>& os, const S& format_str, Args&&... args) {
- vprint(os, to_string_view(format_str),
- fmt::make_args_checked<Args...>(format_str, args...));
- }
- FMT_END_NAMESPACE
- #endif // FMT_OSTREAM_H_
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