131 lines
3.9 KiB
C++
131 lines
3.9 KiB
C++
// Formatting library for C++ - std::ostream support
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//
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// Copyright (c) 2012 - present, Victor Zverovich
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// All rights reserved.
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//
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// For the license information refer to format.h.
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#ifndef FMT_OSTREAM_H_
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#define FMT_OSTREAM_H_
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#include <ostream>
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#include "format.h"
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FMT_BEGIN_NAMESPACE
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template <typename OutputIt, typename Char> class basic_printf_context;
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namespace detail {
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// Checks if T has a user-defined operator<<.
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template <typename T, typename Char, typename Enable = void>
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class is_streamable {
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private:
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template <typename U>
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static auto test(int)
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-> bool_constant<sizeof(std::declval<std::basic_ostream<Char>&>()
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<< std::declval<U>()) != 0>;
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template <typename> static auto test(...) -> std::false_type;
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using result = decltype(test<T>(0));
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public:
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is_streamable() = default;
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static const bool value = result::value;
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};
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// Formatting of built-in types and arrays is intentionally disabled because
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// it's handled by standard (non-ostream) formatters.
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template <typename T, typename Char>
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struct is_streamable<
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T, Char,
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enable_if_t<
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std::is_arithmetic<T>::value || std::is_array<T>::value ||
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std::is_pointer<T>::value || std::is_same<T, char8_type>::value ||
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std::is_convertible<T, fmt::basic_string_view<Char>>::value ||
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std::is_same<T, std_string_view<Char>>::value ||
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(std::is_convertible<T, int>::value && !std::is_enum<T>::value)>>
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: std::false_type {};
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// Write the content of buf to os.
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// It is a separate function rather than a part of vprint to simplify testing.
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template <typename Char>
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void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
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const Char* buf_data = buf.data();
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using unsigned_streamsize = std::make_unsigned<std::streamsize>::type;
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unsigned_streamsize size = buf.size();
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unsigned_streamsize max_size = to_unsigned(max_value<std::streamsize>());
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do {
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unsigned_streamsize n = size <= max_size ? size : max_size;
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os.write(buf_data, static_cast<std::streamsize>(n));
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buf_data += n;
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size -= n;
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} while (size != 0);
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}
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template <typename Char, typename T>
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void format_value(buffer<Char>& buf, const T& value,
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locale_ref loc = locale_ref()) {
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auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
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auto&& output = std::basic_ostream<Char>(&format_buf);
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#if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
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if (loc) output.imbue(loc.get<std::locale>());
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#endif
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output << value;
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output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
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}
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template <typename T> struct streamed_view { const T& value; };
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} // namespace detail
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// Formats an object of type T that has an overloaded ostream operator<<.
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template <typename Char>
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struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char> {
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void set_debug_format() = delete;
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template <typename T, typename OutputIt>
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auto format(const T& value, basic_format_context<OutputIt, Char>& ctx) const
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-> OutputIt {
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auto buffer = basic_memory_buffer<Char>();
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format_value(buffer, value, ctx.locale());
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return formatter<basic_string_view<Char>, Char>::format(
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{buffer.data(), buffer.size()}, ctx);
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}
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};
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using ostream_formatter = basic_ostream_formatter<char>;
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template <typename T, typename Char>
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struct formatter<detail::streamed_view<T>, Char>
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: basic_ostream_formatter<Char> {
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template <typename OutputIt>
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auto format(detail::streamed_view<T> view,
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basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
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return basic_ostream_formatter<Char>::format(view.value, ctx);
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}
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};
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/**
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\rst
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Returns a view that formats `value` via an ostream ``operator<<``.
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**Example**::
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fmt::print("Current thread id: {}\n",
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fmt::streamed(std::this_thread::get_id()));
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\endrst
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*/
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template <typename T>
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auto streamed(const T& value) -> detail::streamed_view<T> {
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return {value};
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}
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FMT_END_NAMESPACE
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#endif // FMT_OSTREAM_H_
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