| // 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 "format.h" |
| #include <ostream> |
| |
| FMT_BEGIN_NAMESPACE |
| namespace internal { |
| |
| template <class Char> |
| class formatbuf : public std::basic_streambuf<Char> { |
| private: |
| typedef typename std::basic_streambuf<Char>::int_type int_type; |
| typedef typename std::basic_streambuf<Char>::traits_type traits_type; |
| |
| basic_buffer<Char> &buffer_; |
| |
| public: |
| formatbuf(basic_buffer<Char> &buffer) : buffer_(buffer) {} |
| |
| protected: |
| // The put-area is actually always empty. This makes the implementation |
| // simpler and has the advantage that the streambuf and the buffer are always |
| // in sync and sputc never writes into uninitialized memory. The obvious |
| // disadvantage is that each call to sputc always results in a (virtual) call |
| // to overflow. There is no disadvantage here for sputn since this always |
| // results in a call to xsputn. |
| |
| int_type overflow(int_type ch = traits_type::eof()) FMT_OVERRIDE { |
| if (!traits_type::eq_int_type(ch, traits_type::eof())) |
| buffer_.push_back(static_cast<Char>(ch)); |
| return ch; |
| } |
| |
| std::streamsize xsputn(const Char *s, std::streamsize count) FMT_OVERRIDE { |
| buffer_.append(s, s + count); |
| return count; |
| } |
| }; |
| |
| template <typename Char> |
| struct test_stream : std::basic_ostream<Char> { |
| private: |
| struct null; |
| // Hide all operator<< from std::basic_ostream<Char>. |
| void operator<<(null); |
| }; |
| |
| // Checks if T has a user-defined operator<< (e.g. not a member of std::ostream). |
| template <typename T, typename Char> |
| class is_streamable { |
| private: |
| template <typename U> |
| static decltype( |
| internal::declval<test_stream<Char>&>() |
| << internal::declval<U>(), std::true_type()) test(int); |
| |
| template <typename> |
| static std::false_type test(...); |
| |
| typedef decltype(test<T>(0)) result; |
| |
| public: |
| static const bool value = result::value; |
| }; |
| |
| // Write the content of buf to os. |
| template <typename Char> |
| void write(std::basic_ostream<Char> &os, basic_buffer<Char> &buf) { |
| const Char *data = buf.data(); |
| typedef std::make_unsigned<std::streamsize>::type UnsignedStreamSize; |
| UnsignedStreamSize size = buf.size(); |
| UnsignedStreamSize max_size = |
| internal::to_unsigned((std::numeric_limits<std::streamsize>::max)()); |
| do { |
| UnsignedStreamSize n = size <= max_size ? size : max_size; |
| os.write(data, static_cast<std::streamsize>(n)); |
| data += n; |
| size -= n; |
| } while (size != 0); |
| } |
| |
| template <typename Char, typename T> |
| void format_value(basic_buffer<Char> &buffer, const T &value) { |
| internal::formatbuf<Char> format_buf(buffer); |
| std::basic_ostream<Char> output(&format_buf); |
| output.exceptions(std::ios_base::failbit | std::ios_base::badbit); |
| output << value; |
| buffer.resize(buffer.size()); |
| } |
| } // namespace internal |
| |
| // Disable conversion to int if T has an overloaded operator<< which is a free |
| // function (not a member of std::ostream). |
| template <typename T, typename Char> |
| struct convert_to_int<T, Char, void> { |
| static const bool value = |
| convert_to_int<T, Char, int>::value && |
| !internal::is_streamable<T, Char>::value; |
| }; |
| |
| // Formats an object of type T that has an overloaded ostream operator<<. |
| template <typename T, typename Char> |
| struct formatter<T, Char, |
| typename std::enable_if< |
| internal::is_streamable<T, Char>::value && |
| !internal::format_type< |
| typename buffer_context<Char>::type, T>::value>::type> |
| : formatter<basic_string_view<Char>, Char> { |
| |
| template <typename Context> |
| auto format(const T &value, Context &ctx) -> decltype(ctx.out()) { |
| basic_memory_buffer<Char> buffer; |
| internal::format_value(buffer, value); |
| basic_string_view<Char> str(buffer.data(), buffer.size()); |
| return formatter<basic_string_view<Char>, Char>::format(str, ctx); |
| } |
| }; |
| |
| template <typename Char> |
| inline void vprint(std::basic_ostream<Char> &os, |
| basic_string_view<Char> format_str, |
| basic_format_args<typename buffer_context<Char>::type> args) { |
| basic_memory_buffer<Char> buffer; |
| internal::vformat_to(buffer, format_str, args); |
| internal::write(os, buffer); |
| } |
| /** |
| \rst |
| Prints formatted data to the stream *os*. |
| |
| **Example**:: |
| |
| fmt::print(cerr, "Don't {}!", "panic"); |
| \endrst |
| */ |
| template <typename S, typename... Args> |
| inline typename std::enable_if<internal::is_string<S>::value>::type |
| print(std::basic_ostream<FMT_CHAR(S)> &os, const S &format_str, |
| const Args & ... args) { |
| internal::checked_args<S, Args...> ca(format_str, args...); |
| vprint(os, to_string_view(format_str), *ca); |
| } |
| FMT_END_NAMESPACE |
| |
| #endif // FMT_OSTREAM_H_ |