openmethod/detail/ostdstream.hpp

0001 // Copyright (c) 2018-2025 Jean-Louis Leroy
0002 // Distributed under the Boost Software License, Version 1.0.
0003 // See accompanying file LICENSE_1_0.txt
0004 // or copy at http://www.boost.org/LICENSE_1_0.txt)
0005
0006 #ifndef BOOST_OPENMETHOD_DETAIL_OSTDSTREAM_HPP
0007 #define BOOST_OPENMETHOD_DETAIL_OSTDSTREAM_HPP
0008
0009 #include <array>
0010 #include <cstdio>
0011 #include <charconv>
0012 #include <random>
0013
0014 namespace boost::openmethod {
0015
0016 namespace detail {
0017
0018 // -----------------------------------------------------------------------------
0019 // lightweight ostream
0020
0021 struct ostdstream {
0022     FILE* stream = nullptr;
0023
0024     ostdstream(FILE* s = nullptr) : stream(s) {
0025     }
0026
0027     void on(FILE* s = stderr) {
0028         this->stream = s;
0029     }
0030
0031     void off() {
0032         stream = nullptr;
0033     }
0034
0035     auto is_on() const -> bool {
0036         return stream != nullptr;
0037     }
0038 };
0039
0040 struct ostderr : ostdstream {
0041     ostderr() : ostdstream(stderr) {
0042     }
0043 };
0044
0045 inline ostdstream cerr;
0046
0047 inline auto operator<<(ostdstream& os, const char* str) -> ostdstream& {
0048     if (os.stream) {
0049         fputs(str, os.stream);
0050     }
0051
0052     return os;
0053 }
0054
0055 inline auto
0056 operator<<(ostdstream& os, const std::string_view& view) -> ostdstream& {
0057     if (os.stream) {
0058         fwrite(view.data(), sizeof(*view.data()), view.length(), os.stream);
0059     }
0060
0061     return os;
0062 }
0063
0064 inline auto operator<<(ostdstream& os, const void* value) -> ostdstream& {
0065     if (os.stream) {
0066         std::array<char, 20> str;
0067         auto end = std::to_chars(
0068                        str.data(), str.data() + str.size(),
0069                        reinterpret_cast<uintptr_t>(value), 16)
0070                        .ptr;
0071         os << std::string_view(str.data(), end - str.data());
0072     }
0073
0074     return os;
0075 }
0076
0077 inline auto operator<<(ostdstream& os, void (*value)()) -> ostdstream& {
0078     if (os.stream) {
0079         std::array<char, 20> str;
0080         auto end = std::to_chars(
0081                        str.data(), str.data() + str.size(),
0082                        reinterpret_cast<uintptr_t>(value), 16)
0083                        .ptr;
0084         os << std::string_view(str.data(), end - str.data());
0085     }
0086
0087     return os;
0088 }
0089
0090 inline auto operator<<(ostdstream& os, std::size_t value) -> ostdstream& {
0091     if (os.stream) {
0092         std::array<char, 20> str;
0093         auto end =
0094             std::to_chars(str.data(), str.data() + str.size(), value).ptr;
0095         os << std::string_view(str.data(), end - str.data());
0096     }
0097
0098     return os;
0099 }
0100
0101 } // namespace detail
0102
0103 } // namespace boost::openmethod
0104
0105 #endif