1 // Formatting library for C++ - std::ostream support
2 //
3 // Copyright (c) 2012 - present, Victor Zverovich
4 // All rights reserved.
5 //
6 // For the license information refer to format.h.
7
8 #ifndef FMT_OSTREAM_H_
9 #define FMT_OSTREAM_H_
10
11 #include <fstream> // std::filebuf
12
13 #ifdef _WIN32
14 # ifdef __GLIBCXX__
15 # include <ext/stdio_filebuf.h>
16 # include <ext/stdio_sync_filebuf.h>
17 # endif
18 # include <io.h>
19 #endif
20
21 #include "format.h"
22
23 FMT_BEGIN_NAMESPACE
24 namespace detail {
25
26 template <typename Streambuf> class formatbuf : public Streambuf {
27 private:
28 using char_type = typename Streambuf::char_type;
29 using streamsize = decltype(std::declval<Streambuf>().sputn(nullptr, 0));
30 using int_type = typename Streambuf::int_type;
31 using traits_type = typename Streambuf::traits_type;
32
33 buffer<char_type>& buffer_;
34
35 public:
formatbuf(buffer<char_type> & buf)36 explicit formatbuf(buffer<char_type>& buf) : buffer_(buf) {}
37
38 protected:
39 // The put area is always empty. This makes the implementation simpler and has
40 // the advantage that the streambuf and the buffer are always in sync and
41 // sputc never writes into uninitialized memory. A disadvantage is that each
42 // call to sputc always results in a (virtual) call to overflow. There is no
43 // disadvantage here for sputn since this always results in a call to xsputn.
44
45 auto overflow(int_type ch) -> int_type override {
46 if (!traits_type::eq_int_type(ch, traits_type::eof()))
47 buffer_.push_back(static_cast<char_type>(ch));
48 return ch;
49 }
50
51 auto xsputn(const char_type* s, streamsize count) -> streamsize override {
52 buffer_.append(s, s + count);
53 return count;
54 }
55 };
56
57 // Generate a unique explicit instantion in every translation unit using a tag
58 // type in an anonymous namespace.
59 namespace {
60 struct file_access_tag {};
61 } // namespace
62 template <typename Tag, typename BufType, FILE* BufType::*FileMemberPtr>
63 class file_access {
64 friend auto get_file(BufType& obj) -> FILE* { return obj.*FileMemberPtr; }
65 };
66
67 #if FMT_MSC_VERSION
68 template class file_access<file_access_tag, std::filebuf,
69 &std::filebuf::_Myfile>;
70 auto get_file(std::filebuf&) -> FILE*;
71 #endif
72
73 inline auto write_ostream_unicode(std::ostream& os, fmt::string_view data)
74 -> bool {
75 FILE* f = nullptr;
76 #if FMT_MSC_VERSION
77 if (auto* buf = dynamic_cast<std::filebuf*>(os.rdbuf()))
78 f = get_file(*buf);
79 else
80 return false;
81 #elif defined(_WIN32) && defined(__GLIBCXX__)
82 auto* rdbuf = os.rdbuf();
83 if (auto* sfbuf = dynamic_cast<__gnu_cxx::stdio_sync_filebuf<char>*>(rdbuf))
84 f = sfbuf->file();
85 else if (auto* fbuf = dynamic_cast<__gnu_cxx::stdio_filebuf<char>*>(rdbuf))
86 f = fbuf->file();
87 else
88 return false;
89 #else
90 ignore_unused(os, data, f);
91 #endif
92 #ifdef _WIN32
93 if (f) {
94 int fd = _fileno(f);
95 if (_isatty(fd)) {
96 os.flush();
97 return write_console(fd, data);
98 }
99 }
100 #endif
101 return false;
102 }
103 inline auto write_ostream_unicode(std::wostream&,
104 fmt::basic_string_view<wchar_t>) -> bool {
105 return false;
106 }
107
108 // Write the content of buf to os.
109 // It is a separate function rather than a part of vprint to simplify testing.
110 template <typename Char>
write_buffer(std::basic_ostream<Char> & os,buffer<Char> & buf)111 void write_buffer(std::basic_ostream<Char>& os, buffer<Char>& buf) {
112 const Char* buf_data = buf.data();
113 using unsigned_streamsize = std::make_unsigned<std::streamsize>::type;
114 unsigned_streamsize size = buf.size();
115 unsigned_streamsize max_size = to_unsigned(max_value<std::streamsize>());
116 do {
117 unsigned_streamsize n = size <= max_size ? size : max_size;
118 os.write(buf_data, static_cast<std::streamsize>(n));
119 buf_data += n;
120 size -= n;
121 } while (size != 0);
122 }
123
124 template <typename Char, typename T>
format_value(buffer<Char> & buf,const T & value)125 void format_value(buffer<Char>& buf, const T& value) {
126 auto&& format_buf = formatbuf<std::basic_streambuf<Char>>(buf);
127 auto&& output = std::basic_ostream<Char>(&format_buf);
128 #if !defined(FMT_STATIC_THOUSANDS_SEPARATOR)
129 output.imbue(std::locale::classic()); // The default is always unlocalized.
130 #endif
131 output << value;
132 output.exceptions(std::ios_base::failbit | std::ios_base::badbit);
133 }
134
135 template <typename T> struct streamed_view {
136 const T& value;
137 };
138
139 } // namespace detail
140
141 // Formats an object of type T that has an overloaded ostream operator<<.
142 template <typename Char>
143 struct basic_ostream_formatter : formatter<basic_string_view<Char>, Char> {
144 void set_debug_format() = delete;
145
146 template <typename T, typename OutputIt>
147 auto format(const T& value, basic_format_context<OutputIt, Char>& ctx) const
148 -> OutputIt {
149 auto buffer = basic_memory_buffer<Char>();
150 detail::format_value(buffer, value);
151 return formatter<basic_string_view<Char>, Char>::format(
152 {buffer.data(), buffer.size()}, ctx);
153 }
154 };
155
156 using ostream_formatter = basic_ostream_formatter<char>;
157
158 template <typename T, typename Char>
159 struct formatter<detail::streamed_view<T>, Char>
160 : basic_ostream_formatter<Char> {
161 template <typename OutputIt>
162 auto format(detail::streamed_view<T> view,
163 basic_format_context<OutputIt, Char>& ctx) const -> OutputIt {
164 return basic_ostream_formatter<Char>::format(view.value, ctx);
165 }
166 };
167
168 /**
169 \rst
170 Returns a view that formats `value` via an ostream ``operator<<``.
171
172 **Example**::
173
174 fmt::print("Current thread id: {}\n",
175 fmt::streamed(std::this_thread::get_id()));
176 \endrst
177 */
178 template <typename T>
179 constexpr auto streamed(const T& value) -> detail::streamed_view<T> {
180 return {value};
181 }
182
183 namespace detail {
184
185 inline void vprint_directly(std::ostream& os, string_view format_str,
186 format_args args) {
187 auto buffer = memory_buffer();
188 detail::vformat_to(buffer, format_str, args);
189 detail::write_buffer(os, buffer);
190 }
191
192 } // namespace detail
193
194 FMT_EXPORT template <typename Char>
195 void vprint(std::basic_ostream<Char>& os,
196 basic_string_view<type_identity_t<Char>> format_str,
197 basic_format_args<buffer_context<type_identity_t<Char>>> args) {
198 auto buffer = basic_memory_buffer<Char>();
199 detail::vformat_to(buffer, format_str, args);
200 if (detail::write_ostream_unicode(os, {buffer.data(), buffer.size()})) return;
201 detail::write_buffer(os, buffer);
202 }
203
204 /**
205 \rst
206 Prints formatted data to the stream *os*.
207
208 **Example**::
209
210 fmt::print(cerr, "Don't {}!", "panic");
211 \endrst
212 */
213 FMT_EXPORT template <typename... T>
214 void print(std::ostream& os, format_string<T...> fmt, T&&... args) {
215 const auto& vargs = fmt::make_format_args(args...);
216 if (detail::is_utf8())
217 vprint(os, fmt, vargs);
218 else
219 detail::vprint_directly(os, fmt, vargs);
220 }
221
222 FMT_EXPORT
223 template <typename... Args>
224 void print(std::wostream& os,
225 basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
226 Args&&... args) {
227 vprint(os, fmt, fmt::make_format_args<buffer_context<wchar_t>>(args...));
228 }
229
230 FMT_EXPORT template <typename... T>
231 void println(std::ostream& os, format_string<T...> fmt, T&&... args) {
232 fmt::print(os, "{}\n", fmt::format(fmt, std::forward<T>(args)...));
233 }
234
235 FMT_EXPORT
236 template <typename... Args>
237 void println(std::wostream& os,
238 basic_format_string<wchar_t, type_identity_t<Args>...> fmt,
239 Args&&... args) {
240 print(os, L"{}\n", fmt::format(fmt, std::forward<Args>(args)...));
241 }
242
243 FMT_END_NAMESPACE
244
245 #endif // FMT_OSTREAM_H_
246