From Jason Turner

[print.fun]

C++20 → C++23 3.3 KB 124 lines
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Archived: C++20 | C++23
Markdown: C++20 | C++23
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tmp/tmpsz73yxgz/{from.md → to.md} RENAMED
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+ ### Print functions <a id="print.fun">[[print.fun]]</a>
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+
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+ ``` cpp
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+ template<class... Args>
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+ void print(format_string<Args...> fmt, Args&&... args);
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ print(stdout, fmt, std::forward<Args>(args)...);
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+ ```
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+
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+ ``` cpp
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+ template<class... Args>
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+ void print(FILE* stream, format_string<Args...> fmt, Args&&... args);
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+ ```
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+
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+ *Effects:* If the ordinary literal encoding [[lex.charset]] is UTF-8,
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+ equivalent to:
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+
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+ ``` cpp
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+ vprint_unicode(stream, fmt.str, make_format_args(std::forward<Args>(args)...));
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+ ```
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+
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+ Otherwise, equivalent to:
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+
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+ ``` cpp
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+ vprint_nonunicode(stream, fmt.str, make_format_args(std::forward<Args>(args)...));
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+ ```
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+
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+ ``` cpp
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+ template<class... Args>
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+ void println(format_string<Args...> fmt, Args&&... args);
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ println(stdout, fmt, std::forward<Args>(args)...);
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+ ```
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+
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+ ``` cpp
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+ template<class... Args>
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+ void println(FILE* stream, format_string<Args...> fmt, Args&&... args);
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ print(stream, "{}\n", format(fmt, std::forward<Args>(args)...));
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+ ```
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+
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+ ``` cpp
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+ void vprint_unicode(string_view fmt, format_args args);
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ vprint_unicode(stdout, fmt, args);
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+ ```
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+
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+ ``` cpp
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+ void vprint_unicode(FILE* stream, string_view fmt, format_args args);
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+ ```
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+
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+ *Preconditions:* `stream` is a valid pointer to an output C stream.
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+
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+ *Effects:* The function initializes an automatic variable via
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+
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+ ``` cpp
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+ string out = vformat(fmt, args);
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+ ```
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+
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+ If `stream` refers to a terminal capable of displaying Unicode, writes
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+ `out` to the terminal using the native Unicode API; if `out` contains
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+ invalid code units, the behavior is undefined and implementations are
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+ encouraged to diagnose it. Otherwise writes `out` to `stream` unchanged.
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+ If the native Unicode API is used, the function flushes `stream` before
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+ writing `out`.
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+
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+ [*Note 1*: On POSIX and Windows, `stream` referring to a terminal means
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+ that, respectively, `isatty(fileno(stream))` and
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+ `GetConsoleMode(_get_osfhandle(_fileno(stream)), ...)` return
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+ nonzero. — *end note*]
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+
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+ [*Note 2*: On Windows, the native Unicode API is
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+ `WriteConsoleW`. — *end note*]
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+
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+ *Throws:* Any exception thrown by the call to `vformat`
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+ [[format.err.report]]. `system_error` if writing to the terminal or
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+ `stream` fails. May throw `bad_alloc`.
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+
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+ *Recommended practice:* If invoking the native Unicode API requires
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+ transcoding, implementations should substitute invalid code units with
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+ U+fffd (replacement character) per the Unicode Standard, Chapter 3.9
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+ ‘U+fffd‘ Substitution in Conversion.
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+
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+ ``` cpp
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+ void vprint_nonunicode(string_view fmt, format_args args);
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ vprint_nonunicode(stdout, fmt, args);
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+ ```
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+
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+ ``` cpp
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+ void vprint_nonunicode(FILE* stream, string_view fmt, format_args args);
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+ ```
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+
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+ *Preconditions:* `stream` is a valid pointer to an output C stream.
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+
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+ *Effects:* Writes the result of `vformat(fmt, args)` to `stream`.
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+
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+ *Throws:* Any exception thrown by the call to `vformat`
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+ [[format.err.report]]. `system_error` if writing to `stream` fails. May
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+ throw `bad_alloc`.
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+