From Jason Turner

[text.encoding.members]

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+ #### Members <a id="text.encoding.members">[[text.encoding.members]]</a>
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+
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+ ``` cpp
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+ constexpr explicit text_encoding(string_view enc) noexcept;
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+ ```
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+
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+ *Preconditions:*
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+
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+ - `enc` represents a string in the ordinary literal encoding consisting
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+ only of elements of the basic character set [[lex.charset]].
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+ - `enc.size() <= max_name_length` is `true`.
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+ - `enc.contains(’\0’)` is `false`.
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+
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+ *Ensures:*
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+
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+ - If there exists a primary name or alias `a` of a known registered
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+ character encoding such that *`comp-name`*`(a, enc)` is `true`,
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+ *mib\_* has the value of the enumerator of `id` associated with that
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+ registered character encoding. Otherwise, *`mib_`*` == id::other` is
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+ `true`.
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+ - `enc.compare(`*`name_`*`) == 0` is `true`.
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+
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+ ``` cpp
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+ constexpr text_encoding(id i) noexcept;
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+ ```
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+
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+ *Preconditions:* `i` has the value of one of the enumerators of `id`.
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+
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+ *Ensures:*
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+
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+ - *`mib_`*` == i` is `true`.
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+ - If `(`*`mib_`*` == id::unknown || `*`mib_`*` == id::other)` is `true`,
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+ `strlen(`*`name_`*`) == 0` is `true`. Otherwise,
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+ `ranges::contains(aliases(), string_view(`*`name_`*`))` is `true`.
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+
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+ ``` cpp
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+ constexpr id mib() const noexcept;
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+ ```
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+
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+ *Returns:* *mib\_*.
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+
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+ ``` cpp
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+ constexpr const char* name() const noexcept;
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+ ```
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+
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+ *Returns:* *name\_*.
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+
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+ *Remarks:* `name()` is an NTBS and accessing elements of *name\_*
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+ outside of the range `name()`+\[0, `strlen(name()) + 1`) is undefined
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+ behavior.
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+
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+ ``` cpp
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+ constexpr aliases_view aliases() const noexcept;
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+ ```
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+
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+ Let `r` denote an instance of `aliases_view`. If `*this` represents a
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+ known registered character encoding, then:
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+
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+ - `r.front()` is the primary name of the registered character encoding,
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+ - `r` contains the aliases of the registered character encoding, and
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+ - `r` does not contain duplicate values when compared with `strcmp`.
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+
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+ Otherwise, `r` is an empty range.
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+
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+ Each element in `r` is a non-null, non-empty NTBS encoded in the literal
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+ character encoding and comprising only characters from the basic
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+ character set.
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+
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+ *Returns:* `r`.
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+
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+ [*Note 1*: The order of aliases in `r` is unspecified. — *end note*]
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+
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+ ``` cpp
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+ static consteval text_encoding literal() noexcept;
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+ ```
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+
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+ *Mandates:* `CHAR_BIT == 8` is `true`.
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+
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+ *Returns:* A `text_encoding` object representing the ordinary character
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+ literal encoding [[lex.charset]].
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+
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+ ``` cpp
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+ static text_encoding environment();
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+ ```
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+
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+ *Mandates:* `CHAR_BIT == 8` is `true`.
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+
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+ *Returns:* A `text_encoding` object representing the
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+ *implementation-defined* character encoding scheme of the environment.
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+ On a POSIX implementation, this is the encoding scheme associated with
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+ the POSIX locale denoted by the empty string `""`.
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+
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+ [*Note 2*: This function is not affected by calls to
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+ `setlocale`. — *end note*]
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+
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+ *Recommended practice:* Implementations should return a value that is
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+ not affected by calls to the POSIX function `setenv` and other functions
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+ which can modify the environment [[support.runtime]].
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+
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+ ``` cpp
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+ template<id i>
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+ static bool environment_is();
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+ ```
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+
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+ *Mandates:* `CHAR_BIT == 8` is `true`.
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+
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+ *Returns:* `environment() == i`.
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+
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+ ``` cpp
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+ static constexpr bool comp-name(string_view a, string_view b);
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+ ```
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+
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+ *Returns:* `true` if the two strings `a` and `b` encoded in the ordinary
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+ literal encoding are equal, ignoring, from left-to-right,
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+
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+ - all elements that are not digits or letters [[character.seq.general]],
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+ - character case, and
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+ - any sequence of one or more `0` characters not immediately preceded by
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+ a numeric prefix, where a numeric prefix is a sequence consisting of a
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+ digit in the range \[`1`, `9`\] optionally followed by one or more
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+ elements which are not digits or letters,
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+
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+ and `false` otherwise.
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+
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+ [*Note 3*: This comparison is identical to the “Charset Alias Matching”
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+ algorithm described in the Unicode Technical Standard 22. — *end note*]
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+
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+ [*Example 1*:
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+
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+ ``` cpp
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+ static_assert(comp-name("UTF-8", "utf8") == true);
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+ static_assert(comp-name("u.t.f-008", "utf8") == true);
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+ static_assert(comp-name("ut8", "utf8") == false);
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+ static_assert(comp-name("utf-80", "utf8") == false);
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+ ```
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+
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+ — *end example*]
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+