mirror of https://github.com/rust-lang/rust
1836 lines
60 KiB
Rust
1836 lines
60 KiB
Rust
//! impl char {}
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use crate::slice;
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use crate::str::from_utf8_unchecked_mut;
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use crate::unicode::printable::is_printable;
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use crate::unicode::{self, conversions};
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use super::*;
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impl char {
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/// The lowest valid code point a `char` can have, `'\0'`.
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///
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/// Unlike integer types, `char` actually has a gap in the middle,
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/// meaning that the range of possible `char`s is smaller than you
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/// might expect. Ranges of `char` will automatically hop this gap
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/// for you:
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///
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/// ```
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/// #![feature(char_min)]
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/// let dist = u32::from(char::MAX) - u32::from(char::MIN);
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/// let size = (char::MIN..=char::MAX).count() as u32;
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/// assert!(size < dist);
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/// ```
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///
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/// Despite this gap, the `MIN` and [`MAX`] values can be used as bounds for
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/// all `char` values.
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///
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/// [`MAX`]: char::MAX
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///
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/// # Examples
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///
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/// ```
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/// #![feature(char_min)]
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/// # fn something_which_returns_char() -> char { 'a' }
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/// let c: char = something_which_returns_char();
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/// assert!(char::MIN <= c);
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///
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/// let value_at_min = u32::from(char::MIN);
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/// assert_eq!(char::from_u32(value_at_min), Some('\0'));
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/// ```
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#[unstable(feature = "char_min", issue = "114298")]
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pub const MIN: char = '\0';
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/// The highest valid code point a `char` can have, `'\u{10FFFF}'`.
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///
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/// Unlike integer types, `char` actually has a gap in the middle,
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/// meaning that the range of possible `char`s is smaller than you
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/// might expect. Ranges of `char` will automatically hop this gap
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/// for you:
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///
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/// ```
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/// #![feature(char_min)]
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/// let dist = u32::from(char::MAX) - u32::from(char::MIN);
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/// let size = (char::MIN..=char::MAX).count() as u32;
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/// assert!(size < dist);
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/// ```
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///
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/// Despite this gap, the [`MIN`] and `MAX` values can be used as bounds for
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/// all `char` values.
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///
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/// [`MIN`]: char::MIN
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///
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/// # Examples
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///
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/// ```
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/// # fn something_which_returns_char() -> char { 'a' }
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/// let c: char = something_which_returns_char();
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/// assert!(c <= char::MAX);
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///
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/// let value_at_max = u32::from(char::MAX);
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/// assert_eq!(char::from_u32(value_at_max), Some('\u{10FFFF}'));
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/// assert_eq!(char::from_u32(value_at_max + 1), None);
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/// ```
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#[stable(feature = "assoc_char_consts", since = "1.52.0")]
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pub const MAX: char = '\u{10ffff}';
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/// `U+FFFD REPLACEMENT CHARACTER` (<28>) is used in Unicode to represent a
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/// decoding error.
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///
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/// It can occur, for example, when giving ill-formed UTF-8 bytes to
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/// [`String::from_utf8_lossy`](../std/string/struct.String.html#method.from_utf8_lossy).
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#[stable(feature = "assoc_char_consts", since = "1.52.0")]
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pub const REPLACEMENT_CHARACTER: char = '\u{FFFD}';
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/// The version of [Unicode](https://www.unicode.org/) that the Unicode parts of
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/// `char` and `str` methods are based on.
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///
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/// New versions of Unicode are released regularly and subsequently all methods
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/// in the standard library depending on Unicode are updated. Therefore the
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/// behavior of some `char` and `str` methods and the value of this constant
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/// changes over time. This is *not* considered to be a breaking change.
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///
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/// The version numbering scheme is explained in
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/// [Unicode 11.0 or later, Section 3.1 Versions of the Unicode Standard](https://www.unicode.org/versions/Unicode11.0.0/ch03.pdf#page=4).
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#[stable(feature = "assoc_char_consts", since = "1.52.0")]
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pub const UNICODE_VERSION: (u8, u8, u8) = crate::unicode::UNICODE_VERSION;
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/// Creates an iterator over the UTF-16 encoded code points in `iter`,
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/// returning unpaired surrogates as `Err`s.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// // 𝄞mus<invalid>ic<invalid>
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/// let v = [
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/// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
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/// ];
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///
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/// assert_eq!(
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/// char::decode_utf16(v)
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/// .map(|r| r.map_err(|e| e.unpaired_surrogate()))
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/// .collect::<Vec<_>>(),
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/// vec![
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/// Ok('𝄞'),
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/// Ok('m'), Ok('u'), Ok('s'),
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/// Err(0xDD1E),
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/// Ok('i'), Ok('c'),
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/// Err(0xD834)
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/// ]
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/// );
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/// ```
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///
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/// A lossy decoder can be obtained by replacing `Err` results with the replacement character:
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///
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/// ```
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/// // 𝄞mus<invalid>ic<invalid>
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/// let v = [
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/// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
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/// ];
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///
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/// assert_eq!(
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/// char::decode_utf16(v)
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/// .map(|r| r.unwrap_or(char::REPLACEMENT_CHARACTER))
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/// .collect::<String>(),
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/// "𝄞mus<75>ic<69>"
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/// );
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/// ```
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#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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#[inline]
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pub fn decode_utf16<I: IntoIterator<Item = u16>>(iter: I) -> DecodeUtf16<I::IntoIter> {
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super::decode::decode_utf16(iter)
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}
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/// Converts a `u32` to a `char`.
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///
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/// Note that all `char`s are valid [`u32`]s, and can be cast to one with
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/// [`as`](../std/keyword.as.html):
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///
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/// ```
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/// let c = '💯';
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/// let i = c as u32;
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///
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/// assert_eq!(128175, i);
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/// ```
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///
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/// However, the reverse is not true: not all valid [`u32`]s are valid
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/// `char`s. `from_u32()` will return `None` if the input is not a valid value
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/// for a `char`.
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///
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/// For an unsafe version of this function which ignores these checks, see
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/// [`from_u32_unchecked`].
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///
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/// [`from_u32_unchecked`]: #method.from_u32_unchecked
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// let c = char::from_u32(0x2764);
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///
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/// assert_eq!(Some('❤'), c);
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/// ```
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///
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/// Returning `None` when the input is not a valid `char`:
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///
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/// ```
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/// let c = char::from_u32(0x110000);
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///
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/// assert_eq!(None, c);
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/// ```
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#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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#[rustc_const_stable(feature = "const_char_convert", since = "1.67.0")]
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#[must_use]
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#[inline]
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pub const fn from_u32(i: u32) -> Option<char> {
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super::convert::from_u32(i)
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}
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/// Converts a `u32` to a `char`, ignoring validity.
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///
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/// Note that all `char`s are valid [`u32`]s, and can be cast to one with
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/// `as`:
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///
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/// ```
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/// let c = '💯';
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/// let i = c as u32;
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///
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/// assert_eq!(128175, i);
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/// ```
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///
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/// However, the reverse is not true: not all valid [`u32`]s are valid
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/// `char`s. `from_u32_unchecked()` will ignore this, and blindly cast to
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/// `char`, possibly creating an invalid one.
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///
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/// # Safety
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///
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/// This function is unsafe, as it may construct invalid `char` values.
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///
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/// For a safe version of this function, see the [`from_u32`] function.
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///
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/// [`from_u32`]: #method.from_u32
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// let c = unsafe { char::from_u32_unchecked(0x2764) };
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///
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/// assert_eq!('❤', c);
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/// ```
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#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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#[rustc_const_unstable(feature = "const_char_from_u32_unchecked", issue = "89259")]
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#[must_use]
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#[inline]
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pub const unsafe fn from_u32_unchecked(i: u32) -> char {
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// SAFETY: the safety contract must be upheld by the caller.
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unsafe { super::convert::from_u32_unchecked(i) }
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}
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/// Converts a digit in the given radix to a `char`.
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///
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/// A 'radix' here is sometimes also called a 'base'. A radix of two
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/// indicates a binary number, a radix of ten, decimal, and a radix of
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/// sixteen, hexadecimal, to give some common values. Arbitrary
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/// radices are supported.
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///
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/// `from_digit()` will return `None` if the input is not a digit in
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/// the given radix.
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///
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/// # Panics
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///
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/// Panics if given a radix larger than 36.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// let c = char::from_digit(4, 10);
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///
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/// assert_eq!(Some('4'), c);
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///
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/// // Decimal 11 is a single digit in base 16
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/// let c = char::from_digit(11, 16);
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///
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/// assert_eq!(Some('b'), c);
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/// ```
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///
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/// Returning `None` when the input is not a digit:
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///
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/// ```
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/// let c = char::from_digit(20, 10);
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///
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/// assert_eq!(None, c);
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/// ```
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///
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/// Passing a large radix, causing a panic:
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///
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/// ```should_panic
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/// // this panics
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/// let _c = char::from_digit(1, 37);
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/// ```
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#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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#[rustc_const_stable(feature = "const_char_convert", since = "1.67.0")]
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#[must_use]
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#[inline]
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pub const fn from_digit(num: u32, radix: u32) -> Option<char> {
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super::convert::from_digit(num, radix)
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}
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/// Checks if a `char` is a digit in the given radix.
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///
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/// A 'radix' here is sometimes also called a 'base'. A radix of two
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/// indicates a binary number, a radix of ten, decimal, and a radix of
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/// sixteen, hexadecimal, to give some common values. Arbitrary
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/// radices are supported.
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///
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/// Compared to [`is_numeric()`], this function only recognizes the characters
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/// `0-9`, `a-z` and `A-Z`.
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///
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/// 'Digit' is defined to be only the following characters:
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///
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/// * `0-9`
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/// * `a-z`
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/// * `A-Z`
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///
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/// For a more comprehensive understanding of 'digit', see [`is_numeric()`].
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///
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/// [`is_numeric()`]: #method.is_numeric
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///
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/// # Panics
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///
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/// Panics if given a radix larger than 36.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// assert!('1'.is_digit(10));
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/// assert!('f'.is_digit(16));
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/// assert!(!'f'.is_digit(10));
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/// ```
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///
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/// Passing a large radix, causing a panic:
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///
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/// ```should_panic
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/// // this panics
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/// '1'.is_digit(37);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[inline]
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pub fn is_digit(self, radix: u32) -> bool {
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self.to_digit(radix).is_some()
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}
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/// Converts a `char` to a digit in the given radix.
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///
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/// A 'radix' here is sometimes also called a 'base'. A radix of two
|
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/// indicates a binary number, a radix of ten, decimal, and a radix of
|
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/// sixteen, hexadecimal, to give some common values. Arbitrary
|
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/// radices are supported.
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///
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/// 'Digit' is defined to be only the following characters:
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///
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/// * `0-9`
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/// * `a-z`
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/// * `A-Z`
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///
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/// # Errors
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///
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/// Returns `None` if the `char` does not refer to a digit in the given radix.
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///
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/// # Panics
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///
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/// Panics if given a radix larger than 36.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// assert_eq!('1'.to_digit(10), Some(1));
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/// assert_eq!('f'.to_digit(16), Some(15));
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/// ```
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///
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/// Passing a non-digit results in failure:
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///
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/// ```
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/// assert_eq!('f'.to_digit(10), None);
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/// assert_eq!('z'.to_digit(16), None);
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/// ```
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///
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/// Passing a large radix, causing a panic:
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///
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/// ```should_panic
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/// // this panics
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/// let _ = '1'.to_digit(37);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[rustc_const_stable(feature = "const_char_convert", since = "1.67.0")]
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#[must_use = "this returns the result of the operation, \
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without modifying the original"]
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#[inline]
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pub const fn to_digit(self, radix: u32) -> Option<u32> {
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// If not a digit, a number greater than radix will be created.
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let mut digit = (self as u32).wrapping_sub('0' as u32);
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if radix > 10 {
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assert!(radix <= 36, "to_digit: radix is too high (maximum 36)");
|
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if digit < 10 {
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return Some(digit);
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}
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// Force the 6th bit to be set to ensure ascii is lower case.
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digit = (self as u32 | 0b10_0000).wrapping_sub('a' as u32).saturating_add(10);
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}
|
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// FIXME: once then_some is const fn, use it here
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if digit < radix { Some(digit) } else { None }
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}
|
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|
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/// Returns an iterator that yields the hexadecimal Unicode escape of a
|
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/// character as `char`s.
|
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///
|
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/// This will escape characters with the Rust syntax of the form
|
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/// `\u{NNNNNN}` where `NNNNNN` is a hexadecimal representation.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
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/// ```
|
||
/// for c in '❤'.escape_unicode() {
|
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/// print!("{c}");
|
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/// }
|
||
/// println!();
|
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/// ```
|
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///
|
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/// Using `println!` directly:
|
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///
|
||
/// ```
|
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/// println!("{}", '❤'.escape_unicode());
|
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/// ```
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("\\u{{2764}}");
|
||
/// ```
|
||
///
|
||
/// Using [`to_string`](../std/string/trait.ToString.html#tymethod.to_string):
|
||
///
|
||
/// ```
|
||
/// assert_eq!('❤'.escape_unicode().to_string(), "\\u{2764}");
|
||
/// ```
|
||
#[must_use = "this returns the escaped char as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn escape_unicode(self) -> EscapeUnicode {
|
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EscapeUnicode::new(self)
|
||
}
|
||
|
||
/// An extended version of `escape_debug` that optionally permits escaping
|
||
/// Extended Grapheme codepoints, single quotes, and double quotes. This
|
||
/// allows us to format characters like nonspacing marks better when they're
|
||
/// at the start of a string, and allows escaping single quotes in
|
||
/// characters, and double quotes in strings.
|
||
#[inline]
|
||
pub(crate) fn escape_debug_ext(self, args: EscapeDebugExtArgs) -> EscapeDebug {
|
||
match self {
|
||
'\0' => EscapeDebug::backslash(ascii::Char::Digit0),
|
||
'\t' => EscapeDebug::backslash(ascii::Char::SmallT),
|
||
'\r' => EscapeDebug::backslash(ascii::Char::SmallR),
|
||
'\n' => EscapeDebug::backslash(ascii::Char::SmallN),
|
||
'\\' => EscapeDebug::backslash(ascii::Char::ReverseSolidus),
|
||
'\"' if args.escape_double_quote => EscapeDebug::backslash(ascii::Char::QuotationMark),
|
||
'\'' if args.escape_single_quote => EscapeDebug::backslash(ascii::Char::Apostrophe),
|
||
_ if args.escape_grapheme_extended && self.is_grapheme_extended() => {
|
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EscapeDebug::unicode(self)
|
||
}
|
||
_ if is_printable(self) => EscapeDebug::printable(self),
|
||
_ => EscapeDebug::unicode(self),
|
||
}
|
||
}
|
||
|
||
/// Returns an iterator that yields the literal escape code of a character
|
||
/// as `char`s.
|
||
///
|
||
/// This will escape the characters similar to the [`Debug`](core::fmt::Debug) implementations
|
||
/// of `str` or `char`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
||
/// ```
|
||
/// for c in '\n'.escape_debug() {
|
||
/// print!("{c}");
|
||
/// }
|
||
/// println!();
|
||
/// ```
|
||
///
|
||
/// Using `println!` directly:
|
||
///
|
||
/// ```
|
||
/// println!("{}", '\n'.escape_debug());
|
||
/// ```
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("\\n");
|
||
/// ```
|
||
///
|
||
/// Using [`to_string`](../std/string/trait.ToString.html#tymethod.to_string):
|
||
///
|
||
/// ```
|
||
/// assert_eq!('\n'.escape_debug().to_string(), "\\n");
|
||
/// ```
|
||
#[must_use = "this returns the escaped char as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "char_escape_debug", since = "1.20.0")]
|
||
#[inline]
|
||
pub fn escape_debug(self) -> EscapeDebug {
|
||
self.escape_debug_ext(EscapeDebugExtArgs::ESCAPE_ALL)
|
||
}
|
||
|
||
/// Returns an iterator that yields the literal escape code of a character
|
||
/// as `char`s.
|
||
///
|
||
/// The default is chosen with a bias toward producing literals that are
|
||
/// legal in a variety of languages, including C++11 and similar C-family
|
||
/// languages. The exact rules are:
|
||
///
|
||
/// * Tab is escaped as `\t`.
|
||
/// * Carriage return is escaped as `\r`.
|
||
/// * Line feed is escaped as `\n`.
|
||
/// * Single quote is escaped as `\'`.
|
||
/// * Double quote is escaped as `\"`.
|
||
/// * Backslash is escaped as `\\`.
|
||
/// * Any character in the 'printable ASCII' range `0x20` .. `0x7e`
|
||
/// inclusive is not escaped.
|
||
/// * All other characters are given hexadecimal Unicode escapes; see
|
||
/// [`escape_unicode`].
|
||
///
|
||
/// [`escape_unicode`]: #method.escape_unicode
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
||
/// ```
|
||
/// for c in '"'.escape_default() {
|
||
/// print!("{c}");
|
||
/// }
|
||
/// println!();
|
||
/// ```
|
||
///
|
||
/// Using `println!` directly:
|
||
///
|
||
/// ```
|
||
/// println!("{}", '"'.escape_default());
|
||
/// ```
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("\\\"");
|
||
/// ```
|
||
///
|
||
/// Using [`to_string`](../std/string/trait.ToString.html#tymethod.to_string):
|
||
///
|
||
/// ```
|
||
/// assert_eq!('"'.escape_default().to_string(), "\\\"");
|
||
/// ```
|
||
#[must_use = "this returns the escaped char as an iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn escape_default(self) -> EscapeDefault {
|
||
match self {
|
||
'\t' => EscapeDefault::backslash(ascii::Char::SmallT),
|
||
'\r' => EscapeDefault::backslash(ascii::Char::SmallR),
|
||
'\n' => EscapeDefault::backslash(ascii::Char::SmallN),
|
||
'\\' | '\'' | '\"' => EscapeDefault::backslash(self.as_ascii().unwrap()),
|
||
'\x20'..='\x7e' => EscapeDefault::printable(self.as_ascii().unwrap()),
|
||
_ => EscapeDefault::unicode(self),
|
||
}
|
||
}
|
||
|
||
/// Returns the number of bytes this `char` would need if encoded in UTF-8.
|
||
///
|
||
/// That number of bytes is always between 1 and 4, inclusive.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let len = 'A'.len_utf8();
|
||
/// assert_eq!(len, 1);
|
||
///
|
||
/// let len = 'ß'.len_utf8();
|
||
/// assert_eq!(len, 2);
|
||
///
|
||
/// let len = 'ℝ'.len_utf8();
|
||
/// assert_eq!(len, 3);
|
||
///
|
||
/// let len = '💣'.len_utf8();
|
||
/// assert_eq!(len, 4);
|
||
/// ```
|
||
///
|
||
/// The `&str` type guarantees that its contents are UTF-8, and so we can compare the length it
|
||
/// would take if each code point was represented as a `char` vs in the `&str` itself:
|
||
///
|
||
/// ```
|
||
/// // as chars
|
||
/// let eastern = '東';
|
||
/// let capital = '京';
|
||
///
|
||
/// // both can be represented as three bytes
|
||
/// assert_eq!(3, eastern.len_utf8());
|
||
/// assert_eq!(3, capital.len_utf8());
|
||
///
|
||
/// // as a &str, these two are encoded in UTF-8
|
||
/// let tokyo = "東京";
|
||
///
|
||
/// let len = eastern.len_utf8() + capital.len_utf8();
|
||
///
|
||
/// // we can see that they take six bytes total...
|
||
/// assert_eq!(6, tokyo.len());
|
||
///
|
||
/// // ... just like the &str
|
||
/// assert_eq!(len, tokyo.len());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_const_stable(feature = "const_char_len_utf", since = "1.52.0")]
|
||
#[inline]
|
||
pub const fn len_utf8(self) -> usize {
|
||
len_utf8(self as u32)
|
||
}
|
||
|
||
/// Returns the number of 16-bit code units this `char` would need if
|
||
/// encoded in UTF-16.
|
||
///
|
||
/// That number of code units is always either 1 or 2, for unicode scalar values in
|
||
/// the [basic multilingual plane] or [supplementary planes] respectively.
|
||
///
|
||
/// See the documentation for [`len_utf8()`] for more explanation of this
|
||
/// concept. This function is a mirror, but for UTF-16 instead of UTF-8.
|
||
///
|
||
/// [basic multilingual plane]: http://www.unicode.org/glossary/#basic_multilingual_plane
|
||
/// [supplementary planes]: http://www.unicode.org/glossary/#supplementary_planes
|
||
/// [`len_utf8()`]: #method.len_utf8
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let n = 'ß'.len_utf16();
|
||
/// assert_eq!(n, 1);
|
||
///
|
||
/// let len = '💣'.len_utf16();
|
||
/// assert_eq!(len, 2);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_const_stable(feature = "const_char_len_utf", since = "1.52.0")]
|
||
#[inline]
|
||
pub const fn len_utf16(self) -> usize {
|
||
let ch = self as u32;
|
||
if (ch & 0xFFFF) == ch { 1 } else { 2 }
|
||
}
|
||
|
||
/// Encodes this character as UTF-8 into the provided byte buffer,
|
||
/// and then returns the subslice of the buffer that contains the encoded character.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the buffer is not large enough.
|
||
/// A buffer of length four is large enough to encode any `char`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// In both of these examples, 'ß' takes two bytes to encode.
|
||
///
|
||
/// ```
|
||
/// let mut b = [0; 2];
|
||
///
|
||
/// let result = 'ß'.encode_utf8(&mut b);
|
||
///
|
||
/// assert_eq!(result, "ß");
|
||
///
|
||
/// assert_eq!(result.len(), 2);
|
||
/// ```
|
||
///
|
||
/// A buffer that's too small:
|
||
///
|
||
/// ```should_panic
|
||
/// let mut b = [0; 1];
|
||
///
|
||
/// // this panics
|
||
/// 'ß'.encode_utf8(&mut b);
|
||
/// ```
|
||
#[stable(feature = "unicode_encode_char", since = "1.15.0")]
|
||
#[inline]
|
||
pub fn encode_utf8(self, dst: &mut [u8]) -> &mut str {
|
||
// SAFETY: `char` is not a surrogate, so this is valid UTF-8.
|
||
unsafe { from_utf8_unchecked_mut(encode_utf8_raw(self as u32, dst)) }
|
||
}
|
||
|
||
/// Encodes this character as UTF-16 into the provided `u16` buffer,
|
||
/// and then returns the subslice of the buffer that contains the encoded character.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the buffer is not large enough.
|
||
/// A buffer of length 2 is large enough to encode any `char`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// In both of these examples, '𝕊' takes two `u16`s to encode.
|
||
///
|
||
/// ```
|
||
/// let mut b = [0; 2];
|
||
///
|
||
/// let result = '𝕊'.encode_utf16(&mut b);
|
||
///
|
||
/// assert_eq!(result.len(), 2);
|
||
/// ```
|
||
///
|
||
/// A buffer that's too small:
|
||
///
|
||
/// ```should_panic
|
||
/// let mut b = [0; 1];
|
||
///
|
||
/// // this panics
|
||
/// '𝕊'.encode_utf16(&mut b);
|
||
/// ```
|
||
#[stable(feature = "unicode_encode_char", since = "1.15.0")]
|
||
#[inline]
|
||
pub fn encode_utf16(self, dst: &mut [u16]) -> &mut [u16] {
|
||
encode_utf16_raw(self as u32, dst)
|
||
}
|
||
|
||
/// Returns `true` if this `char` has the `Alphabetic` property.
|
||
///
|
||
/// `Alphabetic` is described in Chapter 4 (Character Properties) of the [Unicode Standard] and
|
||
/// specified in the [Unicode Character Database][ucd] [`DerivedCoreProperties.txt`].
|
||
///
|
||
/// [Unicode Standard]: https://www.unicode.org/versions/latest/
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// assert!('a'.is_alphabetic());
|
||
/// assert!('京'.is_alphabetic());
|
||
///
|
||
/// let c = '💝';
|
||
/// // love is many things, but it is not alphabetic
|
||
/// assert!(!c.is_alphabetic());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_alphabetic(self) -> bool {
|
||
match self {
|
||
'a'..='z' | 'A'..='Z' => true,
|
||
c => c > '\x7f' && unicode::Alphabetic(c),
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if this `char` has the `Lowercase` property.
|
||
///
|
||
/// `Lowercase` is described in Chapter 4 (Character Properties) of the [Unicode Standard] and
|
||
/// specified in the [Unicode Character Database][ucd] [`DerivedCoreProperties.txt`].
|
||
///
|
||
/// [Unicode Standard]: https://www.unicode.org/versions/latest/
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// assert!('a'.is_lowercase());
|
||
/// assert!('δ'.is_lowercase());
|
||
/// assert!(!'A'.is_lowercase());
|
||
/// assert!(!'Δ'.is_lowercase());
|
||
///
|
||
/// // The various Chinese scripts and punctuation do not have case, and so:
|
||
/// assert!(!'中'.is_lowercase());
|
||
/// assert!(!' '.is_lowercase());
|
||
/// ```
|
||
///
|
||
/// In a const context:
|
||
///
|
||
/// ```
|
||
/// #![feature(const_unicode_case_lookup)]
|
||
/// const CAPITAL_DELTA_IS_LOWERCASE: bool = 'Δ'.is_lowercase();
|
||
/// assert!(!CAPITAL_DELTA_IS_LOWERCASE);
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
|
||
#[inline]
|
||
pub const fn is_lowercase(self) -> bool {
|
||
match self {
|
||
'a'..='z' => true,
|
||
c => c > '\x7f' && unicode::Lowercase(c),
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if this `char` has the `Uppercase` property.
|
||
///
|
||
/// `Uppercase` is described in Chapter 4 (Character Properties) of the [Unicode Standard] and
|
||
/// specified in the [Unicode Character Database][ucd] [`DerivedCoreProperties.txt`].
|
||
///
|
||
/// [Unicode Standard]: https://www.unicode.org/versions/latest/
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// assert!(!'a'.is_uppercase());
|
||
/// assert!(!'δ'.is_uppercase());
|
||
/// assert!('A'.is_uppercase());
|
||
/// assert!('Δ'.is_uppercase());
|
||
///
|
||
/// // The various Chinese scripts and punctuation do not have case, and so:
|
||
/// assert!(!'中'.is_uppercase());
|
||
/// assert!(!' '.is_uppercase());
|
||
/// ```
|
||
///
|
||
/// In a const context:
|
||
///
|
||
/// ```
|
||
/// #![feature(const_unicode_case_lookup)]
|
||
/// const CAPITAL_DELTA_IS_UPPERCASE: bool = 'Δ'.is_uppercase();
|
||
/// assert!(CAPITAL_DELTA_IS_UPPERCASE);
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[rustc_const_unstable(feature = "const_unicode_case_lookup", issue = "101400")]
|
||
#[inline]
|
||
pub const fn is_uppercase(self) -> bool {
|
||
match self {
|
||
'A'..='Z' => true,
|
||
c => c > '\x7f' && unicode::Uppercase(c),
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if this `char` has the `White_Space` property.
|
||
///
|
||
/// `White_Space` is specified in the [Unicode Character Database][ucd] [`PropList.txt`].
|
||
///
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`PropList.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/PropList.txt
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// assert!(' '.is_whitespace());
|
||
///
|
||
/// // line break
|
||
/// assert!('\n'.is_whitespace());
|
||
///
|
||
/// // a non-breaking space
|
||
/// assert!('\u{A0}'.is_whitespace());
|
||
///
|
||
/// assert!(!'越'.is_whitespace());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_whitespace(self) -> bool {
|
||
match self {
|
||
' ' | '\x09'..='\x0d' => true,
|
||
c => c > '\x7f' && unicode::White_Space(c),
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if this `char` satisfies either [`is_alphabetic()`] or [`is_numeric()`].
|
||
///
|
||
/// [`is_alphabetic()`]: #method.is_alphabetic
|
||
/// [`is_numeric()`]: #method.is_numeric
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// assert!('٣'.is_alphanumeric());
|
||
/// assert!('7'.is_alphanumeric());
|
||
/// assert!('৬'.is_alphanumeric());
|
||
/// assert!('¾'.is_alphanumeric());
|
||
/// assert!('①'.is_alphanumeric());
|
||
/// assert!('K'.is_alphanumeric());
|
||
/// assert!('و'.is_alphanumeric());
|
||
/// assert!('藏'.is_alphanumeric());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_alphanumeric(self) -> bool {
|
||
self.is_alphabetic() || self.is_numeric()
|
||
}
|
||
|
||
/// Returns `true` if this `char` has the general category for control codes.
|
||
///
|
||
/// Control codes (code points with the general category of `Cc`) are described in Chapter 4
|
||
/// (Character Properties) of the [Unicode Standard] and specified in the [Unicode Character
|
||
/// Database][ucd] [`UnicodeData.txt`].
|
||
///
|
||
/// [Unicode Standard]: https://www.unicode.org/versions/latest/
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // U+009C, STRING TERMINATOR
|
||
/// assert!(''.is_control());
|
||
/// assert!(!'q'.is_control());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_control(self) -> bool {
|
||
unicode::Cc(self)
|
||
}
|
||
|
||
/// Returns `true` if this `char` has the `Grapheme_Extend` property.
|
||
///
|
||
/// `Grapheme_Extend` is described in [Unicode Standard Annex #29 (Unicode Text
|
||
/// Segmentation)][uax29] and specified in the [Unicode Character Database][ucd]
|
||
/// [`DerivedCoreProperties.txt`].
|
||
///
|
||
/// [uax29]: https://www.unicode.org/reports/tr29/
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
|
||
#[must_use]
|
||
#[inline]
|
||
pub(crate) fn is_grapheme_extended(self) -> bool {
|
||
unicode::Grapheme_Extend(self)
|
||
}
|
||
|
||
/// Returns `true` if this `char` has one of the general categories for numbers.
|
||
///
|
||
/// The general categories for numbers (`Nd` for decimal digits, `Nl` for letter-like numeric
|
||
/// characters, and `No` for other numeric characters) are specified in the [Unicode Character
|
||
/// Database][ucd] [`UnicodeData.txt`].
|
||
///
|
||
/// This method doesn't cover everything that could be considered a number, e.g. ideographic numbers like '三'.
|
||
/// If you want everything including characters with overlapping purposes then you might want to use
|
||
/// a unicode or language-processing library that exposes the appropriate character properties instead
|
||
/// of looking at the unicode categories.
|
||
///
|
||
/// If you want to parse ASCII decimal digits (0-9) or ASCII base-N, use
|
||
/// `is_ascii_digit` or `is_digit` instead.
|
||
///
|
||
/// [Unicode Standard]: https://www.unicode.org/versions/latest/
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// assert!('٣'.is_numeric());
|
||
/// assert!('7'.is_numeric());
|
||
/// assert!('৬'.is_numeric());
|
||
/// assert!('¾'.is_numeric());
|
||
/// assert!('①'.is_numeric());
|
||
/// assert!(!'K'.is_numeric());
|
||
/// assert!(!'و'.is_numeric());
|
||
/// assert!(!'藏'.is_numeric());
|
||
/// assert!(!'三'.is_numeric());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_numeric(self) -> bool {
|
||
match self {
|
||
'0'..='9' => true,
|
||
c => c > '\x7f' && unicode::N(c),
|
||
}
|
||
}
|
||
|
||
/// Returns an iterator that yields the lowercase mapping of this `char` as one or more
|
||
/// `char`s.
|
||
///
|
||
/// If this `char` does not have a lowercase mapping, the iterator yields the same `char`.
|
||
///
|
||
/// If this `char` has a one-to-one lowercase mapping given by the [Unicode Character
|
||
/// Database][ucd] [`UnicodeData.txt`], the iterator yields that `char`.
|
||
///
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
|
||
///
|
||
/// If this `char` requires special considerations (e.g. multiple `char`s) the iterator yields
|
||
/// the `char`(s) given by [`SpecialCasing.txt`].
|
||
///
|
||
/// [`SpecialCasing.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/SpecialCasing.txt
|
||
///
|
||
/// This operation performs an unconditional mapping without tailoring. That is, the conversion
|
||
/// is independent of context and language.
|
||
///
|
||
/// In the [Unicode Standard], Chapter 4 (Character Properties) discusses case mapping in
|
||
/// general and Chapter 3 (Conformance) discusses the default algorithm for case conversion.
|
||
///
|
||
/// [Unicode Standard]: https://www.unicode.org/versions/latest/
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
||
/// ```
|
||
/// for c in 'İ'.to_lowercase() {
|
||
/// print!("{c}");
|
||
/// }
|
||
/// println!();
|
||
/// ```
|
||
///
|
||
/// Using `println!` directly:
|
||
///
|
||
/// ```
|
||
/// println!("{}", 'İ'.to_lowercase());
|
||
/// ```
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("i\u{307}");
|
||
/// ```
|
||
///
|
||
/// Using [`to_string`](../std/string/trait.ToString.html#tymethod.to_string):
|
||
///
|
||
/// ```
|
||
/// assert_eq!('C'.to_lowercase().to_string(), "c");
|
||
///
|
||
/// // Sometimes the result is more than one character:
|
||
/// assert_eq!('İ'.to_lowercase().to_string(), "i\u{307}");
|
||
///
|
||
/// // Characters that do not have both uppercase and lowercase
|
||
/// // convert into themselves.
|
||
/// assert_eq!('山'.to_lowercase().to_string(), "山");
|
||
/// ```
|
||
#[must_use = "this returns the lowercase character as a new iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn to_lowercase(self) -> ToLowercase {
|
||
ToLowercase(CaseMappingIter::new(conversions::to_lower(self)))
|
||
}
|
||
|
||
/// Returns an iterator that yields the uppercase mapping of this `char` as one or more
|
||
/// `char`s.
|
||
///
|
||
/// If this `char` does not have an uppercase mapping, the iterator yields the same `char`.
|
||
///
|
||
/// If this `char` has a one-to-one uppercase mapping given by the [Unicode Character
|
||
/// Database][ucd] [`UnicodeData.txt`], the iterator yields that `char`.
|
||
///
|
||
/// [ucd]: https://www.unicode.org/reports/tr44/
|
||
/// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
|
||
///
|
||
/// If this `char` requires special considerations (e.g. multiple `char`s) the iterator yields
|
||
/// the `char`(s) given by [`SpecialCasing.txt`].
|
||
///
|
||
/// [`SpecialCasing.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/SpecialCasing.txt
|
||
///
|
||
/// This operation performs an unconditional mapping without tailoring. That is, the conversion
|
||
/// is independent of context and language.
|
||
///
|
||
/// In the [Unicode Standard], Chapter 4 (Character Properties) discusses case mapping in
|
||
/// general and Chapter 3 (Conformance) discusses the default algorithm for case conversion.
|
||
///
|
||
/// [Unicode Standard]: https://www.unicode.org/versions/latest/
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// As an iterator:
|
||
///
|
||
/// ```
|
||
/// for c in 'ß'.to_uppercase() {
|
||
/// print!("{c}");
|
||
/// }
|
||
/// println!();
|
||
/// ```
|
||
///
|
||
/// Using `println!` directly:
|
||
///
|
||
/// ```
|
||
/// println!("{}", 'ß'.to_uppercase());
|
||
/// ```
|
||
///
|
||
/// Both are equivalent to:
|
||
///
|
||
/// ```
|
||
/// println!("SS");
|
||
/// ```
|
||
///
|
||
/// Using [`to_string`](../std/string/trait.ToString.html#tymethod.to_string):
|
||
///
|
||
/// ```
|
||
/// assert_eq!('c'.to_uppercase().to_string(), "C");
|
||
///
|
||
/// // Sometimes the result is more than one character:
|
||
/// assert_eq!('ß'.to_uppercase().to_string(), "SS");
|
||
///
|
||
/// // Characters that do not have both uppercase and lowercase
|
||
/// // convert into themselves.
|
||
/// assert_eq!('山'.to_uppercase().to_string(), "山");
|
||
/// ```
|
||
///
|
||
/// # Note on locale
|
||
///
|
||
/// In Turkish, the equivalent of 'i' in Latin has five forms instead of two:
|
||
///
|
||
/// * 'Dotless': I / ı, sometimes written ï
|
||
/// * 'Dotted': İ / i
|
||
///
|
||
/// Note that the lowercase dotted 'i' is the same as the Latin. Therefore:
|
||
///
|
||
/// ```
|
||
/// let upper_i = 'i'.to_uppercase().to_string();
|
||
/// ```
|
||
///
|
||
/// The value of `upper_i` here relies on the language of the text: if we're
|
||
/// in `en-US`, it should be `"I"`, but if we're in `tr_TR`, it should
|
||
/// be `"İ"`. `to_uppercase()` does not take this into account, and so:
|
||
///
|
||
/// ```
|
||
/// let upper_i = 'i'.to_uppercase().to_string();
|
||
///
|
||
/// assert_eq!(upper_i, "I");
|
||
/// ```
|
||
///
|
||
/// holds across languages.
|
||
#[must_use = "this returns the uppercase character as a new iterator, \
|
||
without modifying the original"]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn to_uppercase(self) -> ToUppercase {
|
||
ToUppercase(CaseMappingIter::new(conversions::to_upper(self)))
|
||
}
|
||
|
||
/// Checks if the value is within the ASCII range.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let ascii = 'a';
|
||
/// let non_ascii = '❤';
|
||
///
|
||
/// assert!(ascii.is_ascii());
|
||
/// assert!(!non_ascii.is_ascii());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[rustc_const_stable(feature = "const_char_is_ascii", since = "1.32.0")]
|
||
#[inline]
|
||
pub const fn is_ascii(&self) -> bool {
|
||
*self as u32 <= 0x7F
|
||
}
|
||
|
||
/// Returns `Some` if the value is within the ASCII range,
|
||
/// or `None` if it's not.
|
||
///
|
||
/// This is preferred to [`Self::is_ascii`] when you're passing the value
|
||
/// along to something else that can take [`ascii::Char`] rather than
|
||
/// needing to check again for itself whether the value is in ASCII.
|
||
#[must_use]
|
||
#[unstable(feature = "ascii_char", issue = "110998")]
|
||
#[inline]
|
||
pub const fn as_ascii(&self) -> Option<ascii::Char> {
|
||
if self.is_ascii() {
|
||
// SAFETY: Just checked that this is ASCII.
|
||
Some(unsafe { ascii::Char::from_u8_unchecked(*self as u8) })
|
||
} else {
|
||
None
|
||
}
|
||
}
|
||
|
||
/// Makes a copy of the value in its ASCII upper case equivalent.
|
||
///
|
||
/// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
|
||
/// but non-ASCII letters are unchanged.
|
||
///
|
||
/// To uppercase the value in-place, use [`make_ascii_uppercase()`].
|
||
///
|
||
/// To uppercase ASCII characters in addition to non-ASCII characters, use
|
||
/// [`to_uppercase()`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let ascii = 'a';
|
||
/// let non_ascii = '❤';
|
||
///
|
||
/// assert_eq!('A', ascii.to_ascii_uppercase());
|
||
/// assert_eq!('❤', non_ascii.to_ascii_uppercase());
|
||
/// ```
|
||
///
|
||
/// [`make_ascii_uppercase()`]: #method.make_ascii_uppercase
|
||
/// [`to_uppercase()`]: #method.to_uppercase
|
||
#[must_use = "to uppercase the value in-place, use `make_ascii_uppercase()`"]
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
|
||
#[inline]
|
||
pub const fn to_ascii_uppercase(&self) -> char {
|
||
if self.is_ascii_lowercase() {
|
||
(*self as u8).ascii_change_case_unchecked() as char
|
||
} else {
|
||
*self
|
||
}
|
||
}
|
||
|
||
/// Makes a copy of the value in its ASCII lower case equivalent.
|
||
///
|
||
/// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
|
||
/// but non-ASCII letters are unchanged.
|
||
///
|
||
/// To lowercase the value in-place, use [`make_ascii_lowercase()`].
|
||
///
|
||
/// To lowercase ASCII characters in addition to non-ASCII characters, use
|
||
/// [`to_lowercase()`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let ascii = 'A';
|
||
/// let non_ascii = '❤';
|
||
///
|
||
/// assert_eq!('a', ascii.to_ascii_lowercase());
|
||
/// assert_eq!('❤', non_ascii.to_ascii_lowercase());
|
||
/// ```
|
||
///
|
||
/// [`make_ascii_lowercase()`]: #method.make_ascii_lowercase
|
||
/// [`to_lowercase()`]: #method.to_lowercase
|
||
#[must_use = "to lowercase the value in-place, use `make_ascii_lowercase()`"]
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
|
||
#[inline]
|
||
pub const fn to_ascii_lowercase(&self) -> char {
|
||
if self.is_ascii_uppercase() {
|
||
(*self as u8).ascii_change_case_unchecked() as char
|
||
} else {
|
||
*self
|
||
}
|
||
}
|
||
|
||
/// Checks that two values are an ASCII case-insensitive match.
|
||
///
|
||
/// Equivalent to <code>[to_ascii_lowercase]\(a) == [to_ascii_lowercase]\(b)</code>.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let upper_a = 'A';
|
||
/// let lower_a = 'a';
|
||
/// let lower_z = 'z';
|
||
///
|
||
/// assert!(upper_a.eq_ignore_ascii_case(&lower_a));
|
||
/// assert!(upper_a.eq_ignore_ascii_case(&upper_a));
|
||
/// assert!(!upper_a.eq_ignore_ascii_case(&lower_z));
|
||
/// ```
|
||
///
|
||
/// [to_ascii_lowercase]: #method.to_ascii_lowercase
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
|
||
#[inline]
|
||
pub const fn eq_ignore_ascii_case(&self, other: &char) -> bool {
|
||
self.to_ascii_lowercase() == other.to_ascii_lowercase()
|
||
}
|
||
|
||
/// Converts this type to its ASCII upper case equivalent in-place.
|
||
///
|
||
/// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
|
||
/// but non-ASCII letters are unchanged.
|
||
///
|
||
/// To return a new uppercased value without modifying the existing one, use
|
||
/// [`to_ascii_uppercase()`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut ascii = 'a';
|
||
///
|
||
/// ascii.make_ascii_uppercase();
|
||
///
|
||
/// assert_eq!('A', ascii);
|
||
/// ```
|
||
///
|
||
/// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[inline]
|
||
pub fn make_ascii_uppercase(&mut self) {
|
||
*self = self.to_ascii_uppercase();
|
||
}
|
||
|
||
/// Converts this type to its ASCII lower case equivalent in-place.
|
||
///
|
||
/// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
|
||
/// but non-ASCII letters are unchanged.
|
||
///
|
||
/// To return a new lowercased value without modifying the existing one, use
|
||
/// [`to_ascii_lowercase()`].
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut ascii = 'A';
|
||
///
|
||
/// ascii.make_ascii_lowercase();
|
||
///
|
||
/// assert_eq!('a', ascii);
|
||
/// ```
|
||
///
|
||
/// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase
|
||
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
|
||
#[inline]
|
||
pub fn make_ascii_lowercase(&mut self) {
|
||
*self = self.to_ascii_lowercase();
|
||
}
|
||
|
||
/// Checks if the value is an ASCII alphabetic character:
|
||
///
|
||
/// - U+0041 'A' ..= U+005A 'Z', or
|
||
/// - U+0061 'a' ..= U+007A 'z'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(uppercase_a.is_ascii_alphabetic());
|
||
/// assert!(uppercase_g.is_ascii_alphabetic());
|
||
/// assert!(a.is_ascii_alphabetic());
|
||
/// assert!(g.is_ascii_alphabetic());
|
||
/// assert!(!zero.is_ascii_alphabetic());
|
||
/// assert!(!percent.is_ascii_alphabetic());
|
||
/// assert!(!space.is_ascii_alphabetic());
|
||
/// assert!(!lf.is_ascii_alphabetic());
|
||
/// assert!(!esc.is_ascii_alphabetic());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_alphabetic(&self) -> bool {
|
||
matches!(*self, 'A'..='Z' | 'a'..='z')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII uppercase character:
|
||
/// U+0041 'A' ..= U+005A 'Z'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(uppercase_a.is_ascii_uppercase());
|
||
/// assert!(uppercase_g.is_ascii_uppercase());
|
||
/// assert!(!a.is_ascii_uppercase());
|
||
/// assert!(!g.is_ascii_uppercase());
|
||
/// assert!(!zero.is_ascii_uppercase());
|
||
/// assert!(!percent.is_ascii_uppercase());
|
||
/// assert!(!space.is_ascii_uppercase());
|
||
/// assert!(!lf.is_ascii_uppercase());
|
||
/// assert!(!esc.is_ascii_uppercase());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_uppercase(&self) -> bool {
|
||
matches!(*self, 'A'..='Z')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII lowercase character:
|
||
/// U+0061 'a' ..= U+007A 'z'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(!uppercase_a.is_ascii_lowercase());
|
||
/// assert!(!uppercase_g.is_ascii_lowercase());
|
||
/// assert!(a.is_ascii_lowercase());
|
||
/// assert!(g.is_ascii_lowercase());
|
||
/// assert!(!zero.is_ascii_lowercase());
|
||
/// assert!(!percent.is_ascii_lowercase());
|
||
/// assert!(!space.is_ascii_lowercase());
|
||
/// assert!(!lf.is_ascii_lowercase());
|
||
/// assert!(!esc.is_ascii_lowercase());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_lowercase(&self) -> bool {
|
||
matches!(*self, 'a'..='z')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII alphanumeric character:
|
||
///
|
||
/// - U+0041 'A' ..= U+005A 'Z', or
|
||
/// - U+0061 'a' ..= U+007A 'z', or
|
||
/// - U+0030 '0' ..= U+0039 '9'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(uppercase_a.is_ascii_alphanumeric());
|
||
/// assert!(uppercase_g.is_ascii_alphanumeric());
|
||
/// assert!(a.is_ascii_alphanumeric());
|
||
/// assert!(g.is_ascii_alphanumeric());
|
||
/// assert!(zero.is_ascii_alphanumeric());
|
||
/// assert!(!percent.is_ascii_alphanumeric());
|
||
/// assert!(!space.is_ascii_alphanumeric());
|
||
/// assert!(!lf.is_ascii_alphanumeric());
|
||
/// assert!(!esc.is_ascii_alphanumeric());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_alphanumeric(&self) -> bool {
|
||
matches!(*self, '0'..='9') | matches!(*self, 'A'..='Z') | matches!(*self, 'a'..='z')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII decimal digit:
|
||
/// U+0030 '0' ..= U+0039 '9'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(!uppercase_a.is_ascii_digit());
|
||
/// assert!(!uppercase_g.is_ascii_digit());
|
||
/// assert!(!a.is_ascii_digit());
|
||
/// assert!(!g.is_ascii_digit());
|
||
/// assert!(zero.is_ascii_digit());
|
||
/// assert!(!percent.is_ascii_digit());
|
||
/// assert!(!space.is_ascii_digit());
|
||
/// assert!(!lf.is_ascii_digit());
|
||
/// assert!(!esc.is_ascii_digit());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_digit(&self) -> bool {
|
||
matches!(*self, '0'..='9')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII octal digit:
|
||
/// U+0030 '0' ..= U+0037 '7'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(is_ascii_octdigit)]
|
||
///
|
||
/// let uppercase_a = 'A';
|
||
/// let a = 'a';
|
||
/// let zero = '0';
|
||
/// let seven = '7';
|
||
/// let nine = '9';
|
||
/// let percent = '%';
|
||
/// let lf = '\n';
|
||
///
|
||
/// assert!(!uppercase_a.is_ascii_octdigit());
|
||
/// assert!(!a.is_ascii_octdigit());
|
||
/// assert!(zero.is_ascii_octdigit());
|
||
/// assert!(seven.is_ascii_octdigit());
|
||
/// assert!(!nine.is_ascii_octdigit());
|
||
/// assert!(!percent.is_ascii_octdigit());
|
||
/// assert!(!lf.is_ascii_octdigit());
|
||
/// ```
|
||
#[must_use]
|
||
#[unstable(feature = "is_ascii_octdigit", issue = "101288")]
|
||
#[rustc_const_unstable(feature = "is_ascii_octdigit", issue = "101288")]
|
||
#[inline]
|
||
pub const fn is_ascii_octdigit(&self) -> bool {
|
||
matches!(*self, '0'..='7')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII hexadecimal digit:
|
||
///
|
||
/// - U+0030 '0' ..= U+0039 '9', or
|
||
/// - U+0041 'A' ..= U+0046 'F', or
|
||
/// - U+0061 'a' ..= U+0066 'f'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(uppercase_a.is_ascii_hexdigit());
|
||
/// assert!(!uppercase_g.is_ascii_hexdigit());
|
||
/// assert!(a.is_ascii_hexdigit());
|
||
/// assert!(!g.is_ascii_hexdigit());
|
||
/// assert!(zero.is_ascii_hexdigit());
|
||
/// assert!(!percent.is_ascii_hexdigit());
|
||
/// assert!(!space.is_ascii_hexdigit());
|
||
/// assert!(!lf.is_ascii_hexdigit());
|
||
/// assert!(!esc.is_ascii_hexdigit());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_hexdigit(&self) -> bool {
|
||
matches!(*self, '0'..='9') | matches!(*self, 'A'..='F') | matches!(*self, 'a'..='f')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII punctuation character:
|
||
///
|
||
/// - U+0021 ..= U+002F `! " # $ % & ' ( ) * + , - . /`, or
|
||
/// - U+003A ..= U+0040 `: ; < = > ? @`, or
|
||
/// - U+005B ..= U+0060 ``[ \ ] ^ _ ` ``, or
|
||
/// - U+007B ..= U+007E `{ | } ~`
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(!uppercase_a.is_ascii_punctuation());
|
||
/// assert!(!uppercase_g.is_ascii_punctuation());
|
||
/// assert!(!a.is_ascii_punctuation());
|
||
/// assert!(!g.is_ascii_punctuation());
|
||
/// assert!(!zero.is_ascii_punctuation());
|
||
/// assert!(percent.is_ascii_punctuation());
|
||
/// assert!(!space.is_ascii_punctuation());
|
||
/// assert!(!lf.is_ascii_punctuation());
|
||
/// assert!(!esc.is_ascii_punctuation());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_punctuation(&self) -> bool {
|
||
matches!(*self, '!'..='/')
|
||
| matches!(*self, ':'..='@')
|
||
| matches!(*self, '['..='`')
|
||
| matches!(*self, '{'..='~')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII graphic character:
|
||
/// U+0021 '!' ..= U+007E '~'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(uppercase_a.is_ascii_graphic());
|
||
/// assert!(uppercase_g.is_ascii_graphic());
|
||
/// assert!(a.is_ascii_graphic());
|
||
/// assert!(g.is_ascii_graphic());
|
||
/// assert!(zero.is_ascii_graphic());
|
||
/// assert!(percent.is_ascii_graphic());
|
||
/// assert!(!space.is_ascii_graphic());
|
||
/// assert!(!lf.is_ascii_graphic());
|
||
/// assert!(!esc.is_ascii_graphic());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_graphic(&self) -> bool {
|
||
matches!(*self, '!'..='~')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII whitespace character:
|
||
/// U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED,
|
||
/// U+000C FORM FEED, or U+000D CARRIAGE RETURN.
|
||
///
|
||
/// Rust uses the WhatWG Infra Standard's [definition of ASCII
|
||
/// whitespace][infra-aw]. There are several other definitions in
|
||
/// wide use. For instance, [the POSIX locale][pct] includes
|
||
/// U+000B VERTICAL TAB as well as all the above characters,
|
||
/// but—from the very same specification—[the default rule for
|
||
/// "field splitting" in the Bourne shell][bfs] considers *only*
|
||
/// SPACE, HORIZONTAL TAB, and LINE FEED as whitespace.
|
||
///
|
||
/// If you are writing a program that will process an existing
|
||
/// file format, check what that format's definition of whitespace is
|
||
/// before using this function.
|
||
///
|
||
/// [infra-aw]: https://infra.spec.whatwg.org/#ascii-whitespace
|
||
/// [pct]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html#tag_07_03_01
|
||
/// [bfs]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(!uppercase_a.is_ascii_whitespace());
|
||
/// assert!(!uppercase_g.is_ascii_whitespace());
|
||
/// assert!(!a.is_ascii_whitespace());
|
||
/// assert!(!g.is_ascii_whitespace());
|
||
/// assert!(!zero.is_ascii_whitespace());
|
||
/// assert!(!percent.is_ascii_whitespace());
|
||
/// assert!(space.is_ascii_whitespace());
|
||
/// assert!(lf.is_ascii_whitespace());
|
||
/// assert!(!esc.is_ascii_whitespace());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_whitespace(&self) -> bool {
|
||
matches!(*self, '\t' | '\n' | '\x0C' | '\r' | ' ')
|
||
}
|
||
|
||
/// Checks if the value is an ASCII control character:
|
||
/// U+0000 NUL ..= U+001F UNIT SEPARATOR, or U+007F DELETE.
|
||
/// Note that most ASCII whitespace characters are control
|
||
/// characters, but SPACE is not.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let uppercase_a = 'A';
|
||
/// let uppercase_g = 'G';
|
||
/// let a = 'a';
|
||
/// let g = 'g';
|
||
/// let zero = '0';
|
||
/// let percent = '%';
|
||
/// let space = ' ';
|
||
/// let lf = '\n';
|
||
/// let esc = '\x1b';
|
||
///
|
||
/// assert!(!uppercase_a.is_ascii_control());
|
||
/// assert!(!uppercase_g.is_ascii_control());
|
||
/// assert!(!a.is_ascii_control());
|
||
/// assert!(!g.is_ascii_control());
|
||
/// assert!(!zero.is_ascii_control());
|
||
/// assert!(!percent.is_ascii_control());
|
||
/// assert!(!space.is_ascii_control());
|
||
/// assert!(lf.is_ascii_control());
|
||
/// assert!(esc.is_ascii_control());
|
||
/// ```
|
||
#[must_use]
|
||
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
|
||
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
|
||
#[inline]
|
||
pub const fn is_ascii_control(&self) -> bool {
|
||
matches!(*self, '\0'..='\x1F' | '\x7F')
|
||
}
|
||
}
|
||
|
||
pub(crate) struct EscapeDebugExtArgs {
|
||
/// Escape Extended Grapheme codepoints?
|
||
pub(crate) escape_grapheme_extended: bool,
|
||
|
||
/// Escape single quotes?
|
||
pub(crate) escape_single_quote: bool,
|
||
|
||
/// Escape double quotes?
|
||
pub(crate) escape_double_quote: bool,
|
||
}
|
||
|
||
impl EscapeDebugExtArgs {
|
||
pub(crate) const ESCAPE_ALL: Self = Self {
|
||
escape_grapheme_extended: true,
|
||
escape_single_quote: true,
|
||
escape_double_quote: true,
|
||
};
|
||
}
|
||
|
||
#[inline]
|
||
const fn len_utf8(code: u32) -> usize {
|
||
if code < MAX_ONE_B {
|
||
1
|
||
} else if code < MAX_TWO_B {
|
||
2
|
||
} else if code < MAX_THREE_B {
|
||
3
|
||
} else {
|
||
4
|
||
}
|
||
}
|
||
|
||
/// Encodes a raw u32 value as UTF-8 into the provided byte buffer,
|
||
/// and then returns the subslice of the buffer that contains the encoded character.
|
||
///
|
||
/// Unlike `char::encode_utf8`, this method also handles codepoints in the surrogate range.
|
||
/// (Creating a `char` in the surrogate range is UB.)
|
||
/// The result is valid [generalized UTF-8] but not valid UTF-8.
|
||
///
|
||
/// [generalized UTF-8]: https://simonsapin.github.io/wtf-8/#generalized-utf8
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the buffer is not large enough.
|
||
/// A buffer of length four is large enough to encode any `char`.
|
||
#[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
|
||
#[doc(hidden)]
|
||
#[inline]
|
||
pub fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> &mut [u8] {
|
||
let len = len_utf8(code);
|
||
match (len, &mut dst[..]) {
|
||
(1, [a, ..]) => {
|
||
*a = code as u8;
|
||
}
|
||
(2, [a, b, ..]) => {
|
||
*a = (code >> 6 & 0x1F) as u8 | TAG_TWO_B;
|
||
*b = (code & 0x3F) as u8 | TAG_CONT;
|
||
}
|
||
(3, [a, b, c, ..]) => {
|
||
*a = (code >> 12 & 0x0F) as u8 | TAG_THREE_B;
|
||
*b = (code >> 6 & 0x3F) as u8 | TAG_CONT;
|
||
*c = (code & 0x3F) as u8 | TAG_CONT;
|
||
}
|
||
(4, [a, b, c, d, ..]) => {
|
||
*a = (code >> 18 & 0x07) as u8 | TAG_FOUR_B;
|
||
*b = (code >> 12 & 0x3F) as u8 | TAG_CONT;
|
||
*c = (code >> 6 & 0x3F) as u8 | TAG_CONT;
|
||
*d = (code & 0x3F) as u8 | TAG_CONT;
|
||
}
|
||
_ => panic!(
|
||
"encode_utf8: need {} bytes to encode U+{:X}, but the buffer has {}",
|
||
len,
|
||
code,
|
||
dst.len(),
|
||
),
|
||
};
|
||
&mut dst[..len]
|
||
}
|
||
|
||
/// Encodes a raw u32 value as UTF-16 into the provided `u16` buffer,
|
||
/// and then returns the subslice of the buffer that contains the encoded character.
|
||
///
|
||
/// Unlike `char::encode_utf16`, this method also handles codepoints in the surrogate range.
|
||
/// (Creating a `char` in the surrogate range is UB.)
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// Panics if the buffer is not large enough.
|
||
/// A buffer of length 2 is large enough to encode any `char`.
|
||
#[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
|
||
#[doc(hidden)]
|
||
#[inline]
|
||
pub fn encode_utf16_raw(mut code: u32, dst: &mut [u16]) -> &mut [u16] {
|
||
// SAFETY: each arm checks whether there are enough bits to write into
|
||
unsafe {
|
||
if (code & 0xFFFF) == code && !dst.is_empty() {
|
||
// The BMP falls through
|
||
*dst.get_unchecked_mut(0) = code as u16;
|
||
slice::from_raw_parts_mut(dst.as_mut_ptr(), 1)
|
||
} else if dst.len() >= 2 {
|
||
// Supplementary planes break into surrogates.
|
||
code -= 0x1_0000;
|
||
*dst.get_unchecked_mut(0) = 0xD800 | ((code >> 10) as u16);
|
||
*dst.get_unchecked_mut(1) = 0xDC00 | ((code as u16) & 0x3FF);
|
||
slice::from_raw_parts_mut(dst.as_mut_ptr(), 2)
|
||
} else {
|
||
panic!(
|
||
"encode_utf16: need {} units to encode U+{:X}, but the buffer has {}",
|
||
char::from_u32_unchecked(code).len_utf16(),
|
||
code,
|
||
dst.len(),
|
||
)
|
||
}
|
||
}
|
||
}
|