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fuchsia / third_party / rust / 1bc403daadbebb553ccc211a0a8eebb73989665f / . / library / core / src / char / methods.rs
blob: 7f3c998aaa5bce96197ca1e77efd79610b31d93b [file] [log] [blame]
//! impl char {}
use super::*;
use crate::intrinsics::const_eval_select;
use crate::slice;
use crate::str::from_utf8_unchecked_mut;
use crate::unicode::printable::is_printable;
use crate::unicode::{self, conversions};
impl char {
/// The lowest valid code point a `char` can have, `'\0'`.
///
/// Unlike integer types, `char` actually has a gap in the middle,
/// meaning that the range of possible `char`s is smaller than you
/// might expect. Ranges of `char` will automatically hop this gap
/// for you:
///
/// ```
/// let dist = u32::from(char::MAX) - u32::from(char::MIN);
/// let size = (char::MIN..=char::MAX).count() as u32;
/// assert!(size < dist);
/// ```
///
/// Despite this gap, the `MIN` and [`MAX`] values can be used as bounds for
/// all `char` values.
///
/// [`MAX`]: char::MAX
///
/// # Examples
///
/// ```
/// # fn something_which_returns_char() -> char { 'a' }
/// let c: char = something_which_returns_char();
/// assert!(char::MIN <= c);
///
/// let value_at_min = u32::from(char::MIN);
/// assert_eq!(char::from_u32(value_at_min), Some('\0'));
/// ```
#[stable(feature = "char_min", since = "CURRENT_RUSTC_VERSION")]
pub const MIN: char = '\0';
/// The highest valid code point a `char` can have, `'\u{10FFFF}'`.
///
/// Unlike integer types, `char` actually has a gap in the middle,
/// meaning that the range of possible `char`s is smaller than you
/// might expect. Ranges of `char` will automatically hop this gap
/// for you:
///
/// ```
/// let dist = u32::from(char::MAX) - u32::from(char::MIN);
/// let size = (char::MIN..=char::MAX).count() as u32;
/// assert!(size < dist);
/// ```
///
/// Despite this gap, the [`MIN`] and `MAX` values can be used as bounds for
/// all `char` values.
///
/// [`MIN`]: char::MIN
///
/// # Examples
///
/// ```
/// # fn something_which_returns_char() -> char { 'a' }
/// let c: char = something_which_returns_char();
/// assert!(c <= char::MAX);
///
/// let value_at_max = u32::from(char::MAX);
/// assert_eq!(char::from_u32(value_at_max), Some('\u{10FFFF}'));
/// assert_eq!(char::from_u32(value_at_max + 1), None);
/// ```
#[stable(feature = "assoc_char_consts", since = "1.52.0")]
pub const MAX: char = '\u{10FFFF}';
/// `U+FFFD REPLACEMENT CHARACTER` (�) is used in Unicode to represent a
/// decoding error.
///
/// It can occur, for example, when giving ill-formed UTF-8 bytes to
/// [`String::from_utf8_lossy`](../std/string/struct.String.html#method.from_utf8_lossy).
#[stable(feature = "assoc_char_consts", since = "1.52.0")]
pub const REPLACEMENT_CHARACTER: char = '\u{FFFD}';
/// The version of [Unicode](https://www.unicode.org/) that the Unicode parts of
/// `char` and `str` methods are based on.
///
/// New versions of Unicode are released regularly and subsequently all methods
/// in the standard library depending on Unicode are updated. Therefore the
/// behavior of some `char` and `str` methods and the value of this constant
/// changes over time. This is *not* considered to be a breaking change.
///
/// The version numbering scheme is explained in
/// [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).
#[stable(feature = "assoc_char_consts", since = "1.52.0")]
pub const UNICODE_VERSION: (u8, u8, u8) = crate::unicode::UNICODE_VERSION;
/// Creates an iterator over the UTF-16 encoded code points in `iter`,
/// returning unpaired surrogates as `Err`s.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // 𝄞mus<invalid>ic<invalid>
/// let v = [
/// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
/// ];
///
/// assert_eq!(
/// char::decode_utf16(v)
/// .map(|r| r.map_err(|e| e.unpaired_surrogate()))
/// .collect::<Vec<_>>(),
/// vec![
/// Ok('𝄞'),
/// Ok('m'), Ok('u'), Ok('s'),
/// Err(0xDD1E),
/// Ok('i'), Ok('c'),
/// Err(0xD834)
/// ]
/// );
/// ```
///
/// A lossy decoder can be obtained by replacing `Err` results with the replacement character:
///
/// ```
/// // 𝄞mus<invalid>ic<invalid>
/// let v = [
/// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
/// ];
///
/// assert_eq!(
/// char::decode_utf16(v)
/// .map(|r| r.unwrap_or(char::REPLACEMENT_CHARACTER))
/// .collect::<String>(),
/// "𝄞mus�ic�"
/// );
/// ```
#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
#[inline]
pub fn decode_utf16<I: IntoIterator<Item = u16>>(iter: I) -> DecodeUtf16<I::IntoIter> {
super::decode::decode_utf16(iter)
}
/// Converts a `u32` to a `char`.
///
/// Note that all `char`s are valid [`u32`]s, and can be cast to one with
/// [`as`](../std/keyword.as.html):
///
/// ```
/// let c = '💯';
/// let i = c as u32;
///
/// assert_eq!(128175, i);
/// ```
///
/// However, the reverse is not true: not all valid [`u32`]s are valid
/// `char`s. `from_u32()` will return `None` if the input is not a valid value
/// for a `char`.
///
/// For an unsafe version of this function which ignores these checks, see
/// [`from_u32_unchecked`].
///
/// [`from_u32_unchecked`]: #method.from_u32_unchecked
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let c = char::from_u32(0x2764);
///
/// assert_eq!(Some('❤'), c);
/// ```
///
/// Returning `None` when the input is not a valid `char`:
///
/// ```
/// let c = char::from_u32(0x110000);
///
/// assert_eq!(None, c);
/// ```
#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
#[rustc_const_stable(feature = "const_char_convert", since = "1.67.0")]
#[must_use]
#[inline]
pub const fn from_u32(i: u32) -> Option<char> {
super::convert::from_u32(i)
}
/// Converts a `u32` to a `char`, ignoring validity.
///
/// Note that all `char`s are valid [`u32`]s, and can be cast to one with
/// `as`:
///
/// ```
/// let c = '💯';
/// let i = c as u32;
///
/// assert_eq!(128175, i);
/// ```
///
/// However, the reverse is not true: not all valid [`u32`]s are valid
/// `char`s. `from_u32_unchecked()` will ignore this, and blindly cast to
/// `char`, possibly creating an invalid one.
///
/// # Safety
///
/// This function is unsafe, as it may construct invalid `char` values.
///
/// For a safe version of this function, see the [`from_u32`] function.
///
/// [`from_u32`]: #method.from_u32
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let c = unsafe { char::from_u32_unchecked(0x2764) };
///
/// assert_eq!('❤', c);
/// ```
#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
#[rustc_const_stable(feature = "const_char_from_u32_unchecked", since = "1.81.0")]
#[must_use]
#[inline]
pub const unsafe fn from_u32_unchecked(i: u32) -> char {
// SAFETY: the safety contract must be upheld by the caller.
unsafe { super::convert::from_u32_unchecked(i) }
}
/// Converts a digit in the given radix to a `char`.
///
/// A 'radix' here is sometimes also called a 'base'. A radix of two
/// indicates a binary number, a radix of ten, decimal, and a radix of
/// sixteen, hexadecimal, to give some common values. Arbitrary
/// radices are supported.
///
/// `from_digit()` will return `None` if the input is not a digit in
/// the given radix.
///
/// # Panics
///
/// Panics if given a radix larger than 36.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let c = char::from_digit(4, 10);
///
/// assert_eq!(Some('4'), c);
///
/// // Decimal 11 is a single digit in base 16
/// let c = char::from_digit(11, 16);
///
/// assert_eq!(Some('b'), c);
/// ```
///
/// Returning `None` when the input is not a digit:
///
/// ```
/// let c = char::from_digit(20, 10);
///
/// assert_eq!(None, c);
/// ```
///
/// Passing a large radix, causing a panic:
///
/// ```should_panic
/// // this panics
/// let _c = char::from_digit(1, 37);
/// ```
#[stable(feature = "assoc_char_funcs", since = "1.52.0")]
#[rustc_const_stable(feature = "const_char_convert", since = "1.67.0")]
#[must_use]
#[inline]
pub const fn from_digit(num: u32, radix: u32) -> Option<char> {
super::convert::from_digit(num, radix)
}
/// Checks if a `char` is a digit in the given radix.
///
/// A 'radix' here is sometimes also called a 'base'. A radix of two
/// indicates a binary number, a radix of ten, decimal, and a radix of
/// sixteen, hexadecimal, to give some common values. Arbitrary
/// radices are supported.
///
/// Compared to [`is_numeric()`], this function only recognizes the characters
/// `0-9`, `a-z` and `A-Z`.
///
/// 'Digit' is defined to be only the following characters:
///
/// * `0-9`
/// * `a-z`
/// * `A-Z`
///
/// For a more comprehensive understanding of 'digit', see [`is_numeric()`].
///
/// [`is_numeric()`]: #method.is_numeric
///
/// # Panics
///
/// Panics if given a radix larger than 36.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// assert!('1'.is_digit(10));
/// assert!('f'.is_digit(16));
/// assert!(!'f'.is_digit(10));
/// ```
///
/// Passing a large radix, causing a panic:
///
/// ```should_panic
/// // this panics
/// '1'.is_digit(37);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn is_digit(self, radix: u32) -> bool {
self.to_digit(radix).is_some()
}
/// Converts a `char` to a digit in the given radix.
///
/// A 'radix' here is sometimes also called a 'base'. A radix of two
/// indicates a binary number, a radix of ten, decimal, and a radix of
/// sixteen, hexadecimal, to give some common values. Arbitrary
/// radices are supported.
///
/// 'Digit' is defined to be only the following characters:
///
/// * `0-9`
/// * `a-z`
/// * `A-Z`
///
/// # Errors
///
/// Returns `None` if the `char` does not refer to a digit in the given radix.
///
/// # Panics
///
/// Panics if given a radix larger than 36.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// assert_eq!('1'.to_digit(10), Some(1));
/// assert_eq!('f'.to_digit(16), Some(15));
/// ```
///
/// Passing a non-digit results in failure:
///
/// ```
/// assert_eq!('f'.to_digit(10), None);
/// assert_eq!('z'.to_digit(16), None);
/// ```
///
/// Passing a large radix, causing a panic:
///
/// ```should_panic
/// // this panics
/// let _ = '1'.to_digit(37);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_char_convert", since = "1.67.0")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn to_digit(self, radix: u32) -> Option<u32> {
// If not a digit, a number greater than radix will be created.
let mut digit = (self as u32).wrapping_sub('0' as u32);
if radix > 10 {
assert!(radix <= 36, "to_digit: radix is too high (maximum 36)");
if digit < 10 {
return Some(digit);
}
// Force the 6th bit to be set to ensure ascii is lower case.
digit = (self as u32 | 0b10_0000).wrapping_sub('a' as u32).saturating_add(10);
}
// FIXME(const-hack): once then_some is const fn, use it here
if digit < radix { Some(digit) } else { None }
}
/// Returns an iterator that yields the hexadecimal Unicode escape of a
/// character as `char`s.
///
/// This will escape characters with the Rust syntax of the form
/// `\u{NNNNNN}` where `NNNNNN` is a hexadecimal representation.
///
/// # Examples
///
/// As an iterator:
///
/// ```
/// for c in '❤'.escape_unicode() {
/// print!("{c}");
/// }
/// println!();
/// ```
///
/// Using `println!` directly:
///
/// ```
/// println!("{}", '❤'.escape_unicode());
/// ```
///
/// 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 {
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() => {
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]
#[must_use]
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]
#[must_use]
pub const fn len_utf16(self) -> usize {
len_utf16(self as u32)
}
/// 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")]
#[rustc_const_unstable(feature = "const_char_encode_utf8", issue = "130512")]
#[inline]
pub const 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")]
#[rustc_const_unstable(feature = "const_char_encode_utf16", issue = "130660")]
#[inline]
pub const 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!('œ'.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")]
#[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
#[inline]
pub const 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")]
#[rustc_const_unstable(feature = "const_make_ascii", issue = "130698")]
#[inline]
pub const 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]
#[must_use]
const fn len_utf8(code: u32) -> usize {
match code {
..MAX_ONE_B => 1,
..MAX_TWO_B => 2,
..MAX_THREE_B => 3,
_ => 4,
}
}
#[inline]
#[must_use]
const fn len_utf16(code: u32) -> usize {
if (code & 0xFFFF) == code { 1 } else { 2 }
}
/// 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")]
#[rustc_const_unstable(feature = "const_char_encode_utf8", issue = "130512")]
#[doc(hidden)]
#[inline]
pub const fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> &mut [u8] {
const fn panic_at_const(_code: u32, _len: usize, _dst_len: usize) {
// Note that we cannot format in constant expressions.
panic!("encode_utf8: buffer does not have enough bytes to encode code point");
}
fn panic_at_rt(code: u32, len: usize, dst_len: usize) {
panic!(
"encode_utf8: need {len} bytes to encode U+{code:04X} but buffer has just {dst_len}",
);
}
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;
}
// FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
_ => const_eval_select((code, len, dst.len()), panic_at_const, panic_at_rt),
};
// SAFETY: `<&mut [u8]>::as_mut_ptr` is guaranteed to return a valid pointer and `len` has been tested to be within bounds.
unsafe { slice::from_raw_parts_mut(dst.as_mut_ptr(), 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")]
#[rustc_const_unstable(feature = "const_char_encode_utf16", issue = "130660")]
#[doc(hidden)]
#[inline]
pub const fn encode_utf16_raw(mut code: u32, dst: &mut [u16]) -> &mut [u16] {
const fn panic_at_const(_code: u32, _len: usize, _dst_len: usize) {
// Note that we cannot format in constant expressions.
panic!("encode_utf16: buffer does not have enough bytes to encode code point");
}
fn panic_at_rt(code: u32, len: usize, dst_len: usize) {
panic!(
"encode_utf16: need {len} bytes to encode U+{code:04X} but buffer has just {dst_len}",
);
}
let len = len_utf16(code);
match (len, &mut *dst) {
(1, [a, ..]) => {
*a = code as u16;
}
(2, [a, b, ..]) => {
code -= 0x1_0000;
*a = (code >> 10) as u16 | 0xD800;
*b = (code & 0x3FF) as u16 | 0xDC00;
}
// FIXME(const-hack): We would prefer to have streamlined panics when formatters become const-friendly.
_ => const_eval_select((code, len, dst.len()), panic_at_const, panic_at_rt),
};
// SAFETY: `<&mut [u16]>::as_mut_ptr` is guaranteed to return a valid pointer and `len` has been tested to be within bounds.
unsafe { slice::from_raw_parts_mut(dst.as_mut_ptr(), len) }
}