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Diffstat (limited to 'library/core/src/char/methods.rs')
| -rw-r--r-- | library/core/src/char/methods.rs | 1741 |
1 files changed, 1741 insertions, 0 deletions
diff --git a/library/core/src/char/methods.rs b/library/core/src/char/methods.rs new file mode 100644 index 000000000..eae567cad --- /dev/null +++ b/library/core/src/char/methods.rs @@ -0,0 +1,1741 @@ +//! impl char {} + +use crate::slice; +use crate::str::from_utf8_unchecked_mut; +use crate::unicode::printable::is_printable; +use crate::unicode::{self, conversions}; + +use super::*; + +impl char { + /// The highest valid code point a `char` can have, `'\u{10FFFF}'`. + /// + /// # Examples + /// + /// ``` + /// # fn something_which_returns_char() -> char { 'a' } + /// let c: char = something_which_returns_char(); + /// assert!(c <= char::MAX); + /// + /// let value_at_max = char::MAX as u32; + /// 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: + /// + /// ``` + /// use std::char::decode_utf16; + /// + /// // 𝄞mus<invalid>ic<invalid> + /// let v = [ + /// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834, + /// ]; + /// + /// assert_eq!( + /// 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: + /// + /// ``` + /// use std::char::{decode_utf16, REPLACEMENT_CHARACTER}; + /// + /// // 𝄞mus<invalid>ic<invalid> + /// let v = [ + /// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834, + /// ]; + /// + /// assert_eq!( + /// decode_utf16(v) + /// .map(|r| r.unwrap_or(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: + /// + /// ``` + /// use std::char; + /// + /// let c = char::from_u32(0x2764); + /// + /// assert_eq!(Some('❤'), c); + /// ``` + /// + /// Returning `None` when the input is not a valid `char`: + /// + /// ``` + /// use std::char; + /// + /// let c = char::from_u32(0x110000); + /// + /// assert_eq!(None, c); + /// ``` + #[stable(feature = "assoc_char_funcs", since = "1.52.0")] + #[rustc_const_unstable(feature = "const_char_convert", issue = "89259")] + #[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: + /// + /// ``` + /// use std::char; + /// + /// let c = unsafe { char::from_u32_unchecked(0x2764) }; + /// + /// assert_eq!('❤', c); + /// ``` + #[stable(feature = "assoc_char_funcs", since = "1.52.0")] + #[rustc_const_unstable(feature = "const_char_convert", issue = "89259")] + #[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: + /// + /// ``` + /// use std::char; + /// + /// 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: + /// + /// ``` + /// use std::char; + /// + /// let c = char::from_digit(20, 10); + /// + /// assert_eq!(None, c); + /// ``` + /// + /// Passing a large radix, causing a panic: + /// + /// ```should_panic + /// use std::char; + /// + /// // this panics + /// let _c = char::from_digit(1, 37); + /// ``` + #[stable(feature = "assoc_char_funcs", since = "1.52.0")] + #[rustc_const_unstable(feature = "const_char_convert", issue = "89259")] + #[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_unstable(feature = "const_char_convert", issue = "89259")] + #[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: 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 { + let c = self as u32; + + // or-ing 1 ensures that for c==0 the code computes that one + // digit should be printed and (which is the same) avoids the + // (31 - 32) underflow + let msb = 31 - (c | 1).leading_zeros(); + + // the index of the most significant hex digit + let ms_hex_digit = msb / 4; + EscapeUnicode { + c: self, + state: EscapeUnicodeState::Backslash, + hex_digit_idx: ms_hex_digit as usize, + } + } + + /// 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 { + let init_state = match self { + '\0' => EscapeDefaultState::Backslash('0'), + '\t' => EscapeDefaultState::Backslash('t'), + '\r' => EscapeDefaultState::Backslash('r'), + '\n' => EscapeDefaultState::Backslash('n'), + '\\' => EscapeDefaultState::Backslash(self), + '"' if args.escape_double_quote => EscapeDefaultState::Backslash(self), + '\'' if args.escape_single_quote => EscapeDefaultState::Backslash(self), + _ if args.escape_grapheme_extended && self.is_grapheme_extended() => { + EscapeDefaultState::Unicode(self.escape_unicode()) + } + _ if is_printable(self) => EscapeDefaultState::Char(self), + _ => EscapeDefaultState::Unicode(self.escape_unicode()), + }; + EscapeDebug(EscapeDefault { state: init_state }) + } + + /// 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 { + let init_state = match self { + '\t' => EscapeDefaultState::Backslash('t'), + '\r' => EscapeDefaultState::Backslash('r'), + '\n' => EscapeDefaultState::Backslash('n'), + '\\' | '\'' | '"' => EscapeDefaultState::Backslash(self), + '\x20'..='\x7e' => EscapeDefaultState::Char(self), + _ => EscapeDefaultState::Unicode(self.escape_unicode()), + }; + EscapeDefault { state: init_state } + } + + /// 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. + /// + /// 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. + /// + /// [`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()); + /// ``` + #[must_use] + #[stable(feature = "rust1", since = "1.0.0")] + #[inline] + pub 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()); + /// ``` + #[must_use] + #[stable(feature = "rust1", since = "1.0.0")] + #[inline] + pub 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`]. Note that this means ideographic numbers like '三' + /// are considered alphabetic, not numeric. Please consider to use `is_ascii_digit` or `is_digit`. + /// + /// 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 + } + + /// 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' | 'A'..='Z' | '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 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' | 'A'..='F' | '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, '!'..='/' | ':'..='@' | '['..='`' | '{'..='~') + } + + /// 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 {}", + from_u32_unchecked(code).len_utf16(), + code, + dst.len(), + ) + } + } +} |