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83c7162d 1//! impl char {}
c34b1796 2
6a06907d 3use crate::intrinsics::likely;
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4use crate::slice;
5use crate::str::from_utf8_unchecked_mut;
6use crate::unicode::printable::is_printable;
dfeec247 7use crate::unicode::{self, conversions};
48663c56 8
83c7162d 9use super::*;
32a655c1 10
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11#[lang = "char"]
12impl char {
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13 /// The highest valid code point a `char` can have.
14 ///
15 /// A `char` is a [Unicode Scalar Value], which means that it is a [Code
16 /// Point], but only ones within a certain range. `MAX` is the highest valid
17 /// code point that's a valid [Unicode Scalar Value].
18 ///
19 /// [Unicode Scalar Value]: http://www.unicode.org/glossary/#unicode_scalar_value
20 /// [Code Point]: http://www.unicode.org/glossary/#code_point
6a06907d 21 #[stable(feature = "assoc_char_consts", since = "1.52.0")]
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22 pub const MAX: char = '\u{10ffff}';
23
24 /// `U+FFFD REPLACEMENT CHARACTER` (�) is used in Unicode to represent a
25 /// decoding error.
26 ///
27 /// It can occur, for example, when giving ill-formed UTF-8 bytes to
28 /// [`String::from_utf8_lossy`](string/struct.String.html#method.from_utf8_lossy).
6a06907d 29 #[stable(feature = "assoc_char_consts", since = "1.52.0")]
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30 pub const REPLACEMENT_CHARACTER: char = '\u{FFFD}';
31
32 /// The version of [Unicode](http://www.unicode.org/) that the Unicode parts of
33 /// `char` and `str` methods are based on.
34 ///
35 /// New versions of Unicode are released regularly and subsequently all methods
36 /// in the standard library depending on Unicode are updated. Therefore the
37 /// behavior of some `char` and `str` methods and the value of this constant
38 /// changes over time. This is *not* considered to be a breaking change.
39 ///
40 /// The version numbering scheme is explained in
41 /// [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).
6a06907d 42 #[stable(feature = "assoc_char_consts", since = "1.52.0")]
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43 pub const UNICODE_VERSION: (u8, u8, u8) = crate::unicode::UNICODE_VERSION;
44
45 /// Creates an iterator over the UTF-16 encoded code points in `iter`,
46 /// returning unpaired surrogates as `Err`s.
47 ///
48 /// # Examples
49 ///
50 /// Basic usage:
51 ///
52 /// ```
53 /// use std::char::decode_utf16;
54 ///
55 /// // 𝄞mus<invalid>ic<invalid>
56 /// let v = [
57 /// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
58 /// ];
59 ///
60 /// assert_eq!(
61 /// decode_utf16(v.iter().cloned())
62 /// .map(|r| r.map_err(|e| e.unpaired_surrogate()))
63 /// .collect::<Vec<_>>(),
64 /// vec![
65 /// Ok('𝄞'),
66 /// Ok('m'), Ok('u'), Ok('s'),
67 /// Err(0xDD1E),
68 /// Ok('i'), Ok('c'),
69 /// Err(0xD834)
70 /// ]
71 /// );
72 /// ```
73 ///
74 /// A lossy decoder can be obtained by replacing `Err` results with the replacement character:
75 ///
76 /// ```
77 /// use std::char::{decode_utf16, REPLACEMENT_CHARACTER};
78 ///
79 /// // 𝄞mus<invalid>ic<invalid>
80 /// let v = [
81 /// 0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0xDD1E, 0x0069, 0x0063, 0xD834,
82 /// ];
83 ///
84 /// assert_eq!(
85 /// decode_utf16(v.iter().cloned())
86 /// .map(|r| r.unwrap_or(REPLACEMENT_CHARACTER))
87 /// .collect::<String>(),
88 /// "𝄞mus�ic�"
89 /// );
90 /// ```
6a06907d 91 #[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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92 #[inline]
93 pub fn decode_utf16<I: IntoIterator<Item = u16>>(iter: I) -> DecodeUtf16<I::IntoIter> {
94 super::decode::decode_utf16(iter)
95 }
96
97 /// Converts a `u32` to a `char`.
98 ///
99 /// Note that all `char`s are valid [`u32`]s, and can be cast to one with
100 /// `as`:
101 ///
102 /// ```
103 /// let c = '💯';
104 /// let i = c as u32;
105 ///
106 /// assert_eq!(128175, i);
107 /// ```
108 ///
109 /// However, the reverse is not true: not all valid [`u32`]s are valid
110 /// `char`s. `from_u32()` will return `None` if the input is not a valid value
111 /// for a `char`.
112 ///
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113 /// For an unsafe version of this function which ignores these checks, see
114 /// [`from_u32_unchecked`].
115 ///
116 /// [`from_u32_unchecked`]: #method.from_u32_unchecked
117 ///
118 /// # Examples
119 ///
120 /// Basic usage:
121 ///
122 /// ```
123 /// use std::char;
124 ///
125 /// let c = char::from_u32(0x2764);
126 ///
127 /// assert_eq!(Some('❤'), c);
128 /// ```
129 ///
130 /// Returning `None` when the input is not a valid `char`:
131 ///
132 /// ```
133 /// use std::char;
134 ///
135 /// let c = char::from_u32(0x110000);
136 ///
137 /// assert_eq!(None, c);
138 /// ```
6a06907d 139 #[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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140 #[inline]
141 pub fn from_u32(i: u32) -> Option<char> {
142 super::convert::from_u32(i)
143 }
144
145 /// Converts a `u32` to a `char`, ignoring validity.
146 ///
147 /// Note that all `char`s are valid [`u32`]s, and can be cast to one with
148 /// `as`:
149 ///
150 /// ```
151 /// let c = '💯';
152 /// let i = c as u32;
153 ///
154 /// assert_eq!(128175, i);
155 /// ```
156 ///
157 /// However, the reverse is not true: not all valid [`u32`]s are valid
158 /// `char`s. `from_u32_unchecked()` will ignore this, and blindly cast to
159 /// `char`, possibly creating an invalid one.
160 ///
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161 /// # Safety
162 ///
163 /// This function is unsafe, as it may construct invalid `char` values.
164 ///
165 /// For a safe version of this function, see the [`from_u32`] function.
166 ///
167 /// [`from_u32`]: #method.from_u32
168 ///
169 /// # Examples
170 ///
171 /// Basic usage:
172 ///
173 /// ```
174 /// use std::char;
175 ///
176 /// let c = unsafe { char::from_u32_unchecked(0x2764) };
177 ///
178 /// assert_eq!('❤', c);
179 /// ```
6a06907d 180 #[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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181 #[inline]
182 pub unsafe fn from_u32_unchecked(i: u32) -> char {
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183 // SAFETY: the safety contract must be upheld by the caller.
184 unsafe { super::convert::from_u32_unchecked(i) }
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185 }
186
187 /// Converts a digit in the given radix to a `char`.
188 ///
189 /// A 'radix' here is sometimes also called a 'base'. A radix of two
190 /// indicates a binary number, a radix of ten, decimal, and a radix of
191 /// sixteen, hexadecimal, to give some common values. Arbitrary
192 /// radices are supported.
193 ///
194 /// `from_digit()` will return `None` if the input is not a digit in
195 /// the given radix.
196 ///
197 /// # Panics
198 ///
199 /// Panics if given a radix larger than 36.
200 ///
201 /// # Examples
202 ///
203 /// Basic usage:
204 ///
205 /// ```
206 /// use std::char;
207 ///
208 /// let c = char::from_digit(4, 10);
209 ///
210 /// assert_eq!(Some('4'), c);
211 ///
212 /// // Decimal 11 is a single digit in base 16
213 /// let c = char::from_digit(11, 16);
214 ///
215 /// assert_eq!(Some('b'), c);
216 /// ```
217 ///
218 /// Returning `None` when the input is not a digit:
219 ///
220 /// ```
221 /// use std::char;
222 ///
223 /// let c = char::from_digit(20, 10);
224 ///
225 /// assert_eq!(None, c);
226 /// ```
227 ///
228 /// Passing a large radix, causing a panic:
229 ///
f035d41b 230 /// ```should_panic
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231 /// use std::char;
232 ///
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233 /// // this panics
234 /// char::from_digit(1, 37);
f9f354fc 235 /// ```
6a06907d 236 #[stable(feature = "assoc_char_funcs", since = "1.52.0")]
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237 #[inline]
238 pub fn from_digit(num: u32, radix: u32) -> Option<char> {
239 super::convert::from_digit(num, radix)
240 }
241
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242 /// Checks if a `char` is a digit in the given radix.
243 ///
244 /// A 'radix' here is sometimes also called a 'base'. A radix of two
245 /// indicates a binary number, a radix of ten, decimal, and a radix of
9cc50fc6 246 /// sixteen, hexadecimal, to give some common values. Arbitrary
476ff2be 247 /// radices are supported.
1a4d82fc 248 ///
fc512014 249 /// Compared to [`is_numeric()`], this function only recognizes the characters
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250 /// `0-9`, `a-z` and `A-Z`.
251 ///
b039eaaf 252 /// 'Digit' is defined to be only the following characters:
1a4d82fc 253 ///
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254 /// * `0-9`
255 /// * `a-z`
256 /// * `A-Z`
257 ///
fc512014 258 /// For a more comprehensive understanding of 'digit', see [`is_numeric()`].
b039eaaf 259 ///
fc512014 260 /// [`is_numeric()`]: #method.is_numeric
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261 ///
262 /// # Panics
263 ///
b039eaaf 264 /// Panics if given a radix larger than 36.
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265 ///
266 /// # Examples
267 ///
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268 /// Basic usage:
269 ///
c34b1796 270 /// ```
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271 /// assert!('1'.is_digit(10));
272 /// assert!('f'.is_digit(16));
273 /// assert!(!'f'.is_digit(10));
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274 /// ```
275 ///
276 /// Passing a large radix, causing a panic:
277 ///
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278 /// ```should_panic
279 /// // this panics
280 /// '1'.is_digit(37);
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281 /// ```
282 #[stable(feature = "rust1", since = "1.0.0")]
283 #[inline]
b039eaaf 284 pub fn is_digit(self, radix: u32) -> bool {
83c7162d 285 self.to_digit(radix).is_some()
b039eaaf 286 }
1a4d82fc 287
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288 /// Converts a `char` to a digit in the given radix.
289 ///
290 /// A 'radix' here is sometimes also called a 'base'. A radix of two
291 /// indicates a binary number, a radix of ten, decimal, and a radix of
9cc50fc6 292 /// sixteen, hexadecimal, to give some common values. Arbitrary
476ff2be 293 /// radices are supported.
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294 ///
295 /// 'Digit' is defined to be only the following characters:
296 ///
297 /// * `0-9`
298 /// * `a-z`
299 /// * `A-Z`
1a4d82fc 300 ///
7453a54e 301 /// # Errors
1a4d82fc 302 ///
b039eaaf 303 /// Returns `None` if the `char` does not refer to a digit in the given radix.
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304 ///
305 /// # Panics
306 ///
b039eaaf 307 /// Panics if given a radix larger than 36.
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308 ///
309 /// # Examples
310 ///
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311 /// Basic usage:
312 ///
313 /// ```
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314 /// assert_eq!('1'.to_digit(10), Some(1));
315 /// assert_eq!('f'.to_digit(16), Some(15));
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316 /// ```
317 ///
318 /// Passing a non-digit results in failure:
319 ///
320 /// ```
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321 /// assert_eq!('f'.to_digit(10), None);
322 /// assert_eq!('z'.to_digit(16), None);
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323 /// ```
324 ///
325 /// Passing a large radix, causing a panic:
326 ///
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327 /// ```should_panic
328 /// // this panics
329 /// '1'.to_digit(37);
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330 /// ```
331 #[stable(feature = "rust1", since = "1.0.0")]
62682a34 332 #[inline]
b039eaaf 333 pub fn to_digit(self, radix: u32) -> Option<u32> {
a1dfa0c6 334 assert!(radix <= 36, "to_digit: radix is too high (maximum 36)");
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335 // the code is split up here to improve execution speed for cases where
336 // the `radix` is constant and 10 or smaller
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337 let val = if likely(radix <= 10) {
338 // If not a digit, a number greater than radix will be created.
339 (self as u32).wrapping_sub('0' as u32)
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340 } else {
341 match self {
342 '0'..='9' => self as u32 - '0' as u32,
343 'a'..='z' => self as u32 - 'a' as u32 + 10,
344 'A'..='Z' => self as u32 - 'A' as u32 + 10,
345 _ => return None,
346 }
83c7162d 347 };
a1dfa0c6 348
60c5eb7d 349 if val < radix { Some(val) } else { None }
b039eaaf 350 }
1a4d82fc 351
c34b1796 352 /// Returns an iterator that yields the hexadecimal Unicode escape of a
32a655c1 353 /// character as `char`s.
1a4d82fc 354 ///
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355 /// This will escape characters with the Rust syntax of the form
356 /// `\u{NNNNNN}` where `NNNNNN` is a hexadecimal representation.
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357 ///
358 /// # Examples
359 ///
32a655c1 360 /// As an iterator:
92a42be0 361 ///
c34b1796 362 /// ```
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363 /// for c in '❤'.escape_unicode() {
364 /// print!("{}", c);
c34b1796 365 /// }
32a655c1 366 /// println!();
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367 /// ```
368 ///
32a655c1 369 /// Using `println!` directly:
c34b1796 370 ///
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371 /// ```
372 /// println!("{}", '❤'.escape_unicode());
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373 /// ```
374 ///
32a655c1 375 /// Both are equivalent to:
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376 ///
377 /// ```
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378 /// println!("\\u{{2764}}");
379 /// ```
c34b1796 380 ///
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381 /// Using `to_string`:
382 ///
383 /// ```
384 /// assert_eq!('❤'.escape_unicode().to_string(), "\\u{2764}");
c34b1796 385 /// ```
85aaf69f 386 #[stable(feature = "rust1", since = "1.0.0")]
62682a34 387 #[inline]
b039eaaf 388 pub fn escape_unicode(self) -> EscapeUnicode {
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389 let c = self as u32;
390
391 // or-ing 1 ensures that for c==0 the code computes that one
392 // digit should be printed and (which is the same) avoids the
393 // (31 - 32) underflow
394 let msb = 31 - (c | 1).leading_zeros();
395
396 // the index of the most significant hex digit
397 let ms_hex_digit = msb / 4;
398 EscapeUnicode {
399 c: self,
400 state: EscapeUnicodeState::Backslash,
401 hex_digit_idx: ms_hex_digit as usize,
402 }
b039eaaf 403 }
1a4d82fc 404
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405 /// An extended version of `escape_debug` that optionally permits escaping
406 /// Extended Grapheme codepoints. This allows us to format characters like
407 /// nonspacing marks better when they're at the start of a string.
94b46f34 408 #[inline]
9fa01778 409 pub(crate) fn escape_debug_ext(self, escape_grapheme_extended: bool) -> EscapeDebug {
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410 let init_state = match self {
411 '\t' => EscapeDefaultState::Backslash('t'),
412 '\r' => EscapeDefaultState::Backslash('r'),
413 '\n' => EscapeDefaultState::Backslash('n'),
414 '\\' | '\'' | '"' => EscapeDefaultState::Backslash(self),
415 _ if escape_grapheme_extended && self.is_grapheme_extended() => {
416 EscapeDefaultState::Unicode(self.escape_unicode())
417 }
418 _ if is_printable(self) => EscapeDefaultState::Char(self),
419 _ => EscapeDefaultState::Unicode(self.escape_unicode()),
420 };
421 EscapeDebug(EscapeDefault { state: init_state })
422 }
423
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424 /// Returns an iterator that yields the literal escape code of a character
425 /// as `char`s.
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426 ///
427 /// This will escape the characters similar to the `Debug` implementations
428 /// of `str` or `char`.
429 ///
430 /// # Examples
431 ///
32a655c1 432 /// As an iterator:
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433 ///
434 /// ```
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435 /// for c in '\n'.escape_debug() {
436 /// print!("{}", c);
5bcae85e 437 /// }
32a655c1 438 /// println!();
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439 /// ```
440 ///
32a655c1 441 /// Using `println!` directly:
5bcae85e 442 ///
32a655c1 443 /// ```
32a655c1 444 /// println!("{}", '\n'.escape_debug());
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445 /// ```
446 ///
32a655c1 447 /// Both are equivalent to:
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448 ///
449 /// ```
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450 /// println!("\\n");
451 /// ```
5bcae85e 452 ///
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453 /// Using `to_string`:
454 ///
455 /// ```
32a655c1 456 /// assert_eq!('\n'.escape_debug().to_string(), "\\n");
5bcae85e 457 /// ```
041b39d2 458 #[stable(feature = "char_escape_debug", since = "1.20.0")]
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459 #[inline]
460 pub fn escape_debug(self) -> EscapeDebug {
94b46f34 461 self.escape_debug_ext(true)
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462 }
463
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464 /// Returns an iterator that yields the literal escape code of a character
465 /// as `char`s.
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466 ///
467 /// The default is chosen with a bias toward producing literals that are
468 /// legal in a variety of languages, including C++11 and similar C-family
469 /// languages. The exact rules are:
470 ///
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471 /// * Tab is escaped as `\t`.
472 /// * Carriage return is escaped as `\r`.
473 /// * Line feed is escaped as `\n`.
474 /// * Single quote is escaped as `\'`.
475 /// * Double quote is escaped as `\"`.
476 /// * Backslash is escaped as `\\`.
477 /// * Any character in the 'printable ASCII' range `0x20` .. `0x7e`
478 /// inclusive is not escaped.
479 /// * All other characters are given hexadecimal Unicode escapes; see
fc512014 480 /// [`escape_unicode`].
b039eaaf 481 ///
fc512014 482 /// [`escape_unicode`]: #method.escape_unicode
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483 ///
484 /// # Examples
485 ///
32a655c1 486 /// As an iterator:
b039eaaf 487 ///
c34b1796 488 /// ```
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489 /// for c in '"'.escape_default() {
490 /// print!("{}", c);
c34b1796 491 /// }
32a655c1 492 /// println!();
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493 /// ```
494 ///
32a655c1 495 /// Using `println!` directly:
c34b1796 496 ///
c34b1796 497 /// ```
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498 /// println!("{}", '"'.escape_default());
499 /// ```
500 ///
32a655c1 501 /// Both are equivalent to:
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502 ///
503 /// ```
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504 /// println!("\\\"");
505 /// ```
506 ///
507 /// Using `to_string`:
c34b1796 508 ///
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509 /// ```
510 /// assert_eq!('"'.escape_default().to_string(), "\\\"");
c34b1796 511 /// ```
85aaf69f 512 #[stable(feature = "rust1", since = "1.0.0")]
62682a34 513 #[inline]
b039eaaf 514 pub fn escape_default(self) -> EscapeDefault {
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515 let init_state = match self {
516 '\t' => EscapeDefaultState::Backslash('t'),
517 '\r' => EscapeDefaultState::Backslash('r'),
518 '\n' => EscapeDefaultState::Backslash('n'),
519 '\\' | '\'' | '"' => EscapeDefaultState::Backslash(self),
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520 '\x20'..='\x7e' => EscapeDefaultState::Char(self),
521 _ => EscapeDefaultState::Unicode(self.escape_unicode()),
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522 };
523 EscapeDefault { state: init_state }
b039eaaf 524 }
1a4d82fc 525
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526 /// Returns the number of bytes this `char` would need if encoded in UTF-8.
527 ///
528 /// That number of bytes is always between 1 and 4, inclusive.
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529 ///
530 /// # Examples
531 ///
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532 /// Basic usage:
533 ///
c34b1796 534 /// ```
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535 /// let len = 'A'.len_utf8();
536 /// assert_eq!(len, 1);
537 ///
538 /// let len = 'ß'.len_utf8();
539 /// assert_eq!(len, 2);
540 ///
541 /// let len = 'ℝ'.len_utf8();
542 /// assert_eq!(len, 3);
c34b1796 543 ///
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544 /// let len = '💣'.len_utf8();
545 /// assert_eq!(len, 4);
546 /// ```
547 ///
548 /// The `&str` type guarantees that its contents are UTF-8, and so we can compare the length it
549 /// would take if each code point was represented as a `char` vs in the `&str` itself:
550 ///
551 /// ```
552 /// // as chars
553 /// let eastern = '東';
dc9dc135 554 /// let capital = '京';
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555 ///
556 /// // both can be represented as three bytes
557 /// assert_eq!(3, eastern.len_utf8());
dc9dc135 558 /// assert_eq!(3, capital.len_utf8());
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559 ///
560 /// // as a &str, these two are encoded in UTF-8
561 /// let tokyo = "東京";
562 ///
dc9dc135 563 /// let len = eastern.len_utf8() + capital.len_utf8();
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564 ///
565 /// // we can see that they take six bytes total...
566 /// assert_eq!(6, tokyo.len());
567 ///
568 /// // ... just like the &str
569 /// assert_eq!(len, tokyo.len());
c34b1796 570 /// ```
85aaf69f 571 #[stable(feature = "rust1", since = "1.0.0")]
6a06907d 572 #[rustc_const_stable(feature = "const_char_len_utf", since = "1.52.0")]
62682a34 573 #[inline]
6a06907d 574 pub const fn len_utf8(self) -> usize {
f9f354fc 575 len_utf8(self as u32)
b039eaaf 576 }
1a4d82fc 577
b039eaaf 578 /// Returns the number of 16-bit code units this `char` would need if
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579 /// encoded in UTF-16.
580 ///
fc512014 581 /// See the documentation for [`len_utf8()`] for more explanation of this
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582 /// concept. This function is a mirror, but for UTF-16 instead of UTF-8.
583 ///
fc512014 584 /// [`len_utf8()`]: #method.len_utf8
b039eaaf 585 ///
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586 /// # Examples
587 ///
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588 /// Basic usage:
589 ///
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590 /// ```
591 /// let n = 'ß'.len_utf16();
c34b1796 592 /// assert_eq!(n, 1);
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593 ///
594 /// let len = '💣'.len_utf16();
595 /// assert_eq!(len, 2);
c34b1796 596 /// ```
85aaf69f 597 #[stable(feature = "rust1", since = "1.0.0")]
6a06907d 598 #[rustc_const_stable(feature = "const_char_len_utf", since = "1.52.0")]
62682a34 599 #[inline]
6a06907d 600 pub const fn len_utf16(self) -> usize {
83c7162d
XL
601 let ch = self as u32;
602 if (ch & 0xFFFF) == ch { 1 } else { 2 }
b039eaaf 603 }
1a4d82fc 604
c30ab7b3
SL
605 /// Encodes this character as UTF-8 into the provided byte buffer,
606 /// and then returns the subslice of the buffer that contains the encoded character.
c34b1796 607 ///
c30ab7b3
SL
608 /// # Panics
609 ///
610 /// Panics if the buffer is not large enough.
611 /// A buffer of length four is large enough to encode any `char`.
c34b1796
AL
612 ///
613 /// # Examples
614 ///
c30ab7b3
SL
615 /// In both of these examples, 'ß' takes two bytes to encode.
616 ///
c34b1796 617 /// ```
c30ab7b3 618 /// let mut b = [0; 2];
c34b1796 619 ///
c30ab7b3
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620 /// let result = 'ß'.encode_utf8(&mut b);
621 ///
622 /// assert_eq!(result, "ß");
623 ///
624 /// assert_eq!(result.len(), 2);
625 /// ```
626 ///
627 /// A buffer that's too small:
628 ///
f035d41b
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629 /// ```should_panic
630 /// let mut b = [0; 1];
c30ab7b3 631 ///
f035d41b
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632 /// // this panics
633 /// 'ß'.encode_utf8(&mut b);
c34b1796 634 /// ```
476ff2be 635 #[stable(feature = "unicode_encode_char", since = "1.15.0")]
62682a34 636 #[inline]
c30ab7b3 637 pub fn encode_utf8(self, dst: &mut [u8]) -> &mut str {
f9f354fc
XL
638 // SAFETY: `char` is not a surrogate, so this is valid UTF-8.
639 unsafe { from_utf8_unchecked_mut(encode_utf8_raw(self as u32, dst)) }
62682a34 640 }
1a4d82fc 641
c30ab7b3
SL
642 /// Encodes this character as UTF-16 into the provided `u16` buffer,
643 /// and then returns the subslice of the buffer that contains the encoded character.
c34b1796 644 ///
c30ab7b3
SL
645 /// # Panics
646 ///
647 /// Panics if the buffer is not large enough.
648 /// A buffer of length 2 is large enough to encode any `char`.
c34b1796
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649 ///
650 /// # Examples
651 ///
c30ab7b3
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652 /// In both of these examples, '𝕊' takes two `u16`s to encode.
653 ///
c34b1796 654 /// ```
c30ab7b3 655 /// let mut b = [0; 2];
c34b1796 656 ///
c30ab7b3
SL
657 /// let result = '𝕊'.encode_utf16(&mut b);
658 ///
659 /// assert_eq!(result.len(), 2);
660 /// ```
661 ///
662 /// A buffer that's too small:
663 ///
f035d41b
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664 /// ```should_panic
665 /// let mut b = [0; 1];
c30ab7b3 666 ///
f035d41b
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667 /// // this panics
668 /// '𝕊'.encode_utf16(&mut b);
c34b1796 669 /// ```
476ff2be 670 #[stable(feature = "unicode_encode_char", since = "1.15.0")]
62682a34 671 #[inline]
c30ab7b3 672 pub fn encode_utf16(self, dst: &mut [u16]) -> &mut [u16] {
f9f354fc 673 encode_utf16_raw(self as u32, dst)
62682a34 674 }
1a4d82fc 675
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676 /// Returns `true` if this `char` has the `Alphabetic` property.
677 ///
678 /// `Alphabetic` is described in Chapter 4 (Character Properties) of the [Unicode Standard] and
679 /// specified in the [Unicode Character Database][ucd] [`DerivedCoreProperties.txt`].
680 ///
681 /// [Unicode Standard]: https://www.unicode.org/versions/latest/
682 /// [ucd]: https://www.unicode.org/reports/tr44/
683 /// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
b039eaaf
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684 ///
685 /// # Examples
686 ///
687 /// Basic usage:
688 ///
689 /// ```
54a0048b
SL
690 /// assert!('a'.is_alphabetic());
691 /// assert!('京'.is_alphabetic());
b039eaaf
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692 ///
693 /// let c = '💝';
694 /// // love is many things, but it is not alphabetic
695 /// assert!(!c.is_alphabetic());
696 /// ```
85aaf69f 697 #[stable(feature = "rust1", since = "1.0.0")]
c34b1796
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698 #[inline]
699 pub fn is_alphabetic(self) -> bool {
700 match self {
8faf50e0 701 'a'..='z' | 'A'..='Z' => true,
dfeec247 702 c => c > '\x7f' && unicode::Alphabetic(c),
c34b1796
AL
703 }
704 }
1a4d82fc 705
e74abb32 706 /// Returns `true` if this `char` has the `Lowercase` property.
1a4d82fc 707 ///
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708 /// `Lowercase` is described in Chapter 4 (Character Properties) of the [Unicode Standard] and
709 /// specified in the [Unicode Character Database][ucd] [`DerivedCoreProperties.txt`].
710 ///
711 /// [Unicode Standard]: https://www.unicode.org/versions/latest/
712 /// [ucd]: https://www.unicode.org/reports/tr44/
713 /// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
b039eaaf
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714 ///
715 /// # Examples
716 ///
717 /// Basic usage:
718 ///
719 /// ```
54a0048b
SL
720 /// assert!('a'.is_lowercase());
721 /// assert!('δ'.is_lowercase());
722 /// assert!(!'A'.is_lowercase());
723 /// assert!(!'Δ'.is_lowercase());
b039eaaf 724 ///
f9f354fc 725 /// // The various Chinese scripts and punctuation do not have case, and so:
54a0048b 726 /// assert!(!'中'.is_lowercase());
f9f354fc 727 /// assert!(!' '.is_lowercase());
b039eaaf 728 /// ```
85aaf69f 729 #[stable(feature = "rust1", since = "1.0.0")]
c34b1796
AL
730 #[inline]
731 pub fn is_lowercase(self) -> bool {
732 match self {
8faf50e0 733 'a'..='z' => true,
dfeec247 734 c => c > '\x7f' && unicode::Lowercase(c),
c34b1796
AL
735 }
736 }
1a4d82fc 737
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738 /// Returns `true` if this `char` has the `Uppercase` property.
739 ///
740 /// `Uppercase` is described in Chapter 4 (Character Properties) of the [Unicode Standard] and
741 /// specified in the [Unicode Character Database][ucd] [`DerivedCoreProperties.txt`].
1a4d82fc 742 ///
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743 /// [Unicode Standard]: https://www.unicode.org/versions/latest/
744 /// [ucd]: https://www.unicode.org/reports/tr44/
745 /// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
b039eaaf
SL
746 ///
747 /// # Examples
748 ///
749 /// Basic usage:
750 ///
751 /// ```
54a0048b
SL
752 /// assert!(!'a'.is_uppercase());
753 /// assert!(!'δ'.is_uppercase());
754 /// assert!('A'.is_uppercase());
755 /// assert!('Δ'.is_uppercase());
b039eaaf 756 ///
f9f354fc 757 /// // The various Chinese scripts and punctuation do not have case, and so:
54a0048b 758 /// assert!(!'中'.is_uppercase());
f9f354fc 759 /// assert!(!' '.is_uppercase());
b039eaaf 760 /// ```
85aaf69f 761 #[stable(feature = "rust1", since = "1.0.0")]
c34b1796
AL
762 #[inline]
763 pub fn is_uppercase(self) -> bool {
764 match self {
8faf50e0 765 'A'..='Z' => true,
dfeec247 766 c => c > '\x7f' && unicode::Uppercase(c),
c34b1796
AL
767 }
768 }
1a4d82fc 769
e74abb32 770 /// Returns `true` if this `char` has the `White_Space` property.
b039eaaf 771 ///
e74abb32
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772 /// `White_Space` is specified in the [Unicode Character Database][ucd] [`PropList.txt`].
773 ///
774 /// [ucd]: https://www.unicode.org/reports/tr44/
775 /// [`PropList.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/PropList.txt
b039eaaf
SL
776 ///
777 /// # Examples
1a4d82fc 778 ///
b039eaaf
SL
779 /// Basic usage:
780 ///
781 /// ```
54a0048b 782 /// assert!(' '.is_whitespace());
b039eaaf
SL
783 ///
784 /// // a non-breaking space
54a0048b 785 /// assert!('\u{A0}'.is_whitespace());
b039eaaf 786 ///
54a0048b 787 /// assert!(!'越'.is_whitespace());
b039eaaf 788 /// ```
85aaf69f 789 #[stable(feature = "rust1", since = "1.0.0")]
c34b1796
AL
790 #[inline]
791 pub fn is_whitespace(self) -> bool {
792 match self {
8faf50e0 793 ' ' | '\x09'..='\x0d' => true,
dfeec247 794 c => c > '\x7f' && unicode::White_Space(c),
c34b1796
AL
795 }
796 }
1a4d82fc 797
e74abb32 798 /// Returns `true` if this `char` satisfies either [`is_alphabetic()`] or [`is_numeric()`].
1a4d82fc 799 ///
e74abb32
XL
800 /// [`is_alphabetic()`]: #method.is_alphabetic
801 /// [`is_numeric()`]: #method.is_numeric
b039eaaf
SL
802 ///
803 /// # Examples
804 ///
805 /// Basic usage:
806 ///
807 /// ```
54a0048b
SL
808 /// assert!('٣'.is_alphanumeric());
809 /// assert!('7'.is_alphanumeric());
810 /// assert!('৬'.is_alphanumeric());
b7449926
XL
811 /// assert!('¾'.is_alphanumeric());
812 /// assert!('①'.is_alphanumeric());
54a0048b
SL
813 /// assert!('K'.is_alphanumeric());
814 /// assert!('و'.is_alphanumeric());
815 /// assert!('藏'.is_alphanumeric());
b039eaaf 816 /// ```
85aaf69f 817 #[stable(feature = "rust1", since = "1.0.0")]
c34b1796
AL
818 #[inline]
819 pub fn is_alphanumeric(self) -> bool {
820 self.is_alphabetic() || self.is_numeric()
821 }
1a4d82fc 822
e74abb32
XL
823 /// Returns `true` if this `char` has the general category for control codes.
824 ///
825 /// Control codes (code points with the general category of `Cc`) are described in Chapter 4
826 /// (Character Properties) of the [Unicode Standard] and specified in the [Unicode Character
827 /// Database][ucd] [`UnicodeData.txt`].
1a4d82fc 828 ///
e74abb32
XL
829 /// [Unicode Standard]: https://www.unicode.org/versions/latest/
830 /// [ucd]: https://www.unicode.org/reports/tr44/
831 /// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
b039eaaf
SL
832 ///
833 /// # Examples
834 ///
835 /// Basic usage:
836 ///
837 /// ```
838 /// // U+009C, STRING TERMINATOR
54a0048b
SL
839 /// assert!('\9c'.is_control());
840 /// assert!(!'q'.is_control());
b039eaaf 841 /// ```
85aaf69f 842 #[stable(feature = "rust1", since = "1.0.0")]
c34b1796 843 #[inline]
b039eaaf 844 pub fn is_control(self) -> bool {
dfeec247 845 unicode::Cc(self)
b039eaaf 846 }
1a4d82fc 847
e74abb32 848 /// Returns `true` if this `char` has the `Grapheme_Extend` property.
94b46f34 849 ///
e74abb32
XL
850 /// `Grapheme_Extend` is described in [Unicode Standard Annex #29 (Unicode Text
851 /// Segmentation)][uax29] and specified in the [Unicode Character Database][ucd]
852 /// [`DerivedCoreProperties.txt`].
853 ///
854 /// [uax29]: https://www.unicode.org/reports/tr29/
855 /// [ucd]: https://www.unicode.org/reports/tr44/
856 /// [`DerivedCoreProperties.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/DerivedCoreProperties.txt
94b46f34
XL
857 #[inline]
858 pub(crate) fn is_grapheme_extended(self) -> bool {
dfeec247 859 unicode::Grapheme_Extend(self)
94b46f34
XL
860 }
861
e74abb32
XL
862 /// Returns `true` if this `char` has one of the general categories for numbers.
863 ///
864 /// The general categories for numbers (`Nd` for decimal digits, `Nl` for letter-like numeric
865 /// characters, and `No` for other numeric characters) are specified in the [Unicode Character
866 /// Database][ucd] [`UnicodeData.txt`].
b039eaaf 867 ///
e74abb32
XL
868 /// [Unicode Standard]: https://www.unicode.org/versions/latest/
869 /// [ucd]: https://www.unicode.org/reports/tr44/
870 /// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
b039eaaf
SL
871 ///
872 /// # Examples
873 ///
874 /// Basic usage:
875 ///
876 /// ```
54a0048b
SL
877 /// assert!('٣'.is_numeric());
878 /// assert!('7'.is_numeric());
879 /// assert!('৬'.is_numeric());
b7449926
XL
880 /// assert!('¾'.is_numeric());
881 /// assert!('①'.is_numeric());
54a0048b
SL
882 /// assert!(!'K'.is_numeric());
883 /// assert!(!'و'.is_numeric());
884 /// assert!(!'藏'.is_numeric());
b039eaaf 885 /// ```
85aaf69f 886 #[stable(feature = "rust1", since = "1.0.0")]
c34b1796
AL
887 #[inline]
888 pub fn is_numeric(self) -> bool {
889 match self {
8faf50e0 890 '0'..='9' => true,
dfeec247 891 c => c > '\x7f' && unicode::N(c),
c34b1796
AL
892 }
893 }
1a4d82fc 894
e74abb32
XL
895 /// Returns an iterator that yields the lowercase mapping of this `char` as one or more
896 /// `char`s.
1a4d82fc 897 ///
e74abb32 898 /// If this `char` does not have a lowercase mapping, the iterator yields the same `char`.
1a4d82fc 899 ///
e74abb32
XL
900 /// If this `char` has a one-to-one lowercase mapping given by the [Unicode Character
901 /// Database][ucd] [`UnicodeData.txt`], the iterator yields that `char`.
1a4d82fc 902 ///
e74abb32
XL
903 /// [ucd]: https://www.unicode.org/reports/tr44/
904 /// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
b039eaaf 905 ///
e74abb32
XL
906 /// If this `char` requires special considerations (e.g. multiple `char`s) the iterator yields
907 /// the `char`(s) given by [`SpecialCasing.txt`].
b039eaaf 908 ///
e74abb32 909 /// [`SpecialCasing.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/SpecialCasing.txt
b039eaaf 910 ///
e74abb32
XL
911 /// This operation performs an unconditional mapping without tailoring. That is, the conversion
912 /// is independent of context and language.
913 ///
914 /// In the [Unicode Standard], Chapter 4 (Character Properties) discusses case mapping in
915 /// general and Chapter 3 (Conformance) discusses the default algorithm for case conversion.
916 ///
917 /// [Unicode Standard]: https://www.unicode.org/versions/latest/
62682a34
SL
918 ///
919 /// # Examples
920 ///
32a655c1 921 /// As an iterator:
b039eaaf 922 ///
62682a34 923 /// ```
32a655c1
SL
924 /// for c in 'İ'.to_lowercase() {
925 /// print!("{}", c);
926 /// }
927 /// println!();
928 /// ```
929 ///
930 /// Using `println!` directly:
931 ///
932 /// ```
933 /// println!("{}", 'İ'.to_lowercase());
934 /// ```
935 ///
936 /// Both are equivalent to:
937 ///
938 /// ```
939 /// println!("i\u{307}");
940 /// ```
941 ///
942 /// Using `to_string`:
943 ///
944 /// ```
945 /// assert_eq!('C'.to_lowercase().to_string(), "c");
3157f602
XL
946 ///
947 /// // Sometimes the result is more than one character:
32a655c1 948 /// assert_eq!('İ'.to_lowercase().to_string(), "i\u{307}");
b039eaaf 949 ///
cc61c64b
XL
950 /// // Characters that do not have both uppercase and lowercase
951 /// // convert into themselves.
32a655c1 952 /// assert_eq!('山'.to_lowercase().to_string(), "山");
62682a34 953 /// ```
c34b1796
AL
954 #[stable(feature = "rust1", since = "1.0.0")]
955 #[inline]
956 pub fn to_lowercase(self) -> ToLowercase {
62682a34
SL
957 ToLowercase(CaseMappingIter::new(conversions::to_lower(self)))
958 }
959
e74abb32
XL
960 /// Returns an iterator that yields the uppercase mapping of this `char` as one or more
961 /// `char`s.
962 ///
963 /// If this `char` does not have a uppercase mapping, the iterator yields the same `char`.
964 ///
965 /// If this `char` has a one-to-one uppercase mapping given by the [Unicode Character
966 /// Database][ucd] [`UnicodeData.txt`], the iterator yields that `char`.
1a4d82fc 967 ///
e74abb32
XL
968 /// [ucd]: https://www.unicode.org/reports/tr44/
969 /// [`UnicodeData.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt
1a4d82fc 970 ///
e74abb32
XL
971 /// If this `char` requires special considerations (e.g. multiple `char`s) the iterator yields
972 /// the `char`(s) given by [`SpecialCasing.txt`].
1a4d82fc 973 ///
e74abb32 974 /// [`SpecialCasing.txt`]: https://www.unicode.org/Public/UCD/latest/ucd/SpecialCasing.txt
1a4d82fc 975 ///
e74abb32
XL
976 /// This operation performs an unconditional mapping without tailoring. That is, the conversion
977 /// is independent of context and language.
1a4d82fc 978 ///
e74abb32
XL
979 /// In the [Unicode Standard], Chapter 4 (Character Properties) discusses case mapping in
980 /// general and Chapter 3 (Conformance) discusses the default algorithm for case conversion.
62682a34 981 ///
e74abb32 982 /// [Unicode Standard]: https://www.unicode.org/versions/latest/
1a4d82fc 983 ///
62682a34
SL
984 /// # Examples
985 ///
32a655c1
SL
986 /// As an iterator:
987 ///
988 /// ```
989 /// for c in 'ß'.to_uppercase() {
990 /// print!("{}", c);
991 /// }
992 /// println!();
993 /// ```
994 ///
995 /// Using `println!` directly:
996 ///
997 /// ```
998 /// println!("{}", 'ß'.to_uppercase());
999 /// ```
1000 ///
1001 /// Both are equivalent to:
1002 ///
1003 /// ```
1004 /// println!("SS");
1005 /// ```
1006 ///
1007 /// Using `to_string`:
b039eaaf
SL
1008 ///
1009 /// ```
32a655c1 1010 /// assert_eq!('c'.to_uppercase().to_string(), "C");
3157f602
XL
1011 ///
1012 /// // Sometimes the result is more than one character:
32a655c1 1013 /// assert_eq!('ß'.to_uppercase().to_string(), "SS");
b039eaaf 1014 ///
cc61c64b
XL
1015 /// // Characters that do not have both uppercase and lowercase
1016 /// // convert into themselves.
32a655c1 1017 /// assert_eq!('山'.to_uppercase().to_string(), "山");
b039eaaf
SL
1018 /// ```
1019 ///
32a655c1
SL
1020 /// # Note on locale
1021 ///
b039eaaf
SL
1022 /// In Turkish, the equivalent of 'i' in Latin has five forms instead of two:
1023 ///
1024 /// * 'Dotless': I / ı, sometimes written ï
1025 /// * 'Dotted': İ / i
1026 ///
1027 /// Note that the lowercase dotted 'i' is the same as the Latin. Therefore:
1028 ///
1029 /// ```
32a655c1 1030 /// let upper_i = 'i'.to_uppercase().to_string();
b039eaaf
SL
1031 /// ```
1032 ///
1033 /// The value of `upper_i` here relies on the language of the text: if we're
3157f602
XL
1034 /// in `en-US`, it should be `"I"`, but if we're in `tr_TR`, it should
1035 /// be `"İ"`. `to_uppercase()` does not take this into account, and so:
b039eaaf 1036 ///
62682a34 1037 /// ```
32a655c1 1038 /// let upper_i = 'i'.to_uppercase().to_string();
b039eaaf 1039 ///
3157f602 1040 /// assert_eq!(upper_i, "I");
62682a34 1041 /// ```
b039eaaf
SL
1042 ///
1043 /// holds across languages.
c34b1796
AL
1044 #[stable(feature = "rust1", since = "1.0.0")]
1045 #[inline]
1046 pub fn to_uppercase(self) -> ToUppercase {
62682a34 1047 ToUppercase(CaseMappingIter::new(conversions::to_upper(self)))
c34b1796 1048 }
abe05a73
XL
1049
1050 /// Checks if the value is within the ASCII range.
1051 ///
1052 /// # Examples
1053 ///
1054 /// ```
1055 /// let ascii = 'a';
1056 /// let non_ascii = '❤';
1057 ///
1058 /// assert!(ascii.is_ascii());
1059 /// assert!(!non_ascii.is_ascii());
1060 /// ```
ff7c6d11 1061 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
dfeec247 1062 #[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.32.0")]
abe05a73 1063 #[inline]
a1dfa0c6 1064 pub const fn is_ascii(&self) -> bool {
abe05a73
XL
1065 *self as u32 <= 0x7F
1066 }
1067
1068 /// Makes a copy of the value in its ASCII upper case equivalent.
1069 ///
1070 /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
1071 /// but non-ASCII letters are unchanged.
1072 ///
fc512014 1073 /// To uppercase the value in-place, use [`make_ascii_uppercase()`].
abe05a73
XL
1074 ///
1075 /// To uppercase ASCII characters in addition to non-ASCII characters, use
fc512014 1076 /// [`to_uppercase()`].
abe05a73
XL
1077 ///
1078 /// # Examples
1079 ///
1080 /// ```
1081 /// let ascii = 'a';
1082 /// let non_ascii = '❤';
1083 ///
1084 /// assert_eq!('A', ascii.to_ascii_uppercase());
1085 /// assert_eq!('❤', non_ascii.to_ascii_uppercase());
1086 /// ```
1087 ///
fc512014
XL
1088 /// [`make_ascii_uppercase()`]: #method.make_ascii_uppercase
1089 /// [`to_uppercase()`]: #method.to_uppercase
ff7c6d11 1090 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
6a06907d 1091 #[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
abe05a73 1092 #[inline]
6a06907d
XL
1093 pub const fn to_ascii_uppercase(&self) -> char {
1094 if self.is_ascii_lowercase() {
1095 (*self as u8).ascii_change_case_unchecked() as char
1096 } else {
1097 *self
1098 }
abe05a73
XL
1099 }
1100
1101 /// Makes a copy of the value in its ASCII lower case equivalent.
1102 ///
1103 /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
1104 /// but non-ASCII letters are unchanged.
1105 ///
fc512014 1106 /// To lowercase the value in-place, use [`make_ascii_lowercase()`].
abe05a73
XL
1107 ///
1108 /// To lowercase ASCII characters in addition to non-ASCII characters, use
fc512014 1109 /// [`to_lowercase()`].
abe05a73
XL
1110 ///
1111 /// # Examples
1112 ///
1113 /// ```
1114 /// let ascii = 'A';
1115 /// let non_ascii = '❤';
1116 ///
1117 /// assert_eq!('a', ascii.to_ascii_lowercase());
1118 /// assert_eq!('❤', non_ascii.to_ascii_lowercase());
1119 /// ```
1120 ///
fc512014
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1121 /// [`make_ascii_lowercase()`]: #method.make_ascii_lowercase
1122 /// [`to_lowercase()`]: #method.to_lowercase
ff7c6d11 1123 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
6a06907d 1124 #[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
abe05a73 1125 #[inline]
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1126 pub const fn to_ascii_lowercase(&self) -> char {
1127 if self.is_ascii_uppercase() {
1128 (*self as u8).ascii_change_case_unchecked() as char
1129 } else {
1130 *self
1131 }
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1132 }
1133
1134 /// Checks that two values are an ASCII case-insensitive match.
1135 ///
1136 /// Equivalent to `to_ascii_lowercase(a) == to_ascii_lowercase(b)`.
1137 ///
1138 /// # Examples
1139 ///
1140 /// ```
1141 /// let upper_a = 'A';
1142 /// let lower_a = 'a';
1143 /// let lower_z = 'z';
1144 ///
1145 /// assert!(upper_a.eq_ignore_ascii_case(&lower_a));
1146 /// assert!(upper_a.eq_ignore_ascii_case(&upper_a));
1147 /// assert!(!upper_a.eq_ignore_ascii_case(&lower_z));
1148 /// ```
ff7c6d11 1149 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
6a06907d 1150 #[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
abe05a73 1151 #[inline]
6a06907d 1152 pub const fn eq_ignore_ascii_case(&self, other: &char) -> bool {
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1153 self.to_ascii_lowercase() == other.to_ascii_lowercase()
1154 }
1155
1156 /// Converts this type to its ASCII upper case equivalent in-place.
1157 ///
1158 /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
1159 /// but non-ASCII letters are unchanged.
1160 ///
1161 /// To return a new uppercased value without modifying the existing one, use
fc512014 1162 /// [`to_ascii_uppercase()`].
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1163 ///
1164 /// # Examples
1165 ///
1166 /// ```
1167 /// let mut ascii = 'a';
1168 ///
1169 /// ascii.make_ascii_uppercase();
1170 ///
1171 /// assert_eq!('A', ascii);
1172 /// ```
1173 ///
fc512014 1174 /// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase
ff7c6d11 1175 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
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1176 #[inline]
1177 pub fn make_ascii_uppercase(&mut self) {
1178 *self = self.to_ascii_uppercase();
1179 }
1180
1181 /// Converts this type to its ASCII lower case equivalent in-place.
1182 ///
1183 /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
1184 /// but non-ASCII letters are unchanged.
1185 ///
1186 /// To return a new lowercased value without modifying the existing one, use
fc512014 1187 /// [`to_ascii_lowercase()`].
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1188 ///
1189 /// # Examples
1190 ///
1191 /// ```
1192 /// let mut ascii = 'A';
1193 ///
1194 /// ascii.make_ascii_lowercase();
1195 ///
1196 /// assert_eq!('a', ascii);
1197 /// ```
1198 ///
fc512014 1199 /// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase
ff7c6d11 1200 #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
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1201 #[inline]
1202 pub fn make_ascii_lowercase(&mut self) {
1203 *self = self.to_ascii_lowercase();
1204 }
1205
1206 /// Checks if the value is an ASCII alphabetic character:
1207 ///
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1208 /// - U+0041 'A' ..= U+005A 'Z', or
1209 /// - U+0061 'a' ..= U+007A 'z'.
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1210 ///
1211 /// # Examples
1212 ///
1213 /// ```
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1214 /// let uppercase_a = 'A';
1215 /// let uppercase_g = 'G';
1216 /// let a = 'a';
1217 /// let g = 'g';
1218 /// let zero = '0';
1219 /// let percent = '%';
1220 /// let space = ' ';
1221 /// let lf = '\n';
1222 /// let esc: char = 0x1b_u8.into();
1223 ///
1224 /// assert!(uppercase_a.is_ascii_alphabetic());
1225 /// assert!(uppercase_g.is_ascii_alphabetic());
1226 /// assert!(a.is_ascii_alphabetic());
1227 /// assert!(g.is_ascii_alphabetic());
1228 /// assert!(!zero.is_ascii_alphabetic());
1229 /// assert!(!percent.is_ascii_alphabetic());
1230 /// assert!(!space.is_ascii_alphabetic());
1231 /// assert!(!lf.is_ascii_alphabetic());
1232 /// assert!(!esc.is_ascii_alphabetic());
1233 /// ```
ff7c6d11 1234 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1235 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1236 #[inline]
74b04a01 1237 pub const fn is_ascii_alphabetic(&self) -> bool {
29967ef6 1238 matches!(*self, 'A'..='Z' | 'a'..='z')
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1239 }
1240
1241 /// Checks if the value is an ASCII uppercase character:
dc9dc135 1242 /// U+0041 'A' ..= U+005A 'Z'.
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1243 ///
1244 /// # Examples
1245 ///
1246 /// ```
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1247 /// let uppercase_a = 'A';
1248 /// let uppercase_g = 'G';
1249 /// let a = 'a';
1250 /// let g = 'g';
1251 /// let zero = '0';
1252 /// let percent = '%';
1253 /// let space = ' ';
1254 /// let lf = '\n';
1255 /// let esc: char = 0x1b_u8.into();
1256 ///
1257 /// assert!(uppercase_a.is_ascii_uppercase());
1258 /// assert!(uppercase_g.is_ascii_uppercase());
1259 /// assert!(!a.is_ascii_uppercase());
1260 /// assert!(!g.is_ascii_uppercase());
1261 /// assert!(!zero.is_ascii_uppercase());
1262 /// assert!(!percent.is_ascii_uppercase());
1263 /// assert!(!space.is_ascii_uppercase());
1264 /// assert!(!lf.is_ascii_uppercase());
1265 /// assert!(!esc.is_ascii_uppercase());
1266 /// ```
ff7c6d11 1267 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1268 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1269 #[inline]
74b04a01 1270 pub const fn is_ascii_uppercase(&self) -> bool {
29967ef6 1271 matches!(*self, 'A'..='Z')
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1272 }
1273
1274 /// Checks if the value is an ASCII lowercase character:
dc9dc135 1275 /// U+0061 'a' ..= U+007A 'z'.
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1276 ///
1277 /// # Examples
1278 ///
1279 /// ```
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1280 /// let uppercase_a = 'A';
1281 /// let uppercase_g = 'G';
1282 /// let a = 'a';
1283 /// let g = 'g';
1284 /// let zero = '0';
1285 /// let percent = '%';
1286 /// let space = ' ';
1287 /// let lf = '\n';
1288 /// let esc: char = 0x1b_u8.into();
1289 ///
1290 /// assert!(!uppercase_a.is_ascii_lowercase());
1291 /// assert!(!uppercase_g.is_ascii_lowercase());
1292 /// assert!(a.is_ascii_lowercase());
1293 /// assert!(g.is_ascii_lowercase());
1294 /// assert!(!zero.is_ascii_lowercase());
1295 /// assert!(!percent.is_ascii_lowercase());
1296 /// assert!(!space.is_ascii_lowercase());
1297 /// assert!(!lf.is_ascii_lowercase());
1298 /// assert!(!esc.is_ascii_lowercase());
1299 /// ```
ff7c6d11 1300 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1301 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1302 #[inline]
74b04a01 1303 pub const fn is_ascii_lowercase(&self) -> bool {
29967ef6 1304 matches!(*self, 'a'..='z')
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1305 }
1306
1307 /// Checks if the value is an ASCII alphanumeric character:
1308 ///
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1309 /// - U+0041 'A' ..= U+005A 'Z', or
1310 /// - U+0061 'a' ..= U+007A 'z', or
1311 /// - U+0030 '0' ..= U+0039 '9'.
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1312 ///
1313 /// # Examples
1314 ///
1315 /// ```
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1316 /// let uppercase_a = 'A';
1317 /// let uppercase_g = 'G';
1318 /// let a = 'a';
1319 /// let g = 'g';
1320 /// let zero = '0';
1321 /// let percent = '%';
1322 /// let space = ' ';
1323 /// let lf = '\n';
1324 /// let esc: char = 0x1b_u8.into();
1325 ///
1326 /// assert!(uppercase_a.is_ascii_alphanumeric());
1327 /// assert!(uppercase_g.is_ascii_alphanumeric());
1328 /// assert!(a.is_ascii_alphanumeric());
1329 /// assert!(g.is_ascii_alphanumeric());
1330 /// assert!(zero.is_ascii_alphanumeric());
1331 /// assert!(!percent.is_ascii_alphanumeric());
1332 /// assert!(!space.is_ascii_alphanumeric());
1333 /// assert!(!lf.is_ascii_alphanumeric());
1334 /// assert!(!esc.is_ascii_alphanumeric());
1335 /// ```
ff7c6d11 1336 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1337 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1338 #[inline]
74b04a01 1339 pub const fn is_ascii_alphanumeric(&self) -> bool {
29967ef6 1340 matches!(*self, '0'..='9' | 'A'..='Z' | 'a'..='z')
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1341 }
1342
1343 /// Checks if the value is an ASCII decimal digit:
dc9dc135 1344 /// U+0030 '0' ..= U+0039 '9'.
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1345 ///
1346 /// # Examples
1347 ///
1348 /// ```
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1349 /// let uppercase_a = 'A';
1350 /// let uppercase_g = 'G';
1351 /// let a = 'a';
1352 /// let g = 'g';
1353 /// let zero = '0';
1354 /// let percent = '%';
1355 /// let space = ' ';
1356 /// let lf = '\n';
1357 /// let esc: char = 0x1b_u8.into();
1358 ///
1359 /// assert!(!uppercase_a.is_ascii_digit());
1360 /// assert!(!uppercase_g.is_ascii_digit());
1361 /// assert!(!a.is_ascii_digit());
1362 /// assert!(!g.is_ascii_digit());
1363 /// assert!(zero.is_ascii_digit());
1364 /// assert!(!percent.is_ascii_digit());
1365 /// assert!(!space.is_ascii_digit());
1366 /// assert!(!lf.is_ascii_digit());
1367 /// assert!(!esc.is_ascii_digit());
1368 /// ```
ff7c6d11 1369 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1370 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1371 #[inline]
74b04a01 1372 pub const fn is_ascii_digit(&self) -> bool {
29967ef6 1373 matches!(*self, '0'..='9')
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1374 }
1375
1376 /// Checks if the value is an ASCII hexadecimal digit:
1377 ///
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1378 /// - U+0030 '0' ..= U+0039 '9', or
1379 /// - U+0041 'A' ..= U+0046 'F', or
1380 /// - U+0061 'a' ..= U+0066 'f'.
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1381 ///
1382 /// # Examples
1383 ///
1384 /// ```
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1385 /// let uppercase_a = 'A';
1386 /// let uppercase_g = 'G';
1387 /// let a = 'a';
1388 /// let g = 'g';
1389 /// let zero = '0';
1390 /// let percent = '%';
1391 /// let space = ' ';
1392 /// let lf = '\n';
1393 /// let esc: char = 0x1b_u8.into();
1394 ///
1395 /// assert!(uppercase_a.is_ascii_hexdigit());
1396 /// assert!(!uppercase_g.is_ascii_hexdigit());
1397 /// assert!(a.is_ascii_hexdigit());
1398 /// assert!(!g.is_ascii_hexdigit());
1399 /// assert!(zero.is_ascii_hexdigit());
1400 /// assert!(!percent.is_ascii_hexdigit());
1401 /// assert!(!space.is_ascii_hexdigit());
1402 /// assert!(!lf.is_ascii_hexdigit());
1403 /// assert!(!esc.is_ascii_hexdigit());
1404 /// ```
ff7c6d11 1405 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1406 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1407 #[inline]
74b04a01 1408 pub const fn is_ascii_hexdigit(&self) -> bool {
29967ef6 1409 matches!(*self, '0'..='9' | 'A'..='F' | 'a'..='f')
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1410 }
1411
1412 /// Checks if the value is an ASCII punctuation character:
1413 ///
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1414 /// - U+0021 ..= U+002F `! " # $ % & ' ( ) * + , - . /`, or
1415 /// - U+003A ..= U+0040 `: ; < = > ? @`, or
1416 /// - U+005B ..= U+0060 ``[ \ ] ^ _ ` ``, or
1417 /// - U+007B ..= U+007E `{ | } ~`
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1418 ///
1419 /// # Examples
1420 ///
1421 /// ```
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1422 /// let uppercase_a = 'A';
1423 /// let uppercase_g = 'G';
1424 /// let a = 'a';
1425 /// let g = 'g';
1426 /// let zero = '0';
1427 /// let percent = '%';
1428 /// let space = ' ';
1429 /// let lf = '\n';
1430 /// let esc: char = 0x1b_u8.into();
1431 ///
1432 /// assert!(!uppercase_a.is_ascii_punctuation());
1433 /// assert!(!uppercase_g.is_ascii_punctuation());
1434 /// assert!(!a.is_ascii_punctuation());
1435 /// assert!(!g.is_ascii_punctuation());
1436 /// assert!(!zero.is_ascii_punctuation());
1437 /// assert!(percent.is_ascii_punctuation());
1438 /// assert!(!space.is_ascii_punctuation());
1439 /// assert!(!lf.is_ascii_punctuation());
1440 /// assert!(!esc.is_ascii_punctuation());
1441 /// ```
ff7c6d11 1442 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1443 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1444 #[inline]
74b04a01 1445 pub const fn is_ascii_punctuation(&self) -> bool {
29967ef6 1446 matches!(*self, '!'..='/' | ':'..='@' | '['..='`' | '{'..='~')
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1447 }
1448
1449 /// Checks if the value is an ASCII graphic character:
dc9dc135 1450 /// U+0021 '!' ..= U+007E '~'.
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1451 ///
1452 /// # Examples
1453 ///
1454 /// ```
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1455 /// let uppercase_a = 'A';
1456 /// let uppercase_g = 'G';
1457 /// let a = 'a';
1458 /// let g = 'g';
1459 /// let zero = '0';
1460 /// let percent = '%';
1461 /// let space = ' ';
1462 /// let lf = '\n';
1463 /// let esc: char = 0x1b_u8.into();
1464 ///
1465 /// assert!(uppercase_a.is_ascii_graphic());
1466 /// assert!(uppercase_g.is_ascii_graphic());
1467 /// assert!(a.is_ascii_graphic());
1468 /// assert!(g.is_ascii_graphic());
1469 /// assert!(zero.is_ascii_graphic());
1470 /// assert!(percent.is_ascii_graphic());
1471 /// assert!(!space.is_ascii_graphic());
1472 /// assert!(!lf.is_ascii_graphic());
1473 /// assert!(!esc.is_ascii_graphic());
1474 /// ```
ff7c6d11 1475 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1476 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1477 #[inline]
74b04a01 1478 pub const fn is_ascii_graphic(&self) -> bool {
29967ef6 1479 matches!(*self, '!'..='~')
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1480 }
1481
1482 /// Checks if the value is an ASCII whitespace character:
1483 /// U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED,
1484 /// U+000C FORM FEED, or U+000D CARRIAGE RETURN.
1485 ///
1486 /// Rust uses the WhatWG Infra Standard's [definition of ASCII
1487 /// whitespace][infra-aw]. There are several other definitions in
1488 /// wide use. For instance, [the POSIX locale][pct] includes
1489 /// U+000B VERTICAL TAB as well as all the above characters,
1490 /// but—from the very same specification—[the default rule for
1491 /// "field splitting" in the Bourne shell][bfs] considers *only*
1492 /// SPACE, HORIZONTAL TAB, and LINE FEED as whitespace.
1493 ///
1494 /// If you are writing a program that will process an existing
1495 /// file format, check what that format's definition of whitespace is
1496 /// before using this function.
1497 ///
1498 /// [infra-aw]: https://infra.spec.whatwg.org/#ascii-whitespace
1499 /// [pct]: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html#tag_07_03_01
1500 /// [bfs]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05
1501 ///
1502 /// # Examples
1503 ///
1504 /// ```
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1505 /// let uppercase_a = 'A';
1506 /// let uppercase_g = 'G';
1507 /// let a = 'a';
1508 /// let g = 'g';
1509 /// let zero = '0';
1510 /// let percent = '%';
1511 /// let space = ' ';
1512 /// let lf = '\n';
1513 /// let esc: char = 0x1b_u8.into();
1514 ///
1515 /// assert!(!uppercase_a.is_ascii_whitespace());
1516 /// assert!(!uppercase_g.is_ascii_whitespace());
1517 /// assert!(!a.is_ascii_whitespace());
1518 /// assert!(!g.is_ascii_whitespace());
1519 /// assert!(!zero.is_ascii_whitespace());
1520 /// assert!(!percent.is_ascii_whitespace());
1521 /// assert!(space.is_ascii_whitespace());
1522 /// assert!(lf.is_ascii_whitespace());
1523 /// assert!(!esc.is_ascii_whitespace());
1524 /// ```
ff7c6d11 1525 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1526 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1527 #[inline]
74b04a01 1528 pub const fn is_ascii_whitespace(&self) -> bool {
29967ef6 1529 matches!(*self, '\t' | '\n' | '\x0C' | '\r' | ' ')
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1530 }
1531
1532 /// Checks if the value is an ASCII control character:
dc9dc135 1533 /// U+0000 NUL ..= U+001F UNIT SEPARATOR, or U+007F DELETE.
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1534 /// Note that most ASCII whitespace characters are control
1535 /// characters, but SPACE is not.
1536 ///
1537 /// # Examples
1538 ///
1539 /// ```
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1540 /// let uppercase_a = 'A';
1541 /// let uppercase_g = 'G';
1542 /// let a = 'a';
1543 /// let g = 'g';
1544 /// let zero = '0';
1545 /// let percent = '%';
1546 /// let space = ' ';
1547 /// let lf = '\n';
1548 /// let esc: char = 0x1b_u8.into();
1549 ///
1550 /// assert!(!uppercase_a.is_ascii_control());
1551 /// assert!(!uppercase_g.is_ascii_control());
1552 /// assert!(!a.is_ascii_control());
1553 /// assert!(!g.is_ascii_control());
1554 /// assert!(!zero.is_ascii_control());
1555 /// assert!(!percent.is_ascii_control());
1556 /// assert!(!space.is_ascii_control());
1557 /// assert!(lf.is_ascii_control());
1558 /// assert!(esc.is_ascii_control());
1559 /// ```
ff7c6d11 1560 #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
3dfed10e 1561 #[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
abe05a73 1562 #[inline]
74b04a01 1563 pub const fn is_ascii_control(&self) -> bool {
29967ef6 1564 matches!(*self, '\0'..='\x1F' | '\x7F')
abe05a73 1565 }
e9174d1e 1566}
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1567
1568#[inline]
6a06907d 1569const fn len_utf8(code: u32) -> usize {
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1570 if code < MAX_ONE_B {
1571 1
1572 } else if code < MAX_TWO_B {
1573 2
1574 } else if code < MAX_THREE_B {
1575 3
1576 } else {
1577 4
1578 }
1579}
1580
1581/// Encodes a raw u32 value as UTF-8 into the provided byte buffer,
1582/// and then returns the subslice of the buffer that contains the encoded character.
1583///
1584/// Unlike `char::encode_utf8`, this method also handles codepoints in the surrogate range.
1585/// (Creating a `char` in the surrogate range is UB.)
1586/// The result is valid [generalized UTF-8] but not valid UTF-8.
1587///
1588/// [generalized UTF-8]: https://simonsapin.github.io/wtf-8/#generalized-utf8
1589///
1590/// # Panics
1591///
1592/// Panics if the buffer is not large enough.
1593/// A buffer of length four is large enough to encode any `char`.
1594#[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
1595#[doc(hidden)]
1596#[inline]
1597pub fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> &mut [u8] {
1598 let len = len_utf8(code);
1599 match (len, &mut dst[..]) {
1600 (1, [a, ..]) => {
1601 *a = code as u8;
1602 }
1603 (2, [a, b, ..]) => {
1604 *a = (code >> 6 & 0x1F) as u8 | TAG_TWO_B;
1605 *b = (code & 0x3F) as u8 | TAG_CONT;
1606 }
1607 (3, [a, b, c, ..]) => {
1608 *a = (code >> 12 & 0x0F) as u8 | TAG_THREE_B;
1609 *b = (code >> 6 & 0x3F) as u8 | TAG_CONT;
1610 *c = (code & 0x3F) as u8 | TAG_CONT;
1611 }
1612 (4, [a, b, c, d, ..]) => {
1613 *a = (code >> 18 & 0x07) as u8 | TAG_FOUR_B;
1614 *b = (code >> 12 & 0x3F) as u8 | TAG_CONT;
1615 *c = (code >> 6 & 0x3F) as u8 | TAG_CONT;
1616 *d = (code & 0x3F) as u8 | TAG_CONT;
1617 }
1618 _ => panic!(
1619 "encode_utf8: need {} bytes to encode U+{:X}, but the buffer has {}",
1620 len,
1621 code,
1622 dst.len(),
1623 ),
1624 };
1625 &mut dst[..len]
1626}
1627
1628/// Encodes a raw u32 value as UTF-16 into the provided `u16` buffer,
1629/// and then returns the subslice of the buffer that contains the encoded character.
1630///
1631/// Unlike `char::encode_utf16`, this method also handles codepoints in the surrogate range.
1632/// (Creating a `char` in the surrogate range is UB.)
1633///
1634/// # Panics
1635///
1636/// Panics if the buffer is not large enough.
1637/// A buffer of length 2 is large enough to encode any `char`.
1638#[unstable(feature = "char_internals", reason = "exposed only for libstd", issue = "none")]
1639#[doc(hidden)]
1640#[inline]
1641pub fn encode_utf16_raw(mut code: u32, dst: &mut [u16]) -> &mut [u16] {
1642 // SAFETY: each arm checks whether there are enough bits to write into
1643 unsafe {
1644 if (code & 0xFFFF) == code && !dst.is_empty() {
1645 // The BMP falls through
1646 *dst.get_unchecked_mut(0) = code as u16;
1647 slice::from_raw_parts_mut(dst.as_mut_ptr(), 1)
1648 } else if dst.len() >= 2 {
1649 // Supplementary planes break into surrogates.
1650 code -= 0x1_0000;
1651 *dst.get_unchecked_mut(0) = 0xD800 | ((code >> 10) as u16);
1652 *dst.get_unchecked_mut(1) = 0xDC00 | ((code as u16) & 0x3FF);
1653 slice::from_raw_parts_mut(dst.as_mut_ptr(), 2)
1654 } else {
1655 panic!(
1656 "encode_utf16: need {} units to encode U+{:X}, but the buffer has {}",
1657 from_u32_unchecked(code).len_utf16(),
1658 code,
1659 dst.len(),
1660 )
1661 }
1662 }
1663}