diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/librustc_unicode/char.rs | 467 |
1 files changed, 392 insertions, 75 deletions
diff --git a/src/librustc_unicode/char.rs b/src/librustc_unicode/char.rs index e08b3244109..207dc7aacbf 100644 --- a/src/librustc_unicode/char.rs +++ b/src/librustc_unicode/char.rs @@ -110,53 +110,122 @@ impl Iterator for CaseMappingIter { #[stable(feature = "rust1", since = "1.0.0")] #[lang = "char"] impl char { - /// Checks if a `char` parses as a numeric digit in the given 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, hexicdecimal, to give some common values. Arbitrary + /// radicum are supported. /// /// Compared to `is_numeric()`, this function only recognizes the characters /// `0-9`, `a-z` and `A-Z`. /// - /// # Return value + /// 'Digit' is defined to be only the following characters: /// - /// Returns `true` if `c` is a valid digit under `radix`, and `false` - /// otherwise. + /// * `0-9` + /// * `a-z` + /// * `A-Z` + /// + /// For a more comprehensive understanding of 'digit', see [`is_numeric()`][is_numeric]. + /// + /// [is_numeric]: #method.is_numeric /// /// # Panics /// - /// Panics if given a radix > 36. + /// Panics if given a radix larger than 36. /// /// # Examples /// + /// Basic usage: + /// /// ``` - /// let c = '1'; + /// let d = '1'; /// - /// assert!(c.is_digit(10)); + /// assert!(d.is_digit(10)); /// - /// assert!('f'.is_digit(16)); + /// let d = 'f'; + /// + /// assert!(d.is_digit(16)); + /// assert!(!d.is_digit(10)); + /// ``` + /// + /// Passing a large radix, causing a panic: + /// + /// ``` + /// use std::thread; + /// + /// let result = thread::spawn(|| { + /// let d = '1'; + /// + /// // this panics + /// d.is_digit(37); + /// }).join(); + /// + /// assert!(result.is_err()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_digit(self, radix: u32) -> bool { C::is_digit(self, radix) } - /// Converts a character to the corresponding digit. + /// 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, hexicdecimal, to give some common values. Arbitrary + /// radicum are supported. + /// + /// 'Digit' is defined to be only the following characters: /// - /// # Return value + /// * `0-9` + /// * `a-z` + /// * `A-Z` /// - /// If `c` is between '0' and '9', the corresponding value between 0 and - /// 9. If `c` is 'a' or 'A', 10. If `c` is 'b' or 'B', 11, etc. Returns - /// none if the character does not refer to a digit in the given radix. + /// # Failure + /// + /// Returns `None` if the `char` does not refer to a digit in the given radix. /// /// # Panics /// - /// Panics if given a radix outside the range [0..36]. + /// Panics if given a radix larger than 36. /// /// # Examples /// + /// Basic usage: + /// + /// ``` + /// let d = '1'; + /// + /// assert_eq!(d.to_digit(10), Some(1)); + /// + /// let d = 'f'; + /// + /// assert_eq!(d.to_digit(16), Some(15)); + /// ``` + /// + /// Passing a non-digit results in failure: + /// /// ``` - /// let c = '1'; + /// let d = 'f'; /// - /// assert_eq!(c.to_digit(10), Some(1)); + /// assert_eq!(d.to_digit(10), None); /// - /// assert_eq!('f'.to_digit(16), Some(15)); + /// let d = 'z'; + /// + /// assert_eq!(d.to_digit(16), None); + /// ``` + /// + /// Passing a large radix, causing a panic: + /// + /// ``` + /// use std::thread; + /// + /// let result = thread::spawn(|| { + /// let d = '1'; + /// + /// d.to_digit(37); + /// }).join(); + /// + /// assert!(result.is_err()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] @@ -195,21 +264,29 @@ impl char { #[inline] pub fn escape_unicode(self) -> EscapeUnicode { C::escape_unicode(self) } - /// Returns an iterator that yields the 'default' ASCII and - /// C++11-like literal escape of a character, as `char`s. + /// Returns an iterator that yields the literal escape code of a `char`. /// /// 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, CR and LF are escaped as '\t', '\r' and '\n' respectively. - /// * Single-quote, double-quote and backslash chars are backslash- - /// escaped. - /// * Any other chars in the range [0x20,0x7e] are not escaped. - /// * Any other chars are given hex Unicode escapes; see `escape_unicode`. + /// * 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]. + /// + /// [escape_unicode]: #method.escape_unicode /// /// # Examples /// + /// Basic usage: + /// /// ``` /// for i in '"'.escape_default() { /// println!("{}", i); @@ -234,29 +311,70 @@ impl char { #[inline] pub fn escape_default(self) -> EscapeDefault { C::escape_default(self) } - /// Returns the number of bytes this character would need if encoded in - /// UTF-8. + /// 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 n = 'ß'.len_utf8(); + /// let len = 'A'.len_utf8(); + /// assert_eq!(len, 1); + /// + /// let len = 'ß'.len_utf8(); + /// assert_eq!(len, 2); /// - /// assert_eq!(n, 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 capitol = '京'; + /// + /// // both can be represented as three bytes + /// assert_eq!(3, eastern.len_utf8()); + /// assert_eq!(3, capitol.len_utf8()); + /// + /// // as a &str, these two are encoded in UTF-8 + /// let tokyo = "東京"; + /// + /// let len = eastern.len_utf8() + capitol.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")] #[inline] pub fn len_utf8(self) -> usize { C::len_utf8(self) } - /// Returns the number of 16-bit code units this character would need if + /// Returns the number of 16-bit code units this `char` would need if /// encoded in UTF-16. /// + /// See the documentation for [`len_utf8()`][len_utf8] for more explanation + /// of this concept. This function is a mirror, but for UTF-16 instead of + /// UTF-8. + /// /// # Examples /// /// ``` /// let n = 'ß'.len_utf16(); - /// /// assert_eq!(n, 1); + /// + /// let len = '💣'.len_utf16(); + /// assert_eq!(len, 2); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] @@ -342,8 +460,24 @@ impl char { C::encode_utf16(self, dst) } - /// Returns whether the specified character is considered a Unicode - /// alphabetic code point. + /// Returns true if this `char` is an alphabetic code point, and false if not. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let c = 'a'; + /// + /// assert!(c.is_alphabetic()); + /// + /// let c = '京'; + /// assert!(c.is_alphabetic()); + /// + /// let c = '💝'; + /// // love is many things, but it is not alphabetic + /// assert!(!c.is_alphabetic()); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_alphabetic(self) -> bool { @@ -354,20 +488,20 @@ impl char { } } - /// Returns whether the specified character satisfies the 'XID_Start' - /// Unicode property. + /// Returns true if this `char` satisfies the 'XID_Start' Unicode property, and false + /// otherwise. /// /// 'XID_Start' is a Unicode Derived Property specified in /// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications), - /// mostly similar to ID_Start but modified for closure under NFKx. + /// mostly similar to `ID_Start` but modified for closure under `NFKx`. #[unstable(feature = "unicode", reason = "mainly needed for compiler internals", issue = "0")] #[inline] pub fn is_xid_start(self) -> bool { derived_property::XID_Start(self) } - /// Returns whether the specified `char` satisfies the 'XID_Continue' - /// Unicode property. + /// Returns true if this `char` satisfies the 'XID_Continue' Unicode property, and false + /// otherwise. /// /// 'XID_Continue' is a Unicode Derived Property specified in /// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications), @@ -378,10 +512,32 @@ impl char { #[inline] pub fn is_xid_continue(self) -> bool { derived_property::XID_Continue(self) } - /// Indicates whether a character is in lowercase. + /// Returns true if this `char` is lowercase, and false otherwise. /// - /// This is defined according to the terms of the Unicode Derived Core + /// 'Lowercase' is defined according to the terms of the Unicode Derived Core /// Property `Lowercase`. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let c = 'a'; + /// assert!(c.is_lowercase()); + /// + /// let c = 'δ'; + /// assert!(c.is_lowercase()); + /// + /// let c = 'A'; + /// assert!(!c.is_lowercase()); + /// + /// let c = 'Δ'; + /// assert!(!c.is_lowercase()); + /// + /// // The various Chinese scripts do not have case, and so: + /// let c = '中'; + /// assert!(!c.is_lowercase()); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_lowercase(self) -> bool { @@ -392,10 +548,32 @@ impl char { } } - /// Indicates whether a character is in uppercase. + /// Returns true if this `char` is uppercase, and false otherwise. /// - /// This is defined according to the terms of the Unicode Derived Core + /// 'Uppercase' is defined according to the terms of the Unicode Derived Core /// Property `Uppercase`. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let c = 'a'; + /// assert!(!c.is_uppercase()); + /// + /// let c = 'δ'; + /// assert!(!c.is_uppercase()); + /// + /// let c = 'A'; + /// assert!(c.is_uppercase()); + /// + /// let c = 'Δ'; + /// assert!(c.is_uppercase()); + /// + /// // The various Chinese scripts do not have case, and so: + /// let c = '中'; + /// assert!(!c.is_uppercase()); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_uppercase(self) -> bool { @@ -406,9 +584,26 @@ impl char { } } - /// Indicates whether a character is whitespace. + /// Returns true if this `char` is whitespace, and false otherwise. /// - /// Whitespace is defined in terms of the Unicode Property `White_Space`. + /// 'Whitespace' is defined according to the terms of the Unicode Derived Core + /// Property `White_Space`. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let c = ' '; + /// assert!(c.is_whitespace()); + /// + /// // a non-breaking space + /// let c = '\u{A0}'; + /// assert!(c.is_whitespace()); + /// + /// let c = '越'; + /// assert!(!c.is_whitespace()); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_whitespace(self) -> bool { @@ -419,25 +614,101 @@ impl char { } } - /// Indicates whether a character is alphanumeric. + /// Returns true if this `char` is alphanumeric, and false otherwise. /// - /// Alphanumericness is defined in terms of the Unicode General Categories + /// 'Alphanumeric'-ness is defined in terms of the Unicode General Categories /// 'Nd', 'Nl', 'No' and the Derived Core Property 'Alphabetic'. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let c = '٣'; + /// assert!(c.is_alphanumeric()); + /// + /// let c = '7'; + /// assert!(c.is_alphanumeric()); + /// + /// let c = '৬'; + /// assert!(c.is_alphanumeric()); + /// + /// let c = 'K'; + /// assert!(c.is_alphanumeric()); + /// + /// let c = 'و'; + /// assert!(c.is_alphanumeric()); + /// + /// let c = '藏'; + /// assert!(c.is_alphanumeric()); + /// + /// let c = '¾'; + /// assert!(!c.is_alphanumeric()); + /// + /// let c = '①'; + /// assert!(!c.is_alphanumeric()); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_alphanumeric(self) -> bool { self.is_alphabetic() || self.is_numeric() } - /// Indicates whether a character is a control code point. + /// Returns true if this `char` is a control code point, and false otherwise. /// - /// Control code points are defined in terms of the Unicode General + /// 'Control code point' is defined in terms of the Unicode General /// Category `Cc`. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// // U+009C, STRING TERMINATOR + /// let c = ''; + /// assert!(c.is_control()); + /// + /// let c = 'q'; + /// assert!(!c.is_control()); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_control(self) -> bool { general_category::Cc(self) } - /// Indicates whether the character is numeric (Nd, Nl, or No). + /// Returns true if this `char` is numeric, and false otherwise. + /// + /// 'Numeric'-ness is defined in terms of the Unicode General Categories + /// 'Nd', 'Nl', 'No'. + /// + /// # Examples + /// + /// Basic usage: + /// + /// ``` + /// let c = '٣'; + /// assert!(c.is_numeric()); + /// + /// let c = '7'; + /// assert!(c.is_numeric()); + /// + /// let c = '৬'; + /// assert!(c.is_numeric()); + /// + /// let c = 'K'; + /// assert!(!c.is_numeric()); + /// + /// let c = 'و'; + /// assert!(!c.is_numeric()); + /// + /// let c = '藏'; + /// assert!(!c.is_numeric()); + /// + /// let c = '¾'; + /// assert!(!c.is_numeric()); + /// + /// let c = '①'; + /// assert!(!c.is_numeric()); + /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn is_numeric(self) -> bool { @@ -448,21 +719,36 @@ impl char { } } - /// Converts a character to its lowercase equivalent. + /// Returns an iterator that yields the lowercase equivalent of a `char`. /// - /// This performs complex unconditional mappings with no tailoring. - /// See `to_uppercase()` for references and more information. + /// If no conversion is possible then an iterator with just the input character is returned. /// - /// # Return value + /// This performs complex unconditional mappings with no tailoring: it maps + /// one Unicode character to its lowercase equivalent according to the + /// [Unicode database] and the additional complex mappings + /// [`SpecialCasing.txt`]. Conditional mappings (based on context or + /// language) are not considered here. /// - /// Returns an iterator which yields the characters corresponding to the - /// lowercase equivalent of the character. If no conversion is possible then - /// an iterator with just the input character is returned. + /// For a full reference, see [here][reference]. + /// + /// [Unicode database]: ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt + /// + /// [`SpecialCasing.txt`]: ftp://ftp.unicode.org/Public/UNIDATA/SpecialCasing.txt + /// + /// [reference]: http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf#G33992 /// /// # Examples /// + /// Basic usage: + /// /// ``` - /// assert_eq!(Some('c'), 'C'.to_lowercase().next()); + /// let c = 'c'; + /// + /// assert_eq!(c.to_uppercase().next(), Some('C')); + /// + /// // Japanese scripts do not have case, and so: + /// let c = '山'; + /// assert_eq!(c.to_uppercase().next(), Some('山')); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] @@ -470,33 +756,63 @@ impl char { ToLowercase(CaseMappingIter::new(conversions::to_lower(self))) } - /// Converts a character to its uppercase equivalent. - /// - /// This performs complex unconditional mappings with no tailoring: - /// it maps one Unicode character to its uppercase equivalent - /// according to the Unicode database [1] - /// and the additional complex mappings [`SpecialCasing.txt`]. - /// Conditional mappings (based on context or language) are not considered here. + /// Returns an iterator that yields the uppercase equivalent of a `char`. /// - /// A full reference can be found here [2]. + /// If no conversion is possible then an iterator with just the input character is returned. /// - /// # Return value + /// This performs complex unconditional mappings with no tailoring: it maps + /// one Unicode character to its uppercase equivalent according to the + /// [Unicode database] and the additional complex mappings + /// [`SpecialCasing.txt`]. Conditional mappings (based on context or + /// language) are not considered here. /// - /// Returns an iterator which yields the characters corresponding to the - /// uppercase equivalent of the character. If no conversion is possible then - /// an iterator with just the input character is returned. + /// For a full reference, see [here][reference]. /// - /// [1]: ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt + /// [Unicode database]: ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt /// /// [`SpecialCasing.txt`]: ftp://ftp.unicode.org/Public/UNIDATA/SpecialCasing.txt /// - /// [2]: http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf#G33992 + /// [reference]: http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf#G33992 /// /// # Examples /// + /// Basic usage: + /// + /// ``` + /// let c = 'c'; + /// assert_eq!(c.to_uppercase().next(), Some('C')); + /// + /// // Japanese does not have case, and so: + /// let c = '山'; + /// assert_eq!(c.to_uppercase().next(), Some('山')); + /// ``` + /// + /// 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 i = 'i'; + /// + /// let upper_i = i.to_uppercase().next(); /// ``` - /// assert_eq!(Some('C'), 'c'.to_uppercase().next()); + /// + /// The value of `upper_i` here relies on the language of the text: if we're + /// in `en-US`, it should be `Some('I')`, but if we're in `tr_TR`, it should + /// be `Some('İ')`. `to_uppercase()` does not take this into account, and so: + /// /// ``` + /// let i = 'i'; + /// + /// let upper_i = i.to_uppercase().next(); + /// + /// assert_eq!(Some('I'), upper_i); + /// ``` + /// + /// holds across languages. #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn to_uppercase(self) -> ToUppercase { @@ -504,7 +820,7 @@ impl char { } } -/// An iterator that decodes UTF-16 encoded codepoints from an iterator of `u16`s. +/// An iterator that decodes UTF-16 encoded code points from an iterator of `u16`s. #[unstable(feature = "decode_utf16", reason = "recently exposed", issue = "27830")] #[derive(Clone)] pub struct DecodeUtf16<I> where I: Iterator<Item=u16> { @@ -512,7 +828,7 @@ pub struct DecodeUtf16<I> where I: Iterator<Item=u16> { buf: Option<u16>, } -/// Create an iterator over the UTF-16 encoded codepoints in `iterable`, +/// Create an iterator over the UTF-16 encoded code points in `iterable`, /// returning unpaired surrogates as `Err`s. /// /// # Examples @@ -612,7 +928,8 @@ impl<I: Iterator<Item=u16>> Iterator for DecodeUtf16<I> { } } -/// 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`. +/// `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`](../string/struct.String.html#method.from_utf8_lossy). #[unstable(feature = "decode_utf16", reason = "recently added", issue = "27830")] pub const REPLACEMENT_CHARACTER: char = '\u{FFFD}'; |