| // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| //! A character type. |
| //! |
| //! The `char` type represents a single character. More specifically, since |
| //! 'character' isn't a well-defined concept in Unicode, `char` is a '[Unicode |
| //! scalar value]', which is similar to, but not the same as, a '[Unicode code |
| //! point]'. |
| //! |
| //! [Unicode scalar value]: http://www.unicode.org/glossary/#unicode_scalar_value |
| //! [Unicode code point]: http://www.unicode.org/glossary/#code_point |
| //! |
| //! This module exists for technical reasons, the primary documentation for |
| //! `char` is directly on [the `char` primitive type](../primitive.char.html) |
| //! itself. |
| //! |
| //! This module is the home of the iterator implementations for the iterators |
| //! implemented on `char`, as well as some useful constants and conversion |
| //! functions that convert various types to `char`. |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| |
| use core::char::CharExt as C; |
| use core::option::Option::{self, Some, None}; |
| use core::iter::Iterator; |
| use tables::{derived_property, property, general_category, conversions}; |
| |
| // stable reexports |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub use core::char::{MAX, from_u32, from_u32_unchecked, from_digit, EscapeUnicode, EscapeDefault}; |
| |
| // unstable reexports |
| #[unstable(feature = "unicode", issue = "27783")] |
| pub use tables::UNICODE_VERSION; |
| |
| /// Returns an iterator that yields the lowercase equivalent of a `char`. |
| /// |
| /// This `struct` is created by the [`to_lowercase()`] method on [`char`]. See |
| /// its documentation for more. |
| /// |
| /// [`to_lowercase()`]: ../primitive.char.html#method.to_lowercase |
| /// [`char`]: ../primitive.char.html |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct ToLowercase(CaseMappingIter); |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl Iterator for ToLowercase { |
| type Item = char; |
| fn next(&mut self) -> Option<char> { |
| self.0.next() |
| } |
| } |
| |
| /// Returns an iterator that yields the uppercase equivalent of a `char`. |
| /// |
| /// This `struct` is created by the [`to_uppercase()`] method on [`char`]. See |
| /// its documentation for more. |
| /// |
| /// [`to_uppercase()`]: ../primitive.char.html#method.to_uppercase |
| /// [`char`]: ../primitive.char.html |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct ToUppercase(CaseMappingIter); |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl Iterator for ToUppercase { |
| type Item = char; |
| fn next(&mut self) -> Option<char> { |
| self.0.next() |
| } |
| } |
| |
| |
| enum CaseMappingIter { |
| Three(char, char, char), |
| Two(char, char), |
| One(char), |
| Zero, |
| } |
| |
| impl CaseMappingIter { |
| fn new(chars: [char; 3]) -> CaseMappingIter { |
| if chars[2] == '\0' { |
| if chars[1] == '\0' { |
| CaseMappingIter::One(chars[0]) // Including if chars[0] == '\0' |
| } else { |
| CaseMappingIter::Two(chars[0], chars[1]) |
| } |
| } else { |
| CaseMappingIter::Three(chars[0], chars[1], chars[2]) |
| } |
| } |
| } |
| |
| impl Iterator for CaseMappingIter { |
| type Item = char; |
| fn next(&mut self) -> Option<char> { |
| match *self { |
| CaseMappingIter::Three(a, b, c) => { |
| *self = CaseMappingIter::Two(b, c); |
| Some(a) |
| } |
| CaseMappingIter::Two(b, c) => { |
| *self = CaseMappingIter::One(c); |
| Some(b) |
| } |
| CaseMappingIter::One(c) => { |
| *self = CaseMappingIter::Zero; |
| Some(c) |
| } |
| CaseMappingIter::Zero => None, |
| } |
| } |
| } |
| |
| #[lang = "char"] |
| impl char { |
| /// 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 |
| /// radicum 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]. |
| /// |
| /// [is_numeric]: #method.is_numeric |
| /// |
| /// # Panics |
| /// |
| /// Panics if given a radix larger than 36. |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// let d = '1'; |
| /// |
| /// assert!(d.is_digit(10)); |
| /// |
| /// 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 `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 |
| /// radicum are supported. |
| /// |
| /// 'Digit' is defined to be only the following characters: |
| /// |
| /// * `0-9` |
| /// * `a-z` |
| /// * `A-Z` |
| /// |
| /// # Failure |
| /// |
| /// 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: |
| /// |
| /// ``` |
| /// 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 d = 'f'; |
| /// |
| /// assert_eq!(d.to_digit(10), None); |
| /// |
| /// 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] |
| pub fn to_digit(self, radix: u32) -> Option<u32> { |
| C::to_digit(self, radix) |
| } |
| |
| /// Returns an iterator that yields the hexadecimal Unicode escape of a |
| /// character, as `char`s. |
| /// |
| /// All characters are escaped with Rust syntax of the form `\\u{NNNN}` |
| /// where `NNNN` is the shortest hexadecimal representation. |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// for c in '❤'.escape_unicode() { |
| /// print!("{}", c); |
| /// } |
| /// println!(""); |
| /// ``` |
| /// |
| /// This prints: |
| /// |
| /// ```text |
| /// \u{2764} |
| /// ``` |
| /// |
| /// Collecting into a `String`: |
| /// |
| /// ``` |
| /// let heart: String = '❤'.escape_unicode().collect(); |
| /// |
| /// assert_eq!(heart, r"\u{2764}"); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn escape_unicode(self) -> EscapeUnicode { |
| C::escape_unicode(self) |
| } |
| |
| /// 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 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); |
| /// } |
| /// ``` |
| /// |
| /// This prints: |
| /// |
| /// ```text |
| /// \ |
| /// " |
| /// ``` |
| /// |
| /// Collecting into a `String`: |
| /// |
| /// ``` |
| /// let quote: String = '"'.escape_default().collect(); |
| /// |
| /// assert_eq!(quote, "\\\""); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[inline] |
| pub fn escape_default(self) -> EscapeDefault { |
| C::escape_default(self) |
| } |
| |
| /// Returns the number of bytes this `char` would need if encoded in UTF-8. |
| /// |
| /// That number of bytes is always between 1 and 4, inclusive. |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// let len = 'A'.len_utf8(); |
| /// assert_eq!(len, 1); |
| /// |
| /// let len = 'ß'.len_utf8(); |
| /// assert_eq!(len, 2); |
| /// |
| /// let len = 'ℝ'.len_utf8(); |
| /// assert_eq!(len, 3); |
| /// |
| /// let len = '💣'.len_utf8(); |
| /// assert_eq!(len, 4); |
| /// ``` |
| /// |
| /// The `&str` type guarantees that its contents are UTF-8, and so we can compare the length it |
| /// would take if each code point was represented as a `char` vs in the `&str` itself: |
| /// |
| /// ``` |
| /// // as chars |
| /// let eastern = '東'; |
| /// let 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 `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")] |
| #[inline] |
| pub fn len_utf16(self) -> usize { |
| C::len_utf16(self) |
| } |
| |
| /// Encodes this character as UTF-8 into the provided byte buffer, and then |
| /// returns the number of bytes written. |
| /// |
| /// If the buffer is not large enough, nothing will be written into it and a |
| /// `None` will be returned. A buffer of length four is large enough to |
| /// encode any `char`. |
| /// |
| /// # Examples |
| /// |
| /// In both of these examples, 'ß' takes two bytes to encode. |
| /// |
| /// ``` |
| /// #![feature(unicode)] |
| /// |
| /// let mut b = [0; 2]; |
| /// |
| /// let result = 'ß'.encode_utf8(&mut b); |
| /// |
| /// assert_eq!(result, Some(2)); |
| /// ``` |
| /// |
| /// A buffer that's too small: |
| /// |
| /// ``` |
| /// #![feature(unicode)] |
| /// |
| /// let mut b = [0; 1]; |
| /// |
| /// let result = 'ß'.encode_utf8(&mut b); |
| /// |
| /// assert_eq!(result, None); |
| /// ``` |
| #[unstable(feature = "unicode", |
| reason = "pending decision about Iterator/Writer/Reader", |
| issue = "27784")] |
| #[inline] |
| pub fn encode_utf8(self, dst: &mut [u8]) -> Option<usize> { |
| C::encode_utf8(self, dst) |
| } |
| |
| /// Encodes this character as UTF-16 into the provided `u16` buffer, and |
| /// then returns the number of `u16`s written. |
| /// |
| /// If the buffer is not large enough, nothing will be written into it and a |
| /// `None` will be returned. A buffer of length 2 is large enough to encode |
| /// any `char`. |
| /// |
| /// # Examples |
| /// |
| /// In both of these examples, 'ß' takes one `u16` to encode. |
| /// |
| /// ``` |
| /// #![feature(unicode)] |
| /// |
| /// let mut b = [0; 1]; |
| /// |
| /// let result = 'ß'.encode_utf16(&mut b); |
| /// |
| /// assert_eq!(result, Some(1)); |
| /// ``` |
| /// |
| /// A buffer that's too small: |
| /// |
| /// ``` |
| /// #![feature(unicode)] |
| /// |
| /// let mut b = [0; 0]; |
| /// |
| /// let result = 'ß'.encode_utf8(&mut b); |
| /// |
| /// assert_eq!(result, None); |
| /// ``` |
| #[unstable(feature = "unicode", |
| reason = "pending decision about Iterator/Writer/Reader", |
| issue = "27784")] |
| #[inline] |
| pub fn encode_utf16(self, dst: &mut [u16]) -> Option<usize> { |
| C::encode_utf16(self, dst) |
| } |
| |
| /// 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 { |
| match self { |
| 'a'...'z' | 'A'...'Z' => true, |
| c if c > '\x7f' => derived_property::Alphabetic(c), |
| _ => false, |
| } |
| } |
| |
| /// 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`. |
| #[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 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), |
| /// mostly similar to 'ID_Continue' but modified for closure under NFKx. |
| #[unstable(feature = "unicode", |
| reason = "mainly needed for compiler internals", |
| issue = "0")] |
| #[inline] |
| pub fn is_xid_continue(self) -> bool { |
| derived_property::XID_Continue(self) |
| } |
| |
| /// Returns true if this `char` is lowercase, and false otherwise. |
| /// |
| /// '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 { |
| match self { |
| 'a'...'z' => true, |
| c if c > '\x7f' => derived_property::Lowercase(c), |
| _ => false, |
| } |
| } |
| |
| /// Returns true if this `char` is uppercase, and false otherwise. |
| /// |
| /// '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 { |
| match self { |
| 'A'...'Z' => true, |
| c if c > '\x7f' => derived_property::Uppercase(c), |
| _ => false, |
| } |
| } |
| |
| /// Returns true if this `char` is whitespace, and false otherwise. |
| /// |
| /// '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 { |
| match self { |
| ' ' | '\x09'...'\x0d' => true, |
| c if c > '\x7f' => property::White_Space(c), |
| _ => false, |
| } |
| } |
| |
| /// Returns true if this `char` is alphanumeric, and false otherwise. |
| /// |
| /// '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() |
| } |
| |
| /// Returns true if this `char` is a control code point, and false otherwise. |
| /// |
| /// '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) |
| } |
| |
| /// 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 { |
| match self { |
| '0'...'9' => true, |
| c if c > '\x7f' => general_category::N(c), |
| _ => false, |
| } |
| } |
| |
| /// Returns an iterator that yields the lowercase equivalent of a `char`. |
| /// |
| /// If no conversion is possible then an iterator with just the input character is returned. |
| /// |
| /// 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. |
| /// |
| /// 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: |
| /// |
| /// ``` |
| /// 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] |
| pub fn to_lowercase(self) -> ToLowercase { |
| ToLowercase(CaseMappingIter::new(conversions::to_lower(self))) |
| } |
| |
| /// Returns an iterator that yields the uppercase equivalent of a `char`. |
| /// |
| /// If no conversion is possible then an iterator with just the input character is returned. |
| /// |
| /// 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. |
| /// |
| /// 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: |
| /// |
| /// ``` |
| /// 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(); |
| /// ``` |
| /// |
| /// 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 { |
| ToUppercase(CaseMappingIter::new(conversions::to_upper(self))) |
| } |
| } |
| |
| /// 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> |
| { |
| iter: I, |
| buf: Option<u16>, |
| } |
| |
| /// Create an iterator over the UTF-16 encoded code points in `iterable`, |
| /// returning unpaired surrogates as `Err`s. |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// #![feature(decode_utf16)] |
| /// |
| /// use std::char::decode_utf16; |
| /// |
| /// fn main() { |
| /// // 𝄞mus<invalid>ic<invalid> |
| /// let v = [0xD834, 0xDD1E, 0x006d, 0x0075, |
| /// 0x0073, 0xDD1E, 0x0069, 0x0063, |
| /// 0xD834]; |
| /// |
| /// assert_eq!(decode_utf16(v.iter().cloned()).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: |
| /// |
| /// ``` |
| /// #![feature(decode_utf16)] |
| /// |
| /// use std::char::{decode_utf16, REPLACEMENT_CHARACTER}; |
| /// |
| /// fn main() { |
| /// // 𝄞mus<invalid>ic<invalid> |
| /// let v = [0xD834, 0xDD1E, 0x006d, 0x0075, |
| /// 0x0073, 0xDD1E, 0x0069, 0x0063, |
| /// 0xD834]; |
| /// |
| /// assert_eq!(decode_utf16(v.iter().cloned()) |
| /// .map(|r| r.unwrap_or(REPLACEMENT_CHARACTER)) |
| /// .collect::<String>(), |
| /// "𝄞mus�ic�"); |
| /// } |
| /// ``` |
| #[unstable(feature = "decode_utf16", reason = "recently exposed", issue = "27830")] |
| #[inline] |
| pub fn decode_utf16<I: IntoIterator<Item = u16>>(iterable: I) -> DecodeUtf16<I::IntoIter> { |
| DecodeUtf16 { |
| iter: iterable.into_iter(), |
| buf: None, |
| } |
| } |
| |
| #[unstable(feature = "decode_utf16", reason = "recently exposed", issue = "27830")] |
| impl<I: Iterator<Item=u16>> Iterator for DecodeUtf16<I> { |
| type Item = Result<char, u16>; |
| |
| fn next(&mut self) -> Option<Result<char, u16>> { |
| let u = match self.buf.take() { |
| Some(buf) => buf, |
| None => match self.iter.next() { |
| Some(u) => u, |
| None => return None, |
| }, |
| }; |
| |
| if u < 0xD800 || 0xDFFF < u { |
| // not a surrogate |
| Some(Ok(unsafe { from_u32_unchecked(u as u32) })) |
| } else if u >= 0xDC00 { |
| // a trailing surrogate |
| Some(Err(u)) |
| } else { |
| let u2 = match self.iter.next() { |
| Some(u2) => u2, |
| // eof |
| None => return Some(Err(u)), |
| }; |
| if u2 < 0xDC00 || u2 > 0xDFFF { |
| // not a trailing surrogate so we're not a valid |
| // surrogate pair, so rewind to redecode u2 next time. |
| self.buf = Some(u2); |
| return Some(Err(u)); |
| } |
| |
| // all ok, so lets decode it. |
| let c = (((u - 0xD800) as u32) << 10 | (u2 - 0xDC00) as u32) + 0x1_0000; |
| Some(Ok(unsafe { from_u32_unchecked(c) })) |
| } |
| } |
| |
| #[inline] |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| let (low, high) = self.iter.size_hint(); |
| // we could be entirely valid surrogates (2 elements per |
| // char), or entirely non-surrogates (1 element per char) |
| (low / 2, high) |
| } |
| } |
| |
| /// `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}'; |