// 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 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. //! Unicode string slices. //! //! *[See also the `str` primitive type](../../std/primitive.str.html).* #![stable(feature = "rust1", since = "1.0.0")] // Many of the usings in this module are only used in the test configuration. // It's cleaner to just turn off the unused_imports warning than to fix them. #![allow(unused_imports)] use core::str as core_str; use core::str::pattern::Pattern; use core::str::pattern::{Searcher, ReverseSearcher, DoubleEndedSearcher}; use core::mem; use core::iter::FusedIterator; use rustc_unicode::str::{UnicodeStr, Utf16Encoder}; use vec_deque::VecDeque; use borrow::{Borrow, ToOwned}; use string::String; use rustc_unicode; use vec::Vec; use slice::SliceConcatExt; use boxed::Box; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{FromStr, Utf8Error}; #[allow(deprecated)] #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{Lines, LinesAny}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{Split, RSplit}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{SplitN, RSplitN}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{SplitTerminator, RSplitTerminator}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{Matches, RMatches}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{MatchIndices, RMatchIndices}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{from_utf8, Chars, CharIndices, Bytes}; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::{from_utf8_unchecked, ParseBoolError}; #[stable(feature = "rust1", since = "1.0.0")] pub use rustc_unicode::str::SplitWhitespace; #[stable(feature = "rust1", since = "1.0.0")] pub use core::str::pattern; #[unstable(feature = "slice_concat_ext", reason = "trait should not have to exist", issue = "27747")] impl> SliceConcatExt for [S] { type Output = String; fn concat(&self) -> String { if self.is_empty() { return String::new(); } // `len` calculation may overflow but push_str will check boundaries let len = self.iter().map(|s| s.borrow().len()).sum(); let mut result = String::with_capacity(len); for s in self { result.push_str(s.borrow()) } result } fn join(&self, sep: &str) -> String { if self.is_empty() { return String::new(); } // concat is faster if sep.is_empty() { return self.concat(); } // this is wrong without the guarantee that `self` is non-empty // `len` calculation may overflow but push_str but will check boundaries let len = sep.len() * (self.len() - 1) + self.iter().map(|s| s.borrow().len()).sum::(); let mut result = String::with_capacity(len); let mut first = true; for s in self { if first { first = false; } else { result.push_str(sep); } result.push_str(s.borrow()); } result } fn connect(&self, sep: &str) -> String { self.join(sep) } } /// External iterator for a string's UTF-16 code units. /// /// For use with the `std::iter` module. #[derive(Clone)] #[stable(feature = "encode_utf16", since = "1.8.0")] pub struct EncodeUtf16<'a> { encoder: Utf16Encoder>, } #[stable(feature = "encode_utf16", since = "1.8.0")] impl<'a> Iterator for EncodeUtf16<'a> { type Item = u16; #[inline] fn next(&mut self) -> Option { self.encoder.next() } #[inline] fn size_hint(&self) -> (usize, Option) { self.encoder.size_hint() } } #[unstable(feature = "fused", issue = "35602")] impl<'a> FusedIterator for EncodeUtf16<'a> {} // Return the initial codepoint accumulator for the first byte. // The first byte is special, only want bottom 5 bits for width 2, 4 bits // for width 3, and 3 bits for width 4 macro_rules! utf8_first_byte { ($byte:expr, $width:expr) => (($byte & (0x7F >> $width)) as u32) } // return the value of $ch updated with continuation byte $byte macro_rules! utf8_acc_cont_byte { ($ch:expr, $byte:expr) => (($ch << 6) | ($byte & 63) as u32) } #[stable(feature = "rust1", since = "1.0.0")] impl Borrow for String { #[inline] fn borrow(&self) -> &str { &self[..] } } #[stable(feature = "rust1", since = "1.0.0")] impl ToOwned for str { type Owned = String; fn to_owned(&self) -> String { unsafe { String::from_utf8_unchecked(self.as_bytes().to_owned()) } } } /// Methods for string slices. #[lang = "str"] #[cfg(not(test))] impl str { /// Returns the length of `self`. /// /// This length is in bytes, not [`char`]s or graphemes. In other words, /// it may not be what a human considers the length of the string. /// /// [`char`]: primitive.char.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let len = "foo".len(); /// assert_eq!(3, len); /// /// let len = "ƒoo".len(); // fancy f! /// assert_eq!(4, len); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn len(&self) -> usize { core_str::StrExt::len(self) } /// Returns true if this slice has a length of zero bytes. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = ""; /// assert!(s.is_empty()); /// /// let s = "not empty"; /// assert!(!s.is_empty()); /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub fn is_empty(&self) -> bool { core_str::StrExt::is_empty(self) } /// Checks that `index`-th byte lies at the start and/or end of a /// UTF-8 code point sequence. /// /// The start and end of the string (when `index == self.len()`) are /// considered to be /// boundaries. /// /// Returns `false` if `index` is greater than `self.len()`. /// /// # Examples /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// assert!(s.is_char_boundary(0)); /// // start of `老` /// assert!(s.is_char_boundary(6)); /// assert!(s.is_char_boundary(s.len())); /// /// // second byte of `ö` /// assert!(!s.is_char_boundary(2)); /// /// // third byte of `老` /// assert!(!s.is_char_boundary(8)); /// ``` #[stable(feature = "is_char_boundary", since = "1.9.0")] #[inline] pub fn is_char_boundary(&self, index: usize) -> bool { core_str::StrExt::is_char_boundary(self, index) } /// Converts a string slice to a byte slice. /// /// # Examples /// /// Basic usage: /// /// ``` /// let bytes = "bors".as_bytes(); /// assert_eq!(b"bors", bytes); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline(always)] pub fn as_bytes(&self) -> &[u8] { core_str::StrExt::as_bytes(self) } /// Converts a string slice to a raw pointer. /// /// As string slices are a slice of bytes, the raw pointer points to a /// [`u8`]. This pointer will be pointing to the first byte of the string /// slice. /// /// [`u8`]: primitive.u8.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = "Hello"; /// let ptr = s.as_ptr(); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn as_ptr(&self) -> *const u8 { core_str::StrExt::as_ptr(self) } /// Creates a string slice from another string slice, bypassing safety /// checks. /// /// This new slice goes from `begin` to `end`, including `begin` but /// excluding `end`. /// /// To get a mutable string slice instead, see the /// [`slice_mut_unchecked()`] method. /// /// [`slice_mut_unchecked()`]: #method.slice_mut_unchecked /// /// # Safety /// /// Callers of this function are responsible that three preconditions are /// satisfied: /// /// * `begin` must come before `end`. /// * `begin` and `end` must be byte positions within the string slice. /// * `begin` and `end` must lie on UTF-8 sequence boundaries. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// /// unsafe { /// assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21)); /// } /// /// let s = "Hello, world!"; /// /// unsafe { /// assert_eq!("world", s.slice_unchecked(7, 12)); /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str { core_str::StrExt::slice_unchecked(self, begin, end) } /// Creates a string slice from another string slice, bypassing safety /// checks. /// /// This new slice goes from `begin` to `end`, including `begin` but /// excluding `end`. /// /// To get an immutable string slice instead, see the /// [`slice_unchecked()`] method. /// /// [`slice_unchecked()`]: #method.slice_unchecked /// /// # Safety /// /// Callers of this function are responsible that three preconditions are /// satisfied: /// /// * `begin` must come before `end`. /// * `begin` and `end` must be byte positions within the string slice. /// * `begin` and `end` must lie on UTF-8 sequence boundaries. #[stable(feature = "str_slice_mut", since = "1.5.0")] #[inline] pub unsafe fn slice_mut_unchecked(&mut self, begin: usize, end: usize) -> &mut str { core_str::StrExt::slice_mut_unchecked(self, begin, end) } /// Divide one string slice into two at an index. /// /// The argument, `mid`, should be a byte offset from the start of the /// string. It must also be on the boundary of a UTF-8 code point. /// /// The two slices returned go from the start of the string slice to `mid`, /// and from `mid` to the end of the string slice. /// /// To get mutable string slices instead, see the [`split_at_mut()`] /// method. /// /// [`split_at_mut()`]: #method.split_at_mut /// /// # Panics /// /// Panics if `mid` is not on a UTF-8 code point boundary, or if it is /// beyond the last code point of the string slice. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = "Per Martin-Löf"; /// /// let (first, last) = s.split_at(3); /// /// assert_eq!("Per", first); /// assert_eq!(" Martin-Löf", last); /// ``` #[inline] #[stable(feature = "str_split_at", since = "1.4.0")] pub fn split_at(&self, mid: usize) -> (&str, &str) { core_str::StrExt::split_at(self, mid) } /// Divide one mutable string slice into two at an index. /// /// The argument, `mid`, should be a byte offset from the start of the /// string. It must also be on the boundary of a UTF-8 code point. /// /// The two slices returned go from the start of the string slice to `mid`, /// and from `mid` to the end of the string slice. /// /// To get immutable string slices instead, see the [`split_at()`] method. /// /// [`split_at()`]: #method.split_at /// /// # Panics /// /// Panics if `mid` is not on a UTF-8 code point boundary, or if it is /// beyond the last code point of the string slice. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut s = "Per Martin-Löf".to_string(); /// /// let (first, last) = s.split_at_mut(3); /// /// assert_eq!("Per", first); /// assert_eq!(" Martin-Löf", last); /// ``` #[inline] #[stable(feature = "str_split_at", since = "1.4.0")] pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str) { core_str::StrExt::split_at_mut(self, mid) } /// Returns an iterator over the `char`s of a string slice. /// /// As a string slice consists of valid UTF-8, we can iterate through a /// string slice by [`char`]. This method returns such an iterator. /// /// It's important to remember that [`char`] represents a Unicode Scalar /// Value, and may not match your idea of what a 'character' is. Iteration /// over grapheme clusters may be what you actually want. /// /// [`char`]: primitive.char.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let word = "goodbye"; /// /// let count = word.chars().count(); /// assert_eq!(7, count); /// /// let mut chars = word.chars(); /// /// assert_eq!(Some('g'), chars.next()); /// assert_eq!(Some('o'), chars.next()); /// assert_eq!(Some('o'), chars.next()); /// assert_eq!(Some('d'), chars.next()); /// assert_eq!(Some('b'), chars.next()); /// assert_eq!(Some('y'), chars.next()); /// assert_eq!(Some('e'), chars.next()); /// /// assert_eq!(None, chars.next()); /// ``` /// /// Remember, [`char`]s may not match your human intuition about characters: /// /// ``` /// let y = "y̆"; /// /// let mut chars = y.chars(); /// /// assert_eq!(Some('y'), chars.next()); // not 'y̆' /// assert_eq!(Some('\u{0306}'), chars.next()); /// /// assert_eq!(None, chars.next()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn chars(&self) -> Chars { core_str::StrExt::chars(self) } /// Returns an iterator over the [`char`]s of a string slice, and their /// positions. /// /// As a string slice consists of valid UTF-8, we can iterate through a /// string slice by [`char`]. This method returns an iterator of both /// these [`char`]s, as well as their byte positions. /// /// The iterator yields tuples. The position is first, the [`char`] is /// second. /// /// [`char`]: primitive.char.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let word = "goodbye"; /// /// let count = word.char_indices().count(); /// assert_eq!(7, count); /// /// let mut char_indices = word.char_indices(); /// /// assert_eq!(Some((0, 'g')), char_indices.next()); /// assert_eq!(Some((1, 'o')), char_indices.next()); /// assert_eq!(Some((2, 'o')), char_indices.next()); /// assert_eq!(Some((3, 'd')), char_indices.next()); /// assert_eq!(Some((4, 'b')), char_indices.next()); /// assert_eq!(Some((5, 'y')), char_indices.next()); /// assert_eq!(Some((6, 'e')), char_indices.next()); /// /// assert_eq!(None, char_indices.next()); /// ``` /// /// Remember, [`char`]s may not match your human intuition about characters: /// /// ``` /// let y = "y̆"; /// /// let mut char_indices = y.char_indices(); /// /// assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆') /// assert_eq!(Some((1, '\u{0306}')), char_indices.next()); /// /// assert_eq!(None, char_indices.next()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn char_indices(&self) -> CharIndices { core_str::StrExt::char_indices(self) } /// An iterator over the bytes of a string slice. /// /// As a string slice consists of a sequence of bytes, we can iterate /// through a string slice by byte. This method returns such an iterator. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut bytes = "bors".bytes(); /// /// assert_eq!(Some(b'b'), bytes.next()); /// assert_eq!(Some(b'o'), bytes.next()); /// assert_eq!(Some(b'r'), bytes.next()); /// assert_eq!(Some(b's'), bytes.next()); /// /// assert_eq!(None, bytes.next()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn bytes(&self) -> Bytes { core_str::StrExt::bytes(self) } /// Split a string slice by whitespace. /// /// The iterator returned will return string slices that are sub-slices of /// the original string slice, separated by any amount of whitespace. /// /// 'Whitespace' is defined according to the terms of the Unicode Derived /// Core Property `White_Space`. /// /// # Examples /// /// Basic usage: /// /// ``` /// let mut iter = "A few words".split_whitespace(); /// /// assert_eq!(Some("A"), iter.next()); /// assert_eq!(Some("few"), iter.next()); /// assert_eq!(Some("words"), iter.next()); /// /// assert_eq!(None, iter.next()); /// ``` /// /// All kinds of whitespace are considered: /// /// ``` /// let mut iter = " Mary had\ta\u{2009}little \n\t lamb".split_whitespace(); /// assert_eq!(Some("Mary"), iter.next()); /// assert_eq!(Some("had"), iter.next()); /// assert_eq!(Some("a"), iter.next()); /// assert_eq!(Some("little"), iter.next()); /// assert_eq!(Some("lamb"), iter.next()); /// /// assert_eq!(None, iter.next()); /// ``` #[stable(feature = "split_whitespace", since = "1.1.0")] #[inline] pub fn split_whitespace(&self) -> SplitWhitespace { UnicodeStr::split_whitespace(self) } /// An iterator over the lines of a string, as string slices. /// /// Lines are ended with either a newline (`\n`) or a carriage return with /// a line feed (`\r\n`). /// /// The final line ending is optional. /// /// # Examples /// /// Basic usage: /// /// ``` /// let text = "foo\r\nbar\n\nbaz\n"; /// let mut lines = text.lines(); /// /// assert_eq!(Some("foo"), lines.next()); /// assert_eq!(Some("bar"), lines.next()); /// assert_eq!(Some(""), lines.next()); /// assert_eq!(Some("baz"), lines.next()); /// /// assert_eq!(None, lines.next()); /// ``` /// /// The final line ending isn't required: /// /// ``` /// let text = "foo\nbar\n\r\nbaz"; /// let mut lines = text.lines(); /// /// assert_eq!(Some("foo"), lines.next()); /// assert_eq!(Some("bar"), lines.next()); /// assert_eq!(Some(""), lines.next()); /// assert_eq!(Some("baz"), lines.next()); /// /// assert_eq!(None, lines.next()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] #[inline] pub fn lines(&self) -> Lines { core_str::StrExt::lines(self) } /// An iterator over the lines of a string. #[stable(feature = "rust1", since = "1.0.0")] #[rustc_deprecated(since = "1.4.0", reason = "use lines() instead now")] #[inline] #[allow(deprecated)] pub fn lines_any(&self) -> LinesAny { core_str::StrExt::lines_any(self) } /// Returns an iterator of `u16` over the string encoded as UTF-16. #[stable(feature = "encode_utf16", since = "1.8.0")] pub fn encode_utf16(&self) -> EncodeUtf16 { EncodeUtf16 { encoder: Utf16Encoder::new(self[..].chars()) } } /// Returns `true` if the given pattern matches a sub-slice of /// this string slice. /// /// Returns `false` if it does not. /// /// # Examples /// /// Basic usage: /// /// ``` /// let bananas = "bananas"; /// /// assert!(bananas.contains("nana")); /// assert!(!bananas.contains("apples")); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn contains<'a, P: Pattern<'a>>(&'a self, pat: P) -> bool { core_str::StrExt::contains(self, pat) } /// Returns `true` if the given pattern matches a prefix of this /// string slice. /// /// Returns `false` if it does not. /// /// # Examples /// /// Basic usage: /// /// ``` /// let bananas = "bananas"; /// /// assert!(bananas.starts_with("bana")); /// assert!(!bananas.starts_with("nana")); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn starts_with<'a, P: Pattern<'a>>(&'a self, pat: P) -> bool { core_str::StrExt::starts_with(self, pat) } /// Returns `true` if the given pattern matches a suffix of this /// string slice. /// /// Returns `false` if it does not. /// /// # Examples /// /// Basic usage: /// /// ``` /// let bananas = "bananas"; /// /// assert!(bananas.ends_with("anas")); /// assert!(!bananas.ends_with("nana")); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn ends_with<'a, P: Pattern<'a>>(&'a self, pat: P) -> bool where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::ends_with(self, pat) } /// Returns the byte index of the first character of this string slice that /// matches the pattern. /// /// Returns [`None`] if the pattern doesn't match. /// /// The pattern can be a `&str`, [`char`], or a closure that determines if /// a character matches. /// /// [`char`]: primitive.char.html /// [`None`]: option/enum.Option.html#variant.None /// /// # Examples /// /// Simple patterns: /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// /// assert_eq!(s.find('L'), Some(0)); /// assert_eq!(s.find('é'), Some(14)); /// assert_eq!(s.find("Léopard"), Some(13)); /// ``` /// /// More complex patterns with closures: /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// /// assert_eq!(s.find(char::is_whitespace), Some(5)); /// assert_eq!(s.find(char::is_lowercase), Some(1)); /// ``` /// /// Not finding the pattern: /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// let x: &[_] = &['1', '2']; /// /// assert_eq!(s.find(x), None); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn find<'a, P: Pattern<'a>>(&'a self, pat: P) -> Option { core_str::StrExt::find(self, pat) } /// Returns the byte index of the last character of this string slice that /// matches the pattern. /// /// Returns [`None`] if the pattern doesn't match. /// /// The pattern can be a `&str`, [`char`], or a closure that determines if /// a character matches. /// /// [`char`]: primitive.char.html /// [`None`]: option/enum.Option.html#variant.None /// /// # Examples /// /// Simple patterns: /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// /// assert_eq!(s.rfind('L'), Some(13)); /// assert_eq!(s.rfind('é'), Some(14)); /// ``` /// /// More complex patterns with closures: /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// /// assert_eq!(s.rfind(char::is_whitespace), Some(12)); /// assert_eq!(s.rfind(char::is_lowercase), Some(20)); /// ``` /// /// Not finding the pattern: /// /// ``` /// let s = "Löwe 老虎 Léopard"; /// let x: &[_] = &['1', '2']; /// /// assert_eq!(s.rfind(x), None); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn rfind<'a, P: Pattern<'a>>(&'a self, pat: P) -> Option where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::rfind(self, pat) } /// An iterator over substrings of this string slice, separated by /// characters matched by a pattern. /// /// The pattern can be a `&str`, [`char`], or a closure that determines the /// split. /// /// # Iterator behavior /// /// The returned iterator will be a [`DoubleEndedIterator`] if the pattern /// allows a reverse search and forward/reverse search yields the same /// elements. This is true for, eg, [`char`] but not for `&str`. /// /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html /// /// If the pattern allows a reverse search but its results might differ /// from a forward search, the [`rsplit()`] method can be used. /// /// [`char`]: primitive.char.html /// [`rsplit()`]: #method.rsplit /// /// # Examples /// /// Simple patterns: /// /// ``` /// let v: Vec<&str> = "Mary had a little lamb".split(' ').collect(); /// assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]); /// /// let v: Vec<&str> = "".split('X').collect(); /// assert_eq!(v, [""]); /// /// let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect(); /// assert_eq!(v, ["lion", "", "tiger", "leopard"]); /// /// let v: Vec<&str> = "lion::tiger::leopard".split("::").collect(); /// assert_eq!(v, ["lion", "tiger", "leopard"]); /// /// let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect(); /// assert_eq!(v, ["abc", "def", "ghi"]); /// /// let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect(); /// assert_eq!(v, ["lion", "tiger", "leopard"]); /// ``` /// /// A more complex pattern, using a closure: /// /// ``` /// let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect(); /// assert_eq!(v, ["abc", "def", "ghi"]); /// ``` /// /// If a string contains multiple contiguous separators, you will end up /// with empty strings in the output: /// /// ``` /// let x = "||||a||b|c".to_string(); /// let d: Vec<_> = x.split('|').collect(); /// /// assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]); /// ``` /// /// Contiguous separators are separated by the empty string. /// /// ``` /// let x = "(///)".to_string(); /// let d: Vec<_> = x.split('/').collect();; /// /// assert_eq!(d, &["(", "", "", ")"]); /// ``` /// /// Separators at the start or end of a string are neighbored /// by empty strings. /// /// ``` /// let d: Vec<_> = "010".split("0").collect(); /// assert_eq!(d, &["", "1", ""]); /// ``` /// /// When the empty string is used as a separator, it separates /// every character in the string, along with the beginning /// and end of the string. /// /// ``` /// let f: Vec<_> = "rust".split("").collect(); /// assert_eq!(f, &["", "r", "u", "s", "t", ""]); /// ``` /// /// Contiguous separators can lead to possibly surprising behavior /// when whitespace is used as the separator. This code is correct: /// /// ``` /// let x = " a b c".to_string(); /// let d: Vec<_> = x.split(' ').collect(); /// /// assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]); /// ``` /// /// It does _not_ give you: /// /// ```,ignore /// assert_eq!(d, &["a", "b", "c"]); /// ``` /// /// Use [`split_whitespace()`] for this behavior. /// /// [`split_whitespace()`]: #method.split_whitespace #[stable(feature = "rust1", since = "1.0.0")] pub fn split<'a, P: Pattern<'a>>(&'a self, pat: P) -> Split<'a, P> { core_str::StrExt::split(self, pat) } /// An iterator over substrings of the given string slice, separated by /// characters matched by a pattern and yielded in reverse order. /// /// The pattern can be a `&str`, [`char`], or a closure that determines the /// split. /// /// [`char`]: primitive.char.html /// /// # Iterator behavior /// /// The returned iterator requires that the pattern supports a reverse /// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse /// search yields the same elements. /// /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html /// /// For iterating from the front, the [`split()`] method can be used. /// /// [`split()`]: #method.split /// /// # Examples /// /// Simple patterns: /// /// ``` /// let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect(); /// assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]); /// /// let v: Vec<&str> = "".rsplit('X').collect(); /// assert_eq!(v, [""]); /// /// let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect(); /// assert_eq!(v, ["leopard", "tiger", "", "lion"]); /// /// let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect(); /// assert_eq!(v, ["leopard", "tiger", "lion"]); /// ``` /// /// A more complex pattern, using a closure: /// /// ``` /// let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect(); /// assert_eq!(v, ["ghi", "def", "abc"]); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn rsplit<'a, P: Pattern<'a>>(&'a self, pat: P) -> RSplit<'a, P> where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::rsplit(self, pat) } /// An iterator over substrings of the given string slice, separated by /// characters matched by a pattern. /// /// The pattern can be a `&str`, [`char`], or a closure that determines the /// split. /// /// Equivalent to [`split()`], except that the trailing substring /// is skipped if empty. /// /// [`split()`]: #method.split /// /// This method can be used for string data that is _terminated_, /// rather than _separated_ by a pattern. /// /// # Iterator behavior /// /// The returned iterator will be a [`DoubleEndedIterator`] if the pattern /// allows a reverse search and forward/reverse search yields the same /// elements. This is true for, eg, [`char`] but not for `&str`. /// /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html /// [`char`]: primitive.char.html /// /// If the pattern allows a reverse search but its results might differ /// from a forward search, the [`rsplit_terminator()`] method can be used. /// /// [`rsplit_terminator()`]: #method.rsplit_terminator /// /// # Examples /// /// Basic usage: /// /// ``` /// let v: Vec<&str> = "A.B.".split_terminator('.').collect(); /// assert_eq!(v, ["A", "B"]); /// /// let v: Vec<&str> = "A..B..".split_terminator(".").collect(); /// assert_eq!(v, ["A", "", "B", ""]); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn split_terminator<'a, P: Pattern<'a>>(&'a self, pat: P) -> SplitTerminator<'a, P> { core_str::StrExt::split_terminator(self, pat) } /// An iterator over substrings of `self`, separated by characters /// matched by a pattern and yielded in reverse order. /// /// The pattern can be a simple `&str`, [`char`], or a closure that /// determines the split. /// Additional libraries might provide more complex patterns like /// regular expressions. /// /// [`char`]: primitive.char.html /// /// Equivalent to [`split()`], except that the trailing substring is /// skipped if empty. /// /// [`split()`]: #method.split /// /// This method can be used for string data that is _terminated_, /// rather than _separated_ by a pattern. /// /// # Iterator behavior /// /// The returned iterator requires that the pattern supports a /// reverse search, and it will be double ended if a forward/reverse /// search yields the same elements. /// /// For iterating from the front, the [`split_terminator()`] method can be /// used. /// /// [`split_terminator()`]: #method.split_terminator /// /// # Examples /// /// ``` /// let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect(); /// assert_eq!(v, ["B", "A"]); /// /// let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect(); /// assert_eq!(v, ["", "B", "", "A"]); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn rsplit_terminator<'a, P: Pattern<'a>>(&'a self, pat: P) -> RSplitTerminator<'a, P> where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::rsplit_terminator(self, pat) } /// An iterator over substrings of the given string slice, separated by a /// pattern, restricted to returning at most `n` items. /// /// If `n` substrings are returned, the last substring (the `n`th substring) /// will contain the remainder of the string. /// /// The pattern can be a `&str`, [`char`], or a closure that determines the /// split. /// /// [`char`]: primitive.char.html /// /// # Iterator behavior /// /// The returned iterator will not be double ended, because it is /// not efficient to support. /// /// If the pattern allows a reverse search, the [`rsplitn()`] method can be /// used. /// /// [`rsplitn()`]: #method.rsplitn /// /// # Examples /// /// Simple patterns: /// /// ``` /// let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect(); /// assert_eq!(v, ["Mary", "had", "a little lambda"]); /// /// let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect(); /// assert_eq!(v, ["lion", "", "tigerXleopard"]); /// /// let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect(); /// assert_eq!(v, ["abcXdef"]); /// /// let v: Vec<&str> = "".splitn(1, 'X').collect(); /// assert_eq!(v, [""]); /// ``` /// /// A more complex pattern, using a closure: /// /// ``` /// let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect(); /// assert_eq!(v, ["abc", "defXghi"]); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn splitn<'a, P: Pattern<'a>>(&'a self, n: usize, pat: P) -> SplitN<'a, P> { core_str::StrExt::splitn(self, n, pat) } /// An iterator over substrings of this string slice, separated by a /// pattern, starting from the end of the string, restricted to returning /// at most `n` items. /// /// If `n` substrings are returned, the last substring (the `n`th substring) /// will contain the remainder of the string. /// /// The pattern can be a `&str`, [`char`], or a closure that /// determines the split. /// /// [`char`]: primitive.char.html /// /// # Iterator behavior /// /// The returned iterator will not be double ended, because it is not /// efficient to support. /// /// For splitting from the front, the [`splitn()`] method can be used. /// /// [`splitn()`]: #method.splitn /// /// # Examples /// /// Simple patterns: /// /// ``` /// let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect(); /// assert_eq!(v, ["lamb", "little", "Mary had a"]); /// /// let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect(); /// assert_eq!(v, ["leopard", "tiger", "lionX"]); /// /// let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect(); /// assert_eq!(v, ["leopard", "lion::tiger"]); /// ``` /// /// A more complex pattern, using a closure: /// /// ``` /// let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect(); /// assert_eq!(v, ["ghi", "abc1def"]); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn rsplitn<'a, P: Pattern<'a>>(&'a self, n: usize, pat: P) -> RSplitN<'a, P> where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::rsplitn(self, n, pat) } /// An iterator over the matches of a pattern within the given string /// slice. /// /// The pattern can be a `&str`, [`char`], or a closure that /// determines if a character matches. /// /// [`char`]: primitive.char.html /// /// # Iterator behavior /// /// The returned iterator will be a [`DoubleEndedIterator`] if the pattern /// allows a reverse search and forward/reverse search yields the same /// elements. This is true for, eg, [`char`] but not for `&str`. /// /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html /// [`char`]: primitive.char.html /// /// If the pattern allows a reverse search but its results might differ /// from a forward search, the [`rmatches()`] method can be used. /// /// [`rmatches()`]: #method.rmatches /// /// # Examples /// /// Basic usage: /// /// ``` /// let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect(); /// assert_eq!(v, ["abc", "abc", "abc"]); /// /// let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect(); /// assert_eq!(v, ["1", "2", "3"]); /// ``` #[stable(feature = "str_matches", since = "1.2.0")] pub fn matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> Matches<'a, P> { core_str::StrExt::matches(self, pat) } /// An iterator over the matches of a pattern within this string slice, /// yielded in reverse order. /// /// The pattern can be a `&str`, [`char`], or a closure that determines if /// a character matches. /// /// [`char`]: primitive.char.html /// /// # Iterator behavior /// /// The returned iterator requires that the pattern supports a reverse /// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse /// search yields the same elements. /// /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html /// /// For iterating from the front, the [`matches()`] method can be used. /// /// [`matches()`]: #method.matches /// /// # Examples /// /// Basic usage: /// /// ``` /// let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect(); /// assert_eq!(v, ["abc", "abc", "abc"]); /// /// let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect(); /// assert_eq!(v, ["3", "2", "1"]); /// ``` #[stable(feature = "str_matches", since = "1.2.0")] pub fn rmatches<'a, P: Pattern<'a>>(&'a self, pat: P) -> RMatches<'a, P> where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::rmatches(self, pat) } /// An iterator over the disjoint matches of a pattern within this string /// slice as well as the index that the match starts at. /// /// For matches of `pat` within `self` that overlap, only the indices /// corresponding to the first match are returned. /// /// The pattern can be a `&str`, [`char`], or a closure that determines /// if a character matches. /// /// [`char`]: primitive.char.html /// /// # Iterator behavior /// /// The returned iterator will be a [`DoubleEndedIterator`] if the pattern /// allows a reverse search and forward/reverse search yields the same /// elements. This is true for, eg, [`char`] but not for `&str`. /// /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html /// /// If the pattern allows a reverse search but its results might differ /// from a forward search, the [`rmatch_indices()`] method can be used. /// /// [`rmatch_indices()`]: #method.rmatch_indices /// /// # Examples /// /// Basic usage: /// /// ``` /// let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect(); /// assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]); /// /// let v: Vec<_> = "1abcabc2".match_indices("abc").collect(); /// assert_eq!(v, [(1, "abc"), (4, "abc")]); /// /// let v: Vec<_> = "ababa".match_indices("aba").collect(); /// assert_eq!(v, [(0, "aba")]); // only the first `aba` /// ``` #[stable(feature = "str_match_indices", since = "1.5.0")] pub fn match_indices<'a, P: Pattern<'a>>(&'a self, pat: P) -> MatchIndices<'a, P> { core_str::StrExt::match_indices(self, pat) } /// An iterator over the disjoint matches of a pattern within `self`, /// yielded in reverse order along with the index of the match. /// /// For matches of `pat` within `self` that overlap, only the indices /// corresponding to the last match are returned. /// /// The pattern can be a `&str`, [`char`], or a closure that determines if a /// character matches. /// /// [`char`]: primitive.char.html /// /// # Iterator behavior /// /// The returned iterator requires that the pattern supports a reverse /// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse /// search yields the same elements. /// /// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html /// /// For iterating from the front, the [`match_indices()`] method can be used. /// /// [`match_indices()`]: #method.match_indices /// /// # Examples /// /// Basic usage: /// /// ``` /// let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect(); /// assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]); /// /// let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect(); /// assert_eq!(v, [(4, "abc"), (1, "abc")]); /// /// let v: Vec<_> = "ababa".rmatch_indices("aba").collect(); /// assert_eq!(v, [(2, "aba")]); // only the last `aba` /// ``` #[stable(feature = "str_match_indices", since = "1.5.0")] pub fn rmatch_indices<'a, P: Pattern<'a>>(&'a self, pat: P) -> RMatchIndices<'a, P> where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::rmatch_indices(self, pat) } /// Returns a string slice with leading and trailing whitespace removed. /// /// 'Whitespace' is defined according to the terms of the Unicode Derived /// Core Property `White_Space`. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = " Hello\tworld\t"; /// /// assert_eq!("Hello\tworld", s.trim()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn trim(&self) -> &str { UnicodeStr::trim(self) } /// Returns a string slice with leading whitespace removed. /// /// 'Whitespace' is defined according to the terms of the Unicode Derived /// Core Property `White_Space`. /// /// # Text directionality /// /// A string is a sequence of bytes. 'Left' in this context means the first /// position of that byte string; for a language like Arabic or Hebrew /// which are 'right to left' rather than 'left to right', this will be /// the _right_ side, not the left. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = " Hello\tworld\t"; /// /// assert_eq!("Hello\tworld\t", s.trim_left()); /// ``` /// /// Directionality: /// /// ``` /// let s = " English"; /// assert!(Some('E') == s.trim_left().chars().next()); /// /// let s = " עברית"; /// assert!(Some('ע') == s.trim_left().chars().next()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn trim_left(&self) -> &str { UnicodeStr::trim_left(self) } /// Returns a string slice with trailing whitespace removed. /// /// 'Whitespace' is defined according to the terms of the Unicode Derived /// Core Property `White_Space`. /// /// # Text directionality /// /// A string is a sequence of bytes. 'Right' in this context means the last /// position of that byte string; for a language like Arabic or Hebrew /// which are 'right to left' rather than 'left to right', this will be /// the _left_ side, not the right. /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = " Hello\tworld\t"; /// /// assert_eq!(" Hello\tworld", s.trim_right()); /// ``` /// /// Directionality: /// /// ``` /// let s = "English "; /// assert!(Some('h') == s.trim_right().chars().rev().next()); /// /// let s = "עברית "; /// assert!(Some('ת') == s.trim_right().chars().rev().next()); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn trim_right(&self) -> &str { UnicodeStr::trim_right(self) } /// Returns a string slice with all prefixes and suffixes that match a /// pattern repeatedly removed. /// /// The pattern can be a [`char`] or a closure that determines if a /// character matches. /// /// [`char`]: primitive.char.html /// /// # Examples /// /// Simple patterns: /// /// ``` /// assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar"); /// assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar"); /// /// let x: &[_] = &['1', '2']; /// assert_eq!("12foo1bar12".trim_matches(x), "foo1bar"); /// ``` /// /// A more complex pattern, using a closure: /// /// ``` /// assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar"); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn trim_matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> &'a str where P::Searcher: DoubleEndedSearcher<'a> { core_str::StrExt::trim_matches(self, pat) } /// Returns a string slice with all prefixes that match a pattern /// repeatedly removed. /// /// The pattern can be a `&str`, [`char`], or a closure that determines if /// a character matches. /// /// [`char`]: primitive.char.html /// /// # Text directionality /// /// A string is a sequence of bytes. 'Left' in this context means the first /// position of that byte string; for a language like Arabic or Hebrew /// which are 'right to left' rather than 'left to right', this will be /// the _right_ side, not the left. /// /// # Examples /// /// Basic usage: /// /// ``` /// assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11"); /// assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123"); /// /// let x: &[_] = &['1', '2']; /// assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12"); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn trim_left_matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> &'a str { core_str::StrExt::trim_left_matches(self, pat) } /// Returns a string slice with all suffixes that match a pattern /// repeatedly removed. /// /// The pattern can be a `&str`, [`char`], or a closure that /// determines if a character matches. /// /// [`char`]: primitive.char.html /// /// # Text directionality /// /// A string is a sequence of bytes. 'Right' in this context means the last /// position of that byte string; for a language like Arabic or Hebrew /// which are 'right to left' rather than 'left to right', this will be /// the _left_ side, not the right. /// /// # Examples /// /// Simple patterns: /// /// ``` /// assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar"); /// assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar"); /// /// let x: &[_] = &['1', '2']; /// assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar"); /// ``` /// /// A more complex pattern, using a closure: /// /// ``` /// assert_eq!("1fooX".trim_left_matches(|c| c == '1' || c == 'X'), "fooX"); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn trim_right_matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> &'a str where P::Searcher: ReverseSearcher<'a> { core_str::StrExt::trim_right_matches(self, pat) } /// Parses this string slice into another type. /// /// Because `parse()` is so general, it can cause problems with type /// inference. As such, `parse()` is one of the few times you'll see /// the syntax affectionately known as the 'turbofish': `::<>`. This /// helps the inference algorithm understand specifically which type /// you're trying to parse into. /// /// `parse()` can parse any type that implements the [`FromStr`] trait. /// /// [`FromStr`]: str/trait.FromStr.html /// /// # Errors /// /// Will return [`Err`] if it's not possible to parse this string slice into /// the desired type. /// /// [`Err`]: str/trait.FromStr.html#associatedtype.Err /// /// # Example /// /// Basic usage /// /// ``` /// let four: u32 = "4".parse().unwrap(); /// /// assert_eq!(4, four); /// ``` /// /// Using the 'turbofish' instead of annotating `four`: /// /// ``` /// let four = "4".parse::(); /// /// assert_eq!(Ok(4), four); /// ``` /// /// Failing to parse: /// /// ``` /// let nope = "j".parse::(); /// /// assert!(nope.is_err()); /// ``` #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub fn parse(&self) -> Result { core_str::StrExt::parse(self) } /// Replaces all matches of a pattern with another string. /// /// `replace` creates a new [`String`], and copies the data from this string slice into it. /// While doing so, it attempts to find matches of a pattern. If it finds any, it /// replaces them with the replacement string slice. /// /// [`String`]: string/struct.String.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = "this is old"; /// /// assert_eq!("this is new", s.replace("old", "new")); /// ``` /// /// When the pattern doesn't match: /// /// ``` /// let s = "this is old"; /// assert_eq!(s, s.replace("cookie monster", "little lamb")); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn replace<'a, P: Pattern<'a>>(&'a self, from: P, to: &str) -> String { let mut result = String::new(); let mut last_end = 0; for (start, part) in self.match_indices(from) { result.push_str(unsafe { self.slice_unchecked(last_end, start) }); result.push_str(to); last_end = start + part.len(); } result.push_str(unsafe { self.slice_unchecked(last_end, self.len()) }); result } /// Replaces first N matches of a pattern with another string. /// /// `replacen` creates a new [`String`], and copies the data from this string slice into it. /// While doing so, it attempts to find matches of a pattern. If it finds any, it /// replaces them with the replacement string slice at most `N` times. /// /// [`String`]: string/struct.String.html /// /// # Examples /// /// Basic usage: /// /// ``` /// # #![feature(str_replacen)] /// let s = "foo foo 123 foo"; /// assert_eq!("new new 123 foo", s.replacen("foo", "new", 2)); /// assert_eq!("faa fao 123 foo", s.replacen('o', "a", 3)); /// assert_eq!("foo foo new23 foo", s.replacen(char::is_numeric, "new", 1)); /// ``` /// /// When the pattern doesn't match: /// /// ``` /// # #![feature(str_replacen)] /// let s = "this is old"; /// assert_eq!(s, s.replacen("cookie monster", "little lamb", 10)); /// ``` #[unstable(feature = "str_replacen", issue = "36436", reason = "only need to replace first N matches")] pub fn replacen<'a, P: Pattern<'a>>(&'a self, pat: P, to: &str, count: usize) -> String { // Hope to reduce the times of re-allocation let mut result = String::with_capacity(32); let mut last_end = 0; for (start, part) in self.match_indices(pat).take(count) { result.push_str(unsafe { self.slice_unchecked(last_end, start) }); result.push_str(to); last_end = start + part.len(); } result.push_str(unsafe { self.slice_unchecked(last_end, self.len()) }); result } /// Returns the lowercase equivalent of this string slice, as a new [`String`]. /// /// 'Lowercase' is defined according to the terms of the Unicode Derived Core Property /// `Lowercase`. /// /// [`String`]: string/struct.String.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = "HELLO"; /// /// assert_eq!("hello", s.to_lowercase()); /// ``` /// /// A tricky example, with sigma: /// /// ``` /// let sigma = "Σ"; /// /// assert_eq!("σ", sigma.to_lowercase()); /// /// // but at the end of a word, it's ς, not σ: /// let odysseus = "ὈΔΥΣΣΕΎΣ"; /// /// assert_eq!("ὀδυσσεύς", odysseus.to_lowercase()); /// ``` /// /// Languages without case are not changed: /// /// ``` /// let new_year = "农历新年"; /// /// assert_eq!(new_year, new_year.to_lowercase()); /// ``` #[stable(feature = "unicode_case_mapping", since = "1.2.0")] pub fn to_lowercase(&self) -> String { let mut s = String::with_capacity(self.len()); for (i, c) in self[..].char_indices() { if c == 'Σ' { // Σ maps to σ, except at the end of a word where it maps to ς. // This is the only conditional (contextual) but language-independent mapping // in `SpecialCasing.txt`, // so hard-code it rather than have a generic "condition" mechanism. // See https://github.com/rust-lang/rust/issues/26035 map_uppercase_sigma(self, i, &mut s) } else { s.extend(c.to_lowercase()); } } return s; fn map_uppercase_sigma(from: &str, i: usize, to: &mut String) { // See http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf#G33992 // for the definition of `Final_Sigma`. debug_assert!('Σ'.len_utf8() == 2); let is_word_final = case_ignoreable_then_cased(from[..i].chars().rev()) && !case_ignoreable_then_cased(from[i + 2..].chars()); to.push_str(if is_word_final { "ς" } else { "σ" }); } fn case_ignoreable_then_cased>(iter: I) -> bool { use rustc_unicode::derived_property::{Cased, Case_Ignorable}; match iter.skip_while(|&c| Case_Ignorable(c)).next() { Some(c) => Cased(c), None => false, } } } /// Returns the uppercase equivalent of this string slice, as a new [`String`]. /// /// 'Uppercase' is defined according to the terms of the Unicode Derived Core Property /// `Uppercase`. /// /// [`String`]: string/struct.String.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let s = "hello"; /// /// assert_eq!("HELLO", s.to_uppercase()); /// ``` /// /// Scripts without case are not changed: /// /// ``` /// let new_year = "农历新年"; /// /// assert_eq!(new_year, new_year.to_uppercase()); /// ``` #[stable(feature = "unicode_case_mapping", since = "1.2.0")] pub fn to_uppercase(&self) -> String { let mut s = String::with_capacity(self.len()); s.extend(self.chars().flat_map(|c| c.to_uppercase())); return s; } /// Escapes each char in `s` with `char::escape_debug`. #[unstable(feature = "str_escape", reason = "return type may change to be an iterator", issue = "27791")] pub fn escape_debug(&self) -> String { self.chars().flat_map(|c| c.escape_debug()).collect() } /// Escapes each char in `s` with `char::escape_default`. #[unstable(feature = "str_escape", reason = "return type may change to be an iterator", issue = "27791")] pub fn escape_default(&self) -> String { self.chars().flat_map(|c| c.escape_default()).collect() } /// Escapes each char in `s` with `char::escape_unicode`. #[unstable(feature = "str_escape", reason = "return type may change to be an iterator", issue = "27791")] pub fn escape_unicode(&self) -> String { self.chars().flat_map(|c| c.escape_unicode()).collect() } /// Converts a `Box` into a [`String`] without copying or allocating. /// /// [`String`]: string/struct.String.html /// /// # Examples /// /// Basic usage: /// /// ``` /// let string = String::from("birthday gift"); /// let boxed_str = string.clone().into_boxed_str(); /// /// assert_eq!(boxed_str.into_string(), string); /// ``` #[stable(feature = "box_str", since = "1.4.0")] pub fn into_string(self: Box) -> String { unsafe { let slice = mem::transmute::, Box<[u8]>>(self); String::from_utf8_unchecked(slice.into_vec()) } } /// Create a [`String`] by repeating a string `n` times. /// /// [`String`]: string/struct.String.html /// /// # Examples /// /// Basic usage: /// /// ``` /// #![feature(repeat_str)] /// /// assert_eq!("abc".repeat(4), String::from("abcabcabcabc")); /// ``` #[unstable(feature = "repeat_str", issue = "37079")] pub fn repeat(&self, n: usize) -> String { let mut s = String::with_capacity(self.len() * n); s.extend((0..n).map(|_| self)); s } }