Struct bytestring::ByteString [−][src]
pub struct ByteString(_);Expand description
An immutable UTF-8 encoded string with Bytes as a storage.
Implementations
Unwraps this ByteString into the underlying Bytes object.
Creates a new ByteString from a &'static str.
Creates a new ByteString from a Bytes.
Safety
This function is unsafe because it does not check the bytes passed to it are valid UTF-8.
If this constraint is violated, it may cause memory unsafety issues with future users of
the ByteString, as we assume that ByteStrings are valid UTF-8. However, the most likely
issue is that the data gets corrupted.
Methods from Deref<Target = str>
Returns the length of self.
This length is in bytes, not chars or graphemes. In other words,
it might not be what a human considers the length of the string.
Examples
Basic usage:
let len = "foo".len();
assert_eq!(3, len);
assert_eq!("ƒoo".len(), 4); // fancy f!
assert_eq!("ƒoo".chars().count(), 3);Returns true if self has a length of zero bytes.
Examples
Basic usage:
let s = "";
assert!(s.is_empty());
let s = "not empty";
assert!(!s.is_empty());Checks that index-th byte is the first byte in a UTF-8 code point
sequence or the end of the string.
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));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.
The caller must ensure that the returned pointer is never written to.
If you need to mutate the contents of the string slice, use as_mut_ptr.
Examples
Basic usage:
let s = "Hello";
let ptr = s.as_ptr();1.20.0[src]pub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output> where
I: SliceIndex<str>,
pub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output> where
I: SliceIndex<str>,
Returns a subslice of str.
This is the non-panicking alternative to indexing the str. Returns
None whenever equivalent indexing operation would panic.
Examples
let v = String::from("🗻∈🌏");
assert_eq!(Some("🗻"), v.get(0..4));
// indices not on UTF-8 sequence boundaries
assert!(v.get(1..).is_none());
assert!(v.get(..8).is_none());
// out of bounds
assert!(v.get(..42).is_none());1.20.0[src]pub unsafe fn get_unchecked<I>(&self, i: I) -> &<I as SliceIndex<str>>::Output where
I: SliceIndex<str>,
pub unsafe fn get_unchecked<I>(&self, i: I) -> &<I as SliceIndex<str>>::Output where
I: SliceIndex<str>,
Returns an unchecked subslice of str.
This is the unchecked alternative to indexing the str.
Safety
Callers of this function are responsible that these preconditions are satisfied:
- The starting index must not exceed the ending index;
- Indexes must be within bounds of the original slice;
- Indexes must lie on UTF-8 sequence boundaries.
Failing that, the returned string slice may reference invalid memory or
violate the invariants communicated by the str type.
Examples
let v = "🗻∈🌏";
unsafe {
assert_eq!("🗻", v.get_unchecked(0..4));
assert_eq!("∈", v.get_unchecked(4..7));
assert_eq!("🌏", v.get_unchecked(7..11));
}👎 Deprecated since 1.29.0: use get_unchecked(begin..end) instead
use get_unchecked(begin..end) instead
Creates a string slice from another string slice, bypassing safety checks.
This is generally not recommended, use with caution! For a safe
alternative see str and Index.
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.
Safety
Callers of this function are responsible that three preconditions are satisfied:
beginmust not exceedend.beginandendmust be byte positions within the string slice.beginandendmust 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));
}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.
Panics
Panics if mid is not on a UTF-8 code point boundary, or if it is
past the end of 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);Returns an iterator over the chars 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 might not match your idea of what a ‘character’ is. Iteration
over grapheme clusters may be what you actually want. This functionality
is not provided by Rust’s standard library, check crates.io instead.
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, chars might not match your 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());Returns an iterator over the chars 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 chars, as well as their byte positions.
The iterator yields tuples. The position is first, the char is
second.
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, chars might not match your intuition about characters:
let yes = "y̆es";
let mut char_indices = yes.char_indices();
assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
assert_eq!(Some((1, '\u{0306}')), char_indices.next());
// note the 3 here - the last character took up two bytes
assert_eq!(Some((3, 'e')), char_indices.next());
assert_eq!(Some((4, 's')), char_indices.next());
assert_eq!(None, char_indices.next());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());Splits 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. If you only want to split on ASCII whitespace
instead, use split_ascii_whitespace.
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());Splits a string slice by ASCII whitespace.
The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of ASCII whitespace.
To split by Unicode Whitespace instead, use split_whitespace.
Examples
Basic usage:
let mut iter = "A few words".split_ascii_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 ASCII whitespace are considered:
let mut iter = " Mary had\ta little \n\t lamb".split_ascii_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());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. A string that ends with a final line ending will return the same lines as an otherwise identical string without a final line ending.
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());👎 Deprecated since 1.4.0: use lines() instead now
use lines() instead now
An iterator over the lines of a string.
Returns an iterator of u16 over the string encoded as UTF-16.
Examples
Basic usage:
let text = "Zażółć gęślą jaźń";
let utf8_len = text.len();
let utf16_len = text.encode_utf16().count();
assert!(utf16_len <= utf8_len);Returns true if the given pattern matches a sub-slice of
this string slice.
Returns false if it does not.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
Basic usage:
let bananas = "bananas";
assert!(bananas.contains("nana"));
assert!(!bananas.contains("apples"));Returns true if the given pattern matches a prefix of this
string slice.
Returns false if it does not.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
Basic usage:
let bananas = "bananas";
assert!(bananas.starts_with("bana"));
assert!(!bananas.starts_with("nana"));Returns true if the given pattern matches a suffix of this
string slice.
Returns false if it does not.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
Basic usage:
let bananas = "bananas";
assert!(bananas.ends_with("anas"));
assert!(!bananas.ends_with("nana"));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, a slice of chars, or a
function or closure that determines if a character matches.
Examples
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi";
assert_eq!(s.find('L'), Some(0));
assert_eq!(s.find('é'), Some(14));
assert_eq!(s.find("pard"), Some(17));More complex patterns using point-free style and 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));
assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1));
assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));Not finding the pattern:
let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];
assert_eq!(s.find(x), None);Returns the byte index for the first character of the rightmost match of the pattern in this string slice.
Returns None if the pattern doesn’t match.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
Simple patterns:
let s = "Löwe 老虎 Léopard Gepardi";
assert_eq!(s.rfind('L'), Some(13));
assert_eq!(s.rfind('é'), Some(14));
assert_eq!(s.rfind("pard"), Some(24));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);An iterator over substrings of this string slice, separated by characters matched by a pattern.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
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, e.g., char, but not for &str.
If the pattern allows a reverse search but its results might differ
from a forward search, the rsplit method can be used.
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"]);If the pattern is a slice of chars, split on each occurrence of any of the characters:
let v: Vec<&str> = "2020-11-03 23:59".split(&['-', ' ', ':', '@'][..]).collect();
assert_eq!(v, ["2020", "11", "03", "23", "59"]);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:
assert_eq!(d, &["a", "b", "c"]);Use split_whitespace for this behavior.
1.51.0[src]pub fn split_inclusive<'a, P>(&'a self, pat: P) -> SplitInclusive<'a, P> where
P: Pattern<'a>,
pub fn split_inclusive<'a, P>(&'a self, pat: P) -> SplitInclusive<'a, P> where
P: Pattern<'a>,
An iterator over substrings of this string slice, separated by
characters matched by a pattern. Differs from the iterator produced by
split in that split_inclusive leaves the matched part as the
terminator of the substring.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
.split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);If the last element of the string is matched, that element will be considered the terminator of the preceding substring. That substring will be the last item returned by the iterator.
let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n"
.split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);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, a slice of chars, or a
function or closure that determines if a character matches.
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.
For iterating from the front, the split method can be used.
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"]);1.0.0[src]pub fn split_terminator<'a, P>(&'a self, pat: P) -> SplitTerminator<'a, P> where
P: Pattern<'a>,
pub fn split_terminator<'a, P>(&'a self, pat: P) -> SplitTerminator<'a, P> where
P: Pattern<'a>,
An iterator over substrings of the given string slice, separated by characters matched by a pattern.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Equivalent to split, except that the trailing substring
is skipped if empty.
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, e.g., char, but not for &str.
If the pattern allows a reverse search but its results might differ
from a forward search, the rsplit_terminator method can be used.
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", ""]);
let v: Vec<&str> = "A.B:C.D".split_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["A", "B", "C", "D"]);1.0.0[src]pub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
An iterator over substrings of self, separated by characters
matched by a pattern and yielded in reverse order.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Equivalent to split, except that the trailing substring is
skipped if empty.
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.
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"]);
let v: Vec<&str> = "A.B:C.D".rsplit_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["D", "C", "B", "A"]);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 nth substring)
will contain the remainder of the string.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
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.
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"]);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 nth substring)
will contain the remainder of the string.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
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.
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"]);Splits the string on the first occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.
Examples
assert_eq!("cfg".split_once('='), None);
assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));Splits the string on the last occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.
Examples
assert_eq!("cfg".rsplit_once('='), None);
assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));An iterator over the disjoint matches of a pattern within the given string slice.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
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, e.g., char, but not for &str.
If the pattern allows a reverse search but its results might differ
from a forward search, the rmatches method can be used.
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"]);An iterator over the disjoint matches of a pattern within this string slice, yielded in reverse order.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
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.
For iterating from the front, the matches method can be used.
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"]);1.5.0[src]pub fn match_indices<'a, P>(&'a self, pat: P) -> MatchIndices<'a, P> where
P: Pattern<'a>,
pub fn match_indices<'a, P>(&'a self, pat: P) -> MatchIndices<'a, P> where
P: Pattern<'a>,
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, a slice of chars, or a
function or closure that determines if a character matches.
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, e.g., char, but not for &str.
If the pattern allows a reverse search but its results might differ
from a forward search, the rmatch_indices method can be used.
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`1.5.0[src]pub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
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, a slice of chars, or a
function or closure that determines if a character matches.
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.
For iterating from the front, the match_indices method can be used.
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`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());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. start in this context means the first
position of that byte string; for a left-to-right language like English or
Russian, this will be left side, and for right-to-left languages like
Arabic or Hebrew, this will be the right side.
Examples
Basic usage:
let s = " Hello\tworld\t";
assert_eq!("Hello\tworld\t", s.trim_start());Directionality:
let s = " English ";
assert!(Some('E') == s.trim_start().chars().next());
let s = " עברית ";
assert!(Some('ע') == s.trim_start().chars().next());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. end in this context means the last
position of that byte string; for a left-to-right language like English or
Russian, this will be right side, and for right-to-left languages like
Arabic or Hebrew, this will be the left side.
Examples
Basic usage:
let s = " Hello\tworld\t";
assert_eq!(" Hello\tworld", s.trim_end());Directionality:
let s = " English ";
assert!(Some('h') == s.trim_end().chars().rev().next());
let s = " עברית ";
assert!(Some('ת') == s.trim_end().chars().rev().next());👎 Deprecated since 1.33.0: superseded by trim_start
superseded by trim_start
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());👎 Deprecated since 1.33.0: superseded by trim_end
superseded by trim_end
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());1.0.0[src]pub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: DoubleEndedSearcher<'a>,
pub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: DoubleEndedSearcher<'a>,
Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.
The pattern can be a char, a slice of chars, or a function
or closure that determines if a character matches.
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");Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Text directionality
A string is a sequence of bytes. start in this context means the first
position of that byte string; for a left-to-right language like English or
Russian, this will be left side, and for right-to-left languages like
Arabic or Hebrew, this will be the right side.
Examples
Basic usage:
assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");Returns a string slice with the prefix removed.
If the string starts with the pattern prefix, returns substring after the prefix, wrapped
in Some. Unlike trim_start_matches, this method removes the prefix exactly once.
If the string does not start with prefix, returns None.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar"));
assert_eq!("foo:bar".strip_prefix("bar"), None);
assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));1.45.0[src]pub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn strip_suffix<'a, P>(&'a self, suffix: P) -> Option<&'a str> where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
Returns a string slice with the suffix removed.
If the string ends with the pattern suffix, returns the substring before the suffix,
wrapped in Some. Unlike trim_end_matches, this method removes the suffix exactly once.
If the string does not end with suffix, returns None.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Examples
assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar"));
assert_eq!("bar:foo".strip_suffix("bar"), None);
assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));1.30.0[src]pub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
pub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
Text directionality
A string is a sequence of bytes. end in this context means the last
position of that byte string; for a left-to-right language like English or
Russian, this will be right side, and for right-to-left languages like
Arabic or Hebrew, this will be the left side.
Examples
Simple patterns:
assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");
let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");A more complex pattern, using a closure:
assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");👎 Deprecated since 1.33.0: superseded by trim_start_matches
superseded by trim_start_matches
Returns a string slice with all prefixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
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");1.0.0[src]pub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
👎 Deprecated since 1.33.0: superseded by trim_end_matches
pub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str where
P: Pattern<'a>,
<P as Pattern<'a>>::Searcher: ReverseSearcher<'a>,
superseded by trim_end_matches
Returns a string slice with all suffixes that match a pattern repeatedly removed.
The pattern can be a &str, char, a slice of chars, or a
function or closure that determines if a character matches.
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_right_matches(|c| c == '1' || c == 'X'), "1foo");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 into any type that implements the FromStr trait.
Errors
Will return Err if it’s not possible to parse this string slice into
the desired type.
Examples
Basic usage
let four: u32 = "4".parse().unwrap();
assert_eq!(4, four);Using the ‘turbofish’ instead of annotating four:
let four = "4".parse::<u32>();
assert_eq!(Ok(4), four);Failing to parse:
let nope = "j".parse::<u32>();
assert!(nope.is_err());Checks if all characters in this string are within the ASCII range.
Examples
let ascii = "hello!\n";
let non_ascii = "Grüße, Jürgen ❤";
assert!(ascii.is_ascii());
assert!(!non_ascii.is_ascii());Checks that two strings are an ASCII case-insensitive match.
Same as to_ascii_lowercase(a) == to_ascii_lowercase(b),
but without allocating and copying temporaries.
Examples
assert!("Ferris".eq_ignore_ascii_case("FERRIS"));
assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));Return an iterator that escapes each char in self with char::escape_debug.
Note: only extended grapheme codepoints that begin the string will be escaped.
Examples
As an iterator:
for c in "❤\n!".escape_debug() {
print!("{}", c);
}
println!();Using println! directly:
println!("{}", "❤\n!".escape_debug());Both are equivalent to:
println!("❤\\n!");Using to_string:
assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");Return an iterator that escapes each char in self with char::escape_default.
Examples
As an iterator:
for c in "❤\n!".escape_default() {
print!("{}", c);
}
println!();Using println! directly:
println!("{}", "❤\n!".escape_default());Both are equivalent to:
println!("\\u{{2764}}\\n!");Using to_string:
assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");Return an iterator that escapes each char in self with char::escape_unicode.
Examples
As an iterator:
for c in "❤\n!".escape_unicode() {
print!("{}", c);
}
println!();Using println! directly:
println!("{}", "❤\n!".escape_unicode());Both are equivalent to:
println!("\\u{{2764}}\\u{{a}}\\u{{21}}");Using to_string:
assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");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.
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"));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 count times.
Examples
Basic usage:
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:
let s = "this is old";
assert_eq!(s, s.replacen("cookie monster", "little lamb", 10));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.
Since some characters can expand into multiple characters when changing
the case, this function returns a String instead of modifying the
parameter in-place.
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());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.
Since some characters can expand into multiple characters when changing
the case, this function returns a String instead of modifying the
parameter in-place.
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());One character can become multiple:
let s = "tschüß";
assert_eq!("TSCHÜSS", s.to_uppercase());Creates a new String by repeating a string n times.
Panics
This function will panic if the capacity would overflow.
Examples
Basic usage:
assert_eq!("abc".repeat(4), String::from("abcabcabcabc"));A panic upon overflow:
// this will panic at runtime
let huge = "0123456789abcdef".repeat(usize::MAX);Returns a copy of this string where each character is mapped to its ASCII upper case equivalent.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To uppercase the value in-place, use make_ascii_uppercase.
To uppercase ASCII characters in addition to non-ASCII characters, use
to_uppercase.
Examples
let s = "Grüße, Jürgen ❤";
assert_eq!("GRüßE, JüRGEN ❤", s.to_ascii_uppercase());Returns a copy of this string where each character is mapped to its ASCII lower case equivalent.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To lowercase the value in-place, use make_ascii_lowercase.
To lowercase ASCII characters in addition to non-ASCII characters, use
to_lowercase.
Examples
let s = "Grüße, Jürgen ❤";
assert_eq!("grüße, jürgen ❤", s.to_ascii_lowercase());Trait Implementations
Returns the “default value” for a type. Read more
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
Auto Trait Implementations
impl RefUnwindSafe for ByteString
impl Send for ByteString
impl Sync for ByteString
impl Unpin for ByteString
impl UnwindSafe for ByteString
Blanket Implementations
Mutably borrows from an owned value. Read more