Struct zbuf::StrBuf [−] [src]

pub struct StrBuf(_);

A “zero copy” string buffer.

See crate documentation for an overview.

Methods

impl StrBuf
[src]

Return a new, empty, inline buffer.

Return a new buffer with capacity for at least (typically more than) the given number of bytes.

Panics

Panics if the requested capacity is greater than std::u32::MAX (4 gigabytes).

Examples

assert!(StrBuf::with_capacity(17).capacity() >= 17);

Converts a bytes buffer into a string buffer.

This takes O(length) time to check that the input is well-formed in UTF-8, and returns Err(_) if it is not. No heap memory is allocated or data copied, since this takes ownership of the bytes buffer.

If you already know for sure that a bytes buffer is well-formed in UTF-8, consider the unsafe from_utf8_unchecked method, which takes O(1) time, instead.

Examples

assert!(StrBuf::from_utf8(BytesBuf::from(&b"abc"[..])).is_ok());
assert!(StrBuf::from_utf8(BytesBuf::from(&b"ab\x80"[..])).is_err());

Converts a bytes buffer into a string buffer without checking UTF-8 well-formedness.

This takes O(1) time. No heap memory is allocated or data copied, since this takes ownership of the bytes buffer.

Safety

The given bytes buffer must be well-formed in UTF-8.

Examples

let bytes_buf = BytesBuf::from(b"abc".as_ref());
let str_buf = unsafe {
    StrBuf::from_utf8_unchecked(bytes_buf)
};
assert_eq!(str_buf, "abc");

Converts a bytes buffer into a string buffer.

This takes O(length) time to check that the input is well-formed in UTF-8, and replaces invalid byte sequences (decoding errors) with the replacement character U+FFFD. No heap memory is allocated or data copied, since this takes ownership of the bytes buffer.

If you want to handle decoding errors differently, consider the from_utf8 method which returns a Result.

Examples

assert_eq!(StrBuf::from_utf8_lossy(BytesBuf::from(&b"abc"[..])), "abc");
assert_eq!(StrBuf::from_utf8_lossy(BytesBuf::from(&b"ab\x80"[..])), "ab�");

Converts an iterator of bytes buffers into a string buffer.

This takes O(total length) time to check that the input is well-formed in UTF-8, and returns an error at the first invalid byte sequence (decoding error). No heap memory is allocated or data copied, since this takes ownership of the bytes buffer.

Examples

let chunks = [
    &[0xF0, 0x9F][..],
    &[0x8E],
    &[0x89],
];
assert_eq!(StrBuf::from_utf8_iter(&chunks).unwrap(), "🎉");

Converts an iterator of bytes buffers into a string buffer.

This takes O(total length) time to check that the input is well-formed in UTF-8, and replaces invalid byte sequences (decoding errors) with the replacement character U+FFFD. No heap memory is allocated or data copied, since this takes ownership of the bytes buffer.

Examples

let chunks = [
    &[0xF0, 0x9F][..],
    &[0x8E],
    &[0x89, 0xF0, 0x9F],
];
assert_eq!(StrBuf::from_utf8_iter_lossy(&chunks), "🎉�");

Return a shared (immutable) reference to the bytes buffer representation of this string buffer.

Examples

let buf = StrBuf::from("🎉").as_bytes_buf().clone();
assert_eq!(buf, [0xF0, 0x9F, 0x8E, 0x89]);

Return the length of this buffer, in bytes.

Examples

assert_eq!(StrBuf::from("🎉").len(), 4);

Return whether this buffer is empty.

Examples

assert_eq!(BytesBuf::new().is_empty(), true);
assert_eq!(BytesBuf::from(b"abc".as_ref()).is_empty(), false);

Return the capacity of this buffer: the length to which it can grow without re-allocating.

Examples

assert!(StrBuf::with_capacity(17).capacity() >= 17);

Remove the given number of bytes from the front (the start) of the buffer.

This takes O(1) time and does not copy any heap-allocated data.

Panics

Panics if bytes is out of bounds or not at a char boundary.

Examples

let mut buf = StrBuf::from("hello");
buf.pop_front(2);
assert_eq!(buf, "llo");

Remove the given number of bytes from the back (the end) of the buffer.

This takes O(1) time and does not copy any heap-allocated data.

Panics

Panics if bytes is out of bounds or not at a char boundary.

Examples

let mut buf = StrBuf::from("hello");
buf.pop_back(2);
assert_eq!(buf, "hel");

Split the buffer into two at the given index.

Return a new buffer that contains bytes [at, len), while self contains bytes [0, at).

Panics

Panics if at is out of bounds or not at a char boundary.

Examples

let mut buf = StrBuf::from("hello");
let tail = buf.split_off(2);
assert_eq!(buf, "he");
assert_eq!(tail, "llo");

This makes the buffer empty but, unless it is shared, does not change its capacity

If potentially freeing memory is preferable, consider buf = StrBuf::empty() instead.

Examples

let mut buf = StrBuf::from("hello");
assert_eq!(buf, "hello");
buf.clear();
assert_eq!(buf, "");
assert!(buf.capacity() > 0);

Shortens the buffer to the specified length.

If new_len is greater than the buffer’s current length, this has no effect.

Panics

Panics if new_len is not at a char boundary.

Examples

let mut buf = StrBuf::from("hello");
buf.truncate(10);
assert_eq!(buf, "hello");
buf.truncate(2);
assert_eq!(buf, "he");

Ensures that the buffer has capacity for at least (typically more than) additional bytes beyond its current length.

This copies the data if this buffer is shared or if the existing capacity is insufficient.

Examples

let mut buf = StrBuf::from(&*"abc".repeat(10));
assert!(buf.capacity() < 100);
buf.reserve(100);
assert!(buf.capacity() >= 130);

Extend this buffer by writing to its existing capacity.

The closure is given a potentially-uninitialized mutable string slice, and returns the number of consecutive bytes written from the start of the slice. The buffer’s length is increased by that much.

If self.reserve(additional) is called immediately before this method, the slice is at least additional bytes long. Without a reserve call the slice can be any length, including zero.

This copies the existing data if there are other references to this buffer.

Safety

The closure must not read from the given slice, which may be uninitialized. It must initialize the 0..written range and make it well-formed in UTF-8, where written is the return value.

Panics

Panics if the value returned by the closure is larger than the given closure’s length.

Examples

let mut buf = StrBuf::from("hello");
buf.reserve(10);
unsafe {
    buf.write_to_uninitialized_tail(|uninitialized_str| {
        let uninitialized_bytes = as_bytes_mut(uninitialized_str);
        for byte in &mut uninitialized_bytes[..3] {
            *byte = b'!'
        }
        3
    })
}
assert_eq!(buf, "hello!!!");

/// https://github.com/rust-lang/rust/issues/41119
unsafe fn as_bytes_mut(s: &mut str) -> &mut [u8] {
    ::std::mem::transmute(s)
}

Extend this buffer by writing to its existing capacity.

The closure is given a mutable string slice that has been overwritten with zeros (which takes O(n) extra time). The buffer’s length is increased by the closure’s return value.

If self.reserve(additional) is called immediately before this method, the slice is at least additional bytes long. Without a reserve call the slice can be any length, including zero.

This copies the existing data if there are other references to this buffer.

Panics

Panics if the value returned by the closure is larger than the given closure’s length, or if it is not at a char boundary.

Examples

let mut buf = StrBuf::from("hello");
buf.reserve(10);
buf.write_to_zeroed_tail(|tail| {
    let tail = unsafe {
        as_bytes_mut(tail)
    };
    for byte in &mut tail[..3] {
        *byte = b'!'
    }
    10
});
assert_eq!(buf, "hello!!!\0\0\0\0\0\0\0");

/// https://github.com/rust-lang/rust/issues/41119
unsafe fn as_bytes_mut(s: &mut str) -> &mut [u8] {
    ::std::mem::transmute(s)
}

Appends the given string slice onto the end of this buffer.

This copies the existing data if this buffer is shared or if the existing capacity is insufficient.

Examples

let mut buf = StrBuf::from("hello");
buf.push_str(" world!");
assert_eq!(buf, "hello world!");

Appends the given character onto the end of this buffer.

This copies the existing data if this buffer is shared or if the existing capacity is insufficient.

Examples

let mut buf = StrBuf::from("hello");
buf.push_char('!');
assert_eq!(buf, "hello!");

Appends the given string buffer onto the end of this buffer.

This is similar to push_str, but sometimes more efficient.

Examples

This allocates only once:

let string = "abc".repeat(20);
let mut buf = StrBuf::from(&*string);
let tail = buf.split_off(50);
assert_eq!(buf.len(), 50);
assert_eq!(tail.len(), 10);
buf.push_buf(&tail);
assert_eq!(buf, string);

Methods from Deref<Target = str>

Returns the length of self.

This length is in bytes, not chars or graphemes. In other words, it may not be what a human considers the length of the string.

Examples

Basic usage:

let len = "foo".len();
assert_eq!(3, len);

let len = "ƒoo".len(); // fancy f!
assert_eq!(4, len);

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 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));

Converts a string slice to a byte slice.

Examples

Basic usage:

let bytes = "bors".as_bytes();
assert_eq!(b"bors", bytes);

🔬 This is a nightly-only experimental API. (str_mut_extras)

Converts a mutable string slice to a mutable byte slice.

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.

Examples

Basic usage:

let s = "Hello";
let ptr = s.as_ptr();

🔬 This is a nightly-only experimental API. (str_checked_slicing)

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 = "🗻∈🌏";
assert_eq!(Some("🗻"), v.get(0..4));
assert!(v.get(1..).is_none());
assert!(v.get(..8).is_none());
assert!(v.get(..42).is_none());

🔬 This is a nightly-only experimental API. (str_checked_slicing)

Returns a mutable subslice of str.

This is the non-panicking alternative to indexing the str. Returns None whenever equivalent indexing operation would panic.

Examples

let mut v = String::from("🗻∈🌏");
assert_eq!(Some("🗻"), v.get_mut(0..4).map(|v| &*v));
assert!(v.get_mut(1..).is_none());
assert!(v.get_mut(..8).is_none());
assert!(v.get_mut(..42).is_none());

🔬 This is a nightly-only experimental API. (str_checked_slicing)

Returns a 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 come before 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));
}

🔬 This is a nightly-only experimental API. (str_checked_slicing)

Returns a mutable, 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 come before 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 mut v = String::from("🗻∈🌏");
unsafe {
    assert_eq!("🗻", v.get_unchecked_mut(0..4));
    assert_eq!("∈", v.get_unchecked_mut(4..7));
    assert_eq!("🌏", v.get_unchecked_mut(7..11));
}

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:

  • 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));
}

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 IndexMut.

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.

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.

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 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);

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.

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);

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 may not match your idea of what a 'character' is. Iteration over grapheme clusters may be what you actually want.

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 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());

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 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());

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());

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());

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());

Deprecated since 1.4.0

: use lines() instead now

An iterator over the lines of a string.

Returns an iterator of u16 over the string encoded as UTF-16.

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"));

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"));

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"));

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.

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);

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.

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);

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.

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"]);

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.

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.

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"]);

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.

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.

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", ""]);

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.

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"]);

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, or a closure that determines the split.

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, or a closure that determines the split.

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"]);

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.

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.

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 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.

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"]);

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.

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.

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`

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.

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. '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());

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());

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.

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, or a 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");

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.

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");

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.

Errors

Will return Err if it's not possible to parse this string slice into the desired type.

Example

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());

🔬 This is a nightly-only experimental API. (str_box_extras)

Converts a Box<str> into a Box<[u8]> without copying or allocating.

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());

🔬 This is a nightly-only experimental API. (str_escape)

return type may change to be an iterator

Escapes each char in s with char::escape_debug.

🔬 This is a nightly-only experimental API. (str_escape)

return type may change to be an iterator

Escapes each char in s with char::escape_default.

🔬 This is a nightly-only experimental API. (str_escape)

return type may change to be an iterator

Escapes each char in s with char::escape_unicode.

Converts a Box<str> into a String without copying or allocating.

Examples

Basic usage:

let string = String::from("birthday gift");
let boxed_str = string.clone().into_boxed_str();

assert_eq!(boxed_str.into_string(), string);

Create a String by repeating a string n times.

Examples

Basic usage:

assert_eq!("abc".repeat(4), String::from("abcabcabcabc"));

Trait Implementations

impl Clone for StrBuf
[src]

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

impl Default for StrBuf
[src]

Returns the "default value" for a type. Read more

impl Hash for StrBuf
[src]

Feeds this value into the given [Hasher]. Read more

Feeds a slice of this type into the given [Hasher]. Read more

impl Eq for StrBuf
[src]

impl Ord for StrBuf
[src]

This method returns an Ordering between self and other. Read more

impl Deref for StrBuf
[src]

The resulting type after dereferencing

The method called to dereference a value

impl DerefMut for StrBuf
[src]

This copies the existing data if there are other references to this buffer.

The method called to mutably dereference a value

impl AsRef<str> for StrBuf
[src]

Performs the conversion.

impl AsMut<str> for StrBuf
[src]

Performs the conversion.

impl<'a> From<&'a str> for StrBuf
[src]

Performs the conversion.

impl Debug for StrBuf
[src]

Formats the value using the given formatter.

impl Display for StrBuf
[src]

Formats the value using the given formatter. Read more

impl<T: AsRef<str>> PartialEq<T> for StrBuf
[src]

This method tests for self and other values to be equal, and is used by ==. Read more

This method tests for !=.

impl<T: AsRef<str>> PartialOrd<T> for StrBuf
[src]

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

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

impl Extend<char> for StrBuf
[src]

Extends a collection with the contents of an iterator. Read more

impl FromIterator<char> for StrBuf
[src]

Creates a value from an iterator. Read more

impl<'a> Extend<&'a char> for StrBuf
[src]

Extends a collection with the contents of an iterator. Read more

impl<'a> FromIterator<&'a char> for StrBuf
[src]

Creates a value from an iterator. Read more

impl<'a> Extend<&'a str> for StrBuf
[src]

Extends a collection with the contents of an iterator. Read more

impl<'a> FromIterator<&'a str> for StrBuf
[src]

Creates a value from an iterator. Read more

impl<'a> Extend<&'a StrBuf> for StrBuf
[src]

Extends a collection with the contents of an iterator. Read more

impl<'a> FromIterator<&'a StrBuf> for StrBuf
[src]

Creates a value from an iterator. Read more

impl Extend<StrBuf> for StrBuf
[src]

Extends a collection with the contents of an iterator. Read more

impl FromIterator<StrBuf> for StrBuf
[src]

Creates a value from an iterator. Read more

impl Write for StrBuf
[src]

Writes a slice of bytes into this writer, returning whether the write succeeded. Read more

Writes a [char] into this writer, returning whether the write succeeded. Read more

Glue for usage of the [write!] macro with implementors of this trait. Read more