Struct NonEmptyString 

pub struct NonEmptyString { /* private fields */ }

Available on crate features std or alloc only.

Represents non-empty String values.

Implementations

impl NonEmptyString

pub const fn new(string: String) -> Result<Self, EmptyString>

Constructs Self, provided that the String is non-empty.

Errors

Returns EmptyString if the string is empty.

Examples

Basic snippet:

use non_empty_str::NonEmptyString;

let message = NonEmptyString::new("Hello, world!".to_owned()).unwrap();

Handling possible errors and recovering empty strings:

use non_empty_str::NonEmptyString;

let empty_owned = NonEmptyString::new(String::new()).unwrap_err();

let empty = empty_owned.get();

pub const unsafe fn new_unchecked(inner: String) -> Self

Constructs Self without checking if the string is non-empty.

Safety

The caller must ensure that the string is non-empty.

pub fn from_non_empty_str(string: &NonEmptyStr) -> Self

Constructs Self from NonEmptyStr via cloning.

Examples

Basic snippet:

use non_empty_str::{NonEmptyString, NonEmptyStr};

let nekit = NonEmptyStr::from_str("nekit").unwrap();

let owned = NonEmptyString::from_non_empty_str(nekit);

pub const fn is_empty(&self) -> bool

👎Deprecated: this string is never empty

Checks if the string is empty. Always returns false.

This method is deprecated since the string is never empty.

pub const fn len(&self) -> Size

Returns the length of the string in bytes as Size.

pub const fn capacity(&self) -> Size

Returns the capacity of the string in bytes as Size.

pub const fn as_str(&self) -> &str

Extracts the string slice containing the entire string.

pub const fn as_mut_str(&mut self) -> &mut str

Returns the mutable string slice containing the entire string.

pub const fn as_non_empty_str(&self) -> &NonEmptyStr

Returns contained string reference as NonEmptyStr.

pub const fn as_non_empty_mut_str(&mut self) -> &mut NonEmptyStr

Returns contained mutable string reference as NonEmptyStr.

pub const fn as_bytes(&self) -> &[u8]

Returns the underlying bytes of the string.

pub const unsafe fn as_bytes_mut(&mut self) -> &mut [u8]

Returns the underlying mutable bytes of the string.

Safety

The caller must ensure that the bytes remain valid UTF-8.

pub const fn as_non_empty_bytes(&self) -> &NonEmptyBytes

Returns the underlying bytes of the string as NonEmptyBytes.

pub const unsafe fn as_non_empty_bytes_mut(&mut self) -> &mut NonEmptyBytes

Returns the underlying mutable bytes of the string as NonEmptyBytes.

Safety

The caller must ensure that the bytes remain valid UTF-8.

pub const fn as_string(&self) -> &String

Returns the contained string reference.

pub fn from_utf8_lossy(bytes: &[u8]) -> Result<NonEmptyCowStr<'_>, EmptySlice>

Similar to from_non_empty_utf8_lossy, but accepts the possibility of empty bytes.

Errors

Returns EmptySlice if the given bytes are empty.

pub fn from_utf8_lossy_owned(bytes: Vec<u8>) -> Result<Self, EmptyByteVec>

Similar to from_non_empty_utf8_lossy_owned, but accepts the possibility of empty byte vectors.

Errors

Returns EmptyByteVec if the given byte vector is empty.

pub fn from_non_empty_utf8_lossy( non_empty: &NonEmptyBytes, ) -> NonEmptyCowStr<'_>

Converts the given NonEmptyBytes to non-empty string, including invalid characters.

Any invalid UTF-8 sequences will be replaced with char::REPLACEMENT_CHARACTER.

This function returns NonEmptyCowStr<'_>, since it may borrow the input bytes in case they are valid UTF-8, or allocate new non-empty string otherwise.

pub fn from_non_empty_utf8_lossy_owned(non_empty: NonEmptyByteVec) -> Self

Converts the given NonEmptyByteVec to non-empty string, including invalid characters.

Any invalid UTF-8 sequences will be replaced with char::REPLACEMENT_CHARACTER.

This function does not guarantee reuse of the original byte vector allocation.

pub fn from_utf8(bytes: Vec<u8>) -> Result<Self, FromMaybeEmptyUtf8Error>

Converts the given byte vector to non-empty string if it is non-empty and valid UTF-8.

Errors

Returns FromMaybeEmptyUtf8Error if the byte vector is empty or invalid UTF-8.

pub fn from_non_empty_utf8( non_empty: NonEmptyByteVec, ) -> Result<Self, FromNonEmptyUtf8Error>

Converts the given NonEmptyByteVec to non-empty string if it is valid UTF-8.

Errors

Returns FromNonEmptyUtf8Error if the byte vector is invalid UTF-8.

pub unsafe fn from_non_empty_utf8_unchecked(non_empty: NonEmptyByteVec) -> Self

Constructs Self from the given NonEmptyByteVec without checking for UTF-8 validity.

Safety

The caller must ensure that the non-empty byte vector is valid UTF-8.

pub unsafe fn from_utf8_unchecked(bytes: Vec<u8>) -> Self

Constructs Self from the given byte vector without checking for emptiness or UTF-8 validity.

Safety

The caller must ensure that the byte vector is non-empty and valid UTF-8.

pub const unsafe fn as_mut_string(&mut self) -> &mut String

Returns the contained mutable string reference.

Safety

The caller must ensure that the string remains non-empty.

pub fn into_string(self) -> String

Returns the contained String.

pub fn into_bytes(self) -> Vec<u8>

Converts Self into the underlying byte vector.

pub fn into_non_empty_bytes(self) -> NonEmptyByteVec

Converts Self into the underlying byte vector as NonEmptyByteVec.

pub fn push(&mut self, character: char)

Appends the given char to the end of this string.

pub fn push_str(&mut self, string: &str)

Appends the given str onto the end of this string.

pub fn extend_from_within<R: RangeBounds<usize>>(&mut self, source: R)

Copies bytes from the given range to the end of the string.

Panics

Panics if the range is out of bounds or not on character boundaries.

pub fn extend_from<S: AsRef<str>>(&mut self, string: S)

Appends anything that can be converted to string onto the end of this string.

pub fn reserve(&mut self, additional: Size)

Reserves capacity for at least additional more bytes to be added.

Note that the additional capacity is required to be non-zero via Size.

This method can over-allocate to speculatively avoid frequent reallocations.

Does nothing if the capacity is already sufficient.

Panics

Panics on capacity overflow.

pub fn reserve_exact(&mut self, additional: Size)

Reserves the minimum capacity for exactly additional more values to be added.

Note that the additional capacity is required to be non-zero via Size.

Unlike reserve, this method will not deliberately over-allocate to speculatively avoid frequent reallocations.

Does nothing if the capacity is already sufficient.

Panics

Panics on capacity overflow.

pub fn try_reserve(&mut self, additional: Size) -> Result<(), TryReserveError>

Tries to reserve capacity for at least additional more bytes to be added.

Note that the additional capacity is required to be non-zero via Size.

This method can over-allocate to speculatively avoid frequent reallocations.

Does nothing if the capacity is already sufficient.

Errors

Returns TryReserveError if the allocation fails or capacity overflows.

pub fn try_reserve_exact( &mut self, additional: Size, ) -> Result<(), TryReserveError>

Tries to reserve the minimum capacity for exactly additional more bytes to be added.

Note that the additional capacity is required to be non-zero via Size.

Unlike try_reserve, this method will not deliberately over-allocate to speculatively avoid frequent reallocations.

Does nothing if the capacity is already sufficient.

Errors

Returns TryReserveError if the allocation fails or capacity overflows.

pub fn shrink_to_fit(&mut self)

Shrinks the capacity of the string as much as possible.

pub fn shrink_to(&mut self, capacity: Size)

Shrinks the capacity of the string to the specified amount.

The capacity will remain at least as large as both the length and the supplied amount.

Does nothing if the current capacity is less than or equal to the specified amount.

pub fn truncate(&mut self, new: Size)

Shortens this string to the specified non-zero length.

Does nothing if new is greater than or equal to the string’s len.

pub fn next_empty(&self) -> bool

Checks whether the string is almost empty, meaning it only contains one character.

pub fn next_non_empty(&self) -> bool

The negated version of next_empty.

pub fn pop(&mut self) -> Option<char>

Removes the last character from the string and returns it, or None if the string would become empty.

pub fn leak<'a>(self) -> &'a mut str

Consumes and leaks the string, returning the mutable reference of its contents.

pub fn leak_non_empty<'a>(self) -> &'a mut NonEmptyStr

Similar to leak, but returns NonEmptyStr.

pub fn insert(&mut self, index: usize, character: char)

Inserts the given character at the specified index, shifting all bytes after it to the right.

Panics

Panics if the index is out of bounds or not on character boundary.

pub fn insert_str(&mut self, index: usize, string: &str)

Inserts the given string at the specified index, shifting all bytes after it to the right.

Panics

Panics if the index is out of bounds or not on character boundary.

pub fn insert_from<S: AsRef<str>>(&mut self, index: usize, string: S)

Inserts anything that can be converted to string at the specified index, shifting all bytes after it to the right.

Panics

Panics if the index is out of bounds or not on character boundary.

pub fn remove(&mut self, index: usize) -> Option<char>

Removes and returns the character at the given index within the string, shifting all bytes after it to the left.

Returns None if the string would become empty.

Panics

Panics if the index is out of bounds or not on character boundary.

pub fn split_off(&mut self, at: Size) -> String

Splits the string into two at the given non-zero index.

The index has to be non-zero to guaratee that the string would remain non-empty.

Panics

Panics if the provided index is out of bounds or not on character boundary.

impl NonEmptyString

pub fn single(character: char) -> Self

Constructs Self containing single provided character.

pub fn with_capacity_and_char(capacity: Size, character: char) -> Self

Constructs Self with the specified capacity in bytes, pushing the provided character.

impl NonEmptyString

pub fn from_non_empty_boxed_str(non_empty: NonEmptyBoxedStr) -> Self

Constructs Self from NonEmptyBoxedStr.

pub fn into_non_empty_boxed_str(self) -> NonEmptyBoxedStr

Converts Self into NonEmptyBoxedStr.

pub fn into_boxed_str(self) -> Box<str>

Converts Self into Box<str>.

pub fn into_boxed_bytes(self) -> Box<[u8]>

Converts Self into Box<[u8]>.

pub fn into_non_empty_boxed_bytes(self) -> NonEmptyBoxedBytes

Converts Self into NonEmptyBoxedBytes.

Methods from Deref<Target = NonEmptyStr>

pub fn as_str(&self) -> &str

Returns the contained string.

Examples

use non_empty_str::NonEmptyStr;

let string = "Hello, world!";

let non_empty = NonEmptyStr::from_str(string).unwrap();

assert_eq!(non_empty.as_str(), string);

pub fn as_mut_str(&mut self) -> &mut str

Returns the contained mutable string.

pub fn is_empty(&self) -> bool

👎Deprecated: this string is never empty

Checks if the string is empty. Always returns false.

This method is deprecated since the string is never empty.

pub fn len(&self) -> Size

Returns the length of the string in bytes as Size.

pub fn as_bytes(&self) -> &[u8]

Returns the underlying bytes of the string.

pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8]

Returns the underlying mutable bytes of the string.

Safety

The caller must ensure that the bytes remain valid UTF-8.

pub fn as_non_empty_bytes(&self) -> &NonEmptyBytes

Returns the underlying bytes of the string as NonEmptyBytes.

pub unsafe fn as_non_empty_bytes_mut(&mut self) -> &mut NonEmptyBytes

Returns the underlying mutable bytes of the string as NonEmptyBytes.

Safety

The caller must ensure that the bytes remain valid UTF-8.

pub fn bytes(&self) -> BytesIter<'_>

Returns non-empty iterators over the bytes in this string.

pub fn chars(&self) -> Chars<'_>

Returns non-empty iterators over the characters in this string.

pub fn char_indices(&self) -> CharIndices<'_>

Returns non-empty iterators over the characters and their positions in this string.

pub fn encode_utf16(&self) -> EncodeUtf16<'_>

Returns non-empty iterators over the UTF-16 encoding of this string.

pub fn escape_debug(&self) -> EscapeDebug<'_>

Returns non-empty iterators over the debug-escaped characters in this string.

pub fn escape_default(&self) -> EscapeDefault<'_>

Returns non-empty iterators over the default-escaped characters in this string.

pub fn escape_unicode(&self) -> EscapeUnicode<'_>

Returns non-empty iterators over the Unicode-escaped characters in this string.

pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_>

Represents iterators over the non-ASCII-whitespace non-empty substrings of this string.

pub fn split_whitespace(&self) -> SplitWhitespace<'_>

Represents iterators over the non-whitespace non-empty substrings of this string.

pub fn as_ptr(&self) -> *const u8

Returns the raw pointer to the underlying bytes of the string.

The caller must ensure that the pointer is never written to.

pub fn as_mut_ptr(&mut self) -> *mut u8

Returns the mutable pointer to the underlying bytes of the string.

The caller must ensure that the string remains valid UTF-8.

pub fn is_char_boundary(&self, index: usize) -> bool

Checks that the provided index lies on the character boundary.

The start and end of the string are considered to be boundaries.

Returns false if the index is out of bounds.

pub fn split_at(&self, index: Size) -> (&Self, &str)

Splits the string into two at the given non-zero index.

The index has to be non-zero in order to guarantee non-emptiness of the left string.

Panics

Panics if the index is out of bounds or not on character boundary.

pub fn split_at_mut(&mut self, index: Size) -> (&mut Self, &mut str)

Splits the mutable string into two at the given non-zero index.

The index has to be non-zero in order to guarantee non-emptiness of the left string.

Panics

Panics if the index is out of bounds or not on character boundary.

pub fn split_at_checked(&self, index: Size) -> Option<(&Self, &str)>

Splits the string into two at the given non-zero index, returning None if out of bounds or not on character boundary.

The index has to be non-zero in order to guarantee non-emptiness of the left string.

pub fn split_at_mut_checked( &mut self, index: Size, ) -> Option<(&mut Self, &mut str)>

Splits the mutable string into two at the given non-zero index, returning None if out of bounds or not on character boundary.

The index has to be non-zero in order to guarantee non-emptiness of the left string.

pub fn parse_non_empty<F: FromNonEmptyStr>(&self) -> Result<F, F::Error>

Parses this non-empty string into another type.

parse_non_empty can be used with any type that implements the FromNonEmptyStr trait.

Errors

Returns F::Error if parsing fails.

pub fn lines(&self) -> Lines<'_>

Returns non-empty iterators over the lines of this string.

pub fn is_ascii(&self) -> bool

Checks if all characters of the string are in the ASCII range.

pub fn eq_ignore_ascii_case(&self, other: &Self) -> bool

Checks that the two strings are ASCII case-insensitively equal.

pub fn make_ascii_uppercase(&mut self)

Converts the string to its ASCII uppercase equivalent in-place.

pub fn make_ascii_lowercase(&mut self)

Converts the string to its ASCII lowercase equivalent in-place.

pub fn trim_ascii_start(&self) -> &str

Returns new string with leading ASCII whitespace removed.

pub fn trim_ascii_end(&self) -> &str

Returns new string with trailing ASCII whitespace removed.

pub fn trim_ascii(&self) -> &str

Returns new string with leading and trailing ASCII whitespace removed.

pub fn to_non_empty_string(&self) -> NonEmptyString

Converts Self to NonEmptyString via cloning.

pub fn to_non_empty_bytes(&self) -> NonEmptyByteVec

Converts Self to NonEmptyByteVec via cloning.

pub fn to_lowercase(&self) -> String

Converts this string to its lowercase equivalent.

pub fn to_uppercase(&self) -> String

Converts this string to its uppercase equivalent.

pub fn repeat(&self, count: Size) -> NonEmptyString

Creates NonEmptyString by repeating this string certain number of times.

Note that the count is non-zero in order to guarantee that the resulting string is non-empty.

Panics

Panics on capacity overflow.

pub fn to_non_empty_lowercase(&self) -> NonEmptyString

Converts this string to its lowercase equivalent as NonEmptyString.

pub fn to_non_empty_uppercase(&self) -> NonEmptyString

Converts this string to its uppercase equivalent as NonEmptyString.

Methods from Deref<Target = str>

pub fn len(&self) -> usize

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

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

assert_eq!("ƒoo".len(), 4); // fancy f!
assert_eq!("ƒoo".chars().count(), 3);

pub fn is_empty(&self) -> bool

Returns true if self has a length of zero bytes.

Examples

let s = "";
assert!(s.is_empty());

let s = "not empty";
assert!(!s.is_empty());

pub fn is_char_boundary(&self, index: usize) -> bool

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));

pub fn floor_char_boundary(&self, index: usize) -> usize

Finds the closest x not exceeding index where is_char_boundary(x) is true.

This method can help you truncate a string so that it’s still valid UTF-8, but doesn’t exceed a given number of bytes. Note that this is done purely at the character level and can still visually split graphemes, even though the underlying characters aren’t split. For example, the emoji 🧑‍🔬 (scientist) could be split so that the string only includes 🧑 (person) instead.

Examples

let s = "❤️🧡💛💚💙💜";
assert_eq!(s.len(), 26);
assert!(!s.is_char_boundary(13));

let closest = s.floor_char_boundary(13);
assert_eq!(closest, 10);
assert_eq!(&s[..closest], "❤️🧡");

pub fn ceil_char_boundary(&self, index: usize) -> usize

Finds the closest x not below index where is_char_boundary(x) is true.

If index is greater than the length of the string, this returns the length of the string.

This method is the natural complement to floor_char_boundary. See that method for more details.

Examples

let s = "❤️🧡💛💚💙💜";
assert_eq!(s.len(), 26);
assert!(!s.is_char_boundary(13));

let closest = s.ceil_char_boundary(13);
assert_eq!(closest, 14);
assert_eq!(&s[..closest], "❤️🧡💛");

pub fn as_bytes(&self) -> &[u8]

Converts a string slice to a byte slice. To convert the byte slice back into a string slice, use the from_utf8 function.

Examples

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

pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8]

Converts a mutable string slice to a mutable byte slice.

Safety

The caller must ensure that the content of the slice is valid UTF-8 before the borrow ends and the underlying str is used.

Use of a str whose contents are not valid UTF-8 is undefined behavior.

Examples

Basic usage:

let mut s = String::from("Hello");
let bytes = unsafe { s.as_bytes_mut() };

assert_eq!(b"Hello", bytes);

Mutability:

let mut s = String::from("🗻∈🌏");

unsafe {
    let bytes = s.as_bytes_mut();

    bytes[0] = 0xF0;
    bytes[1] = 0x9F;
    bytes[2] = 0x8D;
    bytes[3] = 0x94;
}

assert_eq!("🍔∈🌏", s);

pub fn as_ptr(&self) -> *const u8

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

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

pub fn as_mut_ptr(&mut self) -> *mut u8

Converts a mutable 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.

It is your responsibility to make sure that the string slice only gets modified in a way that it remains valid UTF-8.

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());

pub fn get_mut<I>( &mut self, i: I, ) -> Option<&mut <I as SliceIndex<str>>::Output>

where I: SliceIndex<str>,

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("hello");
// correct length
assert!(v.get_mut(0..5).is_some());
// out of bounds
assert!(v.get_mut(..42).is_none());
assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));

assert_eq!("hello", v);
{
    let s = v.get_mut(0..2);
    let s = s.map(|s| {
        s.make_ascii_uppercase();
        &*s
    });
    assert_eq!(Some("HE"), s);
}
assert_eq!("HEllo", v);

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));
}

pub unsafe fn get_unchecked_mut<I>( &mut self, i: I, ) -> &mut <I as SliceIndex<str>>::Output

where I: SliceIndex<str>,

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 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 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));
}

pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str

👎Deprecated since 1.29.0: 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:

• begin must not exceed end.
• begin and end must be byte positions within the string slice.
• begin and end must lie on UTF-8 sequence boundaries.

Examples

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));
}

pub unsafe fn slice_mut_unchecked( &mut self, begin: usize, end: usize, ) -> &mut str

👎Deprecated since 1.29.0: use get_unchecked_mut(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 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 not exceed end.
• begin and end must be byte positions within the string slice.
• begin and end must lie on UTF-8 sequence boundaries.

pub fn split_at(&self, mid: usize) -> (&str, &str)

Divides 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. For a non-panicking alternative see split_at_checked.

Examples

let s = "Per Martin-Löf";

let (first, last) = s.split_at(3);

assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);

pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)

Divides 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 past the end of the last code point of the string slice. For a non-panicking alternative see split_at_mut_checked.

Examples

let mut s = "Per Martin-Löf".to_string();
{
    let (first, last) = s.split_at_mut(3);
    first.make_ascii_uppercase();
    assert_eq!("PER", first);
    assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);

pub fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)>

Divides one string slice into two at an index.

The argument, mid, should be a valid byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point. The method returns None if that’s not the case.

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_checked method.

Examples

let s = "Per Martin-Löf";

let (first, last) = s.split_at_checked(3).unwrap();
assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);

assert_eq!(None, s.split_at_checked(13));  // Inside “ö”
assert_eq!(None, s.split_at_checked(16));  // Beyond the string length

pub fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut str, &mut str)>

Divides one mutable string slice into two at an index.

The argument, mid, should be a valid byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point. The method returns None if that’s not the case.

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_checked method.

Examples

let mut s = "Per Martin-Löf".to_string();
if let Some((first, last)) = s.split_at_mut_checked(3) {
    first.make_ascii_uppercase();
    assert_eq!("PER", first);
    assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);

assert_eq!(None, s.split_at_mut_checked(13));  // Inside “ö”
assert_eq!(None, s.split_at_mut_checked(16));  // Beyond the string length

pub fn chars(&self) -> Chars<'_>

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());

pub fn char_indices(&self) -> CharIndices<'_>

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 previous 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());

pub fn bytes(&self) -> Bytes<'_>

Returns 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

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());

pub fn split_whitespace(&self) -> SplitWhitespace<'_>

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());

If the string is empty or all whitespace, the iterator yields no string slices:

assert_eq!("".split_whitespace().next(), None);
assert_eq!("   ".split_whitespace().next(), None);

pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_>

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.

This uses the same definition as char::is_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());

Various kinds of ASCII whitespace are considered (see char::is_ascii_whitespace):

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());

If the string is empty or all ASCII whitespace, the iterator yields no string slices:

assert_eq!("".split_ascii_whitespace().next(), None);
assert_eq!("   ".split_ascii_whitespace().next(), None);

pub fn lines(&self) -> Lines<'_>

Returns an iterator over the lines of a string, as string slices.

Lines are split at line endings that are either newlines (\n) or sequences of a carriage return followed by a line feed (\r\n).

Line terminators are not included in the lines returned by the iterator.

Note that any carriage return (\r) not immediately followed by a line feed (\n) does not split a line. These carriage returns are thereby included in the produced lines.

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\r";
let mut lines = text.lines();

assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
// Trailing carriage return is included in the last line
assert_eq!(Some("baz\r"), lines.next());

assert_eq!(None, lines.next());

The final line does not require any ending:

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());

pub fn lines_any(&self) -> LinesAny<'_>

👎Deprecated since 1.4.0: use lines() instead now

Returns an iterator over the lines of a string.

pub fn encode_utf16(&self) -> EncodeUtf16<'_>

Returns an iterator of u16 over the string encoded as native endian UTF-16 (without byte-order mark).

Examples

let text = "Zażółć gęślą jaźń";

let utf8_len = text.len();
let utf16_len = text.encode_utf16().count();

assert!(utf16_len <= utf8_len);

pub fn contains<P>(&self, pat: P) -> bool

where P: Pattern,

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

let bananas = "bananas";

assert!(bananas.contains("nana"));
assert!(!bananas.contains("apples"));

pub fn starts_with<P>(&self, pat: P) -> bool

where P: Pattern,

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, in which case this function will return true if the &str is a prefix of this string slice.

The pattern can also be a char, a slice of chars, or a function or closure that determines if a character matches. These will only be checked against the first character of this string slice. Look at the second example below regarding behavior for slices of chars.

Examples

let bananas = "bananas";

assert!(bananas.starts_with("bana"));
assert!(!bananas.starts_with("nana"));

let bananas = "bananas";

// Note that both of these assert successfully.
assert!(bananas.starts_with(&['b', 'a', 'n', 'a']));
assert!(bananas.starts_with(&['a', 'b', 'c', 'd']));

pub fn ends_with<P>(&self, pat: P) -> bool

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

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

let bananas = "bananas";

assert!(bananas.ends_with("anas"));
assert!(!bananas.ends_with("nana"));

pub fn find<P>(&self, pat: P) -> Option<usize>

where P: Pattern,

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);

pub fn rfind<P>(&self, pat: P) -> Option<usize>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns the byte index for the first character of the last 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);

pub fn split<P>(&self, pat: P) -> Split<'_, P>

where P: Pattern,

Returns 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.

If there are no matches the full string slice is returned as the only item in the iterator.

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> = "AABBCC".split("DD").collect();
assert_eq!(v, ["AABBCC"]);

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.

pub fn split_inclusive<P>(&self, pat: P) -> SplitInclusive<'_, P>

where P: Pattern,

Returns 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"]);

pub fn rsplit<P>(&self, pat: P) -> RSplit<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns 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"]);

pub fn split_terminator<P>(&self, pat: P) -> SplitTerminator<'_, P>

where P: Pattern,

Returns 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

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"]);

pub fn rsplit_terminator<P>(&self, pat: P) -> RSplitTerminator<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns 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"]);

pub fn splitn<P>(&self, n: usize, pat: P) -> SplitN<'_, P>

where P: Pattern,

Returns 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"]);

pub fn rsplitn<P>(&self, n: usize, pat: P) -> RSplitN<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns 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"]);

pub fn split_once<P>(&self, delimiter: P) -> Option<(&str, &str)>

where P: Pattern,

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=".split_once('='), Some(("cfg", "")));
assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));

pub fn rsplit_once<P>(&self, delimiter: P) -> Option<(&str, &str)>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

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")));

pub fn matches<P>(&self, pat: P) -> Matches<'_, P>

where P: Pattern,

Returns 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

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"]);

pub fn rmatches<P>(&self, pat: P) -> RMatches<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns 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

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"]);

pub fn match_indices<P>(&self, pat: P) -> MatchIndices<'_, P>

where P: Pattern,

Returns 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

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`

pub fn rmatch_indices<P>(&self, pat: P) -> RMatchIndices<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns 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

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`

pub fn trim(&self) -> &str

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, which includes newlines.

Examples

let s = "\n Hello\tworld\t\n";

assert_eq!("Hello\tworld", s.trim());

pub fn trim_start(&self) -> &str

Returns a string slice with leading whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space, which includes newlines.

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 = "\n Hello\tworld\t\n";
assert_eq!("Hello\tworld\t\n", 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());

pub fn trim_end(&self) -> &str

Returns a string slice with trailing whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space, which includes newlines.

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 = "\n Hello\tworld\t\n";
assert_eq!("\n 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());

pub fn trim_left(&self) -> &str

👎Deprecated since 1.33.0: 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());

pub fn trim_right(&self) -> &str

👎Deprecated since 1.33.0: 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());

pub fn trim_matches<P>(&self, pat: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> 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");

pub fn trim_start_matches<P>(&self, pat: P) -> &str

where P: Pattern,

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

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");

pub fn strip_prefix<P>(&self, prefix: P) -> Option<&str>

where P: Pattern,

Returns a string slice with the prefix removed.

If the string starts with the pattern prefix, returns the 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"));

pub fn strip_suffix<P>(&self, suffix: P) -> Option<&str>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> 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"));

pub fn trim_prefix<P>(&self, prefix: P) -> &str

where P: Pattern,

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

Returns a string slice with the optional prefix removed.

If the string starts with the pattern prefix, returns the substring after the prefix. Unlike strip_prefix, this method always returns &str for easy method chaining, instead of returning Option<&str>.

If the string does not start with prefix, returns the original string unchanged.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

#![feature(trim_prefix_suffix)]

// Prefix present - removes it
assert_eq!("foo:bar".trim_prefix("foo:"), "bar");
assert_eq!("foofoo".trim_prefix("foo"), "foo");

// Prefix absent - returns original string
assert_eq!("foo:bar".trim_prefix("bar"), "foo:bar");

// Method chaining example
assert_eq!("<https://example.com/>".trim_prefix('<').trim_suffix('>'), "https://example.com/");

pub fn trim_suffix<P>(&self, suffix: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

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

Returns a string slice with the optional suffix removed.

If the string ends with the pattern suffix, returns the substring before the suffix. Unlike strip_suffix, this method always returns &str for easy method chaining, instead of returning Option<&str>.

If the string does not end with suffix, returns the original string unchanged.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

#![feature(trim_prefix_suffix)]

// Suffix present - removes it
assert_eq!("bar:foo".trim_suffix(":foo"), "bar");
assert_eq!("foofoo".trim_suffix("foo"), "foo");

// Suffix absent - returns original string
assert_eq!("bar:foo".trim_suffix("bar"), "bar:foo");

// Method chaining example
assert_eq!("<https://example.com/>".trim_prefix('<').trim_suffix('>'), "https://example.com/");

pub fn trim_end_matches<P>(&self, pat: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> 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");

pub fn trim_left_matches<P>(&self, pat: P) -> &str

where P: Pattern,

👎Deprecated since 1.33.0: 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

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");

pub fn trim_right_matches<P>(&self, pat: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

👎Deprecated since 1.33.0: 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");

pub fn parse<F>(&self) -> Result<F, <F as FromStr>::Err>

where F: FromStr,

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());

pub fn is_ascii(&self) -> bool

Checks if all characters in this string are within the ASCII range.

An empty string returns true.

Examples

let ascii = "hello!\n";
let non_ascii = "Grüße, Jürgen ❤";

assert!(ascii.is_ascii());
assert!(!non_ascii.is_ascii());

pub fn as_ascii(&self) -> Option<&[AsciiChar]>

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

If this string slice is_ascii, returns it as a slice of ASCII characters, otherwise returns None.

pub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]

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

Converts this string slice into a slice of ASCII characters, without checking whether they are valid.

Safety

Every character in this string must be ASCII, or else this is UB.

pub fn eq_ignore_ascii_case(&self, other: &str) -> bool

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"));

pub fn make_ascii_uppercase(&mut self)

Converts this string to its ASCII upper case equivalent in-place.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To return a new uppercased value without modifying the existing one, use to_ascii_uppercase().

Examples

let mut s = String::from("Grüße, Jürgen ❤");

s.make_ascii_uppercase();

assert_eq!("GRüßE, JüRGEN ❤", s);

pub fn make_ascii_lowercase(&mut self)

Converts this string to its ASCII lower case equivalent in-place.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To return a new lowercased value without modifying the existing one, use to_ascii_lowercase().

Examples

let mut s = String::from("GRÜßE, JÜRGEN ❤");

s.make_ascii_lowercase();

assert_eq!("grÜße, jÜrgen ❤", s);

pub fn trim_ascii_start(&self) -> &str

Returns a string slice with leading ASCII whitespace removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!(" \t \u{3000}hello world\n".trim_ascii_start(), "\u{3000}hello world\n");
assert_eq!("  ".trim_ascii_start(), "");
assert_eq!("".trim_ascii_start(), "");

pub fn trim_ascii_end(&self) -> &str

Returns a string slice with trailing ASCII whitespace removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!("\r hello world\u{3000}\n ".trim_ascii_end(), "\r hello world\u{3000}");
assert_eq!("  ".trim_ascii_end(), "");
assert_eq!("".trim_ascii_end(), "");

pub fn trim_ascii(&self) -> &str

Returns a string slice with leading and trailing ASCII whitespace removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!("\r hello world\n ".trim_ascii(), "hello world");
assert_eq!("  ".trim_ascii(), "");
assert_eq!("".trim_ascii(), "");

pub fn escape_debug(&self) -> EscapeDebug<'_>

Returns 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!");

pub fn escape_default(&self) -> EscapeDefault<'_>

Returns 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!");

pub fn escape_unicode(&self) -> EscapeUnicode<'_>

Returns 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}");

pub fn substr_range(&self, substr: &str) -> Option<Range<usize>>

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

Returns the range that a substring points to.

Returns None if substr does not point within self.

Unlike str::find, this does not search through the string. Instead, it uses pointer arithmetic to find where in the string substr is derived from.

This is useful for extending str::split and similar methods.

Note that this method may return false positives (typically either Some(0..0) or Some(self.len()..self.len())) if substr is a zero-length str that points at the beginning or end of another, independent, str.

Examples

#![feature(substr_range)]

let data = "a, b, b, a";
let mut iter = data.split(", ").map(|s| data.substr_range(s).unwrap());

assert_eq!(iter.next(), Some(0..1));
assert_eq!(iter.next(), Some(3..4));
assert_eq!(iter.next(), Some(6..7));
assert_eq!(iter.next(), Some(9..10));

pub fn as_str(&self) -> &str

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

Returns the same string as a string slice &str.

This method is redundant when used directly on &str, but it helps dereferencing other string-like types to string slices, for example references to Box<str> or Arc<str>.

pub fn replace<P>(&self, from: P, to: &str) -> String

where P: Pattern,

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

let s = "this is old";

assert_eq!("this is new", s.replace("old", "new"));
assert_eq!("than an old", s.replace("is", "an"));

When the pattern doesn’t match, it returns this string slice as String:

let s = "this is old";
assert_eq!(s, s.replace("cookie monster", "little lamb"));

pub fn replacen<P>(&self, pat: P, to: &str, count: usize) -> String

where P: Pattern,

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

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, it returns this string slice as String:

let s = "this is old";
assert_eq!(s, s.replacen("cookie monster", "little lamb", 10));

pub fn to_lowercase(&self) -> String

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());

pub fn to_uppercase(&self) -> String

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());

pub fn repeat(&self, n: usize) -> String

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);

pub fn to_ascii_uppercase(&self) -> String

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());

pub fn to_ascii_lowercase(&self) -> String

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

impl Add<&NonEmptyStr> for NonEmptyString

type Output = NonEmptyString

The resulting type after applying the + operator.

fn add(self, non_empty: &NonEmptyStr) -> Self::Output

Performs the + operation.

impl Add<&str> for NonEmptyString

type Output = NonEmptyString

The resulting type after applying the + operator.

fn add(self, string: &str) -> Self::Output

Performs the + operation.

impl AddAssign<&NonEmptyStr> for NonEmptyString

fn add_assign(&mut self, non_empty: &NonEmptyStr)

Performs the += operation.

impl AddAssign<&str> for NonEmptyString

fn add_assign(&mut self, string: &str)

Performs the += operation.

impl AsMut<NonEmptyStr> for NonEmptyString

fn as_mut(&mut self) -> &mut NonEmptyStr

Converts this type into a mutable reference of the (usually inferred) input type.

impl AsMut<NonEmptyString> for NonEmptyString

fn as_mut(&mut self) -> &mut Self

Converts this type into a mutable reference of the (usually inferred) input type.

impl AsMut<str> for NonEmptyString

fn as_mut(&mut self) -> &mut str

Converts this type into a mutable reference of the (usually inferred) input type.

impl AsRef<[u8]> for NonEmptyString

fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NonEmptyStr> for NonEmptyString

fn as_ref(&self) -> &NonEmptyStr

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<NonEmptyString> for NonEmptyString

fn as_ref(&self) -> &Self

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<OsStr> for NonEmptyString

Available on crate feature std only.

fn as_ref(&self) -> &OsStr

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<Path> for NonEmptyString

Available on crate feature std only.

fn as_ref(&self) -> &Path

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<String> for NonEmptyString

fn as_ref(&self) -> &String

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<str> for NonEmptyString

fn as_ref(&self) -> &str

Converts this type into a shared reference of the (usually inferred) input type.

impl Borrow<NonEmptyStr> for NonEmptyString

fn borrow(&self) -> &NonEmptyStr

Immutably borrows from an owned value.

impl Borrow<str> for NonEmptyString

fn borrow(&self) -> &str

Immutably borrows from an owned value.

impl BorrowMut<NonEmptyStr> for NonEmptyString

fn borrow_mut(&mut self) -> &mut NonEmptyStr

Mutably borrows from an owned value.

impl BorrowMut<str> for NonEmptyString

fn borrow_mut(&mut self) -> &mut str

Mutably borrows from an owned value.

impl Clone for NonEmptyString

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for NonEmptyString

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for NonEmptyString

type Target = NonEmptyStr

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for NonEmptyString

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<'de> Deserialize<'de> for NonEmptyString

Available on crate feature serde only.

fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error>

Deserialize this value from the given Serde deserializer.

impl Display for NonEmptyString

fn fmt(&self, formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'s> Extend<&'s NonEmptyStr> for NonEmptyString

fn extend<I: IntoIterator<Item = &'s NonEmptyStr>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl<'c> Extend<&'c char> for NonEmptyString

fn extend<I: IntoIterator<Item = &'c char>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl<'s> Extend<&'s str> for NonEmptyString

fn extend<I: IntoIterator<Item = &'s str>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl Extend<Box<NonEmptyStr>> for NonEmptyString

fn extend<I: IntoIterator<Item = NonEmptyBoxedStr>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl Extend<Box<str>> for NonEmptyString

fn extend<I: IntoIterator<Item = Box<str>>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl<'s> Extend<Cow<'s, NonEmptyStr>> for NonEmptyString

fn extend<I: IntoIterator<Item = Cow<'s, NonEmptyStr>>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl<'s> Extend<Cow<'s, str>> for NonEmptyString

fn extend<I: IntoIterator<Item = Cow<'s, str>>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl Extend<NonEmptyString> for NonEmptyString

fn extend<I: IntoIterator<Item = Self>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl Extend<String> for NonEmptyString

fn extend<I: IntoIterator<Item = String>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl Extend<char> for NonEmptyString

fn extend<I: IntoIterator<Item = char>>(&mut self, iterable: I)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

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

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

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

Reserves capacity in a collection for the given number of additional elements.

impl From<&NonEmptyStr> for NonEmptyString

fn from(non_empty: &NonEmptyStr) -> Self

Converts to this type from the input type.

impl<'s> From<&'s NonEmptyString> for NonEmptyCowStr<'s>

fn from(non_empty: &'s NonEmptyString) -> Self

Converts to this type from the input type.

impl From<&mut NonEmptyStr> for NonEmptyString

fn from(non_empty: &mut NonEmptyStr) -> Self

Converts to this type from the input type.

impl From<Box<NonEmptyStr>> for NonEmptyString

fn from(non_empty: NonEmptyBoxedStr) -> Self

Converts to this type from the input type.

impl From<Cow<'_, NonEmptyStr>> for NonEmptyString

fn from(non_empty: NonEmptyCowStr<'_>) -> Self

Converts to this type from the input type.

impl From<NonEmptyString> for NonEmptyBoxedStr

fn from(non_empty: NonEmptyString) -> Self

Converts to this type from the input type.

impl From<NonEmptyString> for NonEmptyCowStr<'_>

fn from(non_empty: NonEmptyString) -> Self

Converts to this type from the input type.

impl From<NonEmptyString> for String

fn from(non_empty: NonEmptyString) -> Self

Converts to this type from the input type.

impl From<char> for NonEmptyString

fn from(character: char) -> Self

Converts to this type from the input type.

impl<'s> FromNonEmptyIterator<&'s NonEmptyStr> for NonEmptyString

fn from_non_empty_iter<I: IntoNonEmptyIterator<Item = &'s NonEmptyStr>>( iterable: I, ) -> Self

Creates Self from the provided non-empty iterator.

impl<'c> FromNonEmptyIterator<&'c char> for NonEmptyString

fn from_non_empty_iter<I: IntoNonEmptyIterator<Item = &'c char>>( iterable: I, ) -> Self

Creates Self from the provided non-empty iterator.

impl FromNonEmptyIterator<Box<NonEmptyStr>> for NonEmptyString

fn from_non_empty_iter<I: IntoNonEmptyIterator<Item = NonEmptyBoxedStr>>( iterable: I, ) -> Self

Creates Self from the provided non-empty iterator.

impl<'s> FromNonEmptyIterator<Cow<'s, NonEmptyStr>> for NonEmptyString

fn from_non_empty_iter<I: IntoNonEmptyIterator<Item = NonEmptyCowStr<'s>>>( iterable: I, ) -> Self

Creates Self from the provided non-empty iterator.

impl FromNonEmptyIterator<NonEmptyString> for NonEmptyBoxedStr

fn from_non_empty_iter<I: IntoNonEmptyIterator<Item = NonEmptyString>>( iterable: I, ) -> Self

Creates Self from the provided non-empty iterator.

impl FromNonEmptyIterator<NonEmptyString> for NonEmptyString

fn from_non_empty_iter<I: IntoNonEmptyIterator<Item = Self>>( iterable: I, ) -> Self

Creates Self from the provided non-empty iterator.

impl FromNonEmptyIterator<char> for NonEmptyString

fn from_non_empty_iter<I: IntoNonEmptyIterator<Item = char>>( iterable: I, ) -> Self

Creates Self from the provided non-empty iterator.

impl FromNonEmptyStr for NonEmptyString

type Error = Infallible

The associated error type returned when parsing fails.

fn from_non_empty_str(string: &NonEmptyStr) -> Result<Self, Self::Error>

Parses Self from the given non-empty string.

impl FromStr for NonEmptyString

type Err = EmptyStr

The associated error which can be returned from parsing.

fn from_str(string: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for NonEmptyString

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl IntoOwned for NonEmptyString

Available on crate feature ownership only.

type Owned = NonEmptyString

The owned type produced by into_owned.

fn into_owned(self) -> Self::Owned

Consumes Self and converts it into the associated Owned type.

impl Ord for NonEmptyString

fn cmp(&self, other: &NonEmptyString) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for NonEmptyString

fn eq(&self, other: &NonEmptyString) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for NonEmptyString

fn partial_cmp(&self, other: &NonEmptyString) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Serialize for NonEmptyString

Available on crate feature serde only.

fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error>

Serialize this value into the given Serde serializer.

impl TryFrom<&mut str> for NonEmptyString

type Error = EmptyStr

The type returned in the event of a conversion error.

fn try_from(string: &mut str) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<&str> for NonEmptyString

type Error = EmptyStr

The type returned in the event of a conversion error.

fn try_from(string: &str) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<String> for NonEmptyString

type Error = EmptyString

The type returned in the event of a conversion error.

fn try_from(string: String) -> Result<Self, Self::Error>

Performs the conversion.

impl Write for NonEmptyString

fn write_str(&mut self, string: &str) -> Result

Writes a string slice into this writer, returning whether the write succeeded.

fn write_char(&mut self, character: char) -> Result

Writes a char into this writer, returning whether the write succeeded.

fn write_fmt(&mut self, arguments: Arguments<'_>) -> Result

Glue for usage of the write! macro with implementors of this trait.

impl Eq for NonEmptyString

impl StructuralPartialEq for NonEmptyString