Provided Methods

fn as_bstr(self: &Self) -> &BStr

Return this byte slice as a &BStr.

Use &BStr is useful because of its fmt::Debug representation and various other trait implementations (such as PartialEq and PartialOrd). In particular, the Debug implementation for BStr shows its bytes as a normal string. For invalid UTF-8, hex escape sequences are used.

Examples

Basic usage:

use bstr::ByteSlice;

println!("{:?}", b"foo\xFFbar".as_bstr());

fn as_bstr_mut(self: &mut Self) -> &mut BStr

Return this byte slice as a &mut BStr.

Use &mut BStr is useful because of its fmt::Debug representation and various other trait implementations (such as PartialEq and PartialOrd). In particular, the Debug implementation for BStr shows its bytes as a normal string. For invalid UTF-8, hex escape sequences are used.

Examples

Basic usage:

use bstr::ByteSlice;

let mut bytes = *b"foo\xFFbar";
println!("{:?}", &mut bytes.as_bstr_mut());

fn from_os_str(os_str: &OsStr) -> Option<&[u8]>

Create an immutable byte string from an OS string slice.

When the underlying bytes of OS strings are accessible, then this always succeeds and is zero cost. Otherwise, this returns None if the given OS string is not valid UTF-8. (For example, when the underlying bytes are inaccessible on Windows, file paths are allowed to be a sequence of arbitrary 16-bit integers. Not all such sequences can be transcoded to valid UTF-8.)

Examples

Basic usage:

use std::ffi::OsStr;

use bstr::{B, ByteSlice};

let os_str = OsStr::new("foo");
let bs = <[u8]>::from_os_str(os_str).expect("should be valid UTF-8");
assert_eq!(bs, B("foo"));

fn from_path(path: &Path) -> Option<&[u8]>

Create an immutable byte string from a file path.

When the underlying bytes of paths are accessible, then this always succeeds and is zero cost. Otherwise, this returns None if the given path is not valid UTF-8. (For example, when the underlying bytes are inaccessible on Windows, file paths are allowed to be a sequence of arbitrary 16-bit integers. Not all such sequences can be transcoded to valid UTF-8.)

Examples

Basic usage:

use std::path::Path;

use bstr::{B, ByteSlice};

let path = Path::new("foo");
let bs = <[u8]>::from_path(path).expect("should be valid UTF-8");
assert_eq!(bs, B("foo"));

fn to_str(self: &Self) -> Result<&str, Utf8Error>

Safely convert this byte string into a &str if it's valid UTF-8.

If this byte string is not valid UTF-8, then an error is returned. The error returned indicates the first invalid byte found and the length of the error.

In cases where a lossy conversion to &str is acceptable, then use one of the to_str_lossy or to_str_lossy_into methods.

Examples

Basic usage:

# #[cfg(feature = "alloc")] {
use bstr::{B, ByteSlice, ByteVec};

# fn example() -> Result<(), bstr::Utf8Error> {
let s = B("☃βツ").to_str()?;
assert_eq!("☃βツ", s);

let mut bstring = <Vec<u8>>::from("☃βツ");
bstring.push(b'\xFF');
let err = bstring.to_str().unwrap_err();
assert_eq!(8, err.valid_up_to());
# Ok(()) }; example().unwrap()
# }

unsafe fn to_str_unchecked(self: &Self) -> &str

Unsafely convert this byte string into a &str, without checking for valid UTF-8.

Safety

Callers must ensure that this byte string is valid UTF-8 before calling this method. Converting a byte string into a &str that is not valid UTF-8 is considered undefined behavior.

This routine is useful in performance sensitive contexts where the UTF-8 validity of the byte string is already known and it is undesirable to pay the cost of an additional UTF-8 validation check that to_str performs.

Examples

Basic usage:

use bstr::{B, ByteSlice};

// SAFETY: This is safe because string literals are guaranteed to be
// valid UTF-8 by the Rust compiler.
let s = unsafe { B("☃βツ").to_str_unchecked() };
assert_eq!("☃βツ", s);

fn to_str_lossy(self: &Self) -> Cow<'_, str>

Convert this byte string to a valid UTF-8 string by replacing invalid UTF-8 bytes with the Unicode replacement codepoint (U+FFFD).

If the byte string is already valid UTF-8, then no copying or allocation is performed and a borrrowed string slice is returned. If the byte string is not valid UTF-8, then an owned string buffer is returned with invalid bytes replaced by the replacement codepoint.

This method uses the "substitution of maximal subparts" (Unicode Standard, Chapter 3, Section 9) strategy for inserting the replacement codepoint. Specifically, a replacement codepoint is inserted whenever a byte is found that cannot possibly lead to a valid code unit sequence. If there were previous bytes that represented a prefix of a well-formed code unit sequence, then all of those bytes are substituted with a single replacement codepoint. The "substitution of maximal subparts" strategy is the same strategy used by W3C's Encoding standard. For a more precise description of the maximal subpart strategy, see the Unicode Standard, Chapter 3, Section 9. See also Public Review Issue #121.

N.B. Rust's standard library also appears to use the same strategy, but it does not appear to be an API guarantee.

Examples

Basic usage:

use std::borrow::Cow;

use bstr::ByteSlice;

let mut bstring = <Vec<u8>>::from("☃βツ");
assert_eq!(Cow::Borrowed("☃βツ"), bstring.to_str_lossy());

// Add a byte that makes the sequence invalid.
bstring.push(b'\xFF');
assert_eq!(Cow::Borrowed("☃βツ\u{FFFD}"), bstring.to_str_lossy());

This demonstrates the "maximal subpart" substitution logic.

use bstr::{B, ByteSlice};

// \x61 is the ASCII codepoint for 'a'.
// \xF1\x80\x80 is a valid 3-byte code unit prefix.
// \xE1\x80 is a valid 2-byte code unit prefix.
// \xC2 is a valid 1-byte code unit prefix.
// \x62 is the ASCII codepoint for 'b'.
//
// In sum, each of the prefixes is replaced by a single replacement
// codepoint since none of the prefixes are properly completed. This
// is in contrast to other strategies that might insert a replacement
// codepoint for every single byte.
let bs = B(b"\x61\xF1\x80\x80\xE1\x80\xC2\x62");
assert_eq!("a\u{FFFD}\u{FFFD}\u{FFFD}b", bs.to_str_lossy());

fn to_str_lossy_into(self: &Self, dest: &mut String)

Copy the contents of this byte string into the given owned string buffer, while replacing invalid UTF-8 code unit sequences with the Unicode replacement codepoint (U+FFFD).

This method uses the same "substitution of maximal subparts" strategy for inserting the replacement codepoint as the to_str_lossy method.

This routine is useful for amortizing allocation. However, unlike to_str_lossy, this routine will always copy the contents of this byte string into the destination buffer, even if this byte string is valid UTF-8.

Examples

Basic usage:

use std::borrow::Cow;

use bstr::ByteSlice;

let mut bstring = <Vec<u8>>::from("☃βツ");
// Add a byte that makes the sequence invalid.
bstring.push(b'\xFF');

let mut dest = String::new();
bstring.to_str_lossy_into(&mut dest);
assert_eq!("☃βツ\u{FFFD}", dest);

fn to_os_str(self: &Self) -> Result<&OsStr, Utf8Error>

Create an OS string slice from this byte string.

When OS strings can be constructed from arbitrary byte sequences, this always succeeds and is zero cost. Otherwise, this returns a UTF-8 decoding error if this byte string is not valid UTF-8. (For example, assuming the representation of OsStr is opaque on Windows, file paths are allowed to be a sequence of arbitrary 16-bit integers. There is no obvious mapping from an arbitrary sequence of 8-bit integers to an arbitrary sequence of 16-bit integers. If the representation of OsStr is even opened up, then this will convert any sequence of bytes to an OsStr without cost.)

Examples

Basic usage:

use bstr::{B, ByteSlice};

let os_str = b"foo".to_os_str().expect("should be valid UTF-8");
assert_eq!(os_str, "foo");

fn to_os_str_lossy(self: &Self) -> Cow<'_, OsStr>

Lossily create an OS string slice from this byte string.

When OS strings can be constructed from arbitrary byte sequences, this is zero cost and always returns a slice. Otherwise, this will perform a UTF-8 check and lossily convert this byte string into valid UTF-8 using the Unicode replacement codepoint.

Note that this can prevent the correct roundtripping of file paths when the representation of OsStr is opaque.

Examples

Basic usage:

use bstr::ByteSlice;

let os_str = b"foo\xFFbar".to_os_str_lossy();
assert_eq!(os_str.to_string_lossy(), "foo\u{FFFD}bar");

fn to_path(self: &Self) -> Result<&Path, Utf8Error>

Create a path slice from this byte string.

When paths can be constructed from arbitrary byte sequences, this always succeeds and is zero cost. Otherwise, this returns a UTF-8 decoding error if this byte string is not valid UTF-8. (For example, assuming the representation of Path is opaque on Windows, file paths are allowed to be a sequence of arbitrary 16-bit integers. There is no obvious mapping from an arbitrary sequence of 8-bit integers to an arbitrary sequence of 16-bit integers. If the representation of Path is even opened up, then this will convert any sequence of bytes to an Path without cost.)

Examples

Basic usage:

use bstr::ByteSlice;

let path = b"foo".to_path().expect("should be valid UTF-8");
assert_eq!(path.as_os_str(), "foo");

fn to_path_lossy(self: &Self) -> Cow<'_, Path>

Lossily create a path slice from this byte string.

When paths can be constructed from arbitrary byte sequences, this is zero cost and always returns a slice. Otherwise, this will perform a UTF-8 check and lossily convert this byte string into valid UTF-8 using the Unicode replacement codepoint.

Note that this can prevent the correct roundtripping of file paths when the representation of Path is opaque.

Examples

Basic usage:

use bstr::ByteSlice;

let bs = b"foo\xFFbar";
let path = bs.to_path_lossy();
assert_eq!(path.to_string_lossy(), "foo\u{FFFD}bar");

fn repeatn(self: &Self, n: usize) -> Vec<u8>

Create a new byte string by repeating this byte string n times.

Panics

This function panics if the capacity of the new byte string would overflow.

Examples

Basic usage:

use bstr::{B, ByteSlice};

assert_eq!(b"foo".repeatn(4), B("foofoofoofoo"));
assert_eq!(b"foo".repeatn(0), B(""));

fn contains_str<B: AsRef<[u8]>>(self: &Self, needle: B) -> bool

Returns true if and only if this byte string contains the given needle.

Examples

Basic usage:

use bstr::ByteSlice;

assert!(b"foo bar".contains_str("foo"));
assert!(b"foo bar".contains_str("bar"));
assert!(!b"foo".contains_str("foobar"));

fn starts_with_str<B: AsRef<[u8]>>(self: &Self, prefix: B) -> bool

Returns true if and only if this byte string has the given prefix.

Examples

Basic usage:

use bstr::ByteSlice;

assert!(b"foo bar".starts_with_str("foo"));
assert!(!b"foo bar".starts_with_str("bar"));
assert!(!b"foo".starts_with_str("foobar"));

fn ends_with_str<B: AsRef<[u8]>>(self: &Self, suffix: B) -> bool

Returns true if and only if this byte string has the given suffix.

Examples

Basic usage:

use bstr::ByteSlice;

assert!(b"foo bar".ends_with_str("bar"));
assert!(!b"foo bar".ends_with_str("foo"));
assert!(!b"bar".ends_with_str("foobar"));

fn find<B: AsRef<[u8]>>(self: &Self, needle: B) -> Option<usize>

Returns the index of the first occurrence of the given needle.

The needle may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

Note that if you're are searching for the same needle in many different small haystacks, it may be faster to initialize a Finder once, and reuse it for each search.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the needle and the haystack. That is, this runs in O(needle.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"foo bar baz";
assert_eq!(Some(0), s.find("foo"));
assert_eq!(Some(4), s.find("bar"));
assert_eq!(None, s.find("quux"));

fn rfind<B: AsRef<[u8]>>(self: &Self, needle: B) -> Option<usize>

Returns the index of the last occurrence of the given needle.

The needle may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

Note that if you're are searching for the same needle in many different small haystacks, it may be faster to initialize a FinderReverse once, and reuse it for each search.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the needle and the haystack. That is, this runs in O(needle.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"foo bar baz";
assert_eq!(Some(0), s.rfind("foo"));
assert_eq!(Some(4), s.rfind("bar"));
assert_eq!(Some(8), s.rfind("ba"));
assert_eq!(None, s.rfind("quux"));

fn find_iter<'h, 'n, B: ?Sized + AsRef<[u8]>>(self: &'h Self, needle: &'n B) -> Find<'h, 'n>

Returns an iterator of the non-overlapping occurrences of the given needle. The iterator yields byte offset positions indicating the start of each match.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the needle and the haystack. That is, this runs in O(needle.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"foo bar foo foo quux foo";
let matches: Vec<usize> = s.find_iter("foo").collect();
assert_eq!(matches, vec![0, 8, 12, 21]);

An empty string matches at every position, including the position immediately following the last byte:

use bstr::ByteSlice;

let matches: Vec<usize> = b"foo".find_iter("").collect();
assert_eq!(matches, vec![0, 1, 2, 3]);

let matches: Vec<usize> = b"".find_iter("").collect();
assert_eq!(matches, vec![0]);

fn rfind_iter<'h, 'n, B: ?Sized + AsRef<[u8]>>(self: &'h Self, needle: &'n B) -> FindReverse<'h, 'n>

Returns an iterator of the non-overlapping occurrences of the given needle in reverse. The iterator yields byte offset positions indicating the start of each match.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the needle and the haystack. That is, this runs in O(needle.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"foo bar foo foo quux foo";
let matches: Vec<usize> = s.rfind_iter("foo").collect();
assert_eq!(matches, vec![21, 12, 8, 0]);

An empty string matches at every position, including the position immediately following the last byte:

use bstr::ByteSlice;

let matches: Vec<usize> = b"foo".rfind_iter("").collect();
assert_eq!(matches, vec![3, 2, 1, 0]);

let matches: Vec<usize> = b"".rfind_iter("").collect();
assert_eq!(matches, vec![0]);

fn find_byte(self: &Self, byte: u8) -> Option<usize>

Returns the index of the first occurrence of the given byte. If the byte does not occur in this byte string, then None is returned.

Examples

Basic usage:

use bstr::ByteSlice;

assert_eq!(Some(10), b"foo bar baz".find_byte(b'z'));
assert_eq!(None, b"foo bar baz".find_byte(b'y'));

fn rfind_byte(self: &Self, byte: u8) -> Option<usize>

Returns the index of the last occurrence of the given byte. If the byte does not occur in this byte string, then None is returned.

Examples

Basic usage:

use bstr::ByteSlice;

assert_eq!(Some(10), b"foo bar baz".rfind_byte(b'z'));
assert_eq!(None, b"foo bar baz".rfind_byte(b'y'));

fn find_char(self: &Self, ch: char) -> Option<usize>

Returns the index of the first occurrence of the given codepoint. If the codepoint does not occur in this byte string, then None is returned.

Note that if one searches for the replacement codepoint, \u{FFFD}, then only explicit occurrences of that encoding will be found. Invalid UTF-8 sequences will not be matched.

Examples

Basic usage:

use bstr::{B, ByteSlice};

assert_eq!(Some(10), b"foo bar baz".find_char('z'));
assert_eq!(Some(4), B("αβγγδ").find_char('γ'));
assert_eq!(None, b"foo bar baz".find_char('y'));

fn rfind_char(self: &Self, ch: char) -> Option<usize>

Returns the index of the last occurrence of the given codepoint. If the codepoint does not occur in this byte string, then None is returned.

Note that if one searches for the replacement codepoint, \u{FFFD}, then only explicit occurrences of that encoding will be found. Invalid UTF-8 sequences will not be matched.

Examples

Basic usage:

use bstr::{B, ByteSlice};

assert_eq!(Some(10), b"foo bar baz".rfind_char('z'));
assert_eq!(Some(6), B("αβγγδ").rfind_char('γ'));
assert_eq!(None, b"foo bar baz".rfind_char('y'));

fn find_byteset<B: AsRef<[u8]>>(self: &Self, byteset: B) -> Option<usize>

Returns the index of the first occurrence of any of the bytes in the provided set.

The byteset may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8], but note that passing a &str which contains multibyte characters may not behave as you expect: each byte in the &str is treated as an individual member of the byte set.

Note that order is irrelevant for the byteset parameter, and duplicate bytes present in its body are ignored.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the set of bytes and the haystack. That is, this runs in O(byteset.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

assert_eq!(b"foo bar baz".find_byteset(b"zr"), Some(6));
assert_eq!(b"foo baz bar".find_byteset(b"bzr"), Some(4));
assert_eq!(None, b"foo baz bar".find_byteset(b"\t\n"));
// The empty byteset never matches.
assert_eq!(None, b"abc".find_byteset(b""));
assert_eq!(None, b"".find_byteset(b""));

fn find_not_byteset<B: AsRef<[u8]>>(self: &Self, byteset: B) -> Option<usize>

Returns the index of the first occurrence of a byte that is not a member of the provided set.

The byteset may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8], but note that passing a &str which contains multibyte characters may not behave as you expect: each byte in the &str is treated as an individual member of the byte set.

Note that order is irrelevant for the byteset parameter, and duplicate bytes present in its body are ignored.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the set of bytes and the haystack. That is, this runs in O(byteset.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

assert_eq!(b"foo bar baz".find_not_byteset(b"fo "), Some(4));
assert_eq!(b"\t\tbaz bar".find_not_byteset(b" \t\r\n"), Some(2));
assert_eq!(b"foo\nbaz\tbar".find_not_byteset(b"\t\n"), Some(0));
// The negation of the empty byteset matches everything.
assert_eq!(Some(0), b"abc".find_not_byteset(b""));
// But an empty string never contains anything.
assert_eq!(None, b"".find_not_byteset(b""));

fn rfind_byteset<B: AsRef<[u8]>>(self: &Self, byteset: B) -> Option<usize>

Returns the index of the last occurrence of any of the bytes in the provided set.

The byteset may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8], but note that passing a &str which contains multibyte characters may not behave as you expect: each byte in the &str is treated as an individual member of the byte set.

Note that order is irrelevant for the byteset parameter, and duplicate bytes present in its body are ignored.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the set of bytes and the haystack. That is, this runs in O(byteset.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

assert_eq!(b"foo bar baz".rfind_byteset(b"agb"), Some(9));
assert_eq!(b"foo baz bar".rfind_byteset(b"rabz "), Some(10));
assert_eq!(b"foo baz bar".rfind_byteset(b"\n123"), None);

fn rfind_not_byteset<B: AsRef<[u8]>>(self: &Self, byteset: B) -> Option<usize>

Returns the index of the last occurrence of a byte that is not a member of the provided set.

The byteset may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8], but note that passing a &str which contains multibyte characters may not behave as you expect: each byte in the &str is treated as an individual member of the byte set.

Note that order is irrelevant for the byteset parameter, and duplicate bytes present in its body are ignored.

Complexity

This routine is guaranteed to have worst case linear time complexity with respect to both the set of bytes and the haystack. That is, this runs in O(byteset.len() + haystack.len()) time.

This routine is also guaranteed to have worst case constant space complexity.

Examples

Basic usage:

use bstr::ByteSlice;

assert_eq!(b"foo bar baz,\t".rfind_not_byteset(b",\t"), Some(10));
assert_eq!(b"foo baz bar".rfind_not_byteset(b"rabz "), Some(2));
assert_eq!(None, b"foo baz bar".rfind_not_byteset(b"barfoz "));

fn fields_with<F: FnMut(char) -> bool>(self: &Self, f: F) -> FieldsWith<'_, F>

Returns an iterator over the fields in a byte string, separated by contiguous codepoints satisfying the given predicate.

If this byte string is not valid UTF-8, then the given closure will be called with a Unicode replacement codepoint when invalid UTF-8 bytes are seen.

Example

Basic usage:

use bstr::{B, ByteSlice};

let s = b"123foo999999bar1quux123456";
let fields: Vec<&[u8]> = s.fields_with(|c| c.is_numeric()).collect();
assert_eq!(fields, vec![B("foo"), B("bar"), B("quux")]);

A byte string consisting of all codepoints satisfying the predicate yields no elements:

use bstr::ByteSlice;

assert_eq!(0, b"1911354563".fields_with(|c| c.is_numeric()).count());

fn split_str<'h, 's, B: ?Sized + AsRef<[u8]>>(self: &'h Self, splitter: &'s B) -> Split<'h, 's>

Returns an iterator over substrings of this byte string, separated by the given byte string. Each element yielded is guaranteed not to include the splitter substring.

The splitter may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

Examples

Basic usage:

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"Mary had a little lamb".split_str(" ").collect();
assert_eq!(x, vec![
    B("Mary"), B("had"), B("a"), B("little"), B("lamb"),
]);

let x: Vec<&[u8]> = b"".split_str("X").collect();
assert_eq!(x, vec![b""]);

let x: Vec<&[u8]> = b"lionXXtigerXleopard".split_str("X").collect();
assert_eq!(x, vec![B("lion"), B(""), B("tiger"), B("leopard")]);

let x: Vec<&[u8]> = b"lion::tiger::leopard".split_str("::").collect();
assert_eq!(x, vec![B("lion"), B("tiger"), B("leopard")]);

If a string contains multiple contiguous separators, you will end up with empty strings yielded by the iterator:

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"||||a||b|c".split_str("|").collect();
assert_eq!(x, vec![
    B(""), B(""), B(""), B(""), B("a"), B(""), B("b"), B("c"),
]);

let x: Vec<&[u8]> = b"(///)".split_str("/").collect();
assert_eq!(x, vec![B("("), B(""), B(""), B(")")]);

Separators at the start or end of a string are neighbored by empty strings.

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"010".split_str("0").collect();
assert_eq!(x, vec![B(""), B("1"), B("")]);

When the empty string is used as a separator, it splits every byte in the byte string, along with the beginning and end of the byte string.

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"rust".split_str("").collect();
assert_eq!(x, vec![
    B(""), B("r"), B("u"), B("s"), B("t"), B(""),
]);

// Splitting by an empty string is not UTF-8 aware. Elements yielded
// may not be valid UTF-8!
let x: Vec<&[u8]> = B("☃").split_str("").collect();
assert_eq!(x, vec![
    B(""), B(b"\xE2"), B(b"\x98"), B(b"\x83"), B(""),
]);

Contiguous separators, especially whitespace, can lead to possibly surprising behavior. For example, this code is correct:

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"    a  b c".split_str(" ").collect();
assert_eq!(x, vec![
    B(""), B(""), B(""), B(""), B("a"), B(""), B("b"), B("c"),
]);

It does not give you ["a", "b", "c"]. For that behavior, use fields instead.

fn rsplit_str<'h, 's, B: ?Sized + AsRef<[u8]>>(self: &'h Self, splitter: &'s B) -> SplitReverse<'h, 's>

Returns an iterator over substrings of this byte string, separated by the given byte string, in reverse. Each element yielded is guaranteed not to include the splitter substring.

The splitter may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

Examples

Basic usage:

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> =
    b"Mary had a little lamb".rsplit_str(" ").collect();
assert_eq!(x, vec![
    B("lamb"), B("little"), B("a"), B("had"), B("Mary"),
]);

let x: Vec<&[u8]> = b"".rsplit_str("X").collect();
assert_eq!(x, vec![b""]);

let x: Vec<&[u8]> = b"lionXXtigerXleopard".rsplit_str("X").collect();
assert_eq!(x, vec![B("leopard"), B("tiger"), B(""), B("lion")]);

let x: Vec<&[u8]> = b"lion::tiger::leopard".rsplit_str("::").collect();
assert_eq!(x, vec![B("leopard"), B("tiger"), B("lion")]);

If a string contains multiple contiguous separators, you will end up with empty strings yielded by the iterator:

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"||||a||b|c".rsplit_str("|").collect();
assert_eq!(x, vec![
    B("c"), B("b"), B(""), B("a"), B(""), B(""), B(""), B(""),
]);

let x: Vec<&[u8]> = b"(///)".rsplit_str("/").collect();
assert_eq!(x, vec![B(")"), B(""), B(""), B("(")]);

Separators at the start or end of a string are neighbored by empty strings.

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"010".rsplit_str("0").collect();
assert_eq!(x, vec![B(""), B("1"), B("")]);

When the empty string is used as a separator, it splits every byte in the byte string, along with the beginning and end of the byte string.

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"rust".rsplit_str("").collect();
assert_eq!(x, vec![
    B(""), B("t"), B("s"), B("u"), B("r"), B(""),
]);

// Splitting by an empty string is not UTF-8 aware. Elements yielded
// may not be valid UTF-8!
let x: Vec<&[u8]> = B("☃").rsplit_str("").collect();
assert_eq!(x, vec![B(""), B(b"\x83"), B(b"\x98"), B(b"\xE2"), B("")]);

Contiguous separators, especially whitespace, can lead to possibly surprising behavior. For example, this code is correct:

use bstr::{B, ByteSlice};

let x: Vec<&[u8]> = b"    a  b c".rsplit_str(" ").collect();
assert_eq!(x, vec![
    B("c"), B("b"), B(""), B("a"), B(""), B(""), B(""), B(""),
]);

It does not give you ["a", "b", "c"].

fn split_once_str<'a, B: ?Sized + AsRef<[u8]>>(self: &'a Self, splitter: &B) -> Option<(&'a [u8], &'a [u8])>

Split this byte string at the first occurrence of splitter.

If the splitter is found in the byte string, returns a tuple containing the parts of the string before and after the first occurrence of splitter respectively. Otherwise, if there are no occurrences of splitter in the byte string, returns None.

The splitter may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

If you need to split on the last instance of a delimiter instead, see the ByteSlice::rsplit_once_str method .

Examples

Basic usage:

use bstr::{B, ByteSlice};

assert_eq!(
    B("foo,bar").split_once_str(","),
    Some((B("foo"), B("bar"))),
);
assert_eq!(
    B("foo,bar,baz").split_once_str(","),
    Some((B("foo"), B("bar,baz"))),
);
assert_eq!(B("foo").split_once_str(","), None);
assert_eq!(B("foo,").split_once_str(b","), Some((B("foo"), B(""))));
assert_eq!(B(",foo").split_once_str(b","), Some((B(""), B("foo"))));

fn rsplit_once_str<'a, B: ?Sized + AsRef<[u8]>>(self: &'a Self, splitter: &B) -> Option<(&'a [u8], &'a [u8])>

Split this byte string at the last occurrence of splitter.

If the splitter is found in the byte string, returns a tuple containing the parts of the string before and after the last occurrence of splitter, respectively. Otherwise, if there are no occurrences of splitter in the byte string, returns None.

The splitter may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

If you need to split on the first instance of a delimiter instead, see the ByteSlice::split_once_str method.

Examples

Basic usage:

use bstr::{B, ByteSlice};

assert_eq!(
    B("foo,bar").rsplit_once_str(","),
    Some((B("foo"), B("bar"))),
);
assert_eq!(
    B("foo,bar,baz").rsplit_once_str(","),
    Some((B("foo,bar"), B("baz"))),
);
assert_eq!(B("foo").rsplit_once_str(","), None);
assert_eq!(B("foo,").rsplit_once_str(b","), Some((B("foo"), B(""))));
assert_eq!(B(",foo").rsplit_once_str(b","), Some((B(""), B("foo"))));

fn splitn_str<'h, 's, B: ?Sized + AsRef<[u8]>>(self: &'h Self, limit: usize, splitter: &'s B) -> SplitN<'h, 's>

Returns an iterator of at most limit substrings of this byte string, separated by the given byte string. If limit substrings are yielded, then the last substring will contain the remainder of this byte string.

The needle may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

Examples

Basic usage:

use bstr::{B, ByteSlice};

let x: Vec<_> = b"Mary had a little lamb".splitn_str(3, " ").collect();
assert_eq!(x, vec![B("Mary"), B("had"), B("a little lamb")]);

let x: Vec<_> = b"".splitn_str(3, "X").collect();
assert_eq!(x, vec![b""]);

let x: Vec<_> = b"lionXXtigerXleopard".splitn_str(3, "X").collect();
assert_eq!(x, vec![B("lion"), B(""), B("tigerXleopard")]);

let x: Vec<_> = b"lion::tiger::leopard".splitn_str(2, "::").collect();
assert_eq!(x, vec![B("lion"), B("tiger::leopard")]);

let x: Vec<_> = b"abcXdef".splitn_str(1, "X").collect();
assert_eq!(x, vec![B("abcXdef")]);

let x: Vec<_> = b"abcdef".splitn_str(2, "X").collect();
assert_eq!(x, vec![B("abcdef")]);

let x: Vec<_> = b"abcXdef".splitn_str(0, "X").collect();
assert!(x.is_empty());

fn rsplitn_str<'h, 's, B: ?Sized + AsRef<[u8]>>(self: &'h Self, limit: usize, splitter: &'s B) -> SplitNReverse<'h, 's>

Returns an iterator of at most limit substrings of this byte string, separated by the given byte string, in reverse. If limit substrings are yielded, then the last substring will contain the remainder of this byte string.

The needle may be any type that can be cheaply converted into a &[u8]. This includes, but is not limited to, &str and &[u8].

Examples

Basic usage:

use bstr::{B, ByteSlice};

let x: Vec<_> =
    b"Mary had a little lamb".rsplitn_str(3, " ").collect();
assert_eq!(x, vec![B("lamb"), B("little"), B("Mary had a")]);

let x: Vec<_> = b"".rsplitn_str(3, "X").collect();
assert_eq!(x, vec![b""]);

let x: Vec<_> = b"lionXXtigerXleopard".rsplitn_str(3, "X").collect();
assert_eq!(x, vec![B("leopard"), B("tiger"), B("lionX")]);

let x: Vec<_> = b"lion::tiger::leopard".rsplitn_str(2, "::").collect();
assert_eq!(x, vec![B("leopard"), B("lion::tiger")]);

let x: Vec<_> = b"abcXdef".rsplitn_str(1, "X").collect();
assert_eq!(x, vec![B("abcXdef")]);

let x: Vec<_> = b"abcdef".rsplitn_str(2, "X").collect();
assert_eq!(x, vec![B("abcdef")]);

let x: Vec<_> = b"abcXdef".rsplitn_str(0, "X").collect();
assert!(x.is_empty());

fn replace<N: AsRef<[u8]>, R: AsRef<[u8]>>(self: &Self, needle: N, replacement: R) -> Vec<u8>

Replace all matches of the given needle with the given replacement, and the result as a new Vec<u8>.

This routine is useful as a convenience. If you need to reuse an allocation, use replace_into instead.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"this is old".replace("old", "new");
assert_eq!(s, "this is new".as_bytes());

When the pattern doesn't match:

use bstr::ByteSlice;

let s = b"this is old".replace("nada nada", "limonada");
assert_eq!(s, "this is old".as_bytes());

When the needle is an empty string:

use bstr::ByteSlice;

let s = b"foo".replace("", "Z");
assert_eq!(s, "ZfZoZoZ".as_bytes());

fn replacen<N: AsRef<[u8]>, R: AsRef<[u8]>>(self: &Self, needle: N, replacement: R, limit: usize) -> Vec<u8>

Replace up to limit matches of the given needle with the given replacement, and the result as a new Vec<u8>.

This routine is useful as a convenience. If you need to reuse an allocation, use replacen_into instead.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"foofoo".replacen("o", "z", 2);
assert_eq!(s, "fzzfoo".as_bytes());

When the pattern doesn't match:

use bstr::ByteSlice;

let s = b"foofoo".replacen("a", "z", 2);
assert_eq!(s, "foofoo".as_bytes());

When the needle is an empty string:

use bstr::ByteSlice;

let s = b"foo".replacen("", "Z", 2);
assert_eq!(s, "ZfZoo".as_bytes());

fn replace_into<N: AsRef<[u8]>, R: AsRef<[u8]>>(self: &Self, needle: N, replacement: R, dest: &mut Vec<u8>)

Replace all matches of the given needle with the given replacement, and write the result into the provided Vec<u8>.

This does not clear dest before writing to it.

This routine is useful for reusing allocation. For a more convenient API, use replace instead.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"this is old";

let mut dest = vec![];
s.replace_into("old", "new", &mut dest);
assert_eq!(dest, "this is new".as_bytes());

When the pattern doesn't match:

use bstr::ByteSlice;

let s = b"this is old";

let mut dest = vec![];
s.replace_into("nada nada", "limonada", &mut dest);
assert_eq!(dest, "this is old".as_bytes());

When the needle is an empty string:

use bstr::ByteSlice;

let s = b"foo";

let mut dest = vec![];
s.replace_into("", "Z", &mut dest);
assert_eq!(dest, "ZfZoZoZ".as_bytes());

fn replacen_into<N: AsRef<[u8]>, R: AsRef<[u8]>>(self: &Self, needle: N, replacement: R, limit: usize, dest: &mut Vec<u8>)

Replace up to limit matches of the given needle with the given replacement, and write the result into the provided Vec<u8>.

This does not clear dest before writing to it.

This routine is useful for reusing allocation. For a more convenient API, use replacen instead.

Examples

Basic usage:

use bstr::ByteSlice;

let s = b"foofoo";

let mut dest = vec![];
s.replacen_into("o", "z", 2, &mut dest);
assert_eq!(dest, "fzzfoo".as_bytes());

When the pattern doesn't match:

use bstr::ByteSlice;

let s = b"foofoo";

let mut dest = vec![];
s.replacen_into("a", "z", 2, &mut dest);
assert_eq!(dest, "foofoo".as_bytes());

When the needle is an empty string:

use bstr::ByteSlice;

let s = b"foo";

let mut dest = vec![];
s.replacen_into("", "Z", 2, &mut dest);
assert_eq!(dest, "ZfZoo".as_bytes());

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

Returns an iterator over the bytes in this byte string.

Examples

Basic usage:

use bstr::ByteSlice;

let bs = b"foobar";
let bytes: Vec<u8> = bs.bytes().collect();
assert_eq!(bytes, bs);

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

Returns an iterator over the Unicode scalar values in this byte string. If invalid UTF-8 is encountered, then the Unicode replacement codepoint is yielded instead.

Examples

Basic usage:

use bstr::ByteSlice;

let bs = b"\xE2\x98\x83\xFF\xF0\x9D\x9E\x83\xE2\x98\x61";
let chars: Vec<char> = bs.chars().collect();
assert_eq!(vec!['☃', '\u{FFFD}', '𝞃', '\u{FFFD}', 'a'], chars);

Codepoints can also be iterated over in reverse:

use bstr::ByteSlice;

let bs = b"\xE2\x98\x83\xFF\xF0\x9D\x9E\x83\xE2\x98\x61";
let chars: Vec<char> = bs.chars().rev().collect();
assert_eq!(vec!['a', '\u{FFFD}', '𝞃', '\u{FFFD}', '☃'], chars);

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

Returns an iterator over the Unicode scalar values in this byte string along with their starting and ending byte index positions. If invalid UTF-8 is encountered, then the Unicode replacement codepoint is yielded instead.

Note that this is slightly different from the CharIndices iterator provided by the standard library. Aside from working on possibly invalid UTF-8, this iterator provides both the corresponding starting and ending byte indices of each codepoint yielded. The ending position is necessary to slice the original byte string when invalid UTF-8 bytes are converted into a Unicode replacement codepoint, since a single replacement codepoint can substitute anywhere from 1 to 3 invalid bytes (inclusive).

Examples

Basic usage:

use bstr::ByteSlice;

let bs = b"\xE2\x98\x83\xFF\xF0\x9D\x9E\x83\xE2\x98\x61";
let chars: Vec<(usize, usize, char)> = bs.char_indices().collect();
assert_eq!(chars, vec![
    (0, 3, '☃'),
    (3, 4, '\u{FFFD}'),
    (4, 8, '𝞃'),
    (8, 10, '\u{FFFD}'),
    (10, 11, 'a'),
]);

Codepoints can also be iterated over in reverse:

use bstr::ByteSlice;

let bs = b"\xE2\x98\x83\xFF\xF0\x9D\x9E\x83\xE2\x98\x61";
let chars: Vec<(usize, usize, char)> = bs
    .char_indices()
    .rev()
    .collect();
assert_eq!(chars, vec![
    (10, 11, 'a'),
    (8, 10, '\u{FFFD}'),
    (4, 8, '𝞃'),
    (3, 4, '\u{FFFD}'),
    (0, 3, '☃'),
]);

fn utf8_chunks(self: &Self) -> Utf8Chunks<'_>

Iterate over chunks of valid UTF-8.

The iterator returned yields chunks of valid UTF-8 separated by invalid UTF-8 bytes, if they exist. Invalid UTF-8 bytes are always 1-3 bytes, which are determined via the "substitution of maximal subparts" strategy described in the docs for the ByteSlice::to_str_lossy method.

Examples

This example shows how to gather all valid and invalid chunks from a byte slice:

use bstr::{ByteSlice, Utf8Chunk};

let bytes = b"foo\xFD\xFEbar\xFF";

let (mut valid_chunks, mut invalid_chunks) = (vec![], vec![]);
for chunk in bytes.utf8_chunks() {
    if !chunk.valid().is_empty() {
        valid_chunks.push(chunk.valid());
    }
    if !chunk.invalid().is_empty() {
        invalid_chunks.push(chunk.invalid());
    }
}

assert_eq!(valid_chunks, vec!["foo", "bar"]);
assert_eq!(invalid_chunks, vec![b"\xFD", b"\xFE", b"\xFF"]);

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

An iterator over all lines in a byte string, without their terminators.

For this iterator, the only line terminators recognized are \r\n and \n.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let s = b"\
foo

bar\r
baz


quux";
let lines: Vec<&[u8]> = s.lines().collect();
assert_eq!(lines, vec![
    B("foo"), B(""), B("bar"), B("baz"), B(""), B(""), B("quux"),
]);

fn lines_with_terminator(self: &Self) -> LinesWithTerminator<'_>

An iterator over all lines in a byte string, including their terminators.

For this iterator, the only line terminator recognized is \n. (Since line terminators are included, this also handles \r\n line endings.)

Line terminators are only included if they are present in the original byte string. For example, the last line in a byte string may not end with a line terminator.

Concatenating all elements yielded by this iterator is guaranteed to yield the original byte string.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let s = b"\
foo

bar\r
baz


quux";
let lines: Vec<&[u8]> = s.lines_with_terminator().collect();
assert_eq!(lines, vec![
    B("foo\n"),
    B("\n"),
    B("bar\r\n"),
    B("baz\n"),
    B("\n"),
    B("\n"),
    B("quux"),
]);

fn trim_with<F: FnMut(char) -> bool>(self: &Self, trim: F) -> &[u8]

Return a byte string slice with leading and trailing characters satisfying the given predicate removed.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let s = b"123foo5bar789";
assert_eq!(s.trim_with(|c| c.is_numeric()), B("foo5bar"));

fn trim_start_with<F: FnMut(char) -> bool>(self: &Self, trim: F) -> &[u8]

Return a byte string slice with leading characters satisfying the given predicate removed.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let s = b"123foo5bar789";
assert_eq!(s.trim_start_with(|c| c.is_numeric()), B("foo5bar789"));

fn trim_end_with<F: FnMut(char) -> bool>(self: &Self, trim: F) -> &[u8]

Return a byte string slice with trailing characters satisfying the given predicate removed.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let s = b"123foo5bar789";
assert_eq!(s.trim_end_with(|c| c.is_numeric()), B("123foo5bar"));

fn to_ascii_lowercase(self: &Self) -> Vec<u8>

Returns a new Vec<u8> containing the ASCII lowercase equivalent of this byte string.

In this case, lowercase is only defined in ASCII letters. Namely, the letters A-Z are converted to a-z. All other bytes remain unchanged. In particular, the length of the byte string returned is always equivalent to the length of this byte string.

If you'd like to reuse an allocation for performance reasons, then use make_ascii_lowercase to perform the conversion in place.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let s = B("HELLO Β");
assert_eq!("hello Β".as_bytes(), s.to_ascii_lowercase().as_bytes());

Invalid UTF-8 remains as is:

use bstr::{B, ByteSlice};

let s = B(b"FOO\xFFBAR\xE2\x98BAZ");
assert_eq!(s.to_ascii_lowercase(), B(b"foo\xFFbar\xE2\x98baz"));

fn make_ascii_lowercase(self: &mut Self)

Convert this byte string to its lowercase ASCII equivalent in place.

In this case, lowercase is only defined in ASCII letters. Namely, the letters A-Z are converted to a-z. All other bytes remain unchanged.

If you don't need to do the conversion in place and instead prefer convenience, then use to_ascii_lowercase instead.

Examples

Basic usage:

use bstr::ByteSlice;

let mut s = <Vec<u8>>::from("HELLO Β");
s.make_ascii_lowercase();
assert_eq!(s, "hello Β".as_bytes());

Invalid UTF-8 remains as is:

# #[cfg(feature = "alloc")] {
use bstr::{B, ByteSlice, ByteVec};

let mut s = <Vec<u8>>::from_slice(b"FOO\xFFBAR\xE2\x98BAZ");
s.make_ascii_lowercase();
assert_eq!(s, B(b"foo\xFFbar\xE2\x98baz"));
# }

fn to_ascii_uppercase(self: &Self) -> Vec<u8>

Returns a new Vec<u8> containing the ASCII uppercase equivalent of this byte string.

In this case, uppercase is only defined in ASCII letters. Namely, the letters a-z are converted to A-Z. All other bytes remain unchanged. In particular, the length of the byte string returned is always equivalent to the length of this byte string.

If you'd like to reuse an allocation for performance reasons, then use make_ascii_uppercase to perform the conversion in place.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let s = B("hello β");
assert_eq!(s.to_ascii_uppercase(), B("HELLO β"));

Invalid UTF-8 remains as is:

use bstr::{B, ByteSlice};

let s = B(b"foo\xFFbar\xE2\x98baz");
assert_eq!(s.to_ascii_uppercase(), B(b"FOO\xFFBAR\xE2\x98BAZ"));

fn make_ascii_uppercase(self: &mut Self)

Convert this byte string to its uppercase ASCII equivalent in place.

In this case, uppercase is only defined in ASCII letters. Namely, the letters a-z are converted to A-Z. All other bytes remain unchanged.

If you don't need to do the conversion in place and instead prefer convenience, then use to_ascii_uppercase instead.

Examples

Basic usage:

use bstr::{B, ByteSlice};

let mut s = <Vec<u8>>::from("hello β");
s.make_ascii_uppercase();
assert_eq!(s, B("HELLO β"));

Invalid UTF-8 remains as is:

# #[cfg(feature = "alloc")] {
use bstr::{B, ByteSlice, ByteVec};

let mut s = <Vec<u8>>::from_slice(b"foo\xFFbar\xE2\x98baz");
s.make_ascii_uppercase();
assert_eq!(s, B(b"FOO\xFFBAR\xE2\x98BAZ"));
# }

fn escape_bytes(self: &Self) -> EscapeBytes<'_>

Escapes this byte string into a sequence of char values.

When the sequence of char values is concatenated into a string, the result is always valid UTF-8. Any unprintable or invalid UTF-8 in this byte string are escaped using using \xNN notation. Moreover, the characters \0, \r, \n, \t and \ are escaped as well.

This is useful when one wants to get a human readable view of the raw bytes that is also valid UTF-8.

The iterator returned implements the Display trait. So one can do b"foo\xFFbar".escape_bytes().to_string() to get a String with its bytes escaped.

The dual of this function is ByteVec::unescape_bytes.

Note that this is similar to, but not equivalent to the Debug implementation on BStr and BString. The Debug implementations also use the debug representation for all Unicode codepoints. However, this escaping routine only escapes individual bytes. All Unicode codepoints above U+007F are passed through unchanged without any escaping.

Examples

# #[cfg(feature = "alloc")] {
use bstr::{B, ByteSlice};

assert_eq!(r"foo\xFFbar", b"foo\xFFbar".escape_bytes().to_string());
assert_eq!(r"foo\nbar", b"foo\nbar".escape_bytes().to_string());
assert_eq!(r"foo\tbar", b"foo\tbar".escape_bytes().to_string());
assert_eq!(r"foo\\bar", b"foo\\bar".escape_bytes().to_string());
assert_eq!(r"foo☃bar", B("foo☃bar").escape_bytes().to_string());
# }

fn reverse_bytes(self: &mut Self)

Reverse the bytes in this string, in place.

This is not necessarily a well formed operation! For example, if this byte string contains valid UTF-8 that isn't ASCII, then reversing the string will likely result in invalid UTF-8 and otherwise non-sensical content.

Note that this is equivalent to the generic [u8]::reverse method. This method is provided to permit callers to explicitly differentiate between reversing bytes, codepoints and graphemes.

Examples

Basic usage:

use bstr::ByteSlice;

let mut s = <Vec<u8>>::from("hello");
s.reverse_bytes();
assert_eq!(s, "olleh".as_bytes());

fn reverse_chars(self: &mut Self)

Reverse the codepoints in this string, in place.

If this byte string is valid UTF-8, then its reversal by codepoint is also guaranteed to be valid UTF-8.

This operation is equivalent to the following, but without allocating:

use bstr::ByteSlice;

let mut s = <Vec<u8>>::from("foo☃bar");

let mut chars: Vec<char> = s.chars().collect();
chars.reverse();

let reversed: String = chars.into_iter().collect();
assert_eq!(reversed, "rab☃oof");

Note that this is not necessarily a well formed operation. For example, if this byte string contains grapheme clusters with more than one codepoint, then those grapheme clusters will not necessarily be preserved. If you'd like to preserve grapheme clusters, then use reverse_graphemes instead.

Examples

Basic usage:

use bstr::ByteSlice;

let mut s = <Vec<u8>>::from("foo☃bar");
s.reverse_chars();
assert_eq!(s, "rab☃oof".as_bytes());

This example shows that not all reversals lead to a well formed string. For example, in this case, combining marks are used to put accents over some letters, and those accent marks must appear after the codepoints they modify.

use bstr::{B, ByteSlice};

let mut s = <Vec<u8>>::from("résumé");
s.reverse_chars();
assert_eq!(s, B(b"\xCC\x81emus\xCC\x81er"));

A word of warning: the above example relies on the fact that résumé is in decomposed normal form, which means there are separate codepoints for the accents above e. If it is instead in composed normal form, then the example works:

use bstr::{B, ByteSlice};

let mut s = <Vec<u8>>::from("résumé");
s.reverse_chars();
assert_eq!(s, B("émusér"));

The point here is to be cautious and not assume that just because reverse_chars works in one case, that it therefore works in all cases.

fn is_ascii(self: &Self) -> bool

Returns true if and only if every byte in this byte string is ASCII.

ASCII is an encoding that defines 128 codepoints. A byte corresponds to an ASCII codepoint if and only if it is in the inclusive range [0, 127].

Examples

Basic usage:

use bstr::{B, ByteSlice};

assert!(B("abc").is_ascii());
assert!(!B("☃βツ").is_ascii());
assert!(!B(b"\xFF").is_ascii());

fn is_utf8(self: &Self) -> bool

Returns true if and only if the entire byte string is valid UTF-8.

If you need location information about where a byte string's first invalid UTF-8 byte is, then use the to_str method.

Examples

Basic usage:

use bstr::{B, ByteSlice};

assert!(B("abc").is_utf8());
assert!(B("☃βツ").is_utf8());
// invalid bytes
assert!(!B(b"abc\xFF").is_utf8());
// surrogate encoding
assert!(!B(b"\xED\xA0\x80").is_utf8());
// incomplete sequence
assert!(!B(b"\xF0\x9D\x9Ca").is_utf8());
// overlong sequence
assert!(!B(b"\xF0\x82\x82\xAC").is_utf8());

fn last_byte(self: &Self) -> Option<u8>

Returns the last byte in this byte string, if it's non-empty. If this byte string is empty, this returns None.

Note that this is like the generic [u8]::last, except this returns the byte by value instead of a reference to the byte.

Examples

Basic usage:

use bstr::ByteSlice;

assert_eq!(Some(b'z'), b"baz".last_byte());
assert_eq!(None, b"".last_byte());

fn find_non_ascii_byte(self: &Self) -> Option<usize>

Returns the index of the first non-ASCII byte in this byte string (if any such indices exist). Specifically, it returns the index of the first byte with a value greater than or equal to 0x80.

Examples

Basic usage:

use bstr::{ByteSlice, B};

assert_eq!(Some(3), b"abc\xff".find_non_ascii_byte());
assert_eq!(None, b"abcde".find_non_ascii_byte());
assert_eq!(Some(0), B("😀").find_non_ascii_byte());