diff options
| -rw-r--r-- | library/core/src/slice/ascii.rs | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/library/core/src/slice/ascii.rs b/library/core/src/slice/ascii.rs index 080256f493f..a4ad85c9202 100644 --- a/library/core/src/slice/ascii.rs +++ b/library/core/src/slice/ascii.rs @@ -80,6 +80,84 @@ impl [u8] { pub fn escape_ascii(&self) -> EscapeAscii<'_> { EscapeAscii { inner: self.iter().flat_map(EscapeByte) } } + + /// Returns a byte slice with leading ASCII whitespace bytes removed. + /// + /// 'Whitespace' refers to the definition used by + /// `u8::is_ascii_whitespace`. + /// + /// # Examples + /// + /// ``` + /// #![feature(byte_slice_trim_ascii)] + /// + /// assert_eq!(b" \t hello world\n".trim_ascii_start(), b"hello world\n"); + /// assert_eq!(b" ".trim_ascii_start(), b""); + /// assert_eq!(b"".trim_ascii_start(), b""); + /// ``` + #[unstable(feature = "byte_slice_trim_ascii", issue = "94035")] + pub const fn trim_ascii_start(&self) -> &[u8] { + let mut bytes = self; + // Note: A pattern matching based approach (instead of indexing) allows + // making the function const. + while let [first, rest @ ..] = bytes { + if first.is_ascii_whitespace() { + bytes = rest; + } else { + break; + } + } + bytes + } + + /// Returns a byte slice with trailing ASCII whitespace bytes removed. + /// + /// 'Whitespace' refers to the definition used by + /// `u8::is_ascii_whitespace`. + /// + /// # Examples + /// + /// ``` + /// #![feature(byte_slice_trim_ascii)] + /// + /// assert_eq!(b"\r hello world\n ".trim_ascii_end(), b"\r hello world"); + /// assert_eq!(b" ".trim_ascii_end(), b""); + /// assert_eq!(b"".trim_ascii_end(), b""); + /// ``` + #[unstable(feature = "byte_slice_trim_ascii", issue = "94035")] + pub const fn trim_ascii_end(&self) -> &[u8] { + let mut bytes = self; + // Note: A pattern matching based approach (instead of indexing) allows + // making the function const. + while let [rest @ .., last] = bytes { + if last.is_ascii_whitespace() { + bytes = rest; + } else { + break; + } + } + bytes + } + + /// Returns a byte slice with leading and trailing ASCII whitespace bytes + /// removed. + /// + /// 'Whitespace' refers to the definition used by + /// `u8::is_ascii_whitespace`. + /// + /// # Examples + /// + /// ``` + /// #![feature(byte_slice_trim_ascii)] + /// + /// assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world"); + /// assert_eq!(b" ".trim_ascii(), b""); + /// assert_eq!(b"".trim_ascii(), b""); + /// ``` + #[unstable(feature = "byte_slice_trim_ascii", issue = "94035")] + pub const fn trim_ascii(&self) -> &[u8] { + self.trim_ascii_start().trim_ascii_end() + } } impl_fn_for_zst! { |