rust/library/std/src/sys_common/memchr.rs

// Original implementation taken from rust-memchr.
// Copyright 2015 Andrew Gallant, bluss and Nicolas Koch

use crate::sys::memchr as sys;

#[cfg(test)]
mod tests;

/// A safe interface to `memchr`.
///
/// Returns the index corresponding to the first occurrence of `needle` in
/// `haystack`, or `None` if one is not found.
///
/// memchr reduces to super-optimized machine code at around an order of
/// magnitude faster than `haystack.iter().position(|&b| b == needle)`.
/// (See benchmarks.)
///
/// # Examples
///
/// This shows how to find the first position of a byte in a byte string.
///
/// ```ignore (cannot-doctest-private-modules)
/// use memchr::memchr;
///
/// let haystack = b"the quick brown fox";
/// assert_eq!(memchr(b'k', haystack), Some(8));
/// ```
#[inline]
pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
    sys::memchr(needle, haystack)
}

/// A safe interface to `memrchr`.
///
/// Returns the index corresponding to the last occurrence of `needle` in
/// `haystack`, or `None` if one is not found.
///
/// # Examples
///
/// This shows how to find the last position of a byte in a byte string.
///
/// ```ignore (cannot-doctest-private-modules)
/// use memchr::memrchr;
///
/// let haystack = b"the quick brown fox";
/// assert_eq!(memrchr(b'o', haystack), Some(17));
/// ```
#[inline]
pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {
    sys::memrchr(needle, haystack)
}