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    // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
    // file at the top-level directory of this distribution and at
    // http://rust-lang.org/COPYRIGHT.
    //
    // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
    // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
    // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
    // option. This file may not be copied, modified, or distributed
    // except according to those terms.
    //
    // Original implementation taken from rust-memchr
    // Copyright 2015 Andrew Gallant, bluss and Nicolas Koch

    /// 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.)
    ///
    /// # Example
    ///
    /// This shows how to find the first position of a byte in a byte string.
    ///
    /// ```rust,ignore
    /// 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::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.
    ///
    /// # Example
    ///
    /// This shows how to find the last position of a byte in a byte string.
    ///
    /// ```rust,ignore
    /// 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::memchr::memrchr(needle, haystack)
    }

    #[cfg(test)]
    mod tests {
        // test the implementations for the current plattform
        use super::{memchr, memrchr};

        #[test]
        fn matches_one() {
            assert_eq!(Some(0), memchr(b'a', b"a"));
        }

        #[test]
        fn matches_begin() {
            assert_eq!(Some(0), memchr(b'a', b"aaaa"));
        }

        #[test]
        fn matches_end() {
            assert_eq!(Some(4), memchr(b'z', b"aaaaz"));
        }

        #[test]
        fn matches_nul() {
            assert_eq!(Some(4), memchr(b'\x00', b"aaaa\x00"));
        }

        #[test]
        fn matches_past_nul() {
            assert_eq!(Some(5), memchr(b'z', b"aaaa\x00z"));
        }

        #[test]
        fn no_match_empty() {
            assert_eq!(None, memchr(b'a', b""));
        }

        #[test]
        fn no_match() {
            assert_eq!(None, memchr(b'a', b"xyz"));
        }

        #[test]
        fn matches_one_reversed() {
            assert_eq!(Some(0), memrchr(b'a', b"a"));
        }

        #[test]
        fn matches_begin_reversed() {
            assert_eq!(Some(3), memrchr(b'a', b"aaaa"));
        }

        #[test]
        fn matches_end_reversed() {
            assert_eq!(Some(0), memrchr(b'z', b"zaaaa"));
        }

        #[test]
        fn matches_nul_reversed() {
            assert_eq!(Some(4), memrchr(b'\x00', b"aaaa\x00"));
        }

        #[test]
        fn matches_past_nul_reversed() {
            assert_eq!(Some(0), memrchr(b'z', b"z\x00aaaa"));
        }

        #[test]
        fn no_match_empty_reversed() {
            assert_eq!(None, memrchr(b'a', b""));
        }

        #[test]
        fn no_match_reversed() {
            assert_eq!(None, memrchr(b'a', b"xyz"));
        }

        #[test]
        fn each_alignment() {
            let mut data = [1u8; 64];
            let needle = 2;
            let pos = 40;
            data[pos] = needle;
            for start in 0..16 {
                assert_eq!(Some(pos - start), memchr(needle, &data[start..]));
            }
        }
    }

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