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// Copyright (C) 2017-2018 Baidu, Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//  * Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
//  * Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in
//    the documentation and/or other materials provided with the
//    distribution.
//  * Neither the name of Baidu, Inc., nor the names of its
//    contributors may be used to endorse or promote products derived
//    from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


/// A safe interface to `memchr`.
///
/// Returns the index corresponding to the first occurrence of `needle` in
/// `haystack`, or `None` if one is not found.
///
// #[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.
///
// #[inline]
// pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {
//     ::sys::memchr::memrchr(needle, haystack)
// }

use libc;

pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {

    let p = unsafe {
        libc::memchr(
            haystack.as_ptr(),
            needle,
            haystack.len())
    };
    if p.is_null() {
        None
    } else {
        Some(p as usize - (haystack.as_ptr() as usize))
    }
}

pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {

    fn memrchr_specific(needle: u8, haystack: &[u8]) -> Option<usize> {

        // GNU's memrchr() will - unlike memchr() - error if haystack is empty.
        if haystack.is_empty() {return None}
        let p = unsafe {
            libc::memrchr(
                haystack.as_ptr(),
                needle,
                haystack.len())
        };
        if p.is_null() {
            None
        } else {
            Some(p as usize - (haystack.as_ptr() as usize))
        }
    }

    memrchr_specific(needle, haystack)
}