134 lines
3.1 KiB
Rust
134 lines
3.1 KiB
Rust
// Original implementation taken from rust-memchr.
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// Copyright 2015 Andrew Gallant, bluss and Nicolas Koch
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/// A safe interface to `memchr`.
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///
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/// Returns the index corresponding to the first occurrence of `needle` in
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/// `haystack`, or `None` if one is not found.
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///
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/// memchr reduces to super-optimized machine code at around an order of
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/// magnitude faster than `haystack.iter().position(|&b| b == needle)`.
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/// (See benchmarks.)
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///
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/// # Examples
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///
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/// This shows how to find the first position of a byte in a byte string.
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///
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/// ```ignore (cannot-doctest-private-modules)
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/// use memchr::memchr;
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///
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/// let haystack = b"the quick brown fox";
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/// assert_eq!(memchr(b'k', haystack), Some(8));
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/// ```
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#[inline]
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pub fn memchr(needle: u8, haystack: &[u8]) -> Option<usize> {
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crate::sys::memchr::memchr(needle, haystack)
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}
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/// A safe interface to `memrchr`.
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///
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/// Returns the index corresponding to the last occurrence of `needle` in
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/// `haystack`, or `None` if one is not found.
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///
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/// # Examples
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///
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/// This shows how to find the last position of a byte in a byte string.
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///
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/// ```ignore (cannot-doctest-private-modules)
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/// use memchr::memrchr;
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///
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/// let haystack = b"the quick brown fox";
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/// assert_eq!(memrchr(b'o', haystack), Some(17));
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/// ```
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#[inline]
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pub fn memrchr(needle: u8, haystack: &[u8]) -> Option<usize> {
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crate::sys::memchr::memrchr(needle, haystack)
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}
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#[cfg(test)]
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mod tests {
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// test the implementations for the current platform
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use super::{memchr, memrchr};
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#[test]
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fn matches_one() {
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assert_eq!(Some(0), memchr(b'a', b"a"));
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}
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#[test]
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fn matches_begin() {
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assert_eq!(Some(0), memchr(b'a', b"aaaa"));
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}
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#[test]
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fn matches_end() {
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assert_eq!(Some(4), memchr(b'z', b"aaaaz"));
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}
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#[test]
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fn matches_nul() {
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assert_eq!(Some(4), memchr(b'\x00', b"aaaa\x00"));
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}
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#[test]
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fn matches_past_nul() {
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assert_eq!(Some(5), memchr(b'z', b"aaaa\x00z"));
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}
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#[test]
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fn no_match_empty() {
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assert_eq!(None, memchr(b'a', b""));
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}
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#[test]
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fn no_match() {
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assert_eq!(None, memchr(b'a', b"xyz"));
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}
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#[test]
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fn matches_one_reversed() {
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assert_eq!(Some(0), memrchr(b'a', b"a"));
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}
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#[test]
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fn matches_begin_reversed() {
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assert_eq!(Some(3), memrchr(b'a', b"aaaa"));
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}
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#[test]
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fn matches_end_reversed() {
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assert_eq!(Some(0), memrchr(b'z', b"zaaaa"));
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}
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#[test]
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fn matches_nul_reversed() {
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assert_eq!(Some(4), memrchr(b'\x00', b"aaaa\x00"));
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}
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#[test]
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fn matches_past_nul_reversed() {
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assert_eq!(Some(0), memrchr(b'z', b"z\x00aaaa"));
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}
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#[test]
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fn no_match_empty_reversed() {
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assert_eq!(None, memrchr(b'a', b""));
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}
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#[test]
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fn no_match_reversed() {
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assert_eq!(None, memrchr(b'a', b"xyz"));
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}
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#[test]
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fn each_alignment() {
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let mut data = [1u8; 64];
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let needle = 2;
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let pos = 40;
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data[pos] = needle;
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for start in 0..16 {
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assert_eq!(Some(pos - start), memchr(needle, &data[start..]));
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}
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}
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}
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