fast-find 0.1.0

Find fast finds bytes fast
Documentation 
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#[inline]
fn find_in(needle: u8, haystack: &[u8], len: usize) -> Option<usize> {
    let idx = haystack.iter().position(|el| *el == needle)?;
    if len > idx {
        Some(idx)
    } else {
        None
    }
}

/// Returns the index of the first element in the haystack that matches needle, up-to len, or None
#[inline]
pub fn find_in_4(needle: u8, haystack: &[u8; 4], len: usize) -> Option<usize> {
    find_in(needle, haystack, len)
}

/// Returns the index of the first element in the haystack that matches needle, up-to len, or None
pub fn find_in_16(needle: u8, haystack: &[u8; 16], len: usize) -> Option<usize> {
    find_in(needle, haystack, len)
}

/// Returns the index of the first element in the haystack that matches needle, up-to len, or None
pub fn find_in_32(needle: u8, haystack: &[u8; 32], len: usize) -> Option<usize> {
    find_in(needle, haystack, len)
}



#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_find_4() {
        let mut array = [0; 4];

        assert_eq!(find_in_4(4, &array, 4), None);

        array[1] = 4;
        array[3] = 10;

        assert_eq!(find_in_4(4, &array, 4), Some(1));
        assert_eq!(find_in_4(5, &array, 4), None);
        assert_eq!(find_in_4(10, &array, 4), Some(3));

        assert_eq!(find_in_4(4, &array, 2), Some(1));
        assert_eq!(find_in_4(5, &array, 2), None);
        assert_eq!(find_in_4(10, &array, 2), None);
    }

    #[test]
    fn test_find_16() {
        let mut array = [0; 16];

        assert_eq!(find_in_16(4, &array, 16), None);

        array[4] = 4;
        array[6] = 10;

        assert_eq!(find_in_16(4, &array, 16), Some(4));
        assert_eq!(find_in_16(5, &array, 16), None);
        assert_eq!(find_in_16(10, &array, 16), Some(6));

        assert_eq!(find_in_16(4, &array, 5), Some(4));
        assert_eq!(find_in_16(5, &array, 5), None);
        assert_eq!(find_in_16(10, &array, 5), None);
    }

    #[test]
    fn test_find_32() {
        let mut array = [0; 32];

        assert_eq!(find_in_32(4, &array, 16), None);

        array[4] = 4;
        array[6] = 10;
        array[20] = 5;

        assert_eq!(find_in_32(4, &array, 32), Some(4));
        assert_eq!(find_in_32(5, &array, 32), Some(20));
        assert_eq!(find_in_32(10, &array, 32), Some(6));

        assert_eq!(find_in_32(4, &array, 5), Some(4));
        assert_eq!(find_in_32(5, &array, 5), None);
        assert_eq!(find_in_32(10, &array, 5), None);
    }
}