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/// Returns a `bool` saying whether the given string contains the specified pattern, expressed as an array of `&str`. Avoids all heap allocations.
/// 
/// # Examples
/// 
/// ```
/// 
/// let s = "Come va, amico?";
/// assert_eq!(contains!(s; ["me", "v", "a, a"]), true);
/// 
#[macro_export]
macro_rules! contains_bytes {
    ( $bytes:expr; $array:expr ) => ({
        let bytes_len = $bytes.len();
        // The start of the pattern that has to be checked, initialized as a `u8`.
        let mut pat_start = 0u8;
        // It is assigned the first character of the first non empty string.
        for slice in $array {
            if !slice.is_empty() {
                pat_start = slice[0];
                break
            }
        }
        let array_len = $array.len();

        let mut is_contained = false;

        // Counter needed when there are matches, so as to keep track of how many characters have already matched.
        let mut counter = 0;

        'outer: for i in 0..bytes_len {
            // Counter is reset.
            counter = 0;
            // If first character matches..
            if pat_start == $bytes[i] {
                'inner: for ii in 0..array_len {
                    let slice = $array[ii];
                    let len = slice.len();
                    // If slice is empty, skip iteration. If it's last one, returns true.
                    if len == 0 { if ii == array_len - 1 {
                        is_contained = true;
                        break 'outer
                    } else {
                        continue 'inner
                    } }
                    // Avoids out of bounds index.
                    if i + len > bytes_len {
                        break 'outer
                    }

                    // If `slice` matches to the specified portion of `$string`.
                    if *slice == $bytes[i + counter..i + counter + len] {
                        // If it's the last element in the array, break the loop.
                        if ii == array_len - 1 {
                            is_contained = true;
                            break 'outer
                        } else { // Else increase the number of characters that have already matched.
                            counter += len
                        }
                    } else {
                        continue 'outer
                    }
                }
            }
        }

        is_contained
    });
}