std::span

cppreference.com

Example

Run on Compiler Explorer

slide: <T, N: std::size_t>(
    s: std::span<T, N>, offset: std::size_t, width: std::size_t) -> _
== {
    count: std::size_t = 0;
    if offset + width <= s.size() {
        count = width;
    }
    return s.subspan(offset, count);
}

starts_with: <T, N: std::size_t, M: std::size_t>(
    data: std::span<T, N>, prefix: std::span<T, M>) -> _
== {
    return data.size() >= prefix.size()
        && std::equal(prefix.begin(), prefix.end(), data.begin());
}

ends_with: <T, N: std::size_t, M: std::size_t>(
    data: std::span<T, N>, suffix: std::span<T, M>) -> _
== {
    suffix_size:= std::ssize(suffix);
    return
        data.size() >= suffix.size() &&
        std::equal(data.end() - suffix_size, data.end(), suffix.end() - suffix_size);
}

contains: <T, N: std::size_t, M: std::size_t>(
    span: std::span<T, N>, sub: std::span<T, M>) -> _
== {
    return std::ranges::search(span, sub).begin() != span.end();
}

println: (seq) = {
    for seq do (elem) {
        std::cout << "(elem)$ ";
    }
    std::cout << '\n';
}

main: () = {
    a:     std::array  == (0, 1, 2, 3, 4, 5, 6, 7, 8);
    b:     std::array  == (8, 7, 6);
    width: std::size_t == 6;

    (copy offset: std::size_t = 0)
    while true next offset++ {
        (s:= slide(std::span(a), offset, width))
        if !s.empty() {
            println(s);
        }
        else {
            break;
        }
    }

    static_assert(
        ""
        && starts_with(std::span(a), std::span(a.begin(), 4))
        && starts_with(std::span(a.begin() + 1, 4), std::span(a.begin() + 1, 3))
        && !starts_with(std::span(a), std::span(b))
        && !starts_with(std::span(a.begin(), 8), std::span(a.begin() + 1, 3))
        && ends_with(std::span(a), std::span(a.begin() + 6, 3))
        && !ends_with(std::span(a), std::span(a.begin() + 6, 2))
        && contains(std::span(a), std::span(a.begin() + 1, 4))
        && !contains(std::span(a.begin(), 8), std::span(a.begin(), 9))
    );
}

Output

0 1 2 3 4 5 
1 2 3 4 5 6 
2 3 4 5 6 7 
3 4 5 6 7 8