C++ Fixed Size Circular Array

circular.h

#ifndef CIRCULAR_H
#define CIRCULAR_H

/**
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <ezekiel@lcarsos.com> wrote this file.  As long as you retain this notice
 * you can do whatever you want with this stuff. If we meet some day, and you
 * think this stuff is worth it, you can buy me a beer in return.
 * Ezekiel Chopper
 * ----------------------------------------------------------------------------
 */

/**
 * Circular is a circular array using stack space. It allows for native
 * indexing (using negative integers to go "backwards"). It is extremely
 * feature sparse.
 */
template<typename T, unsigned long long N>
class circular {
public:
    const unsigned long long length = N;

    T& operator[](long long i) {
        unsigned long long index = i < 0 ? N + i : i;
        return m_array[index % N];
    }
    const T& operator[](long long i) const {
        unsigned long long index = i < 0 ? N + i : i;
        return m_array[index % N];
    }

private:
    T m_array[N];
};

#endif // CIRCULAR_H