public static void shift()

in src/main/java/org/apache/commons/lang3/ArrayUtils.java [7433:7472]

• 37 lines of code
• 12 McCabe index (conditional complexity)

    public static void shift(final long[] array, int startIndexInclusive, int endIndexExclusive, int offset) {
        if (array == null) {
            return;
        }
        if (startIndexInclusive >= array.length - 1 || endIndexExclusive <= 0) {
            return;
        }
        if (startIndexInclusive < 0) {
            startIndexInclusive = 0;
        }
        if (endIndexExclusive >= array.length) {
            endIndexExclusive = array.length;
        }
        int n = endIndexExclusive - startIndexInclusive;
        if (n <= 1) {
            return;
        }
        offset %= n;
        if (offset < 0) {
            offset += n;
        }
        // For algorithm explanations and proof of O(n) time complexity and O(1) space complexity
        // see https://beradrian.wordpress.com/2015/04/07/shift-an-array-in-on-in-place/
        while (n > 1 && offset > 0) {
            final int n_offset = n - offset;

            if (offset > n_offset) {
                swap(array, startIndexInclusive, startIndexInclusive + n - n_offset,  n_offset);
                n = offset;
                offset -= n_offset;
            } else if (offset < n_offset) {
                swap(array, startIndexInclusive, startIndexInclusive + n_offset,  offset);
                startIndexInclusive += offset;
                n = n_offset;
            } else {
                swap(array, startIndexInclusive, startIndexInclusive + n_offset, offset);
                break;
            }
        }
    }