private static int unlimitedCompare()

in src/main/java/org/apache/commons/text/similarity/LevenshteinDistance.java [259:318]

• 42 lines of code
• 10 McCabe index (conditional complexity)

    private static int unlimitedCompare(CharSequence left, CharSequence right) {
        if (left == null || right == null) {
            throw new IllegalArgumentException("CharSequences must not be null");
        }

        /*
           This implementation use two variable to record the previous cost counts,
           So this implementation use less memory than previous impl.
         */

        int n = left.length(); // length of left
        int m = right.length(); // length of right

        if (n == 0) {
            return m;
        }
        if (m == 0) {
            return n;
        }

        if (n > m) {
            // swap the input strings to consume less memory
            final CharSequence tmp = left;
            left = right;
            right = tmp;
            n = m;
            m = right.length();
        }

        final int[] p = new int[n + 1];

        // indexes into strings left and right
        int i; // iterates through left
        int j; // iterates through right
        int upperLeft;
        int upper;

        char rightJ; // jth character of right
        int cost; // cost

        for (i = 0; i <= n; i++) {
            p[i] = i;
        }

        for (j = 1; j <= m; j++) {
            upperLeft = p[0];
            rightJ = right.charAt(j - 1);
            p[0] = j;

            for (i = 1; i <= n; i++) {
                upper = p[i];
                cost = left.charAt(i - 1) == rightJ ? 0 : 1;
                // minimum of cell to the left+1, to the top+1, diagonally left and up +cost
                p[i] = Math.min(Math.min(p[i - 1] + 1, p[i] + 1), upperLeft + cost);
                upperLeft = upper;
            }
        }

        return p[n];
    }