Examples with LiteralParameters com.facebook.presto.spi.function.LiteralParameters used on opensource projects

Example 21 with LiteralParameters

use of com.facebook.presto.spi.function.LiteralParameters in project presto by prestodb.

the class StringFunctions method levenshteinDistance.

@Description("computes Levenshtein distance between two strings")
@ScalarFunction
@LiteralParameters({ "x", "y" })
@SqlType(StandardTypes.BIGINT)
public static long levenshteinDistance(@SqlType("varchar(x)") Slice left, @SqlType("varchar(y)") Slice right) {
    int[] leftCodePoints = castToCodePoints(left);
    int[] rightCodePoints = castToCodePoints(right);
    if (leftCodePoints.length < rightCodePoints.length) {
        int[] tempCodePoints = leftCodePoints;
        leftCodePoints = rightCodePoints;
        rightCodePoints = tempCodePoints;
    }
    if (rightCodePoints.length == 0) {
        return leftCodePoints.length;
    }
    checkCondition((leftCodePoints.length * (rightCodePoints.length - 1)) <= 1_000_000, INVALID_FUNCTION_ARGUMENT, "The combined inputs for Levenshtein distance are too large");
    int[] distances = new int[rightCodePoints.length];
    for (int i = 0; i < rightCodePoints.length; i++) {
        distances[i] = i + 1;
    }
    for (int i = 0; i < leftCodePoints.length; i++) {
        int leftUpDistance = distances[0];
        if (leftCodePoints[i] == rightCodePoints[0]) {
            distances[0] = i;
        } else {
            distances[0] = Math.min(i, distances[0]) + 1;
        }
        for (int j = 1; j < rightCodePoints.length; j++) {
            int leftUpDistanceNext = distances[j];
            if (leftCodePoints[i] == rightCodePoints[j]) {
                distances[j] = leftUpDistance;
            } else {
                distances[j] = Math.min(distances[j - 1], Math.min(leftUpDistance, distances[j])) + 1;
            }
            leftUpDistance = leftUpDistanceNext;
        }
    }
    return distances[rightCodePoints.length - 1];
}