FluentDecimalOperators.java

package com.facebook.presto.type;

import com.facebook.presto.operator.scalar.ScalarFunction;
import io.airlift.slice.Slice;

import java.math.BigInteger;

import static java.math.BigInteger.TEN;
import static java.util.Arrays.asList;

public class FluentDecimalOperators
{
    @ScalarFunction
    public static final ParametrizedScalar ADD = ParametrizedScalar.builder(FluentDecimalOperators.class)
            .signature("decimal(min(38, 1+max(x,v) + max(x-y, v-w))), max(y,w) as rs", "decimal(x,y)", "decimal(v,w)")
            .methods("addShortShortShort")
            .extraParameters((literals, types) ->
                    asList(Math.pow(10, literals.get("rs") - literals.get("y")),
                           Math.pow(10, literals.get("rs") - literals.get("w"))))
            .methods("addShortShortLong", "addLongLongLong", "addShortLongLong", "addLongShortLong")
            .extraParameters((literals, types) ->
                    asList(TEN.pow(literals.get("rs") - literals.get("y")),
                           TEN.pow(literals.get("rs") - literals.get("w"))))
            .build();

    public static long addShortShortShort(long a, long b, long aRescale, long bRescale)
    {
        return a * aRescale + b * bRescale;
    }

    public static Slice addShortShortLong(long a, long b, BigInteger aRescale, BigInteger bRescale) {...}

    public static Slice addLongLongLong(Slice a, Slice b, BigInteger aRescale, BigInteger bRescale) {...}

    public static Slice addShortLongLong(long a, Slice b, BigInteger aRescale, BigInteger bRescale) {...}

    public static Slice addLongShortLong(Slice a, long b, BigInteger aRescale, BigInteger bRescale) {...}
}