1package io.protobase.f7.formulas.math;
 2
 3import io.protobase.f7.formulas.AbstractFormula;
 4import io.protobase.f7.formulas.FormulaName;
 5import io.protobase.f7.models.GridColumnRowKey;
 6import io.protobase.f7.utils.Converters;
 7import io.protobase.f7.utils.Mappers;
 8
 9import java.util.Arrays;
10import java.util.Objects;
11import java.util.function.BiFunction;
12import java.util.function.Function;
13
14/**
15 * Sum values together.
16 */
17public class SUM extends AbstractFormula {
18  public static FormulaName NAME = FormulaName.SUM;
19  public static SUM SELF = new SUM();
20
21  public SUM() {
22    super();
23  }
24
25  public SUM(Function<Object, Object> lookup, BiFunction<GridColumnRowKey, Object, Object> collateralLookup) {
26    super(lookup, collateralLookup);
27  }
28
29  public Object internal(GridColumnRowKey origin, Object... values) {
30    checkAtLeastLength(values.length, 1, NAME);
31    return Arrays.stream(values)
32        .map(this.lookup)
33        .flatMap(Mappers::toFlatStream)
34        .filter(Objects::nonNull)
35        .map(Converters::toDouble)
36        .reduce(Double::sum)
37        .orElse(0.0);
38  }
39}