utils/common/src/main/java/brooklyn/util/math/MathFunctions.java

package brooklyn.util.math;

import javax.annotation.Nullable;

import com.google.common.base.Function;

public class MathFunctions {

    public static Function<Number, Integer> plus(final int addend) {
        return new Function<Number, Integer>() {
            public Integer apply(@Nullable Number input) {
                if (input==null) return null;
                return input.intValue() + addend;
            }
        };
    }

    public static Function<Number, Double> plus(final double addend) {
        return new Function<Number, Double>() {
            public Double apply(@Nullable Number input) {
                if (input==null) return null;
                return input.doubleValue() + addend;
            }
        };
    }

    public static Function<Number, Integer> times(final int multiplicand) {
        return new Function<Number, Integer>() {
            public Integer apply(@Nullable Number input) {
                if (input==null) return null;
                return input.intValue() * multiplicand;
            }
        };
    }

    public static Function<Number, Double> times(final double multiplicand) {
        return new Function<Number, Double>() {
            public Double apply(@Nullable Number input) {
                if (input==null) return null;
                return input.doubleValue() * multiplicand;
            }
        };
    }

    public static Function<Number, Double> divide(final double divisor) {
        return new Function<Number, Double>() {
            public Double apply(@Nullable Number input) {
                if (input==null) return null;
                return input.doubleValue() / divisor;
            }
        };
    }

    public static <T> Function<T, Double> divide(final Function<T, ? extends Number> input, final double divisor) {
        return new Function<T, Double>() {
            public Double apply(@Nullable T input2) {
                if (input==null) return null;
                Number n = input.apply(input2);
                if (n==null) return null;
                return n.doubleValue() / divisor;
            }
        };
    }
    
}