Added new default methods to the Unit interface.

1 files changed, 46 insertions, 0 deletions

diff --git a/src/org/unitConverter/unit/Unit.java b/src/org/unitConverter/unit/Unit.java
index 86fc5a2..2ac107e 100755
--- a/src/org/unitConverter/unit/Unit.java
+++ b/src/org/unitConverter/unit/Unit.java
@@ -17,6 +17,7 @@
 package org.unitConverter.unit;
 
 import java.util.Objects;
+import java.util.function.DoubleUnaryOperator;
 
 import org.unitConverter.dimension.UnitDimension;
 
@@ -29,6 +30,31 @@ import org.unitConverter.dimension.UnitDimension;
  */
 public interface Unit {
 	/**
+	 * Returns a unit from its base and the functions it uses to convert to and from its base.
+	 * 
+	 * <p>
+	 * For example, to get a unit representing the degree Celsius, the following code can be used:
+	 * 
+	 * {@code Unit.fromConversionFunctions(SI.KELVIN, tempK -> tempK - 273.15, tempC -> tempC + 273.15);}
+	 * </p>
+	 * 
+	 * @param base
+	 *            unit's base
+	 * @param converterFrom
+	 *            function that accepts a value expressed in the unit's base and returns that value expressed in this
+	 *            unit.
+	 * @param converterTo
+	 *            function that accepts a value expressed in the unit and returns that value expressed in the unit's
+	 *            base.
+	 * @return a unit that uses the provided functions to convert.
+	 * @since 2019-05-22
+	 */
+	public static Unit fromConversionFunctions(final BaseUnit base, final DoubleUnaryOperator converterFrom,
+			final DoubleUnaryOperator converterTo) {
+		return FunctionalUnit.valueOf(base, converterFrom, converterTo);
+	}
+
+	/**
 	 * Checks if a value expressed in this unit can be converted to a value expressed in {@code other}
 	 * 
 	 * @param other
@@ -60,6 +86,26 @@ public interface Unit {
 	double convertFromBase(double value);
 
 	/**
+	 * Converts a value expressed in this unit to a value expressed in {@code other}.
+	 * 
+	 * @param other
+	 *            unit to convert to
+	 * @param value
+	 *            value to convert
+	 * @return converted value
+	 * @since 2019-05-22
+	 * @throws IllegalArgumentException
+	 *             if {@code other} is incompatible for conversion with this unit (as tested by
+	 *             {@link Unit#canConvertTo}).
+	 */
+	default double convertTo(final Unit other, final double value) {
+		if (this.canConvertTo(other))
+			return other.convertFromBase(this.convertToBase(value));
+		else
+			throw new IllegalArgumentException(String.format("Cannot convert from %s to %s.", this, other));
+	}
+
+	/**
 	 * Converts from a value expressed in this unit to a value expressed in this unit's base unit.
 	 * <p>
 	 * This must be the inverse of {@code convertFromBase}, so {@code convertToBase(convertFromBase(value))} must be