1 files changed, 73 insertions, 32 deletions

diff --git a/src/org/unitConverter/unit/Unit.java b/src/org/unitConverter/unit/Unit.java
index 54f0ab5..d4eb86e 100644
--- a/src/org/unitConverter/unit/Unit.java
+++ b/src/org/unitConverter/unit/Unit.java
@@ -1,5 +1,5 @@
 /**
- * Copyright (C) 2018 Adrien Hopkins
+ * Copyright (C) 2019 Adrien Hopkins
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -16,19 +16,20 @@
  */
 package org.unitConverter.unit;
 
+import java.util.HashMap;
+import java.util.Map;
 import java.util.Objects;
 import java.util.function.DoubleUnaryOperator;
 
-import org.unitConverter.dimension.UnitDimension;
+import org.unitConverter.math.ObjectProduct;
 
 /**
- * A unit that has an associated base unit, and can convert a value expressed in it to and from that base.
+ * A unit that is composed of base units.
  * 
  * @author Adrien Hopkins
- * @since 2018-12-22
- * @since v0.1.0
+ * @since 2019-10-16
  */
-public interface Unit {
+public abstract class Unit {
 	/**
 	 * Returns a unit from its base and the functions it uses to convert to and from its base.
 	 * 
@@ -51,12 +52,50 @@ public interface Unit {
 	 * @throws NullPointerException
 	 *             if any argument is null
 	 */
-	public static Unit fromConversionFunctions(final BaseUnit base, final DoubleUnaryOperator converterFrom,
-			final DoubleUnaryOperator converterTo) {
+	public static Unit fromConversionFunctions(final ObjectProduct<BaseUnit> base,
+			final DoubleUnaryOperator converterFrom, final DoubleUnaryOperator converterTo) {
 		return FunctionalUnit.valueOf(base, converterFrom, converterTo);
 	}
 
 	/**
+	 * The combination of units that this unit is based on.
+	 * 
+	 * @since 2019-10-16
+	 */
+	private final ObjectProduct<BaseUnit> unitBase;
+
+	/**
+	 * Cache storing the result of getDimension()
+	 *
+	 * @since 2019-10-16
+	 */
+	private transient ObjectProduct<BaseDimension> dimension = null;
+
+	/**
+	 * A constructor that constructs {@code BaseUnit} instances.
+	 * 
+	 * @since 2019-10-16
+	 */
+	Unit() {
+		if (this instanceof BaseUnit) {
+			this.unitBase = ObjectProduct.oneOf((BaseUnit) this);
+		} else
+			throw new AssertionError();
+	}
+
+	/**
+	 * Creates the {@code AbstractUnit}.
+	 * 
+	 * @param unitBase
+	 * @since 2019-10-16
+	 * @throws NullPointerException
+	 *             if unitBase is null
+	 */
+	protected Unit(final ObjectProduct<BaseUnit> unitBase) {
+		this.unitBase = Objects.requireNonNull(unitBase, "unitBase must not be null.");
+	}
+
+	/**
 	 * Checks if a value expressed in this unit can be converted to a value expressed in {@code other}
 	 * 
 	 * @param other
@@ -67,7 +106,7 @@ public interface Unit {
 	 * @throws NullPointerException
 	 *             if other is null
 	 */
-	default boolean canConvertTo(final Unit other) {
+	public final boolean canConvertTo(final Unit other) {
 		Objects.requireNonNull(other, "other must not be null.");
 		return Objects.equals(this.getBase(), other.getBase());
 	}
@@ -88,7 +127,7 @@ public interface Unit {
 	 * @since 2018-12-22
 	 * @since v0.1.0
 	 */
-	double convertFromBase(double value);
+	protected abstract double convertFromBase(double value);
 
 	/**
 	 * Converts a value expressed in this unit to a value expressed in {@code other}.
@@ -101,11 +140,11 @@ public interface Unit {
 	 * @since 2019-05-22
 	 * @throws IllegalArgumentException
 	 *             if {@code other} is incompatible for conversion with this unit (as tested by
-	 *             {@link Unit#canConvertTo}).
+	 *             {@link IUnit#canConvertTo}).
 	 * @throws NullPointerException
 	 *             if other is null
 	 */
-	default double convertTo(final Unit other, final double value) {
+	public final double convertTo(final Unit other, final double value) {
 		Objects.requireNonNull(other, "other must not be null.");
 		if (this.canConvertTo(other))
 			return other.convertFromBase(this.convertToBase(value));
@@ -129,36 +168,38 @@ public interface Unit {
 	 * @since 2018-12-22
 	 * @since v0.1.0
 	 */
-	double convertToBase(double value);
+	protected abstract double convertToBase(double value);
 
 	/**
-	 * <p>
-	 * Returns the base unit associated with this unit.
-	 * </p>
-	 * <p>
-	 * The dimension of this unit must be equal to the dimension of the returned unit.
-	 * </p>
-	 * <p>
-	 * If this unit <i>is</i> a base unit, this method should return this unit.\
-	 * </p>
-	 * 
-	 * @return base unit associated with this unit
+	 * @return combination of units that this unit is based on
 	 * @since 2018-12-22
 	 * @since v0.1.0
 	 */
-	BaseUnit getBase();
+	public final ObjectProduct<BaseUnit> getBase() {
+		return this.unitBase;
+	}
 
 	/**
 	 * @return dimension measured by this unit
 	 * @since 2018-12-22
 	 * @since v0.1.0
 	 */
-	UnitDimension getDimension();
+	public final ObjectProduct<BaseDimension> getDimension() {
+		if (this.dimension == null) {
+			final Map<BaseUnit, Integer> mapping = this.unitBase.exponentMap();
+			final Map<BaseDimension, Integer> dimensionMap = new HashMap<>();
 
-	/**
-	 * @return system that this unit is a part of
-	 * @since 2018-12-23
-	 * @since v0.1.0
-	 */
-	UnitSystem getSystem();
+			for (final BaseUnit key : mapping.keySet()) {
+				dimensionMap.put(key.getBaseDimension(), mapping.get(key));
+			}
+
+			this.dimension = ObjectProduct.fromExponentMapping(dimensionMap);
+		}
+		return this.dimension;
+	}
+
+	@Override
+	public String toString() {
+		return "Unit derived from base " + this.getBase().toString();
+	}
 }