001/*
002 * Units of Measurement Reference Implementation
003 * Copyright (c) 2005-2020, Units of Measurement project.
004 *
005 * All rights reserved.
006 *
007 * Redistribution and use in source and binary forms, with or without modification,
008 * are permitted provided that the following conditions are met:
009 *
010 * 1. Redistributions of source code must retain the above copyright notice,
011 *    this list of conditions and the following disclaimer.
012 *
013 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions
014 *    and the following disclaimer in the documentation and/or other materials provided with the distribution.
015 *
016 * 3. Neither the name of JSR-385, Indriya nor the names of their contributors may be used to endorse or promote products
017 *    derived from this software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
020 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
021 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
022 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
023 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
026 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
028 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package tech.units.indriya.unit;
031
032import java.util.Map;
033import java.util.Objects;
034
035import javax.measure.Dimension;
036import javax.measure.Quantity;
037import javax.measure.Unit;
038import javax.measure.UnitConverter;
039
040import tech.units.indriya.AbstractUnit;
041import tech.uom.lib.common.function.UnitConverterSupplier;
042
043/**
044 * <p>
045 * This class represents the units derived from other units using {@linkplain UnitConverter converters}.
046 * </p>
047 *
048 * <p>
049 * Examples of transformed units:<code>
050 *         CELSIUS = KELVIN.shift(273.15);
051 *         FOOT = METRE.multiply(3048).divide(10000);
052 *         MILLISECOND = MILLI(SECOND);
053 *     </code>
054 * </p>
055 *
056 * <p>
057 * Transformed units have no symbol. But like any other units, they may have labels attached to them (see
058 * {@link javax.measure.format.UnitFormat#label(Unit, String) UnitFormat.label}
059 * </p>
060 *
061 * <p>
062 * Instances of this class are created through the {@link AbstractUnit#transform} method.
063 * </p>
064 *
065 * @param <Q>
066 *          The type of the quantity measured by this unit.
067 *
068 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
069 * @author <a href="mailto:werner@units.tech">Werner Keil</a>
070 * @version 1.2.1, October 12, 2018
071 * @since 1.0
072 */
073public final class TransformedUnit<Q extends Quantity<Q>> extends AbstractUnit<Q> implements UnitConverterSupplier {
074
075  /**
076     *
077     */
078  private static final long serialVersionUID = 1L;
079
080  /**
081   * Holds the parent unit.
082   */
083  private final AbstractUnit<Q> parentUnit;
084
085  /**
086   * Holds the system unit.
087   */
088  private final Unit<Q> systemUnit;
089
090  /**
091   * Holds the converter to the parent unit.
092   */
093  private final UnitConverter converter;
094
095  /**
096   * Creates a transformed unit from the specified system unit. using the parent as symbol
097   * 
098   * @param parentUnit
099   *          the system unit from which this unit is derived.
100   * @param converter
101   *          the converter to the parent units.
102   */
103  public TransformedUnit(Unit<Q> parentUnit, UnitConverter unitConverter) {
104    this(null, parentUnit, unitConverter);
105  }
106
107  /**
108   * Creates a transformed unit from the specified parent unit.
109   *
110   * @param symbol
111   *          the symbol to use with this transformed unit.
112   * @param parentUnit
113   *          the parent unit from which this unit is derived.
114   * @param unitConverter
115   *          the converter to the parent units.
116   */
117  public TransformedUnit(String symbol, Unit<Q> parentUnit, UnitConverter unitConverter) {
118    this(symbol, parentUnit, parentUnit.getSystemUnit(), unitConverter);
119  }
120
121  /**
122   * Creates a transformed unit from the specified parent and system unit. using the parent as symbol
123   * 
124   * @param parentUnit
125   *          the parent unit from which this unit is derived.
126   * @param sysUnit
127   *          the system unit which this unit is based on.
128   * @param converter
129   *          the converter to the parent units.
130   */
131  public TransformedUnit(String symbol, Unit<Q> parentUnit, Unit<Q> sysUnit, UnitConverter unitConverter) {
132    if (parentUnit instanceof AbstractUnit) {
133      final AbstractUnit<Q> abParent = (AbstractUnit<Q>) parentUnit;
134
135      this.systemUnit = sysUnit;
136      // if (!abParent.isSystemUnit()) {
137      // throw new IllegalArgumentException("The parent unit: " + abParent
138      // + " is not a system unit");
139      // }
140      this.parentUnit = abParent;
141      this.converter = unitConverter;
142      setSymbol(symbol);
143      // see https://github.com/unitsofmeasurement/uom-se/issues/54
144    } else {
145      throw new IllegalArgumentException("The parent unit: " + parentUnit + " is not an abstract unit.");
146    }
147  }
148
149  @Override
150  public Dimension getDimension() {
151    return parentUnit.getDimension();
152  }
153
154  @Override
155  public UnitConverter getSystemConverter() {
156    return parentUnit.getSystemConverter().concatenate(converter);
157  }
158
159  /**
160   * Returns the converter to the parent unit.
161   *
162   * @return the converter to the parent unit.
163   */
164  @Override
165  public UnitConverter getConverter() {
166    return converter;
167  }
168
169  @Override
170  protected Unit<Q> toSystemUnit() {
171    return (systemUnit != null ? systemUnit : parentUnit.getSystemUnit());
172  }
173
174  @Override
175  public Map<? extends Unit<?>, Integer> getBaseUnits() {
176    return parentUnit.getBaseUnits();
177  }
178
179  @Override
180  public int hashCode() {
181    return Objects.hash(parentUnit, converter);
182  }
183
184  @Override
185  public boolean equals(Object obj) {
186    if (this == obj) {
187      return true;
188    }
189    if (obj instanceof TransformedUnit) {
190      TransformedUnit<?> other = (TransformedUnit<?>) obj;
191      return Objects.equals(parentUnit, other.parentUnit) 
192                  && Objects.equals(converter, other.converter);
193    } 
194    return false;
195  }
196
197  /**
198   * Returns the parent unit for this unit. The parent unit is the untransformed unit from which this unit is derived.
199   *
200   * @return the untransformed unit from which this unit is derived.
201   */
202  public Unit<Q> getParentUnit() {
203    return parentUnit;
204  }
205}