001/*
002 * Units of Measurement Reference Implementation
003 * Copyright (c) 2005-2017, Jean-Marie Dautelle, Werner Keil, V2COM.
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-363 nor the names of its 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 tec.units.ri;
031
032import java.util.ArrayList;
033import java.util.List;
034
035import javax.measure.UnitConverter;
036
037/**
038 * <p>
039 * The base class for our {@link UnitConverter} implementations.
040 * </p>
041 *
042 * @author <a href="mailto:units@catmedia.us">Werner Keil</a>
043 * @version 1.0, $Date: 2016-10-06 $
044 * @since 1.0
045 */
046public abstract class AbstractConverter implements UnitConverter {
047
048  /**
049   * 
050   */
051  // private static final long serialVersionUID = 5790242858468427131L;
052
053  /**
054   * The ratio of the circumference of a circle to its diameter.
055   **/
056  protected static final double PI = 3.1415926535897932384626433832795;
057
058  /**
059   * Holds identity converter.
060   */
061  public static final AbstractConverter IDENTITY = new Identity();
062
063  /**
064   * Default constructor.
065   */
066  protected AbstractConverter() {
067  }
068
069  /**
070   * Concatenates this physics converter with another unit converter. The resulting converter is equivalent to first converting by the specified
071   * converter (right converter), and then converting by this converter (left converter).
072   *
073   * @param that
074   *          the other converter.
075   * @return the concatenation of this converter with that converter.
076   */
077  public AbstractConverter concatenate(AbstractConverter that) {
078    return (that == IDENTITY) ? this : new Pair(this, that);
079  }
080
081  public boolean isIdentity() {
082    return false;
083  }
084
085  @Override
086  public abstract boolean equals(Object cvtr);
087
088  @Override
089  public abstract int hashCode();
090
091  @Override
092  public abstract AbstractConverter inverse();
093
094  @Override
095  public UnitConverter concatenate(UnitConverter converter) {
096    return (converter == IDENTITY) ? this : new Pair(this, converter);
097  }
098
099  @Override
100  public List<? extends UnitConverter> getConversionSteps() {
101    final List<AbstractConverter> steps = new ArrayList<AbstractConverter>();
102    steps.add(this);
103    return steps;
104  }
105
106  /**
107   * @throws IllegalArgumentException
108   *           if the value is <code>null</code>.
109   */
110  public Number convert(Number value) {
111    if (value != null) {
112      return convert(value.doubleValue());
113    } else {
114      throw new IllegalArgumentException("Value cannot be null");
115    }
116  }
117
118  public abstract double convert(double value);
119
120  /**
121   * This class represents the identity converter (singleton).
122   */
123  private static final class Identity extends AbstractConverter {
124
125    @Override
126    public boolean isIdentity() {
127      return true;
128    }
129
130    @Override
131    public Identity inverse() {
132      return this;
133    }
134
135    @Override
136    public double convert(double value) {
137      return value;
138    }
139
140    @Override
141    public UnitConverter concatenate(UnitConverter converter) {
142      return converter;
143    }
144
145    @Override
146    public boolean equals(Object cvtr) {
147      return (cvtr instanceof Identity);
148    }
149
150    @Override
151    public int hashCode() {
152      return 0;
153    }
154
155    public boolean isLinear() {
156      return true;
157    }
158  }
159
160  /**
161   * This class represents converters made up of two or more separate converters (in matrix notation <code>[pair] = [left] x [right]</code>).
162   */
163  public static final class Pair extends AbstractConverter {
164
165    /**
166     * Holds the first converter.
167     */
168    private final UnitConverter left;
169
170    /**
171     * Holds the second converter.
172     */
173    private final UnitConverter right;
174
175    /**
176     * Creates a compound converter resulting from the combined transformation of the specified converters.
177     *
178     * @param left
179     *          the left converter.
180     * @param right
181     *          the right converter.
182     * @throws IllegalArgumentException
183     *           if either the left or right converter are <code>null</code>
184     */
185    public Pair(UnitConverter left, UnitConverter right) {
186      this.left = left;
187      this.right = right;
188    }
189
190    public boolean isLinear() {
191      return left.isLinear() && right.isLinear();
192    }
193
194    @Override
195    public boolean isIdentity() {
196      return false;
197    }
198
199    @Override
200    public List<UnitConverter> getConversionSteps() {
201      final List<UnitConverter> steps = new ArrayList<UnitConverter>();
202      List<? extends UnitConverter> leftCompound = left.getConversionSteps();
203      List<? extends UnitConverter> rightCompound = right.getConversionSteps();
204      steps.addAll(leftCompound);
205      steps.addAll(rightCompound);
206      return steps;
207    }
208
209    @Override
210    public Pair inverse() {
211      return new Pair(right.inverse(), left.inverse());
212    }
213
214    @Override
215    public double convert(double value) {
216      return left.convert(right.convert(value));
217    }
218
219    @Override
220    public boolean equals(Object cvtr) {
221      if (this == cvtr)
222        return true;
223      if (!(cvtr instanceof Pair))
224        return false;
225      Pair that = (Pair) cvtr;
226      return (this.left.equals(that.left)) && (this.right.equals(that.right));
227    }
228
229    @Override
230    public int hashCode() {
231      return left.hashCode() + right.hashCode();
232    }
233
234    public UnitConverter getLeft() {
235      return left;
236    }
237
238    public UnitConverter getRight() {
239      return right;
240    }
241  }
242}