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.function;
031
032import static tec.units.ri.internal.MathUtil.gcd;
033import static tec.units.ri.internal.MathUtil.negateExact;
034
035import javax.measure.UnitConverter;
036
037import tec.units.ri.AbstractConverter;
038import tec.uom.lib.common.function.ValueSupplier;
039
040/**
041 * <p>
042 * This class represents a converter multiplying numeric values by an exact scaling factor (represented as the quotient of two <code>double</code>
043 * numbers).
044 * </p>
045 *
046 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
047 * @author <a href="mailto:units@catmedia.us">Werner Keil</a>
048 * @version 1.0, October 6, 2016
049 * @since 1.0
050 */
051public final class RationalConverter extends AbstractConverter implements ValueSupplier<Double> {
052
053  /**
054         * 
055         */
056  // private static final long serialVersionUID = 1L;
057
058  /**
059   * Holds the converter dividend.
060   */
061  private final double dividend;
062
063  /**
064   * Holds the converter divisor (always positive).
065   */
066  private final double divisor;
067
068  /**
069   * Constructor
070   *
071   * @param dividend
072   *          the dividend.
073   * @param divisor
074   *          the positive divisor.
075   * @throws IllegalArgumentException
076   *           if <code>divisor &lt;= 0</code>
077   * @throws IllegalArgumentException
078   *           if <code>dividend == divisor</code>
079   */
080  public RationalConverter(double dividend, double divisor) {
081    if (divisor <= 0)
082      throw new IllegalArgumentException("Negative or zero divisor");
083    if (dividend == divisor)
084      throw new IllegalArgumentException("Would result in identity converter");
085    this.dividend = dividend;
086    this.divisor = divisor;
087  }
088
089  /**
090   * Convenience method equivalent to <code>new RationalConverter(dividend, divisor)</code>
091   *
092   * @param dividend
093   *          the dividend.
094   * @param divisor
095   *          the positive divisor.
096   * @throws IllegalArgumentException
097   *           if <code>divisor &lt;= 0</code>
098   * @throws IllegalArgumentException
099   *           if <code>dividend == divisor</code>
100   */
101  public static final RationalConverter of(long dividend, long divisor) {
102    return new RationalConverter((double) dividend, (double) divisor);
103  }
104
105  /**
106   * Convenience method equivalent to <code>new RationalConverter(dividend, divisor)</code>
107   *
108   * @param dividend
109   *          the dividend.
110   * @param divisor
111   *          the positive divisor.
112   * @throws IllegalArgumentException
113   *           if <code>divisor &lt;= 0</code>
114   * @throws IllegalArgumentException
115   *           if <code>dividend == divisor</code>
116   */
117  public static final RationalConverter of(double dividend, double divisor) {
118    return new RationalConverter(dividend, divisor);
119  }
120
121  /**
122   * Returns the integer dividend for this rational converter.
123   *
124   * @return this converter dividend.
125   */
126  public double getDividend() {
127    return dividend;
128  }
129
130  /**
131   * Returns the integer (positive) divisor for this rational converter.
132   *
133   * @return this converter divisor.
134   */
135  public double getDivisor() {
136    return divisor;
137  }
138
139  @Override
140  public double convert(double value) {
141    return value * ((double) dividend / (double) divisor);
142  }
143
144  @Override
145  public UnitConverter concatenate(UnitConverter converter) {
146    if (!(converter instanceof RationalConverter))
147      return super.concatenate(converter);
148    RationalConverter that = (RationalConverter) converter;
149    double newDividend = this.getDividend() * that.getDividend();
150    double newDivisor = this.getDivisor() * that.getDivisor();
151    double gcd = gcd(newDividend, newDivisor);
152    newDividend = newDividend / gcd; // TODO clarify if this works with long
153    newDivisor = newDivisor / gcd;
154    return (newDividend == 1 && newDivisor == 1) ? IDENTITY : new RationalConverter(newDividend, newDivisor);
155  }
156
157  @Override
158  public RationalConverter inverse() {
159    return Math.signum(dividend) == -1 ? new RationalConverter(negateExact(getDivisor()), negateExact(getDividend())) : new RationalConverter(
160        getDivisor(), getDividend());
161  }
162
163  @Override
164  public final String toString() {
165    return "RationalConverter(" + dividend + "," + divisor + ")";
166  }
167
168  @Override
169  public boolean equals(Object obj) {
170    if (!(obj instanceof RationalConverter))
171      return false;
172    RationalConverter that = (RationalConverter) obj;
173    return (this.dividend == that.dividend && this.divisor == that.divisor);
174  }
175
176  @Override
177  public int hashCode() {
178    return Double.valueOf(dividend).hashCode() + Double.valueOf(dividend).hashCode();
179  }
180
181  public boolean isLinear() {
182    return true;
183  }
184
185  public double getAsDouble() {
186    return (double) dividend / (double) divisor;
187  }
188
189  public Double getValue() {
190    return Double.valueOf(getAsDouble());
191  }
192}