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Diffstat (limited to 'src/main/java/org/unitConverter/unit/Unit.java')
| -rw-r--r-- | src/main/java/org/unitConverter/unit/Unit.java | 377 |
1 files changed, 377 insertions, 0 deletions
diff --git a/src/main/java/org/unitConverter/unit/Unit.java b/src/main/java/org/unitConverter/unit/Unit.java new file mode 100644 index 0000000..0a3298f --- /dev/null +++ b/src/main/java/org/unitConverter/unit/Unit.java @@ -0,0 +1,377 @@ +/** + * 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 + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ +package org.unitConverter.unit; + +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.Objects; +import java.util.Set; +import java.util.function.DoubleUnaryOperator; + +import org.unitConverter.math.DecimalComparison; +import org.unitConverter.math.ObjectProduct; + +/** + * A unit that is composed of base units. + * + * @author Adrien Hopkins + * @since 2019-10-16 + */ +public abstract class Unit implements Nameable { + /** + * 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 + * @throws NullPointerException if any argument is null + */ + public static final Unit fromConversionFunctions( + final ObjectProduct<BaseUnit> base, + final DoubleUnaryOperator converterFrom, + final DoubleUnaryOperator converterTo) { + return new FunctionalUnit(base, converterFrom, converterTo); + } + + /** + * 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. + * @param ns names and symbol of unit + * @return a unit that uses the provided functions to convert. + * @since 2019-05-22 + * @throws NullPointerException if any argument is null + */ + public static final Unit fromConversionFunctions( + final ObjectProduct<BaseUnit> base, + final DoubleUnaryOperator converterFrom, + final DoubleUnaryOperator converterTo, final NameSymbol ns) { + return new FunctionalUnit(base, converterFrom, converterTo, ns); + } + + /** + * The combination of units that this unit is based on. + * + * @since 2019-10-16 + */ + private final ObjectProduct<BaseUnit> unitBase; + + /** + * This unit's name(s) and symbol + * + * @since 2020-09-07 + */ + private final NameSymbol nameSymbol; + + /** + * Cache storing the result of getDimension() + * + * @since 2019-10-16 + */ + private transient ObjectProduct<BaseDimension> dimension = null; + + /** + * Creates the {@code Unit}. + * + * @param unitBase base of unit + * @param ns names and symbol of unit + * @since 2019-10-16 + * @throws NullPointerException if unitBase or ns is null + */ + Unit(ObjectProduct<BaseUnit> unitBase, NameSymbol ns) { + this.unitBase = Objects.requireNonNull(unitBase, + "unitBase may not be null"); + this.nameSymbol = Objects.requireNonNull(ns, "ns may not be null"); + } + + /** + * A constructor that constructs {@code BaseUnit} instances. + * + * @since 2019-10-16 + */ + Unit(final String primaryName, final String symbol, + final Set<String> otherNames) { + if (this instanceof BaseUnit) { + this.unitBase = ObjectProduct.oneOf((BaseUnit) this); + } else + throw new AssertionError(); + this.nameSymbol = NameSymbol.of(primaryName, symbol, + new HashSet<>(otherNames)); + } + + /** + * @return this unit as a {@link Unitlike} + * @since 2020-09-07 + */ + public final Unitlike<Double> asUnitlike() { + return Unitlike.fromConversionFunctions(this.getBase(), + this::convertFromBase, this::convertToBase, this.getNameSymbol()); + } + + /** + * Checks if a value expressed in this unit can be converted to a value + * expressed in {@code other} + * + * @param other unit or unitlike form to test with + * @return true if they are compatible + * @since 2019-01-13 + * @since v0.1.0 + * @throws NullPointerException if other is null + */ + public final boolean canConvertTo(final Unit other) { + Objects.requireNonNull(other, "other must not be null."); + return Objects.equals(this.getBase(), other.getBase()); + } + + /** + * Checks if a value expressed in this unit can be converted to a value + * expressed in {@code other} + * + * @param other unit or unitlike form to test with + * @return true if they are compatible + * @since 2019-01-13 + * @since v0.1.0 + * @throws NullPointerException if other is null + */ + public final <W> boolean canConvertTo(final Unitlike<W> other) { + Objects.requireNonNull(other, "other must not be null."); + return Objects.equals(this.getBase(), other.getBase()); + } + + /** + * Converts from a value expressed in this unit's base unit to a value + * expressed in this unit. + * <p> + * This must be the inverse of {@code convertToBase}, so + * {@code convertFromBase(convertToBase(value))} must be equal to + * {@code value} for any value, ignoring precision loss by roundoff error. + * </p> + * <p> + * If this unit <i>is</i> a base unit, this method should return + * {@code value}. + * </p> + * + * @implSpec This method is used by {@link #convertTo}, and its behaviour + * affects the behaviour of {@code convertTo}. + * + * @param value value expressed in <b>base</b> unit + * @return value expressed in <b>this</b> unit + * @since 2018-12-22 + * @since v0.1.0 + */ + protected abstract double convertFromBase(double value); + + /** + * Converts a value expressed in this unit to a value expressed in + * {@code other}. + * + * @implSpec If unit conversion is possible, this implementation returns + * {@code other.convertFromBase(this.convertToBase(value))}. + * Therefore, overriding either of those methods will change the + * output of this method. + * + * @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}). + * @throws NullPointerException if other is null + */ + 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)); + else + throw new IllegalArgumentException( + String.format("Cannot convert from %s to %s.", this, other)); + } + + /** + * Converts a value expressed in this unit to a value expressed in + * {@code other}. + * + * @implSpec If conversion is possible, this implementation returns + * {@code other.convertFromBase(this.convertToBase(value))}. + * Therefore, overriding either of those methods will change the + * output of this method. + * + * @param other unitlike form to convert to + * @param value value to convert + * @param <W> type of value to convert to + * @return converted value + * @since 2020-09-07 + * @throws IllegalArgumentException if {@code other} is incompatible for + * conversion with this unit (as tested by + * {@link Unit#canConvertTo}). + * @throws NullPointerException if other is null + */ + public final <W> W convertTo(final Unitlike<W> other, final double value) { + Objects.requireNonNull(other, "other must not be null."); + 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 equal to + * {@code value} for any value, ignoring precision loss by roundoff error. + * </p> + * <p> + * If this unit <i>is</i> a base unit, this method should return + * {@code value}. + * </p> + * + * @implSpec This method is used by {@link #convertTo}, and its behaviour + * affects the behaviour of {@code convertTo}. + * + * @param value value expressed in <b>this</b> unit + * @return value expressed in <b>base</b> unit + * @since 2018-12-22 + * @since v0.1.0 + */ + protected abstract double convertToBase(double value); + + /** + * @return combination of units that this unit is based on + * @since 2018-12-22 + * @since v0.1.0 + */ + public final ObjectProduct<BaseUnit> getBase() { + return this.unitBase; + } + + /** + * @return dimension measured by this unit + * @since 2018-12-22 + * @since v0.1.0 + */ + public final ObjectProduct<BaseDimension> getDimension() { + if (this.dimension == null) { + final Map<BaseUnit, Integer> mapping = this.unitBase.exponentMap(); + final Map<BaseDimension, Integer> dimensionMap = new HashMap<>(); + + for (final BaseUnit key : mapping.keySet()) { + dimensionMap.put(key.getBaseDimension(), mapping.get(key)); + } + + this.dimension = ObjectProduct.fromExponentMapping(dimensionMap); + } + return this.dimension; + } + + /** + * @return the nameSymbol + * @since 2020-09-07 + */ + @Override + public final NameSymbol getNameSymbol() { + return this.nameSymbol; + } + + /** + * Returns true iff this unit is metric. + * <p> + * "Metric" is defined by three conditions: + * <ul> + * <li>Must be an instance of {@link LinearUnit}.</li> + * <li>Must be based on the SI base units (as determined by getBase())</li> + * <li>The conversion factor must be a power of 10.</li> + * </ul> + * <p> + * Note that this definition excludes some units that many would consider + * "metric", such as the degree Celsius (fails the first condition), + * calories, minutes and hours (fail the third condition). + * <p> + * All SI units (as designated by the BIPM) except the degree Celsius are + * considered "metric" by this definition. + * + * @since 2020-08-27 + */ + public final boolean isMetric() { + // first condition - check that it is a linear unit + if (!(this instanceof LinearUnit)) + return false; + final LinearUnit linear = (LinearUnit) this; + + // second condition - check that + for (final BaseUnit b : linear.getBase().getBaseSet()) { + if (!SI.BaseUnits.BASE_UNITS.contains(b)) + return false; + } + + // third condition - check that conversion factor is a power of 10 + return DecimalComparison + .equals(Math.log10(linear.getConversionFactor()) % 1.0, 0); + } + + @Override + public String toString() { + return this.getPrimaryName().orElse("Unnamed unit") + + (this.getSymbol().isPresent() + ? String.format(" (%s)", this.getSymbol().get()) + : "") + + ", derived from " + + this.getBase().toString(u -> u.getSymbol().get()) + + (this.getOtherNames().isEmpty() ? "" + : ", also called " + String.join(", ", this.getOtherNames())); + } + + /** + * @param ns name(s) and symbol to use + * @return a copy of this unit with provided name(s) and symbol + * @since 2019-10-21 + * @throws NullPointerException if ns is null + */ + public Unit withName(final NameSymbol ns) { + return fromConversionFunctions(this.getBase(), this::convertFromBase, + this::convertToBase, + Objects.requireNonNull(ns, "ns must not be null.")); + } +} |