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/**
* Copyright (C) 2018 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.Objects;
import org.unitConverter.dimension.StandardDimensions;
import org.unitConverter.dimension.UnitDimension;
/**
* A unit that is the base for its dimension. It does not have to be for a base dimension, so units like the Newton and
* Joule are still base units.
* <p>
* {@code BaseUnit} does not have any public constructors or static factories. There are two ways to obtain
* {@code BaseUnit} instances.
* <ol>
* <li>The class {@link SI} in this package has constants for all of the SI base units. You can use these constants and
* multiply or divide them to get other units. For example:
*
* <pre>
* BaseUnit JOULE = SI.KILOGRAM.times(SI.METRE.toExponent(2)).dividedBy(SI.SECOND.toExponent(2));
* </pre>
*
* </li>
* <li>You can also query a unit system for a base unit using a unit dimension. The previously mentioned {@link SI}
* class can do this for SI and SI-derived units (including imperial and USC), but if you want to use another system,
* this is the way to do it. {@link StandardDimensions} contains common unit dimensions that you can use for this. Here
* is an example:
*
* <pre>
* BaseUnit JOULE = SI.SI.getBaseUnit(StandardDimensions.ENERGY);
* </pre>
*
* </li>
* </ol>
*
* @author Adrien Hopkins
* @since 2018-12-23
* @since v0.1.0
*/
public final class BaseUnit extends LinearUnit {
/**
* Is this unit a full base (i.e. m, s, ... but not N, J, ...)
*
* @since 2019-01-15
* @since v0.1.0
*/
private final boolean isFullBase;
/**
* Creates the {@code BaseUnit}.
*
* @param dimension
* dimension measured by unit
* @param system
* system that unit is a part of
* @param name
* name of unit
* @param symbol
* symbol of unit
* @since 2018-12-23
* @since v0.1.0
*/
BaseUnit(final UnitDimension dimension, final UnitSystem system) {
super(dimension, system, 1);
this.isFullBase = dimension.isBase();
}
/**
* Returns the quotient of this unit and another.
* <p>
* Two units can be divided if they are part of the same unit system. If {@code divisor} does not meet this
* condition, an {@code IllegalArgumentException} should be thrown.
* </p>
*
* @param divisor
* unit to divide by
* @return quotient of two units
* @throws IllegalArgumentException
* if {@code divisor} is not compatible for division as described above
* @throws NullPointerException
* if {@code divisor} is null
* @since 2018-12-22
* @since v0.1.0
*/
public BaseUnit dividedBy(final BaseUnit divisor) {
Objects.requireNonNull(divisor, "other must not be null.");
// check that these units can be multiplied
if (!this.getSystem().equals(divisor.getSystem()))
throw new IllegalArgumentException(
String.format("Incompatible units for division \"%s\" and \"%s\".", this, divisor));
return new BaseUnit(this.getDimension().dividedBy(divisor.getDimension()), this.getSystem());
}
/**
* @return true if the unit is a "full base" unit like the metre or second.
* @since 2019-04-10
* @since v0.2.0
*/
public final boolean isFullBase() {
return this.isFullBase;
}
/**
* Returns the product of this unit and another.
* <p>
* Two units can be multiplied if they are part of the same unit system. If {@code multiplier} does not meet this
* condition, an {@code IllegalArgumentException} should be thrown.
* </p>
*
* @param multiplier
* unit to multiply by
* @return product of two units
* @throws IllegalArgumentException
* if {@code multiplier} is not compatible for multiplication as described above
* @throws NullPointerException
* if {@code multiplier} is null
* @since 2018-12-22
* @since v0.1.0
*/
public BaseUnit times(final BaseUnit multiplier) {
Objects.requireNonNull(multiplier, "other must not be null");
// check that these units can be multiplied
if (!this.getSystem().equals(multiplier.getSystem()))
throw new IllegalArgumentException(
String.format("Incompatible units for multiplication \"%s\" and \"%s\".", this, multiplier));
// multiply the units
return new BaseUnit(this.getDimension().times(multiplier.getDimension()), this.getSystem());
}
/**
* Returns this unit, but to an exponent.
*
* @param exponent
* exponent
* @return result of exponentiation
* @since 2019-01-15
* @since v0.1.0
*/
@Override
public BaseUnit toExponent(final int exponent) {
return this.getSystem().getBaseUnit(this.getDimension().toExponent(exponent));
}
@Override
public String toString() {
return String.format("%s base unit of%s dimension %s", this.getSystem(), this.isFullBase ? " base" : "",
this.getDimension());
}
}
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