Units and Measures

Angle.java

package edu.wpi.first.wpilibj.measures.dimensions;

public class Angle implements Dimension {}

AngularVelocity.java

package edu.wpi.first.wpilibj.measures.dimensions;

public class AngularVelocity implements Dimension {}

Dimension.java

package edu.wpi.first.wpilibj.measures.dimensions;

public interface Dimension {}

Distance.java

package edu.wpi.first.wpilibj.measures.dimensions;

public class Distance implements Dimension {}

Measure.java

package edu.wpi.first.wpilibj.measures;

import edu.wpi.first.wpilibj.measures.dimensions.Dimension;

public class Measure<D extends Dimension> {
	
	double value;
	Unit<D> unit;
	
	protected Measure(double value, Unit<D> unit) {
		this.set(value, unit);
	}
	
	public void set(double value, Unit<D> unit) {
		this.value = value;
		this.unit = unit;
	}
	
	public double as(Unit<D> unit) {
		return unit.fromBaseUnits(this.unit.toBaseUnits(this.value));
	}
}

Unit.java

package edu.wpi.first.wpilibj.measures;

import edu.wpi.first.wpilibj.measures.dimensions.Dimension;

/**
 * Instances of Unit define the conversion factors for each unit of a
 * dimension.  They do not hold specific values themselves.
 * @see Units
 */
public class Unit<D extends Dimension> {
	double base;
	
	/**
	 * @param base The amount of this unit per SI base unit.
	 */
	public Unit(double base) {
		this.base = base;
	}

	public double fromBaseUnits(double value) {
		return value / this.base;
	}
	
	public double toBaseUnits(double value) {
		return value * this.base;
	}
	
	/**
	 * Convenience method to create a measure of this unit.
	 */
	public Measure<D> make(double value) {
		return new Measure<D>(value, this);
	}
	
	/**
	 * Convenience method to create a unit that is a scalar multiple of this unit.
	 */
	public Unit<D> times(double factor) {
		return new Unit<D>(this.base * factor);
	}
}

Units.java

package edu.wpi.first.wpilibj.measures;

import edu.wpi.first.wpilibj.measures.dimensions.*;

public class Units {
	public final static Unit<Distance> Meter = new Unit<Distance>(1);
	public final static Unit<Distance> Inch = Meter.times(2.54e-2);
	public final static Unit<Distance> Foot = Inch.times(12);
	public final static Unit<Distance> Yard = Foot.times(3);
	
	public final static Unit<Velocity> MetersPerSecond = new Unit<Velocity>(1);
	public final static Unit<Velocity> FeetPerSecond = new Unit<Velocity>(0.3048);
	public final static Unit<Velocity> MilesPerHour = new Unit<Velocity>(0.44704);
	
	public final static Unit<Angle> Radian = new Unit<Angle>(1);
	public final static Unit<Angle> Revolution = new Unit<Angle>(2 * Math.PI);
	public final static Unit<Angle> Degree = new Unit<Angle>(Math.PI / 180);
	
	public final static Unit<AngularVelocity> RadiansPerSecond = new Unit<AngularVelocity>(1);
	public final static Unit<AngularVelocity> DegreesPerSecond = RadiansPerSecond.times(180 / Math.PI);
	public final static Unit<AngularVelocity> RPM = RadiansPerSecond.times(2*Math.PI / 60);
	
	public final static Unit<ElectricPotential> Volt = new Unit<ElectricPotential>(1);
	
	public final static Unit<ElectricCurrent> Amp = new Unit<ElectricCurrent>(1);
	public final static Unit<ElectricCurrent> Milliamp = new Unit<ElectricCurrent>(0.001);
	
	public final static Unit<Dimensionless> Value = new Unit<Dimensionless>(1);
	public final static Unit<Dimensionless> Percent = Value.times(0.01);
}