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/*
* Copyright (c) 1998-2018 University Corporation for Atmospheric Research/Unidata
* See LICENSE for license information.
*/
package ucar.units;
import javax.annotation.concurrent.Immutable;
/**
* Provides support for units that are offset from reference units (ex: as the
* unit "degree Celsius" is offset from the reference unit "kelvin"). Instances
* of this class are immutable.
*
* @author Steven R. Emmerson
*/
@Immutable
public final class OffsetUnit extends UnitImpl implements DerivableUnit {
private static final long serialVersionUID = 1L;
/**
* The origin of this unit in terms of the reference unit.
*
* @serial
*/
private final double _offset;
/**
* The reference unit.
*
* @serial
*/
private final Unit _unit;
/**
* The derived unit that is convertible with this unit.
*
* @serial
*/
private final DerivedUnit _derivedUnit;
/**
* Constructs from a reference unit and an offset.
*
* @param unit
* The reference unit.
* @param offset
* The origin of this unit in terms of the reference unit. For
* example, a degree Celsius unit would be created as "new
* OffsetUnit(kelvin, 273.15).
*/
public OffsetUnit(final Unit unit, final double offset) {
this(unit, offset, null);
}
/**
* Constructs from a reference unit, and offset, and a unit identifier.
*
* @param unit
* The reference unit.
* @param offset
* The origin of this unit in terms of the reference unit. For
* example, a degree Celsius unit would be created as "new
* OffsetUnit(kelvin, 273.15).
* @param id
* The identifier for the new unit.
*/
public OffsetUnit(final Unit unit, final double offset, final UnitName id) {
super(id);
if (!(unit instanceof OffsetUnit)) {
_unit = unit;
_offset = offset;
} else {
_unit = ((OffsetUnit) unit)._unit;
_offset = ((OffsetUnit) unit)._offset + offset;
}
_derivedUnit = _unit.getDerivedUnit();
}
static Unit getInstance(final Unit unit, final double origin) {
return (origin == 0) ? unit : new OffsetUnit(unit, origin);
}
/**
* Returns the reference unit.
*
* @return The reference unit.
*/
public Unit getUnit() {
return _unit;
}
/**
* Returns the offset. The offset is the location of the origin of this unit
* in terms of the reference unit.
*
* @return The origin of this unit in terms of the reference unit.
*/
public double getOffset() {
return _offset;
}
/*
* From UnitImpl:
*/
/**
* Clones this unit, changing the identifier.
*
* @param id
* The identifier for the new unit.
* @return This unit with its identifier changed.
*/
public Unit clone(final UnitName id) {
return new OffsetUnit(getUnit(), getOffset(), id);
}
@Override
public Unit multiplyBy(final double scale) throws MultiplyException {
if (scale == 0) {
throw new MultiplyException(scale, this);
}
return getInstance(_unit.multiplyBy(scale), _offset / scale);
}
@Override
public Unit shiftTo(final double origin) {
return getInstance(_unit, origin + _offset);
}
/**
* Multiply this unit by another unit.
*
* @param that
* The unit to multiply this unit by.
* @return The product of this unit and that. The offset of
* this unit will be ignored; thus, for example
* "celsius.myMultiplyBy(day)" is equivalent to
* "kelvin.myMultiplyBy(day)".
* @throws MultiplyException
* Can't multiply these units together.
*/
@Override
protected Unit myMultiplyBy(final Unit that) throws MultiplyException {
return that instanceof OffsetUnit ? getUnit().multiplyBy(((OffsetUnit) that).getUnit())
: getUnit().multiplyBy(that);
}
/**
* Divide this unit by another unit.
*
* @param that
* The unit to divide this unit by.
* @return The quotient of this unit and that. The offset of
* this unit will be ignored; thus, for example
* "celsius.myDivideBy(day)" is equivalent to
* "kelvin.myDivideBy(day)".
* @throws OperationException
* Can't divide these units.
*/
@Override
protected Unit myDivideBy(final Unit that) throws OperationException {
return that instanceof OffsetUnit ? getUnit().divideBy(((OffsetUnit) that).getUnit()) : getUnit().divideBy(that);
}
/**
* Divide this unit into another unit.
*
* @param that
* The unit to divide this unit into.
* @return The quotient of that unit and this unit. The offset
* of this unit will be ignored; thus, for example
* "celsius.myDivideInto(day)" is equivalent to
* "kelvin.myDivideInto(day)".
* @throws OperationException
* Can't divide these units.
*/
@Override
protected Unit myDivideInto(final Unit that) throws OperationException {
return that instanceof OffsetUnit ? getUnit().divideInto(((OffsetUnit) that).getUnit())
: getUnit().divideInto(that);
}
/**
* Raise this unit to a power.
*
* @param power
* The power to raise this unit by.
* @return The result of raising this unit by the power power.
* The offset of this unit will be ignored; thus, for example
* "celsius.myRaiseTo(2)" is equivalent to "kelvin.myRaiseTo(2)".
* @throws RaiseException
* Can't raise this unit to a power.
*/
// Ignore offset (e.g. "Cel2" == "K2")
@Override
protected Unit myRaiseTo(final int power) throws RaiseException {
return getUnit().raiseTo(power);
}
/**
* Returns the derived unit that is convertible with this unit.
*
* @return The derived unit that is convertible with this unit.
*/
public DerivedUnit getDerivedUnit() {
return _derivedUnit;
}
/**
* Converts a value in this unit to the equivalent value in the convertible
* derived unit.
*
* @param amount
* The value in this unit.
* @return The equivalent value in the convertible derived unit.
* @throws ConversionException
* Can't convert between units.
*/
public float toDerivedUnit(final float amount) throws ConversionException {
return (float) toDerivedUnit((double) amount);
}
/**
* Converts a value in this unit to the equivalent value in the convertible
* derived unit.
*
* @param amount
* The value in this unit.
* @return The equivalent value in the convertible derived unit.
* @throws ConversionException
* Can't convert between units.
*/
public double toDerivedUnit(final double amount) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
return ((DerivableUnit) getUnit()).toDerivedUnit(amount + getOffset());
}
/**
* Converts values in this unit to the equivalent values in the convertible
* derived unit.
*
* @param input
* The values in this unit.
* @param output
* The equivalent values in the convertible derived unit. May be
* the same array as input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public float[] toDerivedUnit(final float[] input, final float[] output) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
final float origin = (float) getOffset();
for (int i = input.length; --i >= 0;) {
output[i] = input[i] + origin;
}
return ((DerivableUnit) getUnit()).toDerivedUnit(output, output);
}
/**
* Converts values in this unit to the equivalent values in the convertible
* derived unit.
*
* @param input
* The values in this unit.
* @param output
* The equivalent values in the convertible derived unit. May be
* the same array as input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public double[] toDerivedUnit(final double[] input, final double[] output) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(this, getDerivedUnit());
}
final double origin = getOffset();
for (int i = input.length; --i >= 0;) {
output[i] = input[i] + origin;
}
return ((DerivableUnit) getUnit()).toDerivedUnit(output, output);
}
/**
* Converts a value in the convertible derived unit to the equivalent value
* in this unit.
*
* @param amount
* The value in the convertible derived unit.
* @return The equivalent value in this unit.
* @throws ConversionException
* Can't convert between units.
*/
public float fromDerivedUnit(final float amount) throws ConversionException {
return (float) fromDerivedUnit((double) amount);
}
/**
* Converts a value in the convertible derived unit to the equivalent value
* in this unit.
*
* @param amount
* The value in the convertible derived unit.
* @return The equivalent value in this unit.
* @throws ConversionException
* Can't convert between units.
*/
public double fromDerivedUnit(final double amount) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(getDerivedUnit(), this);
}
return ((DerivableUnit) getUnit()).fromDerivedUnit(amount) - getOffset();
}
/**
* Converts values in the convertible derived unit to the equivalent values
* in this unit.
*
* @param input
* The values in the convertible derived unit.
* @param output
* The equivalent values in this unit. May be the same array as
* input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public float[] fromDerivedUnit(final float[] input, final float[] output) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(getDerivedUnit(), this);
}
((DerivableUnit) getUnit()).fromDerivedUnit(input, output);
final float origin = (float) getOffset();
for (int i = input.length; --i >= 0;) {
output[i] -= origin;
}
return output;
}
/**
* Converts values in the convertible derived unit to the equivalent values
* in this unit.
*
* @param input
* The values in the convertible derived unit.
* @param output
* The equivalent values in this unit. May be the same array as
* input.
* @return output.
* @throws ConversionException
* Can't convert between units.
*/
public double[] fromDerivedUnit(final double[] input, final double[] output) throws ConversionException {
if (!(_unit instanceof DerivableUnit)) {
throw new ConversionException(getDerivedUnit(), this);
}
((DerivableUnit) getUnit()).fromDerivedUnit(input, output);
final double origin = getOffset();
for (int i = input.length; --i >= 0;) {
output[i] -= origin;
}
return output;
}
/**
* Indicates if this unit is semantically identical to an object.
*
* @param object
* The object.
* @return true if and only if this unit is semantically
* identical to object
* .
*/
@Override
public boolean equals(final Object object) {
if (this == object) {
return true;
}
if (_offset == 0) {
return object.equals(_unit);
}
if (!(object instanceof OffsetUnit)) {
return false;
}
OffsetUnit that = (OffsetUnit) object;
if (Double.compare(that._offset, _offset) != 0)
return false;
return _unit.equals(that._unit);
}
/**
* Returns the hash code of this instance.
*
* @return The hash code of this instance.
*/
@Override
public int hashCode() {
return (getOffset() == 0 ? 0 : Double.valueOf(getOffset()).hashCode()) ^ getUnit().hashCode();
}
/**
* Indicates if this unit is dimensionless.
*
* @return true if and only if this unit is dimensionless.
*/
public boolean isDimensionless() {
return getUnit().isDimensionless();
}
/**
* Returns the string representation of this unit.
*
* @return The string representation of this unit.
*/
@Override
public String toString() {
final String string = super.toString(); // get symbol or name
return string != null ? string : getCanonicalString();
}
/**
* Returns the canonical string representation of the unit.
*
* @return The canonical string representation.
*/
public String getCanonicalString() {
return "(" + getUnit().toString() + ") @ " + getOffset();
}
}
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