com.ibm.icu.impl.units.SingleUnitImpl Maven / Gradle / Ivy
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// © 2020 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
package com.ibm.icu.impl.units;
import com.ibm.icu.util.MeasureUnit;
public class SingleUnitImpl {
/**
* Simple unit index, unique for every simple unit, -1 for the dimensionless
* unit. This is an index into a string list in unit.txt {ConversionUnits}.
*
* The default value is -1, meaning the dimensionless unit:
* isDimensionless() will return true, until index is changed.
*/
private int index = -1;
/**
* SimpleUnit is the simplest form of a Unit. For example, for "square-millimeter", the simple unit would be "meter"Ò
*
* The default value is "", meaning the dimensionless unit:
* isDimensionless() will return true, until index is changed.
*/
private String simpleUnit = "";
/**
* Determine the power of the `SingleUnit`. For example, for "square-meter", the dimensionality will be `2`.
*
* NOTE:
* Default dimensionality is 1.
*/
private int dimensionality = 1;
/**
* SI Prefix
*/
private MeasureUnit.SIPrefix siPrefix = MeasureUnit.SIPrefix.ONE;
public SingleUnitImpl copy() {
SingleUnitImpl result = new SingleUnitImpl();
result.index = this.index;
result.dimensionality = this.dimensionality;
result.simpleUnit = this.simpleUnit;
result.siPrefix = this.siPrefix;
return result;
}
public MeasureUnit build() {
MeasureUnitImpl measureUnit = new MeasureUnitImpl(this);
return measureUnit.build();
}
/**
* Generates an neutral identifier string for a single unit which means we do not include the dimension signal.
*/
public String getNeutralIdentifier() {
StringBuilder result = new StringBuilder();
int posPower = Math.abs(this.getDimensionality());
assert posPower > 0 : "getIdentifier does not support the dimensionless";
if (posPower == 1) {
// no-op
} else if (posPower == 2) {
result.append("square-");
} else if (posPower == 3) {
result.append("cubic-");
} else if (posPower <= 15) {
result.append("pow");
result.append(posPower);
result.append('-');
} else {
// TODO: IllegalArgumentException might not be appropriate here
throw new IllegalArgumentException("Unit Identifier Syntax Error");
}
result.append(this.getSiPrefix().getIdentifier());
result.append(this.getSimpleUnit());
return result.toString();
}
/**
* Compare this SingleUnitImpl to another SingleUnitImpl for the sake of
* sorting and coalescing.
*
* Takes the sign of dimensionality into account, but not the absolute
* value: per-meter is not considered the same as meter, but meter is
* considered the same as square-meter.
*
* The dimensionless unit generally does not get compared, but if it did, it
* would sort before other units by virtue of index being < 0 and
* dimensionality not being negative.
*/
int compareTo(SingleUnitImpl other) {
if (dimensionality < 0 && other.dimensionality > 0) {
// Positive dimensions first
return 1;
}
if (dimensionality > 0 && other.dimensionality < 0) {
return -1;
}
if (index < other.index) {
return -1;
}
if (index > other.index) {
return 1;
}
if (this.getSiPrefix().getPower() < other.getSiPrefix().getPower()) {
return -1;
}
if (this.getSiPrefix().getPower() > other.getSiPrefix().getPower()) {
return 1;
}
return 0;
}
/**
* Checks whether this SingleUnitImpl is compatible with another for the purpose of coalescing.
*
* Units with the same base unit and SI prefix should match, except that they must also have
* the same dimensionality sign, such that we don't merge numerator and denominator.
*/
boolean isCompatibleWith(SingleUnitImpl other) {
return (compareTo(other) == 0);
}
public String getSimpleUnit() {
return simpleUnit;
}
public void setSimpleUnit(int simpleUnitIndex, String[] simpleUnits) {
this.index = simpleUnitIndex;
this.simpleUnit = simpleUnits[simpleUnitIndex];
}
public int getDimensionality() {
return dimensionality;
}
public void setDimensionality(int dimensionality) {
this.dimensionality = dimensionality;
}
public MeasureUnit.SIPrefix getSiPrefix() {
return siPrefix;
}
public void setSiPrefix(MeasureUnit.SIPrefix siPrefix) {
this.siPrefix = siPrefix;
}
public int getIndex() {
return index;
}
}