com.ibm.icu.impl.units.UnitsConverter 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 static java.math.MathContext.DECIMAL128;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.regex.Pattern;
import com.ibm.icu.impl.IllegalIcuArgumentException;
import com.ibm.icu.util.MeasureUnit;
public class UnitsConverter {
private BigDecimal conversionRate;
private boolean reciprocal;
private BigDecimal offset;
/**
* Constructor of UnitsConverter.
* NOTE:
* - source and target must be under the same category
* - e.g. meter to mile --> both of them are length units.
*
* NOTE:
* This constructor creates an instance of UnitsConverter internally.
*
* @param sourceIdentifier represents the source unit identifier.
* @param targetIdentifier represents the target unit identifier.
*/
public UnitsConverter(String sourceIdentifier, String targetIdentifier) {
this(
MeasureUnitImpl.forIdentifier(sourceIdentifier),
MeasureUnitImpl.forIdentifier(targetIdentifier),
new ConversionRates()
);
}
/**
* Constructor of UnitsConverter.
* NOTE:
* - source and target must be under the same category
* - e.g. meter to mile --> both of them are length units.
*
* @param source represents the source unit.
* @param target represents the target unit.
* @param conversionRates contains all the needed conversion rates.
*/
public UnitsConverter(MeasureUnitImpl source, MeasureUnitImpl target, ConversionRates conversionRates) {
Convertibility convertibility = extractConvertibility(source, target, conversionRates);
if (convertibility != Convertibility.CONVERTIBLE && convertibility != Convertibility.RECIPROCAL) {
throw new IllegalIcuArgumentException("input units must be convertible or reciprocal");
}
Factor sourceToBase = conversionRates.getFactorToBase(source);
Factor targetToBase = conversionRates.getFactorToBase(target);
if (convertibility == Convertibility.CONVERTIBLE) {
this.conversionRate = sourceToBase.divide(targetToBase).getConversionRate();
} else {
assert convertibility == Convertibility.RECIPROCAL;
this.conversionRate = sourceToBase.multiply(targetToBase).getConversionRate();
}
this.reciprocal = convertibility == Convertibility.RECIPROCAL;
// calculate the offset
this.offset = conversionRates.getOffset(source, target, sourceToBase, targetToBase, convertibility);
// We should see no offsets for reciprocal conversions - they don't make sense:
assert convertibility != Convertibility.RECIPROCAL || this.offset == BigDecimal.ZERO;
}
static public Convertibility extractConvertibility(MeasureUnitImpl source, MeasureUnitImpl target, ConversionRates conversionRates) {
ArrayList sourceSingleUnits = conversionRates.extractBaseUnits(source);
ArrayList targetSingleUnits = conversionRates.extractBaseUnits(target);
HashMap dimensionMap = new HashMap<>();
insertInMap(dimensionMap, sourceSingleUnits, 1);
insertInMap(dimensionMap, targetSingleUnits, -1);
if (areDimensionsZeroes(dimensionMap)) return Convertibility.CONVERTIBLE;
insertInMap(dimensionMap, targetSingleUnits, 2);
if (areDimensionsZeroes(dimensionMap)) return Convertibility.RECIPROCAL;
return Convertibility.UNCONVERTIBLE;
}
/**
* Helpers
*/
private static void insertInMap(HashMap dimensionMap, ArrayList singleUnits, int multiplier) {
for (SingleUnitImpl singleUnit :
singleUnits) {
if (dimensionMap.containsKey(singleUnit.getSimpleUnitID())) {
dimensionMap.put(singleUnit.getSimpleUnitID(), dimensionMap.get(singleUnit.getSimpleUnitID()) + singleUnit.getDimensionality() * multiplier);
} else {
dimensionMap.put(singleUnit.getSimpleUnitID(), singleUnit.getDimensionality() * multiplier);
}
}
}
private static boolean areDimensionsZeroes(HashMap dimensionMap) {
for (Integer value :
dimensionMap.values()) {
if (!value.equals(0)) return false;
}
return true;
}
public BigDecimal convert(BigDecimal inputValue) {
BigDecimal result = inputValue.multiply(this.conversionRate).add(offset);
if (this.reciprocal) {
// We should see no offsets for reciprocal conversions - they don't make sense:
assert offset == BigDecimal.ZERO;
if (result == BigDecimal.ZERO) {
// TODO: demonstrate the resulting behaviour in tests... and
// figure out desired behaviour. (Theoretical result should be
// infinity, not 0, but BigDecimal does not support infinity.)
return BigDecimal.ZERO;
}
result = BigDecimal.ONE.divide(result, DECIMAL128);
}
return result;
}
public BigDecimal convertInverse(BigDecimal inputValue) {
BigDecimal result = inputValue;
if (this.reciprocal) {
// We should see no offsets for reciprocal conversions - they don't make sense:
assert offset == BigDecimal.ZERO;
if (result == BigDecimal.ZERO) {
// TODO: demonstrate the resulting behaviour in tests... and
// figure out desired behaviour. (Theoretical result should be
// infinity, not 0, but BigDecimal does not support infinity.)
return BigDecimal.ZERO;
}
result = BigDecimal.ONE.divide(result, DECIMAL128);
}
result = result.subtract(offset).divide(this.conversionRate, DECIMAL128);
return result;
}
public enum Convertibility {
CONVERTIBLE,
RECIPROCAL,
UNCONVERTIBLE,
}
public ConversionInfo getConversionInfo() {
ConversionInfo result = new ConversionInfo();
result.conversionRate = this.conversionRate;
result.offset = this.offset;
result.reciprocal = this.reciprocal;
return result;
}
public static class ConversionInfo {
public BigDecimal conversionRate;
public BigDecimal offset;
public boolean reciprocal;
}
/**
* Responsible for all the Factor operation
* NOTE:
* This class is immutable
*/
static class Factor {
private BigDecimal factorNum;
private BigDecimal factorDen;
// The exponents below correspond to ICU4C's Factor::exponents[].
/** Exponent for the ft_to_m constant */
private int exponentFtToM = 0;
/** Exponent for PI */
private int exponentPi = 0;
/** Exponent for gravity (gravity-of-earth, "g") */
private int exponentGravity = 0;
/** Exponent for Newtonian constant of gravitation "G". */
private int exponentG = 0;
/** Exponent for the imperial-gallon to cubic-meter conversion rate constant */
private int exponentGalImpToM3 = 0;
/** Exponent for the pound to kilogram conversion rate constant */
private int exponentLbToKg = 0;
/** Exponent for the glucose molar mass conversion rate constant */
private int exponentGlucoseMolarMass = 0;
/** Exponent for the item per mole conversion rate constant */
private int exponentItemPerMole = 0;
/**
* Creates Empty Factor
*/
public Factor() {
this.factorNum = BigDecimal.valueOf(1);
this.factorDen = BigDecimal.valueOf(1);
}
public static Factor processFactor(String factor) {
assert (!factor.isEmpty());
// Remove all spaces in the factor
factor = factor.replaceAll("\\s+", "");
String[] fractions = factor.split("/");
assert (fractions.length == 1 || fractions.length == 2);
if (fractions.length == 1) {
return processFactorWithoutDivision(fractions[0]);
}
Factor num = processFactorWithoutDivision(fractions[0]);
Factor den = processFactorWithoutDivision(fractions[1]);
return num.divide(den);
}
private static Factor processFactorWithoutDivision(String factorWithoutDivision) {
Factor result = new Factor();
for (String poweredEntity :
factorWithoutDivision.split(Pattern.quote("*"))) {
result.addPoweredEntity(poweredEntity);
}
return result;
}
/**
* Copy this Factor.
*/
protected Factor copy() {
Factor result = new Factor();
result.factorNum = this.factorNum;
result.factorDen = this.factorDen;
result.exponentFtToM = this.exponentFtToM;
result.exponentPi = this.exponentPi;
result.exponentGravity = this.exponentGravity;
result.exponentG = this.exponentG;
result.exponentGalImpToM3 = this.exponentGalImpToM3;
result.exponentLbToKg = this.exponentLbToKg;
result.exponentGlucoseMolarMass = this.exponentGlucoseMolarMass;
result.exponentItemPerMole = this.exponentItemPerMole;
return result;
}
/**
* Returns a single `BigDecimal` that represent the conversion rate after substituting all the constants.
*
* In ICU4C, see Factor::substituteConstants().
*/
public BigDecimal getConversionRate() {
// TODO: this copies all the exponents then doesn't use them at all.
Factor resultCollector = this.copy();
// TODO(icu-units#92): port C++ unit tests to Java.
// These values are a hard-coded subset of unitConstants in the
// units resources file. A unit test should check that all constants
// in the resource file are at least recognised by the code.
// In ICU4C, these constants live in constantsValues[].
resultCollector.multiply(new BigDecimal("0.3048"), this.exponentFtToM);
// TODO: this recalculates this division every time this is called.
resultCollector.multiply(new BigDecimal("411557987.0").divide(new BigDecimal("131002976.0"), DECIMAL128), this.exponentPi);
resultCollector.multiply(new BigDecimal("9.80665"), this.exponentGravity);
resultCollector.multiply(new BigDecimal("6.67408E-11"), this.exponentG);
resultCollector.multiply(new BigDecimal("0.00454609"), this.exponentGalImpToM3);
resultCollector.multiply(new BigDecimal("0.45359237"), this.exponentLbToKg);
resultCollector.multiply(new BigDecimal("180.1557"), this.exponentGlucoseMolarMass);
resultCollector.multiply(new BigDecimal("6.02214076E+23"), this.exponentItemPerMole);
return resultCollector.factorNum.divide(resultCollector.factorDen, DECIMAL128);
}
/** Multiplies the Factor instance by value^power. */
private void multiply(BigDecimal value, int power) {
if (power == 0) return;
BigDecimal absPoweredValue = value.pow(Math.abs(power), DECIMAL128);
if (power > 0) {
this.factorNum = this.factorNum.multiply(absPoweredValue);
} else {
this.factorDen = this.factorDen.multiply(absPoweredValue);
}
}
/** Apply SI or binary prefix to the Factor. */
public Factor applyPrefix(MeasureUnit.MeasurePrefix unitPrefix) {
Factor result = this.copy();
if (unitPrefix == MeasureUnit.MeasurePrefix.ONE) {
return result;
}
int base = unitPrefix.getBase();
int power = unitPrefix.getPower();
BigDecimal absFactor =
BigDecimal.valueOf(base).pow(Math.abs(power), DECIMAL128);
if (power < 0) {
result.factorDen = this.factorDen.multiply(absFactor);
return result;
}
result.factorNum = this.factorNum.multiply(absFactor);
return result;
}
public Factor power(int power) {
Factor result = new Factor();
if (power == 0) return result;
if (power > 0) {
result.factorNum = this.factorNum.pow(power);
result.factorDen = this.factorDen.pow(power);
} else {
result.factorNum = this.factorDen.pow(power * -1);
result.factorDen = this.factorNum.pow(power * -1);
}
result.exponentFtToM = this.exponentFtToM * power;
result.exponentPi = this.exponentPi * power;
result.exponentGravity = this.exponentGravity * power;
result.exponentG = this.exponentG * power;
result.exponentGalImpToM3 = this.exponentGalImpToM3 * power;
result.exponentLbToKg = this.exponentLbToKg * power;
result.exponentGlucoseMolarMass = this.exponentGlucoseMolarMass * power;
result.exponentItemPerMole = this.exponentItemPerMole * power;
return result;
}
public Factor divide(Factor other) {
Factor result = new Factor();
result.factorNum = this.factorNum.multiply(other.factorDen);
result.factorDen = this.factorDen.multiply(other.factorNum);
result.exponentFtToM = this.exponentFtToM - other.exponentFtToM;
result.exponentPi = this.exponentPi - other.exponentPi;
result.exponentGravity = this.exponentGravity - other.exponentGravity;
result.exponentG = this.exponentG - other.exponentG;
result.exponentGalImpToM3 = this.exponentGalImpToM3 - other.exponentGalImpToM3;
result.exponentLbToKg = this.exponentLbToKg - other.exponentLbToKg;
result.exponentGlucoseMolarMass =
this.exponentGlucoseMolarMass - other.exponentGlucoseMolarMass;
result.exponentItemPerMole = this.exponentItemPerMole - other.exponentItemPerMole;
return result;
}
public Factor multiply(Factor other) {
Factor result = new Factor();
result.factorNum = this.factorNum.multiply(other.factorNum);
result.factorDen = this.factorDen.multiply(other.factorDen);
result.exponentFtToM = this.exponentFtToM + other.exponentFtToM;
result.exponentPi = this.exponentPi + other.exponentPi;
result.exponentGravity = this.exponentGravity + other.exponentGravity;
result.exponentG = this.exponentG + other.exponentG;
result.exponentGalImpToM3 = this.exponentGalImpToM3 + other.exponentGalImpToM3;
result.exponentLbToKg = this.exponentLbToKg + other.exponentLbToKg;
result.exponentGlucoseMolarMass =
this.exponentGlucoseMolarMass + other.exponentGlucoseMolarMass;
result.exponentItemPerMole = this.exponentItemPerMole + other.exponentItemPerMole;
return result;
}
/**
* Adds Entity with power or not. For example, `12 ^ 3` or `12`.
*
* @param poweredEntity
*/
private void addPoweredEntity(String poweredEntity) {
String[] entities = poweredEntity.split(Pattern.quote("^"));
assert (entities.length == 1 || entities.length == 2);
int power = entities.length == 2 ? Integer.parseInt(entities[1]) : 1;
this.addEntity(entities[0], power);
}
private void addEntity(String entity, int power) {
if ("ft_to_m".equals(entity)) {
this.exponentFtToM += power;
} else if ("ft2_to_m2".equals(entity)) {
this.exponentFtToM += 2 * power;
} else if ("ft3_to_m3".equals(entity)) {
this.exponentFtToM += 3 * power;
} else if ("in3_to_m3".equals(entity)) {
this.exponentFtToM += 3 * power;
this.factorDen = this.factorDen.multiply(BigDecimal.valueOf(Math.pow(12, 3)));
} else if ("gal_to_m3".equals(entity)) {
this.factorNum = this.factorNum.multiply(BigDecimal.valueOf(231));
this.exponentFtToM += 3 * power;
this.factorDen = this.factorDen.multiply(BigDecimal.valueOf(12 * 12 * 12));
} else if ("gal_imp_to_m3".equals(entity)) {
this.exponentGalImpToM3 += power;
} else if ("G".equals(entity)) {
this.exponentG += power;
} else if ("gravity".equals(entity)) {
this.exponentGravity += power;
} else if ("lb_to_kg".equals(entity)) {
this.exponentLbToKg += power;
} else if ("glucose_molar_mass".equals(entity)) {
this.exponentGlucoseMolarMass += power;
} else if ("item_per_mole".equals(entity)) {
this.exponentItemPerMole += power;
} else if ("PI".equals(entity)) {
this.exponentPi += power;
} else {
BigDecimal decimalEntity = new BigDecimal(entity).pow(power, DECIMAL128);
this.factorNum = this.factorNum.multiply(decimalEntity);
}
}
}
@Override
public String toString() {
return "UnitsConverter [conversionRate=" + conversionRate + ", offset=" + offset + "]";
}
}