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ICU-21349 Fix confusing names of exponent variables.

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See #1464
This commit is contained in:
Hugo van der Merwe 2020-11-17 10:06:57 +00:00
parent 50bd7969c7
commit f7ab1f7c50
3 changed files with 97 additions and 84 deletions
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43
icu4c/source/i18n/units_converter.cpp
View file

@ -26,7 +26,7 @@ void U_I18N_API Factor::multiplyBy(const Factor &rhs) {
factorNum *= rhs.factorNum;
factorDen *= rhs.factorDen;
for (int i = 0; i < CONSTANTS_COUNT; i++) {
constants[i] += rhs.constants[i];
constantExponents[i] += rhs.constantExponents[i];
}
// NOTE
@ -39,7 +39,7 @@ void U_I18N_API Factor::divideBy(const Factor &rhs) {
factorNum *= rhs.factorDen;
factorDen *= rhs.factorNum;
for (int i = 0; i < CONSTANTS_COUNT; i++) {
constants[i] -= rhs.constants[i];
constantExponents[i] -= rhs.constantExponents[i];
}
// NOTE
@ -51,7 +51,7 @@ void U_I18N_API Factor::divideBy(const Factor &rhs) {
void U_I18N_API Factor::power(int32_t power) {
// multiply all the constant by the power.
for (int i = 0; i < CONSTANTS_COUNT; i++) {
constants[i] *= power;
constantExponents[i] *= power;
}
bool shouldFlip = power < 0; // This means that after applying the absolute power, we should flip
@ -66,14 +66,6 @@ void U_I18N_API Factor::power(int32_t power) {
}
}
void U_I18N_API Factor::flip() {
std::swap(factorNum, factorDen);
for (int i = 0; i < CONSTANTS_COUNT; i++) {
constants[i] *= -1;
}
}
void U_I18N_API Factor::applySiPrefix(UMeasureSIPrefix siPrefix) {
if (siPrefix == UMeasureSIPrefix::UMEASURE_SI_PREFIX_ONE) return; // No need to do anything
@ -89,12 +81,12 @@ void U_I18N_API Factor::applySiPrefix(UMeasureSIPrefix siPrefix) {
void U_I18N_API Factor::substituteConstants() {
for (int i = 0; i < CONSTANTS_COUNT; i++) {
if (this->constants[i] == 0) {
if (this->constantExponents[i] == 0) {
continue;
}
auto absPower = std::abs(this->constants[i]);
Signum powerSig = this->constants[i] < 0 ? Signum::NEGATIVE : Signum::POSITIVE;
auto absPower = std::abs(this->constantExponents[i]);
Signum powerSig = this->constantExponents[i] < 0 ? Signum::NEGATIVE : Signum::POSITIVE;
double absConstantValue = std::pow(constantsValues[i], absPower);
if (powerSig == Signum::NEGATIVE) {
@ -103,7 +95,7 @@ void U_I18N_API Factor::substituteConstants() {
this->factorNum *= absConstantValue;
}
this->constants[i] = 0;
this->constantExponents[i] = 0;
}
}
@ -273,6 +265,7 @@ UBool checkSimpleUnit(const MeasureUnitImpl &unit, UErrorCode &status) {
/**
* Extract conversion rate from `source` to `target`
*/
// In ICU4J, this function is partially inlined in the UnitConverter constructor.
void loadConversionRate(ConversionRate &conversionRate, const MeasureUnitImpl &source,
const MeasureUnitImpl &target, Convertibility unitsState,
const ConversionRates &ratesInfo, UErrorCode &status) {
@ -361,28 +354,28 @@ UBool checkAllDimensionsAreZeros(const MaybeStackVector<UnitIndexAndDimension> &
void U_I18N_API addSingleFactorConstant(StringPiece baseStr, int32_t power, Signum signum,
Factor &factor, UErrorCode &status) {
if (baseStr == "ft_to_m") {
factor.constants[CONSTANT_FT2M] += power * signum;
factor.constantExponents[CONSTANT_FT2M] += power * signum;
} else if (baseStr == "ft2_to_m2") {
factor.constants[CONSTANT_FT2M] += 2 * power * signum;
factor.constantExponents[CONSTANT_FT2M] += 2 * power * signum;
} else if (baseStr == "ft3_to_m3") {
factor.constants[CONSTANT_FT2M] += 3 * power * signum;
factor.constantExponents[CONSTANT_FT2M] += 3 * power * signum;
} else if (baseStr == "in3_to_m3") {
factor.constants[CONSTANT_FT2M] += 3 * power * signum;
factor.constantExponents[CONSTANT_FT2M] += 3 * power * signum;
factor.factorDen *= 12 * 12 * 12;
} else if (baseStr == "gal_to_m3") {
factor.factorNum *= 231;
factor.constants[CONSTANT_FT2M] += 3 * power * signum;
factor.constantExponents[CONSTANT_FT2M] += 3 * power * signum;
factor.factorDen *= 12 * 12 * 12;
} else if (baseStr == "gal_imp_to_m3") {
factor.constants[CONSTANT_GAL_IMP2M3] += power * signum;
factor.constantExponents[CONSTANT_GAL_IMP2M3] += power * signum;
} else if (baseStr == "G") {
factor.constants[CONSTANT_G] += power * signum;
factor.constantExponents[CONSTANT_G] += power * signum;
} else if (baseStr == "gravity") {
factor.constants[CONSTANT_GRAVITY] += power * signum;
factor.constantExponents[CONSTANT_GRAVITY] += power * signum;
} else if (baseStr == "lb_to_kg") {
factor.constants[CONSTANT_LB2KG] += power * signum;
factor.constantExponents[CONSTANT_LB2KG] += power * signum;
} else if (baseStr == "PI") {
factor.constants[CONSTANT_PI] += power * signum;
factor.constantExponents[CONSTANT_PI] += power * signum;
} else {
if (signum == Signum::NEGATIVE) {
factor.factorDen *= std::pow(strToDouble(baseStr, status), power);

22
icu4c/source/i18n/units_converter.h
View file

@ -20,11 +20,12 @@ namespace units {
/* Internal Structure */
// Constants corresponding to unitConstants in CLDR's units.xml.
enum Constants {
CONSTANT_FT2M, // ft2m stands for foot to meter.
CONSTANT_PI, // PI
CONSTANT_GRAVITY, // Gravity
CONSTANT_G,
CONSTANT_FT2M, // ft_to_m
CONSTANT_PI, // PI
CONSTANT_GRAVITY, // Gravity of earth (9.80665 m/s^2), "g".
CONSTANT_G, // Newtonian constant of gravitation, "G".
CONSTANT_GAL_IMP2M3, // Gallon imp to m3
CONSTANT_LB2KG, // Pound to Kilogram
@ -36,6 +37,7 @@ enum Constants {
// resources file. A unit test checks that all constants in the resource
// file are at least recognised by the code. Derived constants' values or
// hard-coded derivations are not checked.
// In ICU4J, these constants live in UnitConverter.Factor.getConversionRate().
static const double constantsValues[CONSTANTS_COUNT] = {
0.3048, // CONSTANT_FT2M
411557987.0 / 131002976.0, // CONSTANT_PI
@ -56,7 +58,9 @@ struct U_I18N_API Factor {
double factorDen = 1;
double offset = 0;
bool reciprocal = false;
int32_t constants[CONSTANTS_COUNT] = {};
// Exponents for the symbolic constants
int32_t constantExponents[CONSTANTS_COUNT] = {};
void multiplyBy(const Factor &rhs);
void divideBy(const Factor &rhs);
@ -64,11 +68,13 @@ struct U_I18N_API Factor {
// Apply the power to the factor.
void power(int32_t power);
// Flip the `Factor`, for example, factor= 2/3, flippedFactor = 3/2
void flip();
// Apply SI prefix to the `Factor`
void applySiPrefix(UMeasureSIPrefix siPrefix);
// Does an in-place substition of the "symbolic constants" based on
// constantExponents (resetting the exponents).
//
// In ICU4J, see UnitConverter.Factor.getConversionRate().
void substituteConstants();
};

116
icu4j/main/classes/core/src/com/ibm/icu/impl/units/UnitConverter.java
View file

@ -96,8 +96,6 @@ public class UnitConverter {
UNCONVERTIBLE,
}
// TODO: improve documentation and Constant implementation
/**
* Responsible for all the Factor operation
* NOTE:
@ -106,15 +104,21 @@ public class UnitConverter {
static class Factor {
private BigDecimal factorNum;
private BigDecimal factorDen;
/* FACTOR CONSTANTS */
private int
CONSTANT_FT2M = 0, // ft2m stands for foot to meter.
CONSTANT_PI = 0, // PI
CONSTANT_GRAVITY = 0, // Gravity
CONSTANT_G = 0,
CONSTANT_GAL_IMP2M3 = 0, // Gallon imp to m3
CONSTANT_LB2KG = 0; // Pound to Kilogram
// 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;
/**
* Creates Empty Factor
@ -160,33 +164,43 @@ public class UnitConverter {
result.factorNum = this.factorNum;
result.factorDen = this.factorDen;
result.CONSTANT_FT2M = this.CONSTANT_FT2M;
result.CONSTANT_PI = this.CONSTANT_PI;
result.CONSTANT_GRAVITY = this.CONSTANT_GRAVITY;
result.CONSTANT_G = this.CONSTANT_G;
result.CONSTANT_GAL_IMP2M3 = this.CONSTANT_GAL_IMP2M3;
result.CONSTANT_LB2KG = this.CONSTANT_LB2KG;
result.exponentFtToM = this.exponentFtToM;
result.exponentPi = this.exponentPi;
result.exponentGravity = this.exponentGravity;
result.exponentG = this.exponentG;
result.exponentGalImpToM3 = this.exponentGalImpToM3;
result.exponentLbToKg = this.exponentLbToKg;
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();
resultCollector.substitute(new BigDecimal("0.3048"), this.CONSTANT_FT2M);
resultCollector.substitute(new BigDecimal("411557987.0").divide(new BigDecimal("131002976.0"), DECIMAL128), this.CONSTANT_PI);
resultCollector.substitute(new BigDecimal("9.80665"), this.CONSTANT_GRAVITY);
resultCollector.substitute(new BigDecimal("6.67408E-11"), this.CONSTANT_G);
resultCollector.substitute(new BigDecimal("0.00454609"), this.CONSTANT_GAL_IMP2M3);
resultCollector.substitute(new BigDecimal("0.45359237"), this.CONSTANT_LB2KG);
// 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);
return resultCollector.factorNum.divide(resultCollector.factorDen, DECIMAL128);
}
private void substitute(BigDecimal value, int power) {
/** 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);
@ -225,12 +239,12 @@ public class UnitConverter {
result.factorDen = this.factorNum.pow(power * -1);
}
result.CONSTANT_FT2M = this.CONSTANT_FT2M * power;
result.CONSTANT_PI = this.CONSTANT_PI * power;
result.CONSTANT_GRAVITY = this.CONSTANT_GRAVITY * power;
result.CONSTANT_G = this.CONSTANT_G * power;
result.CONSTANT_GAL_IMP2M3 = this.CONSTANT_GAL_IMP2M3 * power;
result.CONSTANT_LB2KG = this.CONSTANT_LB2KG * power;
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;
return result;
}
@ -240,12 +254,12 @@ public class UnitConverter {
result.factorNum = this.factorNum.multiply(other.factorDen);
result.factorDen = this.factorDen.multiply(other.factorNum);
result.CONSTANT_FT2M = this.CONSTANT_FT2M - other.CONSTANT_FT2M;
result.CONSTANT_PI = this.CONSTANT_PI - other.CONSTANT_PI;
result.CONSTANT_GRAVITY = this.CONSTANT_GRAVITY - other.CONSTANT_GRAVITY;
result.CONSTANT_G = this.CONSTANT_G - other.CONSTANT_G;
result.CONSTANT_GAL_IMP2M3 = this.CONSTANT_GAL_IMP2M3 - other.CONSTANT_GAL_IMP2M3;
result.CONSTANT_LB2KG = this.CONSTANT_LB2KG - other.CONSTANT_LB2KG;
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;
return result;
}
@ -255,12 +269,12 @@ public class UnitConverter {
result.factorNum = this.factorNum.multiply(other.factorNum);
result.factorDen = this.factorDen.multiply(other.factorDen);
result.CONSTANT_FT2M = this.CONSTANT_FT2M + other.CONSTANT_FT2M;
result.CONSTANT_PI = this.CONSTANT_PI + other.CONSTANT_PI;
result.CONSTANT_GRAVITY = this.CONSTANT_GRAVITY + other.CONSTANT_GRAVITY;
result.CONSTANT_G = this.CONSTANT_G + other.CONSTANT_G;
result.CONSTANT_GAL_IMP2M3 = this.CONSTANT_GAL_IMP2M3 + other.CONSTANT_GAL_IMP2M3;
result.CONSTANT_LB2KG = this.CONSTANT_LB2KG + other.CONSTANT_LB2KG;
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;
return result;
}
@ -280,28 +294,28 @@ public class UnitConverter {
private void addEntity(String entity, int power) {
if ("ft_to_m".equals(entity)) {
this.CONSTANT_FT2M += power;
this.exponentFtToM += power;
} else if ("ft2_to_m2".equals(entity)) {
this.CONSTANT_FT2M += 2 * power;
this.exponentFtToM += 2 * power;
} else if ("ft3_to_m3".equals(entity)) {
this.CONSTANT_FT2M += 3 * power;
this.exponentFtToM += 3 * power;
} else if ("in3_to_m3".equals(entity)) {
this.CONSTANT_FT2M += 3 * power;
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.CONSTANT_FT2M += 3 * power;
this.exponentFtToM += 3 * power;
this.factorDen = this.factorDen.multiply(BigDecimal.valueOf(12 * 12 * 12));
} else if ("gal_imp_to_m3".equals(entity)) {
this.CONSTANT_GAL_IMP2M3 += power;
this.exponentGalImpToM3 += power;
} else if ("G".equals(entity)) {
this.CONSTANT_G += power;
this.exponentG += power;
} else if ("gravity".equals(entity)) {
this.CONSTANT_GRAVITY += power;
this.exponentGravity += power;
} else if ("lb_to_kg".equals(entity)) {
this.CONSTANT_LB2KG += power;
this.exponentLbToKg += power;
} else if ("PI".equals(entity)) {
this.CONSTANT_PI += power;
this.exponentPi += power;
} else {
BigDecimal decimalEntity = new BigDecimal(entity).pow(power, DECIMAL128);
this.factorNum = this.factorNum.multiply(decimalEntity);