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node/deps/icu-small/source/i18n/units_converter.h

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// © 2020 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
#include "unicode/utypes.h"
#if !UCONFIG_NO_FORMATTING
#ifndef __UNITS_CONVERTER_H__
#define __UNITS_CONVERTER_H__
#include "cmemory.h"
#include "measunit_impl.h"
#include "unicode/errorcode.h"
#include "unicode/stringpiece.h"
#include "unicode/uobject.h"
#include "units_converter.h"
#include "units_data.h"
U_NAMESPACE_BEGIN
namespace units {
/* Internal Structure */
// Constants corresponding to unitConstants in CLDR's units.xml.
enum Constants {
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
CONSTANT_GLUCOSE_MOLAR_MASS,
CONSTANT_ITEM_PER_MOLE,
CONSTANT_METERS_PER_AU,
CONSTANT_SEC_PER_JULIAN_YEAR,
CONSTANT_SPEED_OF_LIGHT_METERS_PER_SECOND,
CONSTANT_SHO_TO_M3, // https://en.wikipedia.org/wiki/Japanese_units_of_measurement
CONSTANT_TSUBO_TO_M2, // https://en.wikipedia.org/wiki/Japanese_units_of_measurement
CONSTANT_SHAKU_TO_M, // https://en.wikipedia.org/wiki/Japanese_units_of_measurement
CONSTANT_AMU, // Atomic Mass Unit https://www.nist.gov/pml/special-publication-811/nist-guide-si-chapter-5-units-outside-si#table7
// Must be the last element.
CONSTANTS_COUNT
};
// These values are a hard-coded subset of unitConstants in the units
// 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
9.80665, // CONSTANT_GRAVITY
6.67408E-11, // CONSTANT_G
0.00454609, // CONSTANT_GAL_IMP2M3
0.45359237, // CONSTANT_LB2KG
180.1557, // CONSTANT_GLUCOSE_MOLAR_MASS
6.02214076E+23, // CONSTANT_ITEM_PER_MOLE
149597870700, // CONSTANT_METERS_PER_AU
31557600, // CONSTANT_SEC_PER_JULIAN_YEAR
299792458, // CONSTANT_SPEED_OF_LIGHT_METERS_PER_SECOND
2401.0 / (1331.0 * 1000.0),
400.0 / 121.0,
4.0 / 121.0,
1.66053878283E-27, // CONSTANT_AMU
};
typedef enum Signum {
NEGATIVE = -1,
POSITIVE = 1,
} Signum;
/* Represents a conversion factor */
struct U_I18N_API Factor {
double factorNum = 1;
double factorDen = 1;
double offset = 0;
bool reciprocal = false;
// Exponents for the symbolic constants
int32_t constantExponents[CONSTANTS_COUNT] = {};
void multiplyBy(const Factor &rhs);
void divideBy(const Factor &rhs);
// Apply the power to the factor.
void power(int32_t power);
// Apply SI or binary prefix to the Factor.
void applyPrefix(UMeasurePrefix unitPrefix);
// Does an in-place substitution of the "symbolic constants" based on
// constantExponents (resetting the exponents).
//
// In ICU4J, see UnitConverter.Factor.getConversionRate().
void substituteConstants();
};
struct U_I18N_API ConversionInfo {
double conversionRate;
double offset;
bool reciprocal;
};
/*
* Adds a single factor element to the `Factor`. e.g "ft3m", "2.333" or "cup2m3". But not "cup2m3^3".
*/
void U_I18N_API addSingleFactorConstant(StringPiece baseStr, int32_t power, Signum sigNum,
Factor &factor, UErrorCode &status);
/**
* Represents the conversion rate between `source` and `target`.
* TODO ICU-22683: COnsider moving the handling of special mappings (e.g. beaufort) to a separate
* struct.
*/
struct U_I18N_API ConversionRate : public UMemory {
const MeasureUnitImpl source;
const MeasureUnitImpl target;
CharString specialSource;
CharString specialTarget;
double factorNum = 1;
double factorDen = 1;
double sourceOffset = 0;
double targetOffset = 0;
bool reciprocal = false;
ConversionRate(MeasureUnitImpl &&source, MeasureUnitImpl &&target)
: source(std::move(source)), target(std::move(target)), specialSource(), specialTarget() {}
};
enum Convertibility {
RECIPROCAL,
CONVERTIBLE,
UNCONVERTIBLE,
};
MeasureUnitImpl U_I18N_API extractCompoundBaseUnit(const MeasureUnitImpl &source,
const ConversionRates &conversionRates,
UErrorCode &status);
/**
* Check if the convertibility between `source` and `target`.
* For example:
* `meter` and `foot` are `CONVERTIBLE`.
* `meter-per-second` and `second-per-meter` are `RECIPROCAL`.
* `meter` and `pound` are `UNCONVERTIBLE`.
*
* NOTE:
* Only works with SINGLE and COMPOUND units. If one of the units is a
* MIXED unit, an error will occur. For more information, see UMeasureUnitComplexity.
*/
Convertibility U_I18N_API extractConvertibility(const MeasureUnitImpl &source,
const MeasureUnitImpl &target,
const ConversionRates &conversionRates,
UErrorCode &status);
/**
* Converts from a source `MeasureUnit` to a target `MeasureUnit`.
*
* NOTE:
* Only works with SINGLE and COMPOUND units. If one of the units is a
* MIXED unit, an error will occur. For more information, see UMeasureUnitComplexity.
*/
class U_I18N_API UnitsConverter : public UMemory {
public:
/**
* Constructor of `UnitConverter`.
* 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 `ConversionRates` internally.
*
* @param sourceIdentifier represents the source unit identifier.
* @param targetIdentifier represents the target unit identifier.
* @param status
*/
UnitsConverter(StringPiece sourceIdentifier, StringPiece targetIdentifier, UErrorCode &status);
/**
* Constructor of `UnitConverter`.
* 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 ratesInfo Contains all the needed conversion rates.
* @param status
*/
UnitsConverter(const MeasureUnitImpl &source, const MeasureUnitImpl &target,
const ConversionRates &ratesInfo, UErrorCode &status);
/**
* Compares two single units and returns 1 if the first one is greater, -1 if the second
* one is greater and 0 if they are equal.
*
* NOTE:
* Compares only single units that are convertible.
*/
static int32_t compareTwoUnits(const MeasureUnitImpl &firstUnit, const MeasureUnitImpl &SecondUnit,
const ConversionRates &ratesInfo, UErrorCode &status);
/**
* Convert a measurement expressed in the source unit to a measurement
* expressed in the target unit.
*
* @param inputValue the value to be converted.
* @return the converted value.
*/
double convert(double inputValue) const;
/**
* The inverse of convert(): convert a measurement expressed in the target
* unit to a measurement expressed in the source unit.
*
* @param inputValue the value to be converted.
* @return the converted value.
*/
double convertInverse(double inputValue) const;
ConversionInfo getConversionInfo() const;
private:
ConversionRate conversionRate_;
/**
* Initialises the object.
*/
void init(const ConversionRates &ratesInfo, UErrorCode &status);
/**
* Convert from what should be discrete scale values for a particular unit like beaufort
* to a corresponding value in the base unit (which can have any decimal value, like meters/sec).
* This can handle different scales, specified by minBaseForScaleValues[].
*/
double scaleToBase(double scaleValue, double minBaseForScaleValues[], int scaleMax) const;
/**
* Convert from a value in the base unit (which can have any decimal value, like meters/sec) to a corresponding
* discrete value in a scale (like beaufort), where each scale value represents a range of base values.
* This can handle different scales, specified by minBaseForScaleValues[].
*/
double baseToScale(double baseValue, double minBaseForScaleValues[], int scaleMax) const;
};
} // namespace units
U_NAMESPACE_END
#endif //__UNITS_CONVERTER_H__
#endif /* #if !UCONFIG_NO_FORMATTING */
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