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// © 2017 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
#include "unicode/utypes.h"
#if !UCONFIG_NO_FORMATTING && !UPRV_INCOMPLETE_CPP11_SUPPORT
#ifndef __NUMBER_ROUNDINGUTILS_H__
#define __NUMBER_ROUNDINGUTILS_H__
#include "number_types.h"
U_NAMESPACE_BEGIN
namespace number {
namespace impl {
namespace roundingutils {
enum Section {
SECTION_LOWER_EDGE = -1,
SECTION_UPPER_EDGE = -2,
SECTION_LOWER = 1,
SECTION_MIDPOINT = 2,
SECTION_UPPER = 3
};
/**
* Converts a rounding mode and metadata about the quantity being rounded to a boolean determining
* whether the value should be rounded toward infinity or toward zero.
*
* <p>The parameters are of type int because benchmarks on an x86-64 processor against OpenJDK
* showed that ints were demonstrably faster than enums in switch statements.
*
* @param isEven Whether the digit immediately before the rounding magnitude is even.
* @param isNegative Whether the quantity is negative.
* @param section Whether the part of the quantity to the right of the rounding magnitude is
* exactly halfway between two digits, whether it is in the lower part (closer to zero), or
* whether it is in the upper part (closer to infinity). See {@link #SECTION_LOWER}, {@link
* #SECTION_MIDPOINT}, and {@link #SECTION_UPPER}.
* @param roundingMode The integer version of the {@link RoundingMode}, which you can get via
* {@link RoundingMode#ordinal}.
* @param status Error code, set to U_FORMAT_INEXACT_ERROR if the rounding mode is kRoundUnnecessary.
* @return true if the number should be rounded toward zero; false if it should be rounded toward
* infinity.
*/
inline bool
getRoundingDirection(bool isEven, bool isNegative, Section section, RoundingMode roundingMode,
UErrorCode &status) {
switch (roundingMode) {
case RoundingMode::UNUM_ROUND_UP:
// round away from zero
return false;
case RoundingMode::UNUM_ROUND_DOWN:
// round toward zero
return true;
case RoundingMode::UNUM_ROUND_CEILING:
// round toward positive infinity
return isNegative;
case RoundingMode::UNUM_ROUND_FLOOR:
// round toward negative infinity
return !isNegative;
case RoundingMode::UNUM_ROUND_HALFUP:
switch (section) {
case SECTION_MIDPOINT:
return false;
case SECTION_LOWER:
return true;
case SECTION_UPPER:
return false;
default:
break;
}
break;
case RoundingMode::UNUM_ROUND_HALFDOWN:
switch (section) {
case SECTION_MIDPOINT:
return true;
case SECTION_LOWER:
return true;
case SECTION_UPPER:
return false;
default:
break;
}
break;
case RoundingMode::UNUM_ROUND_HALFEVEN:
switch (section) {
case SECTION_MIDPOINT:
return isEven;
case SECTION_LOWER:
return true;
case SECTION_UPPER:
return false;
default:
break;
}
break;
default:
break;
}
status = U_FORMAT_INEXACT_ERROR;
return false;
}
/**
* Gets whether the given rounding mode's rounding boundary is at the midpoint. The rounding
* boundary is the point at which a number switches from being rounded down to being rounded up.
* For example, with rounding mode HALF_EVEN, HALF_UP, or HALF_DOWN, the rounding boundary is at
* the midpoint, and this function would return true. However, for UP, DOWN, CEILING, and FLOOR,
* the rounding boundary is at the "edge", and this function would return false.
*
* @param roundingMode The integer version of the {@link RoundingMode}.
* @return true if rounding mode is HALF_EVEN, HALF_UP, or HALF_DOWN; false otherwise.
*/
inline bool roundsAtMidpoint(int roundingMode) {
switch (roundingMode) {
case RoundingMode::UNUM_ROUND_UP:
case RoundingMode::UNUM_ROUND_DOWN:
case RoundingMode::UNUM_ROUND_CEILING:
case RoundingMode::UNUM_ROUND_FLOOR:
return false;
default:
return true;
}
}
} // namespace roundingutils
} // namespace impl
} // namespace number
U_NAMESPACE_END
#endif //__NUMBER_ROUNDINGUTILS_H__
#endif /* #if !UCONFIG_NO_FORMATTING */
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