/src/mozilla-central/intl/icu/source/i18n/number_roundingutils.h

Source (jump to first uncovered line)
// © 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
#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;
    }
}

/**
 * Computes the number of fraction digits in a double. Used for computing maxFrac for an increment.
 * Calls into the DoubleToStringConverter library to do so.
 */
digits_t doubleFractionLength(double input);

} // namespace roundingutils


/**
 * Encapsulates a Precision and a RoundingMode and performs rounding on a DecimalQuantity.
 *
 * This class does not exist in Java: instead, the base Precision class is used.
 */
class RoundingImpl {
  public:
    RoundingImpl() = default;  // default constructor: leaves object in undefined state

    RoundingImpl(const Precision& precision, UNumberFormatRoundingMode roundingMode,
                 const CurrencyUnit& currency, UErrorCode& status);

    static RoundingImpl passThrough();

    /** Required for ScientificFormatter */
    bool isSignificantDigits() const;

    /**
     * Rounding endpoint used by Engineering and Compact notation. Chooses the most appropriate multiplier (magnitude
     * adjustment), applies the adjustment, rounds, and returns the chosen multiplier.
     *
     * <p>
     * In most cases, this is simple. However, when rounding the number causes it to cross a multiplier boundary, we
     * need to re-do the rounding. For example, to display 999,999 in Engineering notation with 2 sigfigs, first you
     * guess the multiplier to be -3. However, then you end up getting 1000E3, which is not the correct output. You then
     * change your multiplier to be -6, and you get 1.0E6, which is correct.
     *
     * @param input The quantity to process.
     * @param producer Function to call to return a multiplier based on a magnitude.
     * @return The number of orders of magnitude the input was adjusted by this method.
     */
    int32_t
    chooseMultiplierAndApply(impl::DecimalQuantity &input, const impl::MultiplierProducer &producer,
                             UErrorCode &status);

    void apply(impl::DecimalQuantity &value, UErrorCode &status) const;

    /** Version of {@link #apply} that obeys minInt constraints. Used for scientific notation compatibility mode. */
    void apply(impl::DecimalQuantity &value, int32_t minInt, UErrorCode status);

  private:
    Precision fPrecision;
    UNumberFormatRoundingMode fRoundingMode;
    bool fPassThrough;
};


} // namespace impl
} // namespace number
U_NAMESPACE_END

#endif //__NUMBER_ROUNDINGUTILS_H__

#endif /* #if !UCONFIG_NO_FORMATTING */

Line	Count	Source (jump to first uncovered line)
1		// © 2017 and later: Unicode, Inc. and others.
2		// License & terms of use: http://www.unicode.org/copyright.html
3
4		#include "unicode/utypes.h"
5
6		#if !UCONFIG_NO_FORMATTING
7		#ifndef __NUMBER_ROUNDINGUTILS_H__
8		#define __NUMBER_ROUNDINGUTILS_H__
9
10		#include "number_types.h"
11
12		U_NAMESPACE_BEGIN
13		namespace number {
14		namespace impl {
15		namespace roundingutils {
16
17		enum Section {
18		SECTION_LOWER_EDGE = -1,
19		SECTION_UPPER_EDGE = -2,
20		SECTION_LOWER = 1,
21		SECTION_MIDPOINT = 2,
22		SECTION_UPPER = 3
23		};
24
25		/**
26		* Converts a rounding mode and metadata about the quantity being rounded to a boolean determining
27		* whether the value should be rounded toward infinity or toward zero.
28		*
29		* <p>The parameters are of type int because benchmarks on an x86-64 processor against OpenJDK
30		* showed that ints were demonstrably faster than enums in switch statements.
31		*
32		* @param isEven Whether the digit immediately before the rounding magnitude is even.
33		* @param isNegative Whether the quantity is negative.
34		* @param section Whether the part of the quantity to the right of the rounding magnitude is
35		* exactly halfway between two digits, whether it is in the lower part (closer to zero), or
36		* whether it is in the upper part (closer to infinity). See {@link #SECTION_LOWER}, {@link
37		* #SECTION_MIDPOINT}, and {@link #SECTION_UPPER}.
38		* @param roundingMode The integer version of the {@link RoundingMode}, which you can get via
39		* {@link RoundingMode#ordinal}.
40		* @param status Error code, set to U_FORMAT_INEXACT_ERROR if the rounding mode is kRoundUnnecessary.
41		* @return true if the number should be rounded toward zero; false if it should be rounded toward
42		* infinity.
43		*/
44		inline bool
45		getRoundingDirection(bool isEven, bool isNegative, Section section, RoundingMode roundingMode,
46	0	UErrorCode &status) {
47	0	switch (roundingMode) {
48	0	case RoundingMode::UNUM_ROUND_UP:
49	0	// round away from zero
50	0	return false;
51	0
52	0	case RoundingMode::UNUM_ROUND_DOWN:
53	0	// round toward zero
54	0	return true;
55	0
56	0	case RoundingMode::UNUM_ROUND_CEILING:
57	0	// round toward positive infinity
58	0	return isNegative;
59	0
60	0	case RoundingMode::UNUM_ROUND_FLOOR:
61	0	// round toward negative infinity
62	0	return !isNegative;
63	0
64	0	case RoundingMode::UNUM_ROUND_HALFUP:
65	0	switch (section) {
66	0	case SECTION_MIDPOINT:
67	0	return false;
68	0	case SECTION_LOWER:
69	0	return true;
70	0	case SECTION_UPPER:
71	0	return false;
72	0	default:
73	0	break;
74	0	}
75	0	break;
76	0
77	0	case RoundingMode::UNUM_ROUND_HALFDOWN:
78	0	switch (section) {
79	0	case SECTION_MIDPOINT:
80	0	return true;
81	0	case SECTION_LOWER:
82	0	return true;
83	0	case SECTION_UPPER:
84	0	return false;
85	0	default:
86	0	break;
87	0	}
88	0	break;
89	0
90	0	case RoundingMode::UNUM_ROUND_HALFEVEN:
91	0	switch (section) {
92	0	case SECTION_MIDPOINT:
93	0	return isEven;
94	0	case SECTION_LOWER:
95	0	return true;
96	0	case SECTION_UPPER:
97	0	return false;
98	0	default:
99	0	break;
100	0	}
101	0	break;
102	0
103	0	default:
104	0	break;
105	0	}
106	0
107	0	status = U_FORMAT_INEXACT_ERROR;
108	0	return false;
109	0	}
110
111		/**
112		* Gets whether the given rounding mode's rounding boundary is at the midpoint. The rounding
113		* boundary is the point at which a number switches from being rounded down to being rounded up.
114		* For example, with rounding mode HALF_EVEN, HALF_UP, or HALF_DOWN, the rounding boundary is at
115		* the midpoint, and this function would return true. However, for UP, DOWN, CEILING, and FLOOR,
116		* the rounding boundary is at the "edge", and this function would return false.
117		*
118		* @param roundingMode The integer version of the {@link RoundingMode}.
119		* @return true if rounding mode is HALF_EVEN, HALF_UP, or HALF_DOWN; false otherwise.
120		*/
121		inline bool roundsAtMidpoint(int roundingMode) {
122		switch (roundingMode) {
123		case RoundingMode::UNUM_ROUND_UP:
124		case RoundingMode::UNUM_ROUND_DOWN:
125		case RoundingMode::UNUM_ROUND_CEILING:
126		case RoundingMode::UNUM_ROUND_FLOOR:
127		return false;
128
129		default:
130		return true;
131		}
132		}
133
134		/**
135		* Computes the number of fraction digits in a double. Used for computing maxFrac for an increment.
136		* Calls into the DoubleToStringConverter library to do so.
137		*/
138		digits_t doubleFractionLength(double input);
139
140		} // namespace roundingutils
141
142
143		/**
144		* Encapsulates a Precision and a RoundingMode and performs rounding on a DecimalQuantity.
145		*
146		* This class does not exist in Java: instead, the base Precision class is used.
147		*/
148		class RoundingImpl {
149		public:
150	0	RoundingImpl() = default; // default constructor: leaves object in undefined state
151
152		RoundingImpl(const Precision& precision, UNumberFormatRoundingMode roundingMode,
153		const CurrencyUnit& currency, UErrorCode& status);
154
155		static RoundingImpl passThrough();
156
157		/** Required for ScientificFormatter */
158		bool isSignificantDigits() const;
159
160		/**
161		* Rounding endpoint used by Engineering and Compact notation. Chooses the most appropriate multiplier (magnitude
162		* adjustment), applies the adjustment, rounds, and returns the chosen multiplier.
163		*
164		* <p>
165		* In most cases, this is simple. However, when rounding the number causes it to cross a multiplier boundary, we
166		* need to re-do the rounding. For example, to display 999,999 in Engineering notation with 2 sigfigs, first you
167		* guess the multiplier to be -3. However, then you end up getting 1000E3, which is not the correct output. You then
168		* change your multiplier to be -6, and you get 1.0E6, which is correct.
169		*
170		* @param input The quantity to process.
171		* @param producer Function to call to return a multiplier based on a magnitude.
172		* @return The number of orders of magnitude the input was adjusted by this method.
173		*/
174		int32_t
175		chooseMultiplierAndApply(impl::DecimalQuantity &input, const impl::MultiplierProducer &producer,
176		UErrorCode &status);
177
178		void apply(impl::DecimalQuantity &value, UErrorCode &status) const;
179
180		/** Version of {@link #apply} that obeys minInt constraints. Used for scientific notation compatibility mode. */
181		void apply(impl::DecimalQuantity &value, int32_t minInt, UErrorCode status);
182
183		private:
184		Precision fPrecision;
185		UNumberFormatRoundingMode fRoundingMode;
186		bool fPassThrough;
187		};
188
189
190		} // namespace impl
191		} // namespace number
192		U_NAMESPACE_END
193
194		#endif //__NUMBER_ROUNDINGUTILS_H__
195
196		#endif /* #if !UCONFIG_NO_FORMATTING */

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Created: 2018-09-25 14:53