Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 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" |
Victor Chang | ce4bf3c | 2021-01-19 16:34:24 +0000 | [diff] [blame] | 11 | #include "string_segment.h" |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 12 | |
| 13 | U_NAMESPACE_BEGIN |
| 14 | namespace number { |
| 15 | namespace impl { |
| 16 | namespace roundingutils { |
| 17 | |
| 18 | enum Section { |
| 19 | SECTION_LOWER_EDGE = -1, |
| 20 | SECTION_UPPER_EDGE = -2, |
| 21 | SECTION_LOWER = 1, |
| 22 | SECTION_MIDPOINT = 2, |
| 23 | SECTION_UPPER = 3 |
| 24 | }; |
| 25 | |
| 26 | /** |
| 27 | * Converts a rounding mode and metadata about the quantity being rounded to a boolean determining |
| 28 | * whether the value should be rounded toward infinity or toward zero. |
| 29 | * |
| 30 | * <p>The parameters are of type int because benchmarks on an x86-64 processor against OpenJDK |
| 31 | * showed that ints were demonstrably faster than enums in switch statements. |
| 32 | * |
| 33 | * @param isEven Whether the digit immediately before the rounding magnitude is even. |
| 34 | * @param isNegative Whether the quantity is negative. |
| 35 | * @param section Whether the part of the quantity to the right of the rounding magnitude is |
| 36 | * exactly halfway between two digits, whether it is in the lower part (closer to zero), or |
| 37 | * whether it is in the upper part (closer to infinity). See {@link #SECTION_LOWER}, {@link |
| 38 | * #SECTION_MIDPOINT}, and {@link #SECTION_UPPER}. |
| 39 | * @param roundingMode The integer version of the {@link RoundingMode}, which you can get via |
| 40 | * {@link RoundingMode#ordinal}. |
| 41 | * @param status Error code, set to U_FORMAT_INEXACT_ERROR if the rounding mode is kRoundUnnecessary. |
| 42 | * @return true if the number should be rounded toward zero; false if it should be rounded toward |
| 43 | * infinity. |
| 44 | */ |
| 45 | inline bool |
| 46 | getRoundingDirection(bool isEven, bool isNegative, Section section, RoundingMode roundingMode, |
| 47 | UErrorCode &status) { |
Victor Chang | ce4bf3c | 2021-01-19 16:34:24 +0000 | [diff] [blame] | 48 | if (U_FAILURE(status)) { |
| 49 | return false; |
| 50 | } |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 51 | switch (roundingMode) { |
| 52 | case RoundingMode::UNUM_ROUND_UP: |
| 53 | // round away from zero |
| 54 | return false; |
| 55 | |
| 56 | case RoundingMode::UNUM_ROUND_DOWN: |
| 57 | // round toward zero |
| 58 | return true; |
| 59 | |
| 60 | case RoundingMode::UNUM_ROUND_CEILING: |
| 61 | // round toward positive infinity |
| 62 | return isNegative; |
| 63 | |
| 64 | case RoundingMode::UNUM_ROUND_FLOOR: |
| 65 | // round toward negative infinity |
| 66 | return !isNegative; |
| 67 | |
| 68 | case RoundingMode::UNUM_ROUND_HALFUP: |
| 69 | switch (section) { |
| 70 | case SECTION_MIDPOINT: |
| 71 | return false; |
| 72 | case SECTION_LOWER: |
| 73 | return true; |
| 74 | case SECTION_UPPER: |
| 75 | return false; |
| 76 | default: |
| 77 | break; |
| 78 | } |
| 79 | break; |
| 80 | |
| 81 | case RoundingMode::UNUM_ROUND_HALFDOWN: |
| 82 | switch (section) { |
| 83 | case SECTION_MIDPOINT: |
| 84 | return true; |
| 85 | case SECTION_LOWER: |
| 86 | return true; |
| 87 | case SECTION_UPPER: |
| 88 | return false; |
| 89 | default: |
| 90 | break; |
| 91 | } |
| 92 | break; |
| 93 | |
| 94 | case RoundingMode::UNUM_ROUND_HALFEVEN: |
| 95 | switch (section) { |
| 96 | case SECTION_MIDPOINT: |
| 97 | return isEven; |
| 98 | case SECTION_LOWER: |
| 99 | return true; |
| 100 | case SECTION_UPPER: |
| 101 | return false; |
| 102 | default: |
| 103 | break; |
| 104 | } |
| 105 | break; |
| 106 | |
| 107 | default: |
| 108 | break; |
| 109 | } |
| 110 | |
| 111 | status = U_FORMAT_INEXACT_ERROR; |
| 112 | return false; |
| 113 | } |
| 114 | |
| 115 | /** |
| 116 | * Gets whether the given rounding mode's rounding boundary is at the midpoint. The rounding |
| 117 | * boundary is the point at which a number switches from being rounded down to being rounded up. |
| 118 | * For example, with rounding mode HALF_EVEN, HALF_UP, or HALF_DOWN, the rounding boundary is at |
| 119 | * the midpoint, and this function would return true. However, for UP, DOWN, CEILING, and FLOOR, |
| 120 | * the rounding boundary is at the "edge", and this function would return false. |
| 121 | * |
| 122 | * @param roundingMode The integer version of the {@link RoundingMode}. |
| 123 | * @return true if rounding mode is HALF_EVEN, HALF_UP, or HALF_DOWN; false otherwise. |
| 124 | */ |
| 125 | inline bool roundsAtMidpoint(int roundingMode) { |
| 126 | switch (roundingMode) { |
| 127 | case RoundingMode::UNUM_ROUND_UP: |
| 128 | case RoundingMode::UNUM_ROUND_DOWN: |
| 129 | case RoundingMode::UNUM_ROUND_CEILING: |
| 130 | case RoundingMode::UNUM_ROUND_FLOOR: |
| 131 | return false; |
| 132 | |
| 133 | default: |
| 134 | return true; |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * Computes the number of fraction digits in a double. Used for computing maxFrac for an increment. |
| 140 | * Calls into the DoubleToStringConverter library to do so. |
| 141 | * |
| 142 | * @param singleDigit An output parameter; set to a number if that is the |
| 143 | * only digit in the double, or -1 if there is more than one digit. |
| 144 | */ |
| 145 | digits_t doubleFractionLength(double input, int8_t* singleDigit); |
| 146 | |
| 147 | } // namespace roundingutils |
| 148 | |
| 149 | |
| 150 | /** |
| 151 | * Encapsulates a Precision and a RoundingMode and performs rounding on a DecimalQuantity. |
| 152 | * |
| 153 | * This class does not exist in Java: instead, the base Precision class is used. |
| 154 | */ |
| 155 | class RoundingImpl { |
| 156 | public: |
Victor Chang | d8aa9d5 | 2021-01-05 23:49:57 +0000 | [diff] [blame] | 157 | RoundingImpl() = default; // defaults to pass-through rounder |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 158 | |
| 159 | RoundingImpl(const Precision& precision, UNumberFormatRoundingMode roundingMode, |
| 160 | const CurrencyUnit& currency, UErrorCode& status); |
| 161 | |
| 162 | static RoundingImpl passThrough(); |
| 163 | |
| 164 | /** Required for ScientificFormatter */ |
| 165 | bool isSignificantDigits() const; |
| 166 | |
| 167 | /** |
| 168 | * Rounding endpoint used by Engineering and Compact notation. Chooses the most appropriate multiplier (magnitude |
| 169 | * adjustment), applies the adjustment, rounds, and returns the chosen multiplier. |
| 170 | * |
| 171 | * <p> |
| 172 | * In most cases, this is simple. However, when rounding the number causes it to cross a multiplier boundary, we |
| 173 | * need to re-do the rounding. For example, to display 999,999 in Engineering notation with 2 sigfigs, first you |
| 174 | * guess the multiplier to be -3. However, then you end up getting 1000E3, which is not the correct output. You then |
| 175 | * change your multiplier to be -6, and you get 1.0E6, which is correct. |
| 176 | * |
| 177 | * @param input The quantity to process. |
| 178 | * @param producer Function to call to return a multiplier based on a magnitude. |
| 179 | * @return The number of orders of magnitude the input was adjusted by this method. |
| 180 | */ |
| 181 | int32_t |
| 182 | chooseMultiplierAndApply(impl::DecimalQuantity &input, const impl::MultiplierProducer &producer, |
| 183 | UErrorCode &status); |
| 184 | |
| 185 | void apply(impl::DecimalQuantity &value, UErrorCode &status) const; |
| 186 | |
| 187 | /** Version of {@link #apply} that obeys minInt constraints. Used for scientific notation compatibility mode. */ |
| 188 | void apply(impl::DecimalQuantity &value, int32_t minInt, UErrorCode status); |
| 189 | |
| 190 | private: |
| 191 | Precision fPrecision; |
| 192 | UNumberFormatRoundingMode fRoundingMode; |
Victor Chang | d8aa9d5 | 2021-01-05 23:49:57 +0000 | [diff] [blame] | 193 | bool fPassThrough = true; // default value |
Victor Chang | ce4bf3c | 2021-01-19 16:34:24 +0000 | [diff] [blame] | 194 | |
| 195 | // Permits access to fPrecision. |
| 196 | friend class units::UnitsRouter; |
| 197 | |
| 198 | // Permits access to fPrecision. |
| 199 | friend class UnitConversionHandler; |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 200 | }; |
| 201 | |
Victor Chang | ce4bf3c | 2021-01-19 16:34:24 +0000 | [diff] [blame] | 202 | /** |
| 203 | * Parses Precision-related skeleton strings without knowledge of MacroProps |
| 204 | * - see blueprint_helpers::parseIncrementOption(). |
| 205 | * |
| 206 | * Referencing MacroProps means needing to pull in the .o files that have the |
| 207 | * destructors for the SymbolsWrapper, Usage, and Scale classes. |
| 208 | */ |
| 209 | void parseIncrementOption(const StringSegment &segment, Precision &outPrecision, UErrorCode &status); |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 210 | |
| 211 | } // namespace impl |
| 212 | } // namespace number |
| 213 | U_NAMESPACE_END |
| 214 | |
| 215 | #endif //__NUMBER_ROUNDINGUTILS_H__ |
| 216 | |
| 217 | #endif /* #if !UCONFIG_NO_FORMATTING */ |