1 files changed, 441 insertions, 0 deletions
diff --git a/intl/icu/source/i18n/number_rounding.cpp b/intl/icu/source/i18n/number_rounding.cpp
new file mode 100644
index 0000000000..3ffce673ad
--- /dev/null
+++ b/intl/icu/source/i18n/number_rounding.cpp
@@ -0,0 +1,441 @@
+// © 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
+
+#include "uassert.h"
+#include "unicode/numberformatter.h"
+#include "number_types.h"
+#include "number_decimalquantity.h"
+#include "double-conversion.h"
+#include "number_roundingutils.h"
+#include "putilimp.h"
+
+using namespace icu;
+using namespace icu::number;
+using namespace icu::number::impl;
+
+
+using double_conversion::DoubleToStringConverter;
+
+namespace {
+
+int32_t getRoundingMagnitudeFraction(int maxFrac) {
+    if (maxFrac == -1) {
+        return INT32_MIN;
+    }
+    return -maxFrac;
+}
+
+int32_t getRoundingMagnitudeSignificant(const DecimalQuantity &value, int maxSig) {
+    if (maxSig == -1) {
+        return INT32_MIN;
+    }
+    int magnitude = value.isZeroish() ? 0 : value.getMagnitude();
+    return magnitude - maxSig + 1;
+}
+
+int32_t getDisplayMagnitudeFraction(int minFrac) {
+    if (minFrac == 0) {
+        return INT32_MAX;
+    }
+    return -minFrac;
+}
+
+int32_t getDisplayMagnitudeSignificant(const DecimalQuantity &value, int minSig) {
+    int magnitude = value.isZeroish() ? 0 : value.getMagnitude();
+    return magnitude - minSig + 1;
+}
+
+}
+
+
+MultiplierProducer::~MultiplierProducer() = default;
+
+
+digits_t roundingutils::doubleFractionLength(double input, int8_t* singleDigit) {
+    char buffer[DoubleToStringConverter::kBase10MaximalLength + 1];
+    bool sign; // unused; always positive
+    int32_t length;
+    int32_t point;
+    DoubleToStringConverter::DoubleToAscii(
+            input,
+            DoubleToStringConverter::DtoaMode::SHORTEST,
+            0,
+            buffer,
+            sizeof(buffer),
+            &sign,
+            &length,
+            &point
+    );
+
+    if (singleDigit == nullptr) {
+        // no-op
+    } else if (length == 1) {
+        *singleDigit = buffer[0] - '0';
+    } else {
+        *singleDigit = -1;
+    }
+
+    return static_cast<digits_t>(length - point);
+}
+
+
+Precision Precision::unlimited() {
+    return Precision(RND_NONE, {}, kDefaultMode);
+}
+
+FractionPrecision Precision::integer() {
+    return constructFraction(0, 0);
+}
+
+FractionPrecision Precision::fixedFraction(int32_t minMaxFractionPlaces) {
+    if (minMaxFractionPlaces >= 0 && minMaxFractionPlaces <= kMaxIntFracSig) {
+        return constructFraction(minMaxFractionPlaces, minMaxFractionPlaces);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+FractionPrecision Precision::minFraction(int32_t minFractionPlaces) {
+    if (minFractionPlaces >= 0 && minFractionPlaces <= kMaxIntFracSig) {
+        return constructFraction(minFractionPlaces, -1);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+FractionPrecision Precision::maxFraction(int32_t maxFractionPlaces) {
+    if (maxFractionPlaces >= 0 && maxFractionPlaces <= kMaxIntFracSig) {
+        return constructFraction(0, maxFractionPlaces);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+FractionPrecision Precision::minMaxFraction(int32_t minFractionPlaces, int32_t maxFractionPlaces) {
+    if (minFractionPlaces >= 0 && maxFractionPlaces <= kMaxIntFracSig &&
+        minFractionPlaces <= maxFractionPlaces) {
+        return constructFraction(minFractionPlaces, maxFractionPlaces);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+Precision Precision::fixedSignificantDigits(int32_t minMaxSignificantDigits) {
+    if (minMaxSignificantDigits >= 1 && minMaxSignificantDigits <= kMaxIntFracSig) {
+        return constructSignificant(minMaxSignificantDigits, minMaxSignificantDigits);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+Precision Precision::minSignificantDigits(int32_t minSignificantDigits) {
+    if (minSignificantDigits >= 1 && minSignificantDigits <= kMaxIntFracSig) {
+        return constructSignificant(minSignificantDigits, -1);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+Precision Precision::maxSignificantDigits(int32_t maxSignificantDigits) {
+    if (maxSignificantDigits >= 1 && maxSignificantDigits <= kMaxIntFracSig) {
+        return constructSignificant(1, maxSignificantDigits);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+Precision Precision::minMaxSignificantDigits(int32_t minSignificantDigits, int32_t maxSignificantDigits) {
+    if (minSignificantDigits >= 1 && maxSignificantDigits <= kMaxIntFracSig &&
+        minSignificantDigits <= maxSignificantDigits) {
+        return constructSignificant(minSignificantDigits, maxSignificantDigits);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+IncrementPrecision Precision::increment(double roundingIncrement) {
+    if (roundingIncrement > 0.0) {
+        return constructIncrement(roundingIncrement, 0);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+CurrencyPrecision Precision::currency(UCurrencyUsage currencyUsage) {
+    return constructCurrency(currencyUsage);
+}
+
+Precision FractionPrecision::withMinDigits(int32_t minSignificantDigits) const {
+    if (fType == RND_ERROR) { return *this; } // no-op in error state
+    if (minSignificantDigits >= 1 && minSignificantDigits <= kMaxIntFracSig) {
+        return constructFractionSignificant(*this, minSignificantDigits, -1);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+Precision FractionPrecision::withMaxDigits(int32_t maxSignificantDigits) const {
+    if (fType == RND_ERROR) { return *this; } // no-op in error state
+    if (maxSignificantDigits >= 1 && maxSignificantDigits <= kMaxIntFracSig) {
+        return constructFractionSignificant(*this, -1, maxSignificantDigits);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+// Private method on base class
+Precision Precision::withCurrency(const CurrencyUnit &currency, UErrorCode &status) const {
+    if (fType == RND_ERROR) { return *this; } // no-op in error state
+    U_ASSERT(fType == RND_CURRENCY);
+    const char16_t *isoCode = currency.getISOCurrency();
+    double increment = ucurr_getRoundingIncrementForUsage(isoCode, fUnion.currencyUsage, &status);
+    int32_t minMaxFrac = ucurr_getDefaultFractionDigitsForUsage(
+            isoCode, fUnion.currencyUsage, &status);
+    if (increment != 0.0) {
+        return constructIncrement(increment, minMaxFrac);
+    } else {
+        return constructFraction(minMaxFrac, minMaxFrac);
+    }
+}
+
+// Public method on CurrencyPrecision subclass
+Precision CurrencyPrecision::withCurrency(const CurrencyUnit &currency) const {
+    UErrorCode localStatus = U_ZERO_ERROR;
+    Precision result = Precision::withCurrency(currency, localStatus);
+    if (U_FAILURE(localStatus)) {
+        return {localStatus};
+    }
+    return result;
+}
+
+Precision IncrementPrecision::withMinFraction(int32_t minFrac) const {
+    if (fType == RND_ERROR) { return *this; } // no-op in error state
+    if (minFrac >= 0 && minFrac <= kMaxIntFracSig) {
+        return constructIncrement(fUnion.increment.fIncrement, minFrac);
+    } else {
+        return {U_NUMBER_ARG_OUTOFBOUNDS_ERROR};
+    }
+}
+
+FractionPrecision Precision::constructFraction(int32_t minFrac, int32_t maxFrac) {
+    FractionSignificantSettings settings;
+    settings.fMinFrac = static_cast<digits_t>(minFrac);
+    settings.fMaxFrac = static_cast<digits_t>(maxFrac);
+    settings.fMinSig = -1;
+    settings.fMaxSig = -1;
+    PrecisionUnion union_;
+    union_.fracSig = settings;
+    return {RND_FRACTION, union_, kDefaultMode};
+}
+
+Precision Precision::constructSignificant(int32_t minSig, int32_t maxSig) {
+    FractionSignificantSettings settings;
+    settings.fMinFrac = -1;
+    settings.fMaxFrac = -1;
+    settings.fMinSig = static_cast<digits_t>(minSig);
+    settings.fMaxSig = static_cast<digits_t>(maxSig);
+    PrecisionUnion union_;
+    union_.fracSig = settings;
+    return {RND_SIGNIFICANT, union_, kDefaultMode};
+}
+
+Precision
+Precision::constructFractionSignificant(const FractionPrecision &base, int32_t minSig, int32_t maxSig) {
+    FractionSignificantSettings settings = base.fUnion.fracSig;
+    settings.fMinSig = static_cast<digits_t>(minSig);
+    settings.fMaxSig = static_cast<digits_t>(maxSig);
+    PrecisionUnion union_;
+    union_.fracSig = settings;
+    return {RND_FRACTION_SIGNIFICANT, union_, kDefaultMode};
+}
+
+IncrementPrecision Precision::constructIncrement(double increment, int32_t minFrac) {
+    IncrementSettings settings;
+    // Note: For number formatting, fIncrement is used for RND_INCREMENT but not
+    // RND_INCREMENT_ONE or RND_INCREMENT_FIVE. However, fIncrement is used in all
+    // three when constructing a skeleton.
+    settings.fIncrement = increment;
+    settings.fMinFrac = static_cast<digits_t>(minFrac);
+    // One of the few pre-computed quantities:
+    // Note: it is possible for minFrac to be more than maxFrac... (misleading)
+    int8_t singleDigit;
+    settings.fMaxFrac = roundingutils::doubleFractionLength(increment, &singleDigit);
+    PrecisionUnion union_;
+    union_.increment = settings;
+    if (singleDigit == 1) {
+        // NOTE: In C++, we must return the correct value type with the correct union.
+        // It would be invalid to return a RND_FRACTION here because the methods on the
+        // IncrementPrecision type assume that the union is backed by increment data.
+        return {RND_INCREMENT_ONE, union_, kDefaultMode};
+    } else if (singleDigit == 5) {
+        return {RND_INCREMENT_FIVE, union_, kDefaultMode};
+    } else {
+        return {RND_INCREMENT, union_, kDefaultMode};
+    }
+}
+
+CurrencyPrecision Precision::constructCurrency(UCurrencyUsage usage) {
+    PrecisionUnion union_;
+    union_.currencyUsage = usage;
+    return {RND_CURRENCY, union_, kDefaultMode};
+}
+
+
+RoundingImpl::RoundingImpl(const Precision& precision, UNumberFormatRoundingMode roundingMode,
+                           const CurrencyUnit& currency, UErrorCode& status)
+        : fPrecision(precision), fRoundingMode(roundingMode), fPassThrough(false) {
+    if (precision.fType == Precision::RND_CURRENCY) {
+        fPrecision = precision.withCurrency(currency, status);
+    }
+}
+
+RoundingImpl RoundingImpl::passThrough() {
+    return {};
+}
+
+bool RoundingImpl::isSignificantDigits() const {
+    return fPrecision.fType == Precision::RND_SIGNIFICANT;
+}
+
+int32_t
+RoundingImpl::chooseMultiplierAndApply(impl::DecimalQuantity &input, const impl::MultiplierProducer &producer,
+                                  UErrorCode &status) {
+    // Do not call this method with zero, NaN, or infinity.
+    U_ASSERT(!input.isZeroish());
+
+    // Perform the first attempt at rounding.
+    int magnitude = input.getMagnitude();
+    int multiplier = producer.getMultiplier(magnitude);
+    input.adjustMagnitude(multiplier);
+    apply(input, status);
+
+    // If the number rounded to zero, exit.
+    if (input.isZeroish() || U_FAILURE(status)) {
+        return multiplier;
+    }
+
+    // If the new magnitude after rounding is the same as it was before rounding, then we are done.
+    // This case applies to most numbers.
+    if (input.getMagnitude() == magnitude + multiplier) {
+        return multiplier;
+    }
+
+    // If the above case DIDN'T apply, then we have a case like 99.9 -> 100 or 999.9 -> 1000:
+    // The number rounded up to the next magnitude. Check if the multiplier changes; if it doesn't,
+    // we do not need to make any more adjustments.
+    int _multiplier = producer.getMultiplier(magnitude + 1);
+    if (multiplier == _multiplier) {
+        return multiplier;
+    }
+
+    // We have a case like 999.9 -> 1000, where the correct output is "1K", not "1000".
+    // Fix the magnitude and re-apply the rounding strategy.
+    input.adjustMagnitude(_multiplier - multiplier);
+    apply(input, status);
+    return _multiplier;
+}
+
+/** This is the method that contains the actual rounding logic. */
+void RoundingImpl::apply(impl::DecimalQuantity &value, UErrorCode& status) const {
+    if (fPassThrough) {
+        return;
+    }
+    switch (fPrecision.fType) {
+        case Precision::RND_BOGUS:
+        case Precision::RND_ERROR:
+            // Errors should be caught before the apply() method is called
+            status = U_INTERNAL_PROGRAM_ERROR;
+            break;
+
+        case Precision::RND_NONE:
+            value.roundToInfinity();
+            break;
+
+        case Precision::RND_FRACTION:
+            value.roundToMagnitude(
+                    getRoundingMagnitudeFraction(fPrecision.fUnion.fracSig.fMaxFrac),
+                    fRoundingMode,
+                    status);
+            value.setMinFraction(
+                    uprv_max(0, -getDisplayMagnitudeFraction(fPrecision.fUnion.fracSig.fMinFrac)));
+            break;
+
+        case Precision::RND_SIGNIFICANT:
+            value.roundToMagnitude(
+                    getRoundingMagnitudeSignificant(value, fPrecision.fUnion.fracSig.fMaxSig),
+                    fRoundingMode,
+                    status);
+            value.setMinFraction(
+                    uprv_max(0, -getDisplayMagnitudeSignificant(value, fPrecision.fUnion.fracSig.fMinSig)));
+            // Make sure that digits are displayed on zero.
+            if (value.isZeroish() && fPrecision.fUnion.fracSig.fMinSig > 0) {
+                value.setMinInteger(1);
+            }
+            break;
+
+        case Precision::RND_FRACTION_SIGNIFICANT: {
+            int32_t displayMag = getDisplayMagnitudeFraction(fPrecision.fUnion.fracSig.fMinFrac);
+            int32_t roundingMag = getRoundingMagnitudeFraction(fPrecision.fUnion.fracSig.fMaxFrac);
+            if (fPrecision.fUnion.fracSig.fMinSig == -1) {
+                // Max Sig override
+                int32_t candidate = getRoundingMagnitudeSignificant(
+                        value,
+                        fPrecision.fUnion.fracSig.fMaxSig);
+                roundingMag = uprv_max(roundingMag, candidate);
+            } else {
+                // Min Sig override
+                int32_t candidate = getDisplayMagnitudeSignificant(
+                        value,
+                        fPrecision.fUnion.fracSig.fMinSig);
+                roundingMag = uprv_min(roundingMag, candidate);
+            }
+            value.roundToMagnitude(roundingMag, fRoundingMode, status);
+            value.setMinFraction(uprv_max(0, -displayMag));
+            break;
+        }
+
+        case Precision::RND_INCREMENT:
+            value.roundToIncrement(
+                    fPrecision.fUnion.increment.fIncrement,
+                    fRoundingMode,
+                    status);
+            value.setMinFraction(fPrecision.fUnion.increment.fMinFrac);
+            break;
+
+        case Precision::RND_INCREMENT_ONE:
+            value.roundToMagnitude(
+                    -fPrecision.fUnion.increment.fMaxFrac,
+                    fRoundingMode,
+                    status);
+            value.setMinFraction(fPrecision.fUnion.increment.fMinFrac);
+            break;
+
+        case Precision::RND_INCREMENT_FIVE:
+            value.roundToNickel(
+                    -fPrecision.fUnion.increment.fMaxFrac,
+                    fRoundingMode,
+                    status);
+            value.setMinFraction(fPrecision.fUnion.increment.fMinFrac);
+            break;
+
+        case Precision::RND_CURRENCY:
+            // Call .withCurrency() before .apply()!
+            UPRV_UNREACHABLE;
+
+        default:
+            UPRV_UNREACHABLE;
+    }
+}
+
+void RoundingImpl::apply(impl::DecimalQuantity &value, int32_t minInt, UErrorCode /*status*/) {
+    // This method is intended for the one specific purpose of helping print "00.000E0".
+    U_ASSERT(isSignificantDigits());
+    U_ASSERT(value.isZeroish());
+    value.setMinFraction(fPrecision.fUnion.fracSig.fMinSig - minInt);
+}
+
+#endif /* #if !UCONFIG_NO_FORMATTING */