1 files changed, 177 insertions, 0 deletions
diff --git a/intl/icu/source/i18n/number_scientific.cpp b/intl/icu/source/i18n/number_scientific.cpp
new file mode 100644
index 0000000000..d365d982d4
--- /dev/null
+++ b/intl/icu/source/i18n/number_scientific.cpp
@@ -0,0 +1,177 @@
+// © 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 <cstdlib>
+#include "number_scientific.h"
+#include "number_utils.h"
+#include "formatted_string_builder.h"
+#include "unicode/unum.h"
+#include "number_microprops.h"
+
+using namespace icu;
+using namespace icu::number;
+using namespace icu::number::impl;
+
+// NOTE: The object lifecycle of ScientificModifier and ScientificHandler differ greatly in Java and C++.
+//
+// During formatting, we need to provide an object with state (the exponent) as the inner modifier.
+//
+// In Java, where the priority is put on reducing object creations, the unsafe code path re-uses the
+// ScientificHandler as a ScientificModifier, and the safe code path pre-computes 25 ScientificModifier
+// instances.  This scheme reduces the number of object creations by 1 in both safe and unsafe.
+//
+// In C++, MicroProps provides a pre-allocated ScientificModifier, and ScientificHandler simply populates
+// the state (the exponent) into that ScientificModifier. There is no difference between safe and unsafe.
+
+ScientificModifier::ScientificModifier() : fExponent(0), fHandler(nullptr) {}
+
+void ScientificModifier::set(int32_t exponent, const ScientificHandler *handler) {
+    // ScientificModifier should be set only once.
+    U_ASSERT(fHandler == nullptr);
+    fExponent = exponent;
+    fHandler = handler;
+}
+
+int32_t ScientificModifier::apply(FormattedStringBuilder &output, int32_t /*leftIndex*/, int32_t rightIndex,
+                                  UErrorCode &status) const {
+    // FIXME: Localized exponent separator location.
+    int i = rightIndex;
+    // Append the exponent separator and sign
+    i += output.insert(
+            i,
+            fHandler->fSymbols->getSymbol(DecimalFormatSymbols::ENumberFormatSymbol::kExponentialSymbol),
+            {UFIELD_CATEGORY_NUMBER, UNUM_EXPONENT_SYMBOL_FIELD},
+            status);
+    if (fExponent < 0 && fHandler->fSettings.fExponentSignDisplay != UNUM_SIGN_NEVER) {
+        i += output.insert(
+                i,
+                fHandler->fSymbols
+                        ->getSymbol(DecimalFormatSymbols::ENumberFormatSymbol::kMinusSignSymbol),
+                {UFIELD_CATEGORY_NUMBER, UNUM_EXPONENT_SIGN_FIELD},
+                status);
+    } else if (fExponent >= 0 && fHandler->fSettings.fExponentSignDisplay == UNUM_SIGN_ALWAYS) {
+        i += output.insert(
+                i,
+                fHandler->fSymbols
+                        ->getSymbol(DecimalFormatSymbols::ENumberFormatSymbol::kPlusSignSymbol),
+                {UFIELD_CATEGORY_NUMBER, UNUM_EXPONENT_SIGN_FIELD},
+                status);
+    }
+    // Append the exponent digits (using a simple inline algorithm)
+    int32_t disp = std::abs(fExponent);
+    for (int j = 0; j < fHandler->fSettings.fMinExponentDigits || disp > 0; j++, disp /= 10) {
+        auto d = static_cast<int8_t>(disp % 10);
+        i += utils::insertDigitFromSymbols(
+                output,
+                i - j,
+                d,
+                *fHandler->fSymbols,
+                {UFIELD_CATEGORY_NUMBER, UNUM_EXPONENT_FIELD},
+                status);
+    }
+    return i - rightIndex;
+}
+
+int32_t ScientificModifier::getPrefixLength() const {
+    // TODO: Localized exponent separator location.
+    return 0;
+}
+
+int32_t ScientificModifier::getCodePointCount() const {
+    // NOTE: This method is only called one place, NumberRangeFormatterImpl.
+    // The call site only cares about != 0 and != 1.
+    // Return a very large value so that if this method is used elsewhere, we should notice.
+    return 999;
+}
+
+bool ScientificModifier::isStrong() const {
+    // Scientific is always strong
+    return true;
+}
+
+bool ScientificModifier::containsField(Field field) const {
+    (void)field;
+    // This method is not used for inner modifiers.
+    UPRV_UNREACHABLE_EXIT;
+}
+
+void ScientificModifier::getParameters(Parameters& output) const {
+    // Not part of any plural sets
+    output.obj = nullptr;
+}
+
+bool ScientificModifier::semanticallyEquivalent(const Modifier& other) const {
+    auto* _other = dynamic_cast<const ScientificModifier*>(&other);
+    if (_other == nullptr) {
+        return false;
+    }
+    // TODO: Check for locale symbols and settings as well? Could be less efficient.
+    return fExponent == _other->fExponent;
+}
+
+// Note: Visual Studio does not compile this function without full name space. Why?
+icu::number::impl::ScientificHandler::ScientificHandler(const Notation *notation, const DecimalFormatSymbols *symbols,
+	const MicroPropsGenerator *parent) : 
+	fSettings(notation->fUnion.scientific), fSymbols(symbols), fParent(parent) {}
+
+void ScientificHandler::processQuantity(DecimalQuantity &quantity, MicroProps &micros,
+                                        UErrorCode &status) const {
+    fParent->processQuantity(quantity, micros, status);
+    if (U_FAILURE(status)) { return; }
+
+    // Do not apply scientific notation to special doubles
+    if (quantity.isInfinite() || quantity.isNaN()) {
+        micros.modInner = &micros.helpers.emptyStrongModifier;
+        return;
+    }
+
+    // Treat zero as if it had magnitude 0
+    int32_t exponent;
+    if (quantity.isZeroish()) {
+        if (fSettings.fRequireMinInt && micros.rounder.isSignificantDigits()) {
+            // Show "00.000E0" on pattern "00.000E0"
+            micros.rounder.apply(quantity, fSettings.fEngineeringInterval, status);
+            exponent = 0;
+        } else {
+            micros.rounder.apply(quantity, status);
+            exponent = 0;
+        }
+    } else {
+        exponent = -micros.rounder.chooseMultiplierAndApply(quantity, *this, status);
+    }
+
+    // Use MicroProps's helper ScientificModifier and save it as the modInner.
+    ScientificModifier &mod = micros.helpers.scientificModifier;
+    mod.set(exponent, this);
+    micros.modInner = &mod;
+
+    // Change the exponent only after we select appropriate plural form
+    // for formatting purposes so that we preserve expected formatted
+    // string behavior.
+    quantity.adjustExponent(exponent);
+
+    // We already performed rounding. Do not perform it again.
+    micros.rounder = RoundingImpl::passThrough();
+}
+
+int32_t ScientificHandler::getMultiplier(int32_t magnitude) const {
+    int32_t interval = fSettings.fEngineeringInterval;
+    int32_t digitsShown;
+    if (fSettings.fRequireMinInt) {
+        // For patterns like "000.00E0" and ".00E0"
+        digitsShown = interval;
+    } else if (interval <= 1) {
+        // For patterns like "0.00E0" and "@@@E0"
+        digitsShown = 1;
+    } else {
+        // For patterns like "##0.00"
+        digitsShown = ((magnitude % interval + interval) % interval) + 1;
+    }
+    return digitsShown - magnitude - 1;
+}
+
+#endif /* #if !UCONFIG_NO_FORMATTING */