Bug 1734932 - Add intl::NumberParser; r=platform-i18n-reviewers,gregtatum

Awkwardly, this relies upon a different ICU4C NumberFormat API than
the existing intl::NumberFormat implementation, so it seems best to
have this live in a separate class.

Differential Revision: https://phabricator.services.mozilla.com/D133124

intl/components/gtest/TestNumberParser.cpp

@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "gtest/gtest.h"
+
+#include "mozilla/intl/NumberParser.h"
+
+namespace mozilla::intl {
+
+TEST(IntlNumberParser, Basic)
+{
+  // Try with an English locale
+  UniquePtr<NumberParser> np = NumberParser::TryCreate("en-US", true).unwrap();
+  auto result = np->ParseDouble(MakeStringSpan(u"1,234.56"));
+  ASSERT_TRUE(result.isOk());
+  ASSERT_EQ(result.unwrap().first, 1234.56);
+  ASSERT_EQ(result.unwrap().second, 8);
+
+  // Disable grouping, parsing will stop at the first comma
+  np = NumberParser::TryCreate("en-US", false).unwrap();
+  result = np->ParseDouble(MakeStringSpan(u"1,234.56"));
+  ASSERT_TRUE(result.isOk());
+  ASSERT_EQ(result.unwrap().first, 1);
+  ASSERT_EQ(result.unwrap().second, 1);
+
+  // Try with a Spanish locale
+  np = NumberParser::TryCreate("es-CR", true).unwrap();
+  result = np->ParseDouble(MakeStringSpan(u"1234,56"));
+  ASSERT_TRUE(result.isOk());
+  ASSERT_EQ(result.unwrap().first, 1234.56);
+  ASSERT_EQ(result.unwrap().second, 7);
+}
+
+}  // namespace mozilla::intl

intl/components/gtest/moz.build

@@ -18,6 +18,7 @@ UNIFIED_SOURCES += [
     "TestMeasureUnit.cpp",
     "TestNumberFormat.cpp",
     "TestNumberingSystem.cpp",
+    "TestNumberParser.cpp",
     "TestPluralRules.cpp",
     "TestRelativeTimeFormat.cpp",
     "TestScript.cpp",

intl/components/moz.build

@@ -25,6 +25,7 @@ EXPORTS.mozilla.intl = [
     "src/MeasureUnit.h",
     "src/NumberFormat.h",
     "src/NumberingSystem.h",
+    "src/NumberParser.h",
     "src/NumberPart.h",
     "src/NumberRangeFormat.h",
     "src/PluralRules.h",
@@ -57,6 +58,7 @@ UNIFIED_SOURCES += [
     "src/NumberFormatFields.cpp",
     "src/NumberFormatterSkeleton.cpp",
     "src/NumberingSystem.cpp",
+    "src/NumberParser.cpp",
     "src/NumberRangeFormat.cpp",
     "src/PluralRules.cpp",
     "src/RelativeTimeFormat.cpp",

intl/components/src/NumberParser.cpp

@@ -0,0 +1,45 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "mozilla/intl/NumberParser.h"
+
+namespace mozilla::intl {
+
+/*static*/ Result<UniquePtr<NumberParser>, ICUError> NumberParser::TryCreate(
+    const char* aLocale, bool aUseGrouping) {
+  UniquePtr<NumberParser> nf = MakeUnique<NumberParser>();
+
+  UErrorCode status = U_ZERO_ERROR;
+  nf->mNumberFormat =
+      unum_open(UNUM_DECIMAL, nullptr, 0, aLocale, nullptr, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+
+  if (!aUseGrouping) {
+    unum_setAttribute(nf->mNumberFormat.GetMut(), UNUM_GROUPING_USED, UBool(0));
+  }
+
+  return nf;
+}
+
+NumberParser::~NumberParser() {
+  if (mNumberFormat) {
+    unum_close(mNumberFormat.GetMut());
+  }
+}
+
+Result<std::pair<double, int32_t>, ICUError> NumberParser::ParseDouble(
+    Span<const char16_t> aDouble) const {
+  UErrorCode status = U_ZERO_ERROR;
+  int32_t parsePos = 0;
+  double value = unum_parseDouble(mNumberFormat.GetConst(), aDouble.data(),
+                                  static_cast<int32_t>(aDouble.size()),
+                                  &parsePos, &status);
+  if (U_FAILURE(status)) {
+    return Err(ToICUError(status));
+  }
+  return std::make_pair(value, parsePos);
+}
+
+}  // namespace mozilla::intl

intl/components/src/NumberParser.h

@@ -0,0 +1,46 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef intl_components_NumberParser_h_
+#define intl_components_NumberParser_h_
+
+#include "mozilla/intl/ICUError.h"
+#include "mozilla/intl/ICU4CGlue.h"
+#include "mozilla/Span.h"
+#include "mozilla/UniquePtr.h"
+
+#include "unicode/unum.h"
+
+namespace mozilla::intl {
+
+class NumberParser {
+ public:
+  /**
+   * Initialize a new NumberParser for the provided locale and using the
+   * provided options.
+   */
+  static Result<UniquePtr<NumberParser>, ICUError> TryCreate(
+      const char* aLocale, bool aUseGrouping);
+
+  NumberParser() : mNumberFormat(nullptr){};
+  NumberParser(const NumberParser&) = delete;
+  NumberParser& operator=(const NumberParser&) = delete;
+  ~NumberParser();
+
+  /**
+   * Attempts to parse a string representing a double, returning the parsed
+   * double and the parse position if successful, or an error.
+   *
+   * The parse position is the index into the input string where parsing
+   * stopped because an non-numeric character was encountered.
+   */
+  Result<std::pair<double, int32_t>, ICUError> ParseDouble(
+      Span<const char16_t> aDouble) const;
+
+ private:
+  ICUPointer<UNumberFormat> mNumberFormat;
+};
+
+}  // namespace mozilla::intl
+
+#endif