Bug 1736834 - Part 6: Use Maybe instead of nullptr to represent absent Unicode extensions. r=platform-i18n-reviewers,dminor

Use `Maybe` and return `Span` instead of raw `const char*`.

Differential Revision: https://phabricator.services.mozilla.com/D129042

intl/components/gtest/TestLocale.cpp

@@ -21,8 +21,7 @@ TEST(IntlLocale, LocaleSettersAndGetters)
   ASSERT_TRUE(locale.language().equalTo("fr"));
   ASSERT_TRUE(locale.region().equalTo("CA"));
   ASSERT_TRUE(locale.script().equalTo("Latn"));
-  ASSERT_EQ(MakeStringSpan(locale.unicodeExtension()),
-            MakeStringSpan("u-ca-gregory"));
+  ASSERT_EQ(locale.unicodeExtension().value(), MakeStringSpan("u-ca-gregory"));
 
   TestBuffer<char> buffer;
   ASSERT_TRUE(locale.toString(buffer).isOk());

intl/components/src/Locale.cpp

@@ -158,12 +158,12 @@ ptrdiff_t Locale::unicodeExtensionIndex() const {
   return -1;
 }
 
-const char* Locale::unicodeExtension() const {
+Maybe<Span<const char>> Locale::unicodeExtension() const {
   ptrdiff_t index = unicodeExtensionIndex();
   if (index >= 0) {
-    return extensions()[index].get();
+    return Some(MakeStringSpan(extensions()[index].get()));
   }
-  return nullptr;
+  return Nothing();
 }
 
 ICUResult Locale::setUnicodeExtension(Span<const char> extension) {

intl/components/src/Locale.h

@@ -10,6 +10,7 @@
 #include "mozilla/Assertions.h"
 #include "mozilla/intl/ICUError.h"
 #include "mozilla/intl/ICU4CGlue.h"
+#include "mozilla/Maybe.h"
 #include "mozilla/Span.h"
 #include "mozilla/TextUtils.h"
 #include "mozilla/TypedEnumBits.h"
@@ -252,9 +253,9 @@ class MOZ_STACK_CLASS Locale final {
   const char* privateuse() const { return privateuse_.get(); }
 
   /**
-   * Return the Unicode extension subtag or nullptr if not present.
+   * Return the Unicode extension subtag or Nothing if not present.
    */
-  const char* unicodeExtension() const;
+  Maybe<Span<const char>> unicodeExtension() const;
 
  private:
   ptrdiff_t unicodeExtensionIndex() const;

js/src/builtin/intl/Locale.cpp

@@ -411,10 +411,11 @@ bool js::intl::ApplyUnicodeExtensionToTag(
 
   const char* unicodeExtensionEnd = nullptr;
   const char* unicodeExtensionKeywords = nullptr;
-  if (const char* unicodeExtension = tag.unicodeExtension()) {
-    unicodeExtensionEnd = unicodeExtension + strlen(unicodeExtension);
+  if (auto unicodeExtension = tag.unicodeExtension()) {
+    const char* unicodeExtensionBegin = unicodeExtension->data();
+    unicodeExtensionEnd = unicodeExtensionBegin + unicodeExtension->size();
 
-    SepKeywordIterator<char> iter(unicodeExtension, unicodeExtensionEnd);
+    SepKeywordIterator<char> iter(unicodeExtensionBegin, unicodeExtensionEnd);
 
     // Find the start of the first keyword.
     unicodeExtensionKeywords = iter.next();
@@ -423,7 +424,7 @@ bool js::intl::ApplyUnicodeExtensionToTag(
     const char* attributesEnd = unicodeExtensionKeywords
                                     ? unicodeExtensionKeywords
                                     : unicodeExtensionEnd;
-    if (!newExtension.append(unicodeExtension + 1, attributesEnd)) {
+    if (!newExtension.append(unicodeExtensionBegin + 1, attributesEnd)) {
       return false;
     }
   }