Revert "Disable DateTimeFormat::formatToParts for Apple platform (#1155…

…)"

This reverts commit c5a633f.

doc/IntlAPIs.md

@@ -27,6 +27,7 @@ One popular implementation strategy followed by other engines, is to bundle an i
 - `Intl.DateTimeFormat`*
   - `Intl.DateTimeFormat.supportedLocalesOf`
   - `Intl.DateTimeFormat.prototype.format`
+  - `Intl.DateTimeFormat.prototype.formatToParts`
   - `Intl.DateTimeFormat.prototype.resolvedOptions`
 
 - `Intl.getCanonicalLocales`
@@ -50,7 +51,6 @@ One popular implementation strategy followed by other engines, is to bundle an i
 ## Supported on Android only
 - `Intl.NumberFormat`
   - `Intl.NumberFormat.prototype.formatToParts`
-  - `Intl.DateTimeFormat.prototype.formatToParts`
 
 ## * Limitations on property support
 

lib/Platform/Intl/PlatformIntlApple.mm

@@ -1229,6 +1229,8 @@ uint8_t getCurrencyDigits(std::u16string_view code) {
 
   std::u16string format(double jsTimeValue) noexcept;
 
+  std::vector<Part> formatToParts(double x) noexcept;
+
  private:
   void initializeNSDateFormatter(NSLocale *nsLocale) noexcept;
 
@@ -1895,8 +1897,76 @@ uint8_t getCurrencyDigits(std::u16string_view code) {
   return static_cast<DateTimeFormatApple *>(this)->format(jsTimeValue);
 }
 
+static std::u16string returnTypeOfDate(const char16_t &c16) {
+  if (c16 == u'a')
+    return u"dayPeriod";
+  if (c16 == u'z' || c16 == u'v' || c16 == u'O')
+    return u"timeZoneName";
+  if (c16 == u'G')
+    return u"era";
+  if (c16 == u'y')
+    return u"year";
+  if (c16 == u'M')
+    return u"month";
+  if (c16 == u'E')
+    return u"weekday";
+  if (c16 == u'd')
+    return u"day";
+  if (c16 == u'h' || c16 == u'k' || c16 == u'K' || c16 == u'H')
+    return u"hour";
+  if (c16 == u'm')
+    return u"minute";
+  if (c16 == u's')
+    return u"second";
+  if (c16 == u'S')
+    return u"fractionalSecond";
+  return u"literal";
+}
+
+// Implementer note: This method corresponds roughly to
+// https://402.ecma-international.org/8.0/#sec-formatdatetimetoparts
+std::vector<Part> DateTimeFormatApple::formatToParts(double x) noexcept {
+  // NOTE: We dont have access to localeData.patterns. Instead we use
+  // NSDateFormatter's foramt string, and break it into components.
+  // 1. Let parts be ? PartitionDateTimePattern(dateTimeFormat, x).
+  auto fmt = nsStringToU16String(nsDateFormatter_.dateFormat);
+  std::unique(fmt.begin(), fmt.end());
+  auto formattedDate = format(x);
+  // 2. Let result be ArrayCreate(0).
+  std::vector<Part> result;
+  // 3. Let n be 0.
+  // 4. For each Record { [[Type]], [[Value]] } part in parts, do
+  // a. Let O be OrdinaryObjectCreate(%Object.prototype%).
+  // b. Perform ! CreateDataPropertyOrThrow(O, "type", part.[[Type]]).
+  // c. Perform ! CreateDataPropertyOrThrow(O, "value", part.[[Value]]).
+  // d. Perform ! CreateDataProperty(result, ! ToString(n), O).
+  // e. Increment n by 1.
+  std::u16string currentPart;
+  unsigned n = 0;
+  static auto alphanumerics = NSCharacterSet.alphanumericCharacterSet;
+  for (char16_t c16 : formattedDate) {
+    if ([alphanumerics characterIsMember:c16]) {
+      currentPart += c16;
+      continue;
+    }
+    if (currentPart != u"") {
+      result.push_back(
+          {{u"type", returnTypeOfDate(fmt[n])}, {u"value", currentPart}});
+      currentPart = u"";
+      n++;
+    }
+    result.push_back({{u"type", u"literal"}, {u"value", {c16}}});
+    n++;
+  }
+  // Last format string component.
+  result.push_back(
+      {{u"type", returnTypeOfDate(fmt[n])}, {u"value", currentPart}});
+  // 5. Return result.
+  return result;
+}
+
 std::vector<Part> DateTimeFormat::formatToParts(double x) noexcept {
-  llvm_unreachable("formatToParts is unimplemented on Apple platforms");
+  return static_cast<DateTimeFormatApple *>(this)->formatToParts(x);
 }
 
 class NumberFormatApple : public NumberFormat {

lib/VM/JSLib/Intl.cpp

@@ -929,15 +929,13 @@ void defineIntlDateTimeFormat(Runtime &runtime, Handle<JSObject> intl) {
       false,
       true);
 
-#ifndef __APPLE__
   defineMethod(
       runtime,
       prototype,
       Predefined::getSymbolID(Predefined::formatToParts),
       nullptr,
       intlDateTimeFormatPrototypeFormatToParts,
       1);
-#endif
 
   defineMethod(
       runtime,

test/hermes/intl/date-time-format-apple.js

@@ -150,5 +150,24 @@ print(new Intl.DateTimeFormat('en-US').resolvedOptions().numberingSystem);
 print(new Intl.DateTimeFormat('en-US', { timeZone: 'SGT'}).resolvedOptions().timeZone);
 // CHECK-NEXT: SGT
 
+print(JSON.stringify(new Intl.DateTimeFormat('en-US').formatToParts(date)));
+// CHECK-NEXT: [{"value":"1","type":"month"},{"value":"/","type":"literal"},{"value":"2","type":"day"},{"value":"/","type":"literal"},{"value":"2020","type":"year"}]
+
+print(JSON.stringify(new Intl.DateTimeFormat('en-GB').formatToParts(date)));
+// CHECK-NEXT: [{"value":"02","type":"day"},{"value":"/","type":"literal"},{"value":"01","type":"month"},{"value":"/","type":"literal"},{"value":"2020","type":"year"}]
+
+print(JSON.stringify(new Intl.DateTimeFormat('en-US', {weekday: 'long',
+  year: 'numeric',
+  month: 'numeric',
+  day: 'numeric',
+  hour: 'numeric',
+  minute: 'numeric',
+  second: 'numeric',
+  fractionalSecondDigits: 3,
+  hour12: true,
+  timeZone: 'UTC'
+}).formatToParts(new Date(Date.UTC(2020, 0, 2, 3, 45, 00, 30)))));
+// CHECK-NEXT: [{"value":"Thursday","type":"weekday"},{"value":",","type":"literal"},{"value":" ","type":"literal"},{"value":"1","type":"month"},{"value":"/","type":"literal"},{"value":"2","type":"day"},{"value":"/","type":"literal"},{"value":"2020","type":"year"},{"value":",","type":"literal"},{"value":" ","type":"literal"},{"value":"3","type":"hour"},{"value":":","type":"literal"},{"value":"45","type":"minute"},{"value":":","type":"literal"},{"value":"00","type":"second"},{"value":".","type":"literal"},{"value":"030","type":"fractionalSecond"},{"value":" ","type":"literal"},{"value":"AM","type":"dayPeriod"}]
+
 print(new Date(Date.UTC(2020, 0, 2)).toLocaleString("en-US", {weekday: "short", timeZone: "UTC"}))
 // CHECK-NEXT: Thu

test/hermes/intl/intl.js

@@ -83,9 +83,7 @@ testServiceGetterTypes(Intl.DateTimeFormat, 'format');
 testServiceMethodTypes(Intl.DateTimeFormat, 'formatToParts');
 testServiceMethodTypes(Intl.DateTimeFormat, 'resolvedOptions');
 assert(typeof Intl.DateTimeFormat().format() === 'string');
-if(Intl.DateTimeFormat.prototype.formatToParts) {
-  testParts(Intl.DateTimeFormat().formatToParts());
-}
+testParts(Intl.DateTimeFormat().formatToParts());
 
 testServiceTypes(Intl.NumberFormat);
 testServiceGetterTypes(Intl.NumberFormat, 'format');

utils/testsuite/testsuite_skiplist.py

@@ -1115,7 +1115,11 @@
     "test262/test/intl402/DateTimeFormat/prototype/resolvedOptions/order-dayPeriod.js",
     "test262/test/intl402/DateTimeFormat/prototype/resolvedOptions/hourCycle-timeStyle.js",
     "test262/test/intl402/DateTimeFormat/prototype/resolvedOptions/order-style.js",
-    "test262/test/intl402/DateTimeFormat/prototype/formatToParts",
+    "test262/test/intl402/DateTimeFormat/prototype/formatToParts/related-year-zh.js",
+    "test262/test/intl402/DateTimeFormat/prototype/formatToParts/dayPeriod-narrow-en.js",
+    "test262/test/intl402/DateTimeFormat/prototype/formatToParts/dayPeriod-long-en.js",
+    "test262/test/intl402/DateTimeFormat/prototype/formatToParts/dayPeriod-short-en.js",
+    "test262/test/intl402/DateTimeFormat/prototype/formatToParts/fractionalSecondDigits.js",
     "test262/test/intl402/DateTimeFormat/prototype/format/timedatestyle-en.js",
     "test262/test/intl402/DateTimeFormat/prototype/format/dayPeriod-long-en.js",
     "test262/test/intl402/DateTimeFormat/prototype/format/dayPeriod-narrow-en.js",
@@ -1125,6 +1129,7 @@
     # This test assumes that "year" has some default value. That is an implementation-defined behavior.
     # In our case it remains undefined, which causes this test to fail.
     "test262/test/intl402/DateTimeFormat/default-options-object-prototype.js",
+    "test262/test/intl402/DateTimeFormat/prototype/formatToParts/related-year.js",
     "test262/test/intl402/DateTimeFormat/prototype/format/proleptic-gregorian-calendar.js",
     "test262/test/intl402/DateTimeFormat/prototype/formatRange",
     "test262/test/intl402/DateTimeFormat/prototype/formatRangeToParts",