Add ES9.0 compliant Date toString functions.

Summary:
ES9.0 changes the requirements for the `Date.prototype.toString()`
and `Date.prototype.toUTCString()` functions, which now have a specific
format including the weekday, a more human-readable date and time zone.

Reviewed By: dulinriley

Differential Revision: D16343025

fbshipit-source-id: 405f6a5446e98d56463786deff7c875de21b064d

include/hermes/VM/JSLib/DateUtil.h

@@ -89,11 +89,11 @@ uint32_t monthFromTime(double t);
 double dateFromTime(double t);
 
 //===----------------------------------------------------------------------===//
-// ES5.1 15.9.1.6
+// ES9.0 20.3.1.6
 
 /// Given a timestamp \p t in milliseconds, get the day of the week it is in.
 /// \return 0 for Sunday, 1 for Monday, etc.
-double weekDay(double t);
+int32_t weekDay(double t);
 
 //===----------------------------------------------------------------------===//
 // ES5.1 15.9.1.7
@@ -171,19 +171,17 @@ double timeClip(double t);
 
 /// Creates an ISO 8601 format date string.
 /// The string is of the format YYYY-MM-DD.
-/// Note: The output of this function is implementation-defined by spec.
 /// \param t timestamp in milliseconds since Jan 1 1970.
 /// \param tza unused, placed for compatibility with the other toStrings.
 /// \param buf the buffer to be populated with the resultant string.
-void dateToString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+void dateToISOString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
 
 /// Creates an ISO 8601 format time string.
 /// The string is of the format HH:mm:ss.sssZ where Z is timezone.
-/// Note: The output of this function is implementation-defined by spec.
 /// \param t timestamp in milliseconds since Jan 1 1970.
 /// \param tza time zone adjustment in milliseconds, used for the TZ.
 /// \param buf the buffer to be populated with the resultant string.
-void timeToString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+void timeToISOString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
 
 /// Creates an ISO 8601 format string, in the provided timezone.
 /// The string is of the format YYYY-MM-DDTHH:mm:ss.sssZ where Z is timezone.
@@ -197,18 +195,54 @@ void datetimeToISOString(
     double tza,
     llvm::SmallVectorImpl<char> &buf);
 
-/// Same as datetimeToISOString, but uses space instead of 'T' as the separator.
-void datetimeToUTCString(
-    double t,
-    double tza,
-    llvm::SmallVectorImpl<char> &buf);
-
 void datetimeToLocaleString(double t, llvm::SmallVectorImpl<char16_t> &buf);
 
 void dateToLocaleString(double t, llvm::SmallVectorImpl<char16_t> &buf);
 
 void timeToLocaleString(double t, llvm::SmallVectorImpl<char16_t> &buf);
 
+/// ES9.0 20.3.4.41.2 DateString
+/// Returns a spec-compliant string representing the date of \p t.
+/// \param t timestamp in milliseconds since Jan 1 1970.
+/// \param tza unused, placed for compatibility with the other toStrings.
+/// \param buf the buffer to be populated with the resultant string.
+void dateString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+
+/// ES9.0 20.3.4.41.1 TimeString
+/// Returns a spec-compliant string representing the time of \p t.
+/// \param t timestamp in milliseconds since Jan 1 1970.
+/// \param tza time zone adjustment in milliseconds, used for the TZ.
+/// \param buf the buffer to be populated with the resultant string.
+void timeString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+
+/// ES9.0 20.3.4.41.3 TimeZoneString
+/// Returns a spec-compliant string representing the timezone of \p t.
+/// \param t timestamp in milliseconds since Jan 1 1970.
+/// \param tza time zone adjustment in milliseconds, used for the TZ.
+/// \param buf the buffer to be populated with the resultant string.
+void timeZoneString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+
+/// ES9.0 20.3.4.41.4 ToDateString
+/// Returns a spec-compliant string representing the datetime of \p t.
+/// \param t timestamp in milliseconds since Jan 1 1970.
+/// \param tza unused, placed for compatibility with the other toStrings.
+/// \param buf the buffer to be populated with the resultant string.
+void dateTimeString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+
+/// ES9.0 20.3.4.43 Main logic of Date.prototype.toUTCString.
+/// Returns a spec-compliant string representing the datetime of \p t.
+/// \param t timestamp in milliseconds since Jan 1 1970.
+/// \param tza unused, placed for compatibility with the other toStrings.
+/// \param buf the buffer to be populated with the resultant string.
+void dateTimeUTCString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+
+/// ES9.0 20.3.4.42 ToTimeString
+/// Returns a spec-compliant string representing only the time of \p t.
+/// \param t timestamp in milliseconds since Jan 1 1970.
+/// \param tza unused, placed for compatibility with the other toStrings.
+/// \param buf the buffer to be populated with the resultant string.
+void timeTZString(double t, double tza, llvm::SmallVectorImpl<char> &buf);
+
 //===----------------------------------------------------------------------===//
 // Date parsing
 

lib/VM/JSLib/Date.cpp

@@ -563,7 +563,7 @@ dateConstructor(void *, Runtime *runtime, NativeArgs args) {
 #endif
     double t = curTime();
     double local = localTime(t);
-    datetimeToUTCString(local, local - t, str);
+    dateTimeString(local, local - t, str);
 #ifdef HERMESVM_SYNTH_REPLAY
   }
 #endif
@@ -628,11 +628,11 @@ dateNow(void *, Runtime *runtime, NativeArgs args) {
 static CallResult<HermesValue>
 datePrototypeToStringHelper(void *ctx, Runtime *runtime, NativeArgs args) {
   static ToStringOptions toStringOptions[] = {
-      {datetimeToISOString, false, false},
-      {dateToString, false, false},
-      {timeToString, false, false},
+      {dateTimeString, false, false},
+      {dateString, false, false},
+      {timeTZString, false, false},
       {datetimeToISOString, true, true},
-      {datetimeToUTCString, true, false},
+      {dateTimeUTCString, true, false},
   };
   assert(
       (uint64_t)ctx < (uint64_t)ToStringKind::NumKinds &&

lib/VM/JSLib/DateUtil.cpp

@@ -199,7 +199,7 @@ double dateFromTime(double t) {
 //===----------------------------------------------------------------------===//
 // ES5.1 15.9.1.6
 
-double weekDay(double t) {
+int32_t weekDay(double t) {
   return posfmod((day(t) + 4), 7);
 }
 
@@ -502,7 +502,7 @@ double timeClip(double t) {
 //===----------------------------------------------------------------------===//
 // toString Functions
 
-void dateToString(double t, double, llvm::SmallVectorImpl<char> &buf) {
+void dateToISOString(double t, double, llvm::SmallVectorImpl<char> &buf) {
   llvm::raw_svector_ostream os{buf};
 
   /// Make these ints here because we're printing and we have bounds on
@@ -519,7 +519,7 @@ void dateToString(double t, double, llvm::SmallVectorImpl<char> &buf) {
   }
 }
 
-void timeToString(double t, double tza, llvm::SmallVectorImpl<char> &buf) {
+void timeToISOString(double t, double tza, llvm::SmallVectorImpl<char> &buf) {
   llvm::raw_svector_ostream os{buf};
 
   /// Make all of these ints here because we're printing and we have bounds on
@@ -544,28 +544,21 @@ void timeToString(double t, double tza, llvm::SmallVectorImpl<char> &buf) {
   }
 }
 
-static void datetimeToString(
+static void datetimeToISOString(
     double t,
     double tza,
     llvm::SmallVectorImpl<char> &buf,
     char separator) {
-  dateToString(t, tza, buf);
+  dateToISOString(t, tza, buf);
   buf.push_back(separator);
-  timeToString(t, tza, buf);
+  timeToISOString(t, tza, buf);
 }
 
 void datetimeToISOString(
     double t,
     double tza,
     llvm::SmallVectorImpl<char> &buf) {
-  return datetimeToString(t, tza, buf, 'T');
-}
-
-void datetimeToUTCString(
-    double t,
-    double tza,
-    llvm::SmallVectorImpl<char> &buf) {
-  return datetimeToString(t, tza, buf, ' ');
+  return datetimeToISOString(t, tza, buf, 'T');
 }
 
 void datetimeToLocaleString(double t, llvm::SmallVectorImpl<char16_t> &buf) {
@@ -607,6 +600,105 @@ static const char *const monthNames[12]{
     "Dec",
 };
 
+void dateString(double t, double, llvm::SmallVectorImpl<char> &buf) {
+  llvm::raw_svector_ostream os{buf};
+
+  // Make these ints here because we're printing and we have bounds on
+  // their values. Makes printing very easy.
+  int32_t y = yearFromTime(t);
+  int32_t m = monthFromTime(t); // monthFromTime(t) is 0-indexed.
+  int32_t d = dateFromTime(t);
+  int32_t wd = weekDay(t);
+
+  // 7. Return the string-concatenation of weekday, the code unit 0x0020
+  // (SPACE), month, the code unit 0x0020 (SPACE), day, the code unit 0x0020
+  // (SPACE), and year.
+  // Example: Mon Jul 22 2019
+  os << llvm::format("%s %s %02d %04d", weekdayNames[wd], monthNames[m], d, y);
+}
+
+void timeString(double t, double tza, llvm::SmallVectorImpl<char> &buf) {
+  llvm::raw_svector_ostream os{buf};
+
+  int32_t hour = hourFromTime(t);
+  int32_t minute = minFromTime(t);
+  int32_t second = secFromTime(t);
+
+  // Example: 15:50:49 GMT
+  os << llvm::format("%02d:%02d:%02d GMT", hour, minute, second);
+}
+
+void timeZoneString(double t, double tza, llvm::SmallVectorImpl<char> &buf) {
+  llvm::raw_svector_ostream os{buf};
+
+  // We've already computed the TZA, so use that as the offset.
+  double offset = tza;
+
+  // 4. If offset >= 0, let offsetSign be "+"; otherwise, let offsetSign be "-".
+  char offsetSign = offset >= 0 ? '+' : '-';
+
+  // 5. Let offsetMin be the String representation of MinFromTime(abs(offset)),
+  // formatted as a two-digit decimal number, padded to the left with a zero if
+  // necessary.
+  int32_t offsetMin = minFromTime(std::abs(offset));
+
+  // 6. Let offsetHour be the String representation of
+  // HourFromTime(abs(offset)), formatted as a two-digit decimal number, padded
+  // to the left with a zero if necessary.
+  int32_t offsetHour = hourFromTime(std::abs(offset));
+
+  // 7. Let tzName be an implementation-defined string that is either the empty
+  // string or the string-concatenation of the code unit 0x0020 (SPACE), the
+  // code unit 0x0028 (LEFT PARENTHESIS), an implementation-dependent timezone
+  // name, and the code unit 0x0029 (RIGHT PARENTHESIS).
+  // TODO: Make this something other than empty string.
+
+  // 8. Return the string-concatenation of offsetSign, offsetHour, offsetMin,
+  // and tzName.
+  // Example: -0700
+  os << llvm::format("%c%02d%02d", offsetSign, offsetHour, offsetMin);
+}
+
+void dateTimeString(double tv, double tza, llvm::SmallVectorImpl<char> &buf) {
+  llvm::raw_svector_ostream os{buf};
+  dateString(tv, tza, buf);
+  // Return the string-concatenation of DateString(t), the code unit 0x0020
+  // (SPACE), TimeString(t), and TimeZoneString(tv).
+  // Example: Mon Jul 22 2019 15:51:50 GMT-0700
+  os << " ";
+  timeString(tv, tza, buf);
+  timeZoneString(tv, tza, buf);
+}
+
+void dateTimeUTCString(
+    double tv,
+    double tza,
+    llvm::SmallVectorImpl<char> &buf) {
+  llvm::raw_svector_ostream os{buf};
+
+  // Make these ints here because we're printing and we have bounds on
+  // their values. Makes printing very easy.
+  int32_t y = yearFromTime(tv);
+  int32_t m = monthFromTime(tv); // monthFromTime(t) is 0-indexed.
+  int32_t d = dateFromTime(tv);
+  int32_t wd = weekDay(tv);
+
+  // 8. Return the string-concatenation of weekday, ",", the code unit 0x0020
+  // (SPACE), day, the code unit 0x0020 (SPACE), month, the code unit 0x0020
+  // (SPACE), year, the code unit 0x0020 (SPACE), and TimeString(tv).
+  // Example: Mon Jul 22 2019 15:51:50 GMT
+  os << llvm::format(
+      "%s, %02d %s %04d ", weekdayNames[wd], d, monthNames[m], y);
+  timeString(tv, tza, buf);
+}
+
+void timeTZString(double tv, double tza, llvm::SmallVectorImpl<char> &buf) {
+  // Return the string-concatenation of TimeString(t) and TimeZoneString(tv).
+  // Example: 15:51:50 GMT-0700
+  timeString(tv, tza, buf);
+  timeZoneString(tv, tza, buf);
+}
+
 //===----------------------------------------------------------------------===//
 // Date parsing
 

test/hermes/date-constructor.js

@@ -34,7 +34,8 @@ print(new Date(2017, 0, 0).getTime() === new Date(2016, 11, 31).getTime());
 print(new Date(2017, 0, 1).getTime() === new Date(2016, 12, 1).getTime());
 // CHECK-NEXT: true
 print(Date());
-// CHECK-NEXT:{{[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}.[0-9]{3}-07:00}}
+// CHECK-NEXT: {{... ... .. .... ..:..:.. GMT.....}}
+// {{... ... [0-9]{2} [0-9]{4} [0-9]{2}:[0-9]{2}:[0-9]{2} GMT[-+][0-9]{4} }}
 print(typeof Date());
 // CHECK-NEXT: string
 var lb = new Date().toString();
@@ -56,26 +57,26 @@ try {Date.prototype.setDate(123);} catch(e) {print('caught', e.name)}
 print('toString');
 // CHECK-LABEL: toString
 print(new Date(112).toString());
-// CHECK-NEXT: 1969-12-31T17:00:00.112-07:00
+// CHECK-NEXT: Wed Dec 31 1969 17:00:00 GMT-0700
 print(new Date(2017, 2, 15, 15, 1, 37, 243).toString());
-// CHECK-NEXT: 2017-03-15T15:01:37.243-07:00
+// CHECK-NEXT: Wed Mar 15 2017 15:01:37 GMT-0700
 print(new Date(123123, 2, 15, 15, 1, 37, 243).toString());
-// CHECK-NEXT: +123123-03-15T15:01:37.243-07:00
+// CHECK-NEXT: Thu Mar 15 123123 15:01:37 GMT-0700
 print(new Date(-1, 2, 15, 15, 1, 37, 243).toString());
-// CHECK-NEXT: -000001-03-15T15:01:37.243-07:00
+// CHECK-NEXT: Mon Mar 15 -001 15:01:37 GMT-0700
 print(new Date(NaN, 2, 15, 15, 1, 37, 243).toString());
 // CHECK-NEXT: Invalid Date
 print(new Date('2016T12:30').toString());
-// CHECK-NEXT: 2016-01-01T05:30:00.000-07:00
+// CHECK-NEXT: Fri Jan 01 2016 05:30:00 GMT-0700
 
 print('@@toPrimitive');
 // CHECK-LABEL: @@toPrimitive
 print('"' + new Date(112)[Symbol.toPrimitive].name + '"');
 // CHECK-NEXT: "[Symbol.toPrimitive]"
 print(new Date(112)[Symbol.toPrimitive]('string'));
-// CHECK-NEXT: 1969-12-31T17:00:00.112-07:00
+// CHECK-NEXT: Wed Dec 31 1969 17:00:00 GMT-0700
 print(new Date(112)[Symbol.toPrimitive]('default'));
-// CHECK-NEXT: 1969-12-31T17:00:00.112-07:00
+// CHECK-NEXT: Wed Dec 31 1969 17:00:00 GMT-0700
 print(new Date(112)[Symbol.toPrimitive]('number'));
 // CHECK-NEXT: 112
 try {
@@ -99,7 +100,7 @@ try {
 print('toUTCString');
 // CHECK-LABEL: toUTCString
 print(new Date(2017, 2, 15, 15, 1, 37, 243).toUTCString());
-// CHECK-NEXT: 2017-03-15 22:01:37.243Z
+// CHECK-NEXT: Wed, 15 Mar 2017 22:01:37 GMT
 
 print('toJSON');
 // CHECK-LABEL: toJSON
@@ -117,20 +118,20 @@ try {
 print('toDateString');
 // CHECK-LABEL: toDateString
 print(new Date(112).toDateString());
-// CHECK-NEXT: 1969-12-31
+// CHECK-NEXT: Wed Dec 31 1969
 print(new Date(2017, 2, 15, 15, 1, 37, 243).toDateString());
-// CHECK-NEXT: 2017-03-15
+// CHECK-NEXT: Wed Mar 15 2017
 print(new Date(123123, 2, 15, 15, 1, 37, 243).toDateString());
-// CHECK-NEXT: +123123-03-15
+// CHECK-NEXT: Thu Mar 15 123123
 print(new Date(-1, 2, 15, 15, 1, 37, 243).toDateString());
-// CHECK-NEXT: -000001-03-15
+// CHECK-NEXT: Mon Mar 15 -001
 
 print('toTimeString');
 // CHECK-LABEL: toTimeString
 print(new Date(112).toTimeString());
-// CHECK-NEXT: 17:00:00.112-07:00
+// CHECK-NEXT: 17:00:00 GMT-0700
 print(new Date(2017, 2, 15, 15, 1, 37, 243).toTimeString());
-// CHECK-NEXT: 15:01:37.243-07:00
+// CHECK-NEXT: 15:01:37 GMT-0700
 
 print('UTC');
 // CHECK-LABEL: UTC