Add support for DateTimeFormat.formatToParts

src/runtime/runtime-i18n.cc

Index: src/runtime/runtime-i18n.cc
diff --git a/src/runtime/runtime-i18n.cc b/src/runtime/runtime-i18n.cc
index 8b9d92ec006eb570bf14755087d97987b8d04e2d..15fe52d0d90214f6fb3da68698353a3506d1a4ca 100644
--- a/src/runtime/runtime-i18n.cc
+++ b/src/runtime/runtime-i18n.cc
@@ -25,6 +25,8 @@
 #include "unicode/decimfmt.h"
 #include "unicode/dtfmtsym.h"
 #include "unicode/dtptngen.h"
+#include "unicode/fieldpos.h"
+#include "unicode/fpositer.h"
 #include "unicode/locid.h"
 #include "unicode/normalizer2.h"
 #include "unicode/numfmt.h"
@@ -393,6 +395,140 @@ RUNTIME_FUNCTION(Runtime_InternalDateFormat) {
                    result.length())));
 }
 
+namespace {
+// The list comes from third_party/icu/source/i18n/unicode/udat.h.
+// They're mapped to
+// https://tc39.github.io/ecma402/#table-datetimeformat-components
+// TODO(jshin): Map UDAT.*FIELD to DateTimeFormatPartType enums
+// for each of which return NewStringFromStaticChars or 'AtomicString'
+// if available.
+const char* kIcuDateFieldIdToDateType[] = {
+    "era",           // UDAT_ERA_FIELD = 0,
+    "year",          // UDAT_YEAR_FIELD = 1,
+    "month",         // UDAT_MONTH_FIELD = 2,
+    "day",           // UDAT_DATE_FIELD = 3,
+    "hour",          // UDAT_HOUR_OF_DAY1_FIELD = 4,
+    "hour",          // UDAT_HOUR_OF_DAY0_FIELD = 5,
+    "minute",        // UDAT_MINUTE_FIELD = 6,
+    "second",        // UDAT_SECOND_FIELD = 7,
+    nullptr,         // UDAT_FRACTIONAL_SECOND_FIELD = 8,
+    "weekday",       // UDAT_DAY_OF_WEEK_FIELD = 9,
+    nullptr,         // UDAT_DAY_OF_YEAR_FIELD = 10,
+    nullptr,         // UDAT_DAY_OF_WEEK_IN_MONTH_FIELD = 11,
+    nullptr,         // UDAT_WEEK_OF_YEAR_FIELD = 12,
+    nullptr,         // UDAT_WEEK_OF_MONTH_FIELD = 13,
+    "dayperiod",     // UDAT_AM_PM_FIELD = 14,
+    "hour",          // UDAT_HOUR1_FIELD = 15,
+    "hour",          // UDAT_HOUR0_FIELD = 16,
+    "timeZoneName",  // UDAT_TIMEZONE_FIELD = 17,
+    nullptr,         // UDAT_YEAR_WOY_FIELD = 18,
+    "weekday",       // UDAT_DOW_LOCAL_FIELD = 19,
+    "year",          // UDAT_EXTENDED_YEAR_FIELD = 20,
+    "day",           // UDAT_JULIAN_DAY_FIELD = 21,
+    nullptr,         // UDAT_MILLISECONDS_IN_DAY_FIELD = 22,
+    "timeZoneName",  // UDAT_TIMEZONE_RFC_FIELD = 23,
+    "timeZoneName",  // UDAT_TIMEZONE_GENERIC_FIELD = 24,
+    "weekday",       // UDAT_STANDALONE_DAY_FIELD = 25,
+    "month",         // UDAT_STANDALONE_MONTH_FIELD = 26,
+    nullptr,         // UDAT_QUARTER_FIELD = 27,
+    nullptr,         // UDAT_STANDALONE_QUARTER_FIELD = 28,
+    "timeZoneName",  // UDAT_TIMEZONE_SPECIAL_FIELD = 29,
+    "year",          // UDAT_YEAR_NAME_FIELD = 30,
+    "timeZoneName",  // UDAT_TIMEZONE_LOCALIZED_GMT_OFFSET_FIELD = 31,
+    "timeZoneName",  // UDAT_TIMEZONE_ISO_FIELD = 32,
+    "timeZoneName",  // UDAT_TIMEZONE_ISO_LOCAL_FIELD = 33,
+    nullptr,         // UDAT_RELATED_YEAR_FIELD = 34,
+    nullptr,         // UDAT_TIME_SEPARATOR_FIELD = 35,
+    nullptr,         // UDAT_FIELD_COUNT = 36
+};
+
+bool AddElement(Handle<JSArray> array, int index, const char* type,
+                const icu::UnicodeString& formatted, int32_t begin, int32_t end,
+                Handle<Name> type_literal, Handle<Name> value_literal,
+                Isolate* isolate) {

[jungshik at Google, 2016/08/24 23:03:35]

I guess it can be converted to lambda function if desired. 

[Dan Ehrenberg, 2016/08/25 16:54:45]

What do you mean?

+  Factory* factory = isolate->factory();
+  Handle<JSObject> element = factory->NewJSObject(isolate->object_function());
+  Handle<String> value = factory->NewStringFromAsciiChecked(type);
+  JSObject::AddProperty(element, type_literal, value, NONE);
+
+  icu::UnicodeString field;
+  formatted.extractBetween(begin, end, field);
+  ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+      isolate, value, factory->NewStringFromTwoByte(Vector<const uint16_t>(
+                          reinterpret_cast<const uint16_t*>(field.getBuffer()),
+                          field.length())),
+      false);
+
+  JSObject::AddProperty(element, value_literal, value, NONE);
+  RETURN_ON_EXCEPTION_VALUE(
+      isolate, JSObject::AddDataElement(array, index, element, NONE), false);
+  return true;
+}
+
+}  // namespace
+
+RUNTIME_FUNCTION(Runtime_InternalDateFormatToParts) {
+  HandleScope scope(isolate);
+  Factory* factory = isolate->factory();
+
+  DCHECK(args.length() == 2);
+
+  CONVERT_ARG_HANDLE_CHECKED(JSObject, date_format_holder, 0);
+  CONVERT_ARG_HANDLE_CHECKED(JSDate, date, 1);
+
+  Handle<Object> value;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, value, Object::ToNumber(date));
+
+  icu::SimpleDateFormat* date_format =
+      DateFormat::UnpackDateFormat(isolate, date_format_holder);
+  if (!date_format) return isolate->ThrowIllegalOperation();
+
+  icu::UnicodeString formatted;
+  icu::FieldPositionIterator fpIter;
+  icu::FieldPosition fp;
+  UErrorCode status = U_ZERO_ERROR;
+  date_format->format(value->Number(), formatted, &fpIter, status);
+  if (U_FAILURE(status)) return isolate->heap()->undefined_value();
+
+  Handle<JSArray> result = factory->NewJSArray(0);
+  Handle<Name> type_literal = factory->NewStringFromStaticChars("type");
+  Handle<Name> value_literal = factory->NewStringFromStaticChars("value");

[jungshik at Google, 2016/08/24 23:03:35]

Is there a better way to represent the above two constant static strings? 

[Dan Ehrenberg, 2016/08/25 16:54:45]

Yes, you can add them to the INTERNALIZED_STRING_LIST in src/heap-symbols.h

+
+  int index = 0;
+  int32_t previous_end_pos = 0;
+  while (fpIter.next(fp)) {
+    int32_t fieldId = fp.getField();
+    const char* type = kIcuDateFieldIdToDateType[fieldId];
+    int32_t begin_pos = fp.getBeginIndex();
+    int32_t end_pos = fp.getEndIndex();
+    if (type == nullptr) {
+      previous_end_pos = end_pos;
+      continue;
+    }
+    if (previous_end_pos < begin_pos) {
+      if (!AddElement(result, index, "literal", formatted, previous_end_pos,
+                      begin_pos, type_literal, value_literal, isolate)) {
+        return isolate->heap()->undefined_value();
+      }
+      ++index;
+    }
+    if (!AddElement(result, index, type, formatted, begin_pos, end_pos,
+                    type_literal, value_literal, isolate)) {
+      return isolate->heap()->undefined_value();
+    }
+    previous_end_pos = end_pos;
+    ++index;
+  }
+  int32_t length = formatted.length();
+  if (previous_end_pos < length) {
+    if (!AddElement(result, index, "literal", formatted, previous_end_pos,
+                    length, type_literal, value_literal, isolate)) {
+      return isolate->heap()->undefined_value();
+    }
+  }
+  JSObject::ValidateElements(result);
+  return *result;
+}
 
 RUNTIME_FUNCTION(Runtime_InternalDateParse) {
   HandleScope scope(isolate);