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..be5a02a4bad3058cbc4303305440ffa293c7b6d1 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 +395,132 @@ RUNTIME_FUNCTION(Runtime_InternalDateFormat) {
                    result.length())));
 }
 
+namespace {
+// The list comes from third_party/icu/source/i18n/unicode/udat.h.
+// They're mapped to DateTimeFormat components listed at
+// https://tc39.github.io/ecma402/#sec-datetimeformat-abstracts .
+
+Handle<String> IcuDateFieldIdToDateType(int32_t field_id, Isolate* isolate) {
+  switch (field_id) {
+    case -1:
+      return isolate->factory()->literal_string();
+    case UDAT_YEAR_FIELD:
+    case UDAT_EXTENDED_YEAR_FIELD:
+    case UDAT_YEAR_NAME_FIELD:
+      return isolate->factory()->year_string();
+    case UDAT_MONTH_FIELD:
+    case UDAT_STANDALONE_MONTH_FIELD:
+      return isolate->factory()->month_string();
+    case UDAT_DATE_FIELD:
+      return isolate->factory()->day_string();
+    case UDAT_HOUR_OF_DAY1_FIELD:
+    case UDAT_HOUR_OF_DAY0_FIELD:
+    case UDAT_HOUR1_FIELD:
+    case UDAT_HOUR0_FIELD:
+      return isolate->factory()->hour_string();
+    case UDAT_MINUTE_FIELD:
+      return isolate->factory()->minute_string();
+    case UDAT_SECOND_FIELD:
+      return isolate->factory()->second_string();
+    case UDAT_DAY_OF_WEEK_FIELD:
+    case UDAT_DOW_LOCAL_FIELD:
+    case UDAT_STANDALONE_DAY_FIELD:
+      return isolate->factory()->weekday_string();
+    case UDAT_AM_PM_FIELD:
+      return isolate->factory()->dayperiod_string();
+    case UDAT_TIMEZONE_FIELD:
+    case UDAT_TIMEZONE_RFC_FIELD:
+    case UDAT_TIMEZONE_GENERIC_FIELD:
+    case UDAT_TIMEZONE_SPECIAL_FIELD:
+    case UDAT_TIMEZONE_LOCALIZED_GMT_OFFSET_FIELD:
+    case UDAT_TIMEZONE_ISO_FIELD:
+    case UDAT_TIMEZONE_ISO_LOCAL_FIELD:
+      return isolate->factory()->timeZoneName_string();
+    case UDAT_ERA_FIELD:
+      return isolate->factory()->era_string();
+    default:

[Dan Ehrenberg, 2016/08/26 19:07:10]

Could you add a comment explaining why this is UNREACHABLE? It seems like it's
based on a rather subtle property of CLDR/LDML.

+      UNREACHABLE();
+  }
+}
+
+bool AddElement(Handle<JSArray> array, int index, int32_t field_id,
+                const icu::UnicodeString& formatted, int32_t begin, int32_t end,
+                Isolate* isolate) {
+  HandleScope scope(isolate);
+  Factory* factory = isolate->factory();
+  Handle<JSObject> element = factory->NewJSObject(isolate->object_function());
+  Handle<String> value = IcuDateFieldIdToDateType(field_id, isolate);
+  JSObject::AddProperty(element, factory->type_string(), value, NONE);
+
+  icu::UnicodeString field(formatted.tempSubStringBetween(begin, end));
+  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, factory->value_string(), 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 fp_iter;
+  icu::FieldPosition fp;
+  UErrorCode status = U_ZERO_ERROR;
+  date_format->format(value->Number(), formatted, &fp_iter, status);
+  if (U_FAILURE(status)) return isolate->heap()->undefined_value();
+
+  Handle<JSArray> result = factory->NewJSArray(0);
+  int index = 0;
+  int32_t previous_end_pos = 0;
+  while (fp_iter.next(fp)) {
+    int32_t begin_pos = fp.getBeginIndex();
+    int32_t end_pos = fp.getEndIndex();
+
+    if (previous_end_pos < begin_pos) {
+      if (!AddElement(result, index, -1, formatted, previous_end_pos, begin_pos,
+                      isolate)) {
+        return isolate->heap()->undefined_value();
+      }
+      ++index;
+    }
+    if (!AddElement(result, index, fp.getField(), formatted, begin_pos, end_pos,
+                    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, -1, formatted, previous_end_pos, length,
+                    isolate)) {
+      return isolate->heap()->undefined_value();
+    }
+  }
+  JSObject::ValidateElements(result);
+  return *result;
+}
 
 RUNTIME_FUNCTION(Runtime_InternalDateParse) {
   HandleScope scope(isolate);