[Intl] Add Intl.Segmenter.prototype.segment

Design doc https://goo.gl/fgc2Cp

Bug: v8:6891

Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I8bc5ea3137fd1b66213403ae9ea3461f40efc977
Reviewed-on: https://chromium-review.googlesource.com/c/1257923
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56757}

BUILD.gn

@@ -2265,6 +2265,9 @@ v8_source_set("v8_base") {
     "src/objects/js-relative-time-format-inl.h",
     "src/objects/js-relative-time-format.cc",
     "src/objects/js-relative-time-format.h",
+    "src/objects/js-segment-iterator-inl.h",
+    "src/objects/js-segment-iterator.cc",
+    "src/objects/js-segment-iterator.h",
     "src/objects/js-segmenter-inl.h",
     "src/objects/js-segmenter.cc",
     "src/objects/js-segmenter.h",
@@ -2999,6 +3002,9 @@ v8_source_set("v8_base") {
       "src/objects/js-relative-time-format-inl.h",
       "src/objects/js-relative-time-format.cc",
       "src/objects/js-relative-time-format.h",
+      "src/objects/js-segment-iterator-inl.h",
+      "src/objects/js-segment-iterator.cc",
+      "src/objects/js-segment-iterator.h",
       "src/objects/js-segmenter-inl.h",
       "src/objects/js-segmenter.cc",
       "src/objects/js-segmenter.h",

src/bootstrapper.cc

@@ -42,6 +42,7 @@
 #include "src/objects/js-regexp.h"
 #ifdef V8_INTL_SUPPORT
 #include "src/objects/js-relative-time-format.h"
+#include "src/objects/js-segment-iterator.h"
 #include "src/objects/js-segmenter.h"
 #endif  // V8_INTL_SUPPORT
 #include "src/objects/js-weak-refs.h"
@@ -4766,17 +4767,69 @@ void Genesis::InitializeGlobal_harmony_intl_segmenter() {
   SimpleInstallFunction(isolate(), segmenter_fun, "supportedLocalesOf",
                         Builtins::kSegmenterSupportedLocalesOf, 1, false);
 
-  // Setup %SegmenterPrototype%.
-  Handle<JSObject> prototype(
-      JSObject::cast(segmenter_fun->instance_prototype()), isolate());
+  {
+    // Setup %SegmenterPrototype%.
+    Handle<JSObject> prototype(
+        JSObject::cast(segmenter_fun->instance_prototype()), isolate());
 
-  // Install the @@toStringTag property on the {prototype}.
-  JSObject::AddProperty(isolate(), prototype, factory()->to_string_tag_symbol(),
-                        factory()->NewStringFromStaticChars("Intl.Segmenter"),
-                        static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
+    // Install the @@toStringTag property on the {prototype}.
+    JSObject::AddProperty(
+        isolate(), prototype, factory()->to_string_tag_symbol(),
+        factory()->NewStringFromStaticChars("Intl.Segmenter"),
+        static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
 
-  SimpleInstallFunction(isolate(), prototype, "resolvedOptions",
-                        Builtins::kSegmenterPrototypeResolvedOptions, 0, false);
+    SimpleInstallFunction(isolate(), prototype, "resolvedOptions",
+                          Builtins::kSegmenterPrototypeResolvedOptions, 0,
+                          false);
+
+    SimpleInstallFunction(isolate(), prototype, "segment",
+                          Builtins::kSegmenterPrototypeSegment, 1, false);
+  }
+
+  {
+    // Setup %SegmentIteratorPrototype%.
+    Handle<String> name = factory()->SegmentIterator_string();
+    Handle<JSObject> iterator_prototype(
+        native_context()->initial_iterator_prototype(), isolate());
+
+    Handle<JSObject> prototype =
+        factory()->NewJSObject(isolate()->object_function(), TENURED);
+    JSObject::ForceSetPrototype(prototype, iterator_prototype);
+
+    // Install the @@toStringTag property on the {prototype}.
+    JSObject::AddProperty(
+        isolate(), prototype, factory()->to_string_tag_symbol(), name,
+        static_cast<PropertyAttributes>(DONT_ENUM | READ_ONLY));
+
+    SimpleInstallFunction(isolate(), prototype, "next",
+                          Builtins::kSegmentIteratorPrototypeNext, 0, false);
+
+    SimpleInstallFunction(isolate(), prototype, "following",
+                          Builtins::kSegmentIteratorPrototypeFollowing, 0,
+                          false);
+
+    SimpleInstallFunction(isolate(), prototype, "preceding",
+                          Builtins::kSegmentIteratorPrototypePreceding, 0,
+                          false);
+
+    SimpleInstallGetter(isolate(), prototype,
+                        factory()->InternalizeUtf8String("position"),
+                        Builtins::kSegmentIteratorPrototypePosition, false);
+
+    SimpleInstallGetter(isolate(), prototype,
+                        factory()->InternalizeUtf8String("breakType"),
+                        Builtins::kSegmentIteratorPrototypeBreakType, false);
+
+    // Setup SegmentIterator constructor.
+    Handle<JSFunction> segment_iterator_fun = InstallFunction(
+        isolate(), intl, "SegmentIterator", JS_INTL_SEGMENT_ITERATOR_TYPE,
+        JSSegmentIterator::kSize, 0, prototype, Builtins::kIllegal);
+    segment_iterator_fun->shared()->set_native(false);
+
+    Handle<Map> segment_iterator_map(segment_iterator_fun->initial_map(),
+                                     isolate());
+    native_context()->set_intl_segment_iterator_map(*segment_iterator_map);
+  }
 }
 
 #endif  // V8_INTL_SUPPORT

src/builtins/builtins-definitions.h

@@ -1429,6 +1429,24 @@ namespace internal {
   CPP(RelativeTimeFormatPrototypeResolvedOptions)                      \
   /* ecma402 #sec-intl.RelativeTimeFormat.supportedlocalesof */        \
   CPP(RelativeTimeFormatSupportedLocalesOf)                            \
+  /* ecma402 #sec-Intl.Segmenter */                                    \
+  CPP(SegmenterConstructor)                                            \
+  /* ecma402 #sec-Intl.Segmenter.prototype.resolvedOptions */          \
+  CPP(SegmenterPrototypeResolvedOptions)                               \
+  /* ecma402 #sec-Intl.Segmenter.prototype.segment  */                 \
+  CPP(SegmenterPrototypeSegment)                                       \
+  /* ecma402  #sec-Intl.Segmenter.supportedLocalesOf */                \
+  CPP(SegmenterSupportedLocalesOf)                                     \
+  /* ecma402 #sec-segment-iterator-prototype-breakType */              \
+  CPP(SegmentIteratorPrototypeBreakType)                               \
+  /* ecma402 #sec-segment-iterator-prototype-following */              \
+  CPP(SegmentIteratorPrototypeFollowing)                               \
+  /* ecma402 #sec-segment-iterator-prototype-preceding */              \
+  CPP(SegmentIteratorPrototypePreceding)                               \
+  /* ecma402 #sec-segment-iterator-prototype-position */               \
+  CPP(SegmentIteratorPrototypePosition)                                \
+  /* ecma402 #sec-segment-iterator-prototype-next */                   \
+  CPP(SegmentIteratorPrototypeNext)                                    \
   /* ES #sec-string.prototype.normalize */                             \
   CPP(StringPrototypeNormalizeIntl)                                    \
   /* ecma402 #sup-string.prototype.tolocalelowercase */                \
@@ -1440,12 +1458,6 @@ namespace internal {
   /* ES #sec-string.prototype.touppercase */                           \
   CPP(StringPrototypeToUpperCaseIntl)                                  \
   TFS(StringToLowerCaseIntl, kString)                                  \
-  /* ecma402 #sec-Intl.Segmenter */                                    \
-  CPP(SegmenterConstructor)                                            \
-  /* ecma402 #sec-Intl.Segmenter.prototype.resolvedOptions */          \
-  CPP(SegmenterPrototypeResolvedOptions)                               \
-  /* ecma402  #sec-Intl.Segmenter.supportedLocalesOf */                \
-  CPP(SegmenterSupportedLocalesOf)                                     \
   CPP(V8BreakIteratorConstructor)                                      \
   CPP(V8BreakIteratorInternalAdoptText)                                \
   CPP(V8BreakIteratorInternalBreakType)                                \

src/builtins/builtins-intl.cc

@@ -26,6 +26,7 @@
 #include "src/objects/js-number-format-inl.h"
 #include "src/objects/js-plural-rules-inl.h"
 #include "src/objects/js-relative-time-format-inl.h"
+#include "src/objects/js-segment-iterator-inl.h"
 #include "src/objects/js-segmenter-inl.h"
 #include "src/property-descriptor.h"
 
@@ -1014,6 +1015,62 @@ BUILTIN(CollatorInternalCompare) {
   return *Intl::CompareStrings(isolate, collator_holder, string_x, string_y);
 }
 
+// ecma402 #sec-segment-iterator-prototype-breakType
+BUILTIN(SegmentIteratorPrototypeBreakType) {
+  const char* const method = "get %SegmentIteratorPrototype%.breakType";
+  HandleScope scope(isolate);
+
+  CHECK_RECEIVER(JSSegmentIterator, segment_iterator, method);
+  return *segment_iterator->BreakType();
+}
+
+// ecma402 #sec-segment-iterator-prototype-following
+BUILTIN(SegmentIteratorPrototypeFollowing) {
+  const char* const method = "%SegmentIteratorPrototype%.following";
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSSegmentIterator, segment_iterator, method);
+
+  Handle<Object> from = args.atOrUndefined(isolate, 1);
+
+  Maybe<bool> success =
+      JSSegmentIterator::Following(isolate, segment_iterator, from);
+  MAYBE_RETURN(success, ReadOnlyRoots(isolate).exception());
+  return *isolate->factory()->ToBoolean(success.FromJust());
+}
+
+// ecma402 #sec-segment-iterator-prototype-next
+BUILTIN(SegmentIteratorPrototypeNext) {
+  const char* const method = "%SegmentIteratorPrototype%.next";
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSSegmentIterator, segment_iterator, method);
+
+  RETURN_RESULT_OR_FAILURE(isolate,
+                           JSSegmentIterator::Next(isolate, segment_iterator));
+}
+
+// ecma402 #sec-segment-iterator-prototype-preceding
+BUILTIN(SegmentIteratorPrototypePreceding) {
+  const char* const method = "%SegmentIteratorPrototype%.preceding";
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSSegmentIterator, segment_iterator, method);
+
+  Handle<Object> from = args.atOrUndefined(isolate, 1);
+
+  Maybe<bool> success =
+      JSSegmentIterator::Preceding(isolate, segment_iterator, from);
+  MAYBE_RETURN(success, ReadOnlyRoots(isolate).exception());
+  return *isolate->factory()->ToBoolean(success.FromJust());
+}
+
+// ecma402 #sec-segment-iterator-prototype-position
+BUILTIN(SegmentIteratorPrototypePosition) {
+  const char* const method = "get %SegmentIteratorPrototype%.position";
+  HandleScope scope(isolate);
+
+  CHECK_RECEIVER(JSSegmentIterator, segment_iterator, method);
+  return *JSSegmentIterator::Position(isolate, segment_iterator);
+}
+
 BUILTIN(SegmenterConstructor) {
   HandleScope scope(isolate);
 
@@ -1063,6 +1120,25 @@ BUILTIN(SegmenterPrototypeResolvedOptions) {
   return *JSSegmenter::ResolvedOptions(isolate, segmenter_holder);
 }
 
+// ecma402 #sec-Intl.Segmenter.prototype.segment
+BUILTIN(SegmenterPrototypeSegment) {
+  HandleScope scope(isolate);
+  CHECK_RECEIVER(JSSegmenter, segmenter_holder,
+                 "Intl.Segmenter.prototype.segment");
+  Handle<Object> input_text = args.atOrUndefined(isolate, 1);
+  // 3. Let string be ? ToString(string).
+  Handle<String> text;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, text,
+                                     Object::ToString(isolate, input_text));
+
+  // 4. Return ? CreateSegmentIterator(segment, string).
+  RETURN_RESULT_OR_FAILURE(
+      isolate,
+      JSSegmentIterator::Create(
+          isolate, segmenter_holder->icu_break_iterator()->raw()->clone(),
+          segmenter_holder->granularity(), text));
+}
+
 BUILTIN(V8BreakIteratorConstructor) {
   HandleScope scope(isolate);
   Handle<JSReceiver> new_target;

src/compiler/code-assembler.h

@@ -44,6 +44,7 @@ class JSNumberFormat;
 class JSPluralRules;
 class JSRegExpStringIterator;
 class JSRelativeTimeFormat;
+class JSSegmentIterator;
 class JSSegmenter;
 class JSV8BreakIterator;
 class JSWeakCell;

src/compiler/types.cc

@@ -218,6 +218,7 @@ Type::bitset BitsetType::Lub(const MapRefLike& map) {
     case JS_INTL_NUMBER_FORMAT_TYPE:
     case JS_INTL_PLURAL_RULES_TYPE:
     case JS_INTL_RELATIVE_TIME_FORMAT_TYPE:
+    case JS_INTL_SEGMENT_ITERATOR_TYPE:
     case JS_INTL_SEGMENTER_TYPE:
 #endif  // V8_INTL_SUPPORT
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:

src/contexts.h

@@ -208,6 +208,7 @@ enum ContextLookupFlags {
   V(INTL_NUMBER_FORMAT_FUNCTION_INDEX, JSFunction,                             \
     intl_number_format_function)                                               \
   V(INTL_LOCALE_FUNCTION_INDEX, JSFunction, intl_locale_function)              \
+  V(INTL_SEGMENT_ITERATOR_MAP_INDEX, Map, intl_segment_iterator_map)           \
   V(JS_ARRAY_PACKED_SMI_ELEMENTS_MAP_INDEX, Map,                               \
     js_array_packed_smi_elements_map)                                          \
   V(JS_ARRAY_HOLEY_SMI_ELEMENTS_MAP_INDEX, Map,                                \

src/heap-symbols.h

@@ -7,6 +7,7 @@
 
 #ifdef V8_INTL_SUPPORT
 #define INTERNALIZED_STRING_LIST_GENERATOR_INTL(V, _)               \
+  V(_, breakType_string, "breakType")                               \
   V(_, calendar_string, "calendar")                                 \
   V(_, caseFirst_string, "caseFirst")                               \
   V(_, day_string, "day")                                           \
@@ -14,11 +15,14 @@
   V(_, decimal_string, "decimal")                                   \
   V(_, era_string, "era")                                           \
   V(_, fraction_string, "fraction")                                 \
+  V(_, granularity_string, "granularity")                           \
+  V(_, grapheme_string, "grapheme")                                 \
   V(_, group_string, "group")                                       \
   V(_, h11_string, "h11")                                           \
   V(_, h12_string, "h12")                                           \
   V(_, h23_string, "h23")                                           \
   V(_, h24_string, "h24")                                           \
+  V(_, hard_string, "hard")                                         \
   V(_, hour_string, "hour")                                         \
   V(_, hour12_string, "hour12")                                     \
   V(_, hourCycle_string, "hourCycle")                               \
@@ -28,9 +32,11 @@
   V(_, ignorePunctuation_string, "ignorePunctuation")               \
   V(_, Invalid_Date_string, "Invalid Date")                         \
   V(_, integer_string, "integer")                                   \
+  V(_, lineBreakStyle_string, "lineBreakStyle")                     \
   V(_, literal_string, "literal")                                   \
   V(_, locale_string, "locale")                                     \
   V(_, localeWithExtension_string, "localeWithExtension")           \
+  V(_, loose_string, "loose")                                       \
   V(_, lower_string, "lower")                                       \
   V(_, maximumFractionDigits_string, "maximumFractionDigits")       \
   V(_, maximumSignificantDigits_string, "maximumSignificantDigits") \
@@ -41,14 +47,22 @@
   V(_, minusSign_string, "minusSign")                               \
   V(_, minute_string, "minute")                                     \
   V(_, month_string, "month")                                       \
+  V(_, none_string, "none")                                         \
+  V(_, normal_string, "normal")                                     \
   V(_, numberingSystem_string, "numberingSystem")                   \
   V(_, numeric_string, "numeric")                                   \
   V(_, percentSign_string, "percentSign")                           \
   V(_, plusSign_string, "plusSign")                                 \
   V(_, quarter_string, "quarter")                                   \
   V(_, second_string, "second")                                     \
+  V(_, segment_string, "segment")                                   \
+  V(_, SegmentIterator_string, "Segment Iterator")                  \
   V(_, sensitivity_string, "sensitivity")                           \
+  V(_, sep_string, "sep")                                           \
+  V(_, soft_string, "soft")                                         \
+  V(_, strict_string, "strict")                                     \
   V(_, style_string, "style")                                       \
+  V(_, term_string, "term")                                         \
   V(_, timeZone_string, "timeZone")                                 \
   V(_, timeZoneName_string, "timeZoneName")                         \
   V(_, type_string, "type")                                         \
@@ -151,8 +165,6 @@
   V(_, getPrototypeOf_string, "getPrototypeOf")                       \
   V(_, global_string, "global")                                       \
   V(_, globalThis_string, "globalThis")                               \
-  V(_, granularity_string, "granularity")                             \
-  V(_, grapheme_string, "grapheme")                                   \
   V(_, groups_string, "groups")                                       \
   V(_, has_string, "has")                                             \
   V(_, holdings_string, "holdings")                                   \
@@ -174,11 +186,9 @@
   V(_, lastIndex_string, "lastIndex")                                 \
   V(_, length_string, "length")                                       \
   V(_, let_string, "let")                                             \
-  V(_, lineBreakStyle_string, "lineBreakStyle")                       \
   V(_, line_string, "line")                                           \
   V(_, LinkError_string, "LinkError")                                 \
   V(_, long_string, "long")                                           \
-  V(_, loose_string, "loose")                                         \
   V(_, makeCell_string, "makeCell")                                   \
   V(_, Map_string, "Map")                                             \
   V(_, MapIterator_string, "Map Iterator")                            \
@@ -198,7 +208,6 @@
   V(_, NFKC_string, "NFKC")                                           \
   V(_, NFKD_string, "NFKD")                                           \
   V(_, not_equal, "not-equal")                                        \
-  V(_, normal_string, "normal")                                       \
   V(_, null_string, "null")                                           \
   V(_, null_to_string, "[object Null]")                               \
   V(_, Number_string, "Number")                                       \
@@ -248,7 +257,6 @@
   V(_, stackTraceLimit_string, "stackTraceLimit")                     \
   V(_, star_default_star_string, "*default*")                         \
   V(_, sticky_string, "sticky")                                       \
-  V(_, strict_string, "strict")                                       \
   V(_, String_string, "String")                                       \
   V(_, string_string, "string")                                       \
   V(_, string_to_string, "[object String]")                           \

src/message-template.h

@@ -326,6 +326,8 @@ namespace internal {
   T(LetInLexicalBinding, "let is disallowed as a lexically bound name")        \
   T(LocaleMatcher, "Illegal value for localeMatcher:%")                        \
   T(NormalizationForm, "The normalization form should be one of %.")           \
+  T(ParameterOfFunctionOutOfRange,                                             \
+    "Paramenter % of function %() is % and out of range")                      \
   T(ZeroDigitNumericSeparator,                                                 \
     "Numeric separator can not be used after leading 0.")                      \
   T(NumberFormatRange, "% argument must be between 0 and 100")                 \

src/objects-body-descriptors-inl.h

@@ -833,6 +833,7 @@ ReturnType BodyDescriptorApply(InstanceType type, T1 p1, T2 p2, T3 p3, T4 p4) {
     case JS_INTL_NUMBER_FORMAT_TYPE:
     case JS_INTL_PLURAL_RULES_TYPE:
     case JS_INTL_RELATIVE_TIME_FORMAT_TYPE:
+    case JS_INTL_SEGMENT_ITERATOR_TYPE:
     case JS_INTL_SEGMENTER_TYPE:
 #endif  // V8_INTL_SUPPORT
     case WASM_EXCEPTION_TYPE:

src/objects-debug.cc

@@ -38,6 +38,7 @@
 #include "src/objects/js-regexp-string-iterator-inl.h"
 #ifdef V8_INTL_SUPPORT
 #include "src/objects/js-relative-time-format-inl.h"
+#include "src/objects/js-segment-iterator-inl.h"
 #include "src/objects/js-segmenter-inl.h"
 #endif  // V8_INTL_SUPPORT
 #include "src/objects/js-weak-refs-inl.h"
@@ -404,6 +405,9 @@ void HeapObject::HeapObjectVerify(Isolate* isolate) {
     case JS_INTL_RELATIVE_TIME_FORMAT_TYPE:
       JSRelativeTimeFormat::cast(this)->JSRelativeTimeFormatVerify(isolate);
       break;
+    case JS_INTL_SEGMENT_ITERATOR_TYPE:
+      JSSegmentIterator::cast(this)->JSSegmentIteratorVerify(isolate);
+      break;
     case JS_INTL_SEGMENTER_TYPE:
       JSSegmenter::cast(this)->JSSegmenterVerify(isolate);
       break;
@@ -2023,6 +2027,13 @@ void JSRelativeTimeFormat::JSRelativeTimeFormatVerify(Isolate* isolate) {
   VerifyObjectField(isolate, kFlagsOffset);
 }
 
+void JSSegmentIterator::JSSegmentIteratorVerify(Isolate* isolate) {
+  JSObjectVerify(isolate);
+  VerifyObjectField(isolate, kICUBreakIteratorOffset);
+  VerifyObjectField(isolate, kUnicodeStringOffset);
+  VerifyObjectField(isolate, kFlagsOffset);
+}
+
 void JSSegmenter::JSSegmenterVerify(Isolate* isolate) {
   JSObjectVerify(isolate);
   VerifyObjectField(isolate, kLocaleOffset);

src/objects-definitions.h

@@ -232,6 +232,7 @@ namespace internal {
   V(JS_INTL_NUMBER_FORMAT_TYPE)        \
   V(JS_INTL_PLURAL_RULES_TYPE)         \
   V(JS_INTL_RELATIVE_TIME_FORMAT_TYPE) \
+  V(JS_INTL_SEGMENT_ITERATOR_TYPE)     \
   V(JS_INTL_SEGMENTER_TYPE)            \
   INSTANCE_TYPE_LIST_AFTER_INTL(V)
 #else

src/objects-printer.cc

@@ -38,6 +38,7 @@
 #include "src/objects/js-regexp-string-iterator-inl.h"
 #ifdef V8_INTL_SUPPORT
 #include "src/objects/js-relative-time-format-inl.h"
+#include "src/objects/js-segment-iterator-inl.h"
 #include "src/objects/js-segmenter-inl.h"
 #endif  // V8_INTL_SUPPORT
 #include "src/objects/js-weak-refs-inl.h"
@@ -355,6 +356,9 @@ void HeapObject::HeapObjectPrint(std::ostream& os) {  // NOLINT
     case JS_INTL_RELATIVE_TIME_FORMAT_TYPE:
       JSRelativeTimeFormat::cast(this)->JSRelativeTimeFormatPrint(os);
       break;
+    case JS_INTL_SEGMENT_ITERATOR_TYPE:
+      JSSegmentIterator::cast(this)->JSSegmentIteratorPrint(os);
+      break;
     case JS_INTL_SEGMENTER_TYPE:
       JSSegmenter::cast(this)->JSSegmenterPrint(os);
       break;
@@ -2071,12 +2075,20 @@ void JSRelativeTimeFormat::JSRelativeTimeFormatPrint(
   os << "\n";
 }
 
+void JSSegmentIterator::JSSegmentIteratorPrint(std::ostream& os) {  // NOLINT
+  JSObjectPrintHeader(os, this, "JSSegmentIterator");
+  os << "\n - icu break iterator: " << Brief(icu_break_iterator());
+  os << "\n - unicode string: " << Brief(unicode_string());
+  os << "\n - granularity: " << GranularityAsString();
+  os << "\n";
+}
+
 void JSSegmenter::JSSegmenterPrint(std::ostream& os) {  // NOLINT
   JSObjectPrintHeader(os, this, "JSSegmenter");
   os << "\n - locale: " << Brief(locale());
   os << "\n - granularity: " << GranularityAsString();
   os << "\n - lineBreakStyle: " << LineBreakStyleAsString();
-  os << "\n - icubreak iterator: " << Brief(icu_break_iterator());
+  os << "\n - icu break iterator: " << Brief(icu_break_iterator());
   os << "\n";
 }
 #endif  // V8_INTL_SUPPORT

src/objects.cc

@@ -79,6 +79,7 @@
 #include "src/objects/js-regexp-string-iterator.h"
 #ifdef V8_INTL_SUPPORT
 #include "src/objects/js-relative-time-format.h"
+#include "src/objects/js-segment-iterator.h"
 #include "src/objects/js-segmenter.h"
 #endif  // V8_INTL_SUPPORT
 #include "src/objects/js-weak-refs-inl.h"
@@ -1484,6 +1485,8 @@ int JSObject::GetHeaderSize(InstanceType type,
       return JSPluralRules::kSize;
     case JS_INTL_RELATIVE_TIME_FORMAT_TYPE:
       return JSRelativeTimeFormat::kSize;
+    case JS_INTL_SEGMENT_ITERATOR_TYPE:
+      return JSSegmentIterator::kSize;
     case JS_INTL_SEGMENTER_TYPE:
       return JSSegmenter::kSize;
 #endif  // V8_INTL_SUPPORT
@@ -3242,6 +3245,7 @@ VisitorId Map::GetVisitorId(Map* map) {
     case JS_INTL_NUMBER_FORMAT_TYPE:
     case JS_INTL_PLURAL_RULES_TYPE:
     case JS_INTL_RELATIVE_TIME_FORMAT_TYPE:
+    case JS_INTL_SEGMENT_ITERATOR_TYPE:
     case JS_INTL_SEGMENTER_TYPE:
 #endif  // V8_INTL_SUPPORT
     case WASM_EXCEPTION_TYPE:
@@ -13118,6 +13122,7 @@ bool CanSubclassHaveInobjectProperties(InstanceType instance_type) {
     case JS_INTL_NUMBER_FORMAT_TYPE:
     case JS_INTL_PLURAL_RULES_TYPE:
     case JS_INTL_RELATIVE_TIME_FORMAT_TYPE:
+    case JS_INTL_SEGMENT_ITERATOR_TYPE:
     case JS_INTL_SEGMENTER_TYPE:
     case JS_INTL_V8_BREAK_ITERATOR_TYPE:
 #endif

src/objects.h

@@ -84,6 +84,7 @@
 //         - JSNumberFormat        // If V8_INTL_SUPPORT enabled.
 //         - JSPluralRules         // If V8_INTL_SUPPORT enabled.
 //         - JSRelativeTimeFormat  // If V8_INTL_SUPPORT enabled.
+//         - JSSegmentIterator     // If V8_INTL_SUPPORT enabled.
 //         - JSSegmenter           // If V8_INTL_SUPPORT enabled.
 //         - WasmExceptionObject
 //         - WasmGlobalObject
@@ -537,6 +538,7 @@ enum InstanceType : uint16_t {
   JS_INTL_NUMBER_FORMAT_TYPE,
   JS_INTL_PLURAL_RULES_TYPE,
   JS_INTL_RELATIVE_TIME_FORMAT_TYPE,
+  JS_INTL_SEGMENT_ITERATOR_TYPE,
   JS_INTL_SEGMENTER_TYPE,
 #endif  // V8_INTL_SUPPORT
 
@@ -865,6 +867,7 @@ class ZoneForwardList;
   V(JSNumberFormat)                       \
   V(JSPluralRules)                        \
   V(JSRelativeTimeFormat)                 \
+  V(JSSegmentIterator)                    \
   V(JSSegmenter)
 #else
 #define HEAP_OBJECT_ORDINARY_TYPE_LIST(V) HEAP_OBJECT_ORDINARY_TYPE_LIST_BASE(V)
@@ -995,6 +998,7 @@ class ZoneForwardList;
   V(JSNumberFormat, JS_INTL_NUMBER_FORMAT_TYPE)              \
   V(JSPluralRules, JS_INTL_PLURAL_RULES_TYPE)                \
   V(JSRelativeTimeFormat, JS_INTL_RELATIVE_TIME_FORMAT_TYPE) \
+  V(JSSegmentIterator, JS_INTL_SEGMENT_ITERATOR_TYPE)        \
   V(JSSegmenter, JS_INTL_SEGMENTER_TYPE)
 
 #else

src/objects/intl-objects.cc

@@ -1557,5 +1557,25 @@ Intl::ResolvedLocale Intl::ResolveLocale(
   return Intl::ResolvedLocale{locale, icu_locale, extensions};
 }
 
+Managed<icu::UnicodeString>* Intl::SetTextToBreakIterator(
+    Isolate* isolate, Handle<String> text, icu::BreakIterator* break_iterator) {
+  icu::UnicodeString* u_text;
+  int length = text->length();
+  text = String::Flatten(isolate, text);
+  {
+    DisallowHeapAllocation no_gc;
+    String::FlatContent flat = text->GetFlatContent();
+    std::unique_ptr<uc16[]> sap;
+    const UChar* text_value = GetUCharBufferFromFlat(flat, &sap, length);
+    u_text = new icu::UnicodeString(text_value, length);
+  }
+
+  Handle<Managed<icu::UnicodeString>> new_u_text =
+      Managed<icu::UnicodeString>::FromRawPtr(isolate, 0, u_text);
+
+  break_iterator->setText(*u_text);
+  return *new_u_text;
+}
+
 }  // namespace internal
 }  // namespace v8

src/objects/intl-objects.h

@@ -16,10 +16,12 @@
 #include "src/contexts.h"
 #include "src/intl.h"
 #include "src/objects.h"
+#include "src/objects/managed.h"
 #include "unicode/locid.h"
 #include "unicode/uversion.h"
 
 namespace U_ICU_NAMESPACE {
+class BreakIterator;
 class DecimalFormat;
 class SimpleDateFormat;
 class UnicodeString;
@@ -218,6 +220,11 @@ class Intl {
       Isolate* isolate, const std::set<std::string>& available_locales,
       const std::vector<std::string>& requested_locales, MatcherOption options,
       const std::set<std::string>& relevant_extension_keys);
+
+  // Utility function to set text to BreakIterator.
+  static Managed<icu::UnicodeString>* SetTextToBreakIterator(
+      Isolate* isolate, Handle<String> text,
+      icu::BreakIterator* break_iterator);
 };
 
 }  // namespace internal

src/objects/js-break-iterator.cc

@@ -146,25 +146,12 @@ Handle<JSObject> JSV8BreakIterator::ResolvedOptions(
 void JSV8BreakIterator::AdoptText(
     Isolate* isolate, Handle<JSV8BreakIterator> break_iterator_holder,
     Handle<String> text) {
-  icu::UnicodeString* u_text;
-  int length = text->length();
-  text = String::Flatten(isolate, text);
-  {
-    DisallowHeapAllocation no_gc;
-    String::FlatContent flat = text->GetFlatContent();
-    std::unique_ptr<uc16[]> sap;
-    const UChar* text_value = GetUCharBufferFromFlat(flat, &sap, length);
-    u_text = new icu::UnicodeString(text_value, length);
-  }
-
-  Handle<Managed<icu::UnicodeString>> new_u_text =
-      Managed<icu::UnicodeString>::FromRawPtr(isolate, 0, u_text);
-  break_iterator_holder->set_unicode_string(*new_u_text);
-
   icu::BreakIterator* break_iterator =
       break_iterator_holder->break_iterator()->raw();
   CHECK_NOT_NULL(break_iterator);
-  break_iterator->setText(*u_text);
+  Managed<icu::UnicodeString>* unicode_string =
+      Intl::SetTextToBreakIterator(isolate, text, break_iterator);
+  break_iterator_holder->set_unicode_string(unicode_string);
 }
 
 Handle<String> JSV8BreakIterator::TypeAsString() const {

src/objects/js-segment-iterator-inl.h

+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_INTL_SUPPORT
+#error Internationalization is expected to be enabled.
+#endif  // V8_INTL_SUPPORT
+
+#ifndef V8_OBJECTS_JS_SEGMENT_ITERATOR_INL_H_
+#define V8_OBJECTS_JS_SEGMENT_ITERATOR_INL_H_
+
+#include "src/objects-inl.h"
+#include "src/objects/js-segment-iterator.h"
+
+// Has to be the last include (doesn't have include guards):
+#include "src/objects/object-macros.h"
+
+namespace v8 {
+namespace internal {
+
+// Base segment iterator accessors.
+ACCESSORS(JSSegmentIterator, icu_break_iterator, Managed<icu::BreakIterator>,
+          kICUBreakIteratorOffset)
+ACCESSORS(JSSegmentIterator, unicode_string, Managed<icu::UnicodeString>,
+          kUnicodeStringOffset)
+
+SMI_ACCESSORS(JSSegmentIterator, flags, kFlagsOffset)
+
+CAST_ACCESSOR(JSSegmentIterator);
+
+inline void JSSegmentIterator::set_granularity(
+    JSSegmenter::Granularity granularity) {
+  DCHECK_GT(JSSegmenter::Granularity::COUNT, granularity);
+  int hints = flags();
+  hints = GranularityBits::update(hints, granularity);
+  set_flags(hints);
+}
+
+inline JSSegmenter::Granularity JSSegmentIterator::granularity() const {
+  return GranularityBits::decode(flags());
+}
+
+}  // namespace internal
+}  // namespace v8
+
+#include "src/objects/object-macros-undef.h"
+
+#endif  // V8_OBJECTS_JS_SEGMENT_ITERATOR_INL_H_

src/objects/js-segment-iterator.cc

+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_INTL_SUPPORT
+#error Internationalization is expected to be enabled.
+#endif  // V8_INTL_SUPPORT
+
+#include "src/objects/js-segment-iterator.h"
+
+#include <map>
+#include <memory>
+#include <string>
+
+#include "src/heap/factory.h"
+#include "src/intl.h"
+#include "src/isolate.h"
+#include "src/objects-inl.h"
+#include "src/objects/intl-objects.h"
+#include "src/objects/js-segment-iterator-inl.h"
+#include "src/objects/managed.h"
+#include "unicode/brkiter.h"
+
+namespace v8 {
+namespace internal {
+
+MaybeHandle<String> JSSegmentIterator::GetSegment(Isolate* isolate,
+                                                  int32_t start,
+                                                  int32_t end) const {
+  return Intl::ToString(isolate, *(unicode_string()->raw()), start, end);
+}
+
+Handle<String> JSSegmentIterator::GranularityAsString() const {
+  switch (granularity()) {
+    case JSSegmenter::Granularity::GRAPHEME:
+      return GetReadOnlyRoots().grapheme_string_handle();
+    case JSSegmenter::Granularity::WORD:
+      return GetReadOnlyRoots().word_string_handle();
+    case JSSegmenter::Granularity::SENTENCE:
+      return GetReadOnlyRoots().sentence_string_handle();
+    case JSSegmenter::Granularity::LINE:
+      return GetReadOnlyRoots().line_string_handle();
+    case JSSegmenter::Granularity::COUNT:
+      UNREACHABLE();
+  }
+}
+
+MaybeHandle<JSSegmentIterator> JSSegmentIterator::Create(
+    Isolate* isolate, icu::BreakIterator* break_iterator,
+    JSSegmenter::Granularity granularity, Handle<String> text) {
+  CHECK_NOT_NULL(break_iterator);
+  // 1. Let iterator be ObjectCreate(%SegmentIteratorPrototype%).
+  Handle<Map> map = Handle<Map>(
+      isolate->native_context()->intl_segment_iterator_map(), isolate);
+  Handle<JSObject> result = isolate->factory()->NewJSObjectFromMap(map);
+
+  Handle<JSSegmentIterator> segment_iterator =
+      Handle<JSSegmentIterator>::cast(result);
+
+  segment_iterator->set_flags(0);
+  segment_iterator->set_granularity(granularity);
+  // 2. Let iterator.[[SegmentIteratorSegmenter]] be segmenter.
+  Handle<Managed<icu::BreakIterator>> managed_break_iterator =
+      Managed<icu::BreakIterator>::FromRawPtr(isolate, 0, break_iterator);
+  segment_iterator->set_icu_break_iterator(*managed_break_iterator);
+
+  // 3. Let iterator.[[SegmentIteratorString]] be string.
+  Managed<icu::UnicodeString>* unicode_string =
+      Intl::SetTextToBreakIterator(isolate, text, break_iterator);
+  segment_iterator->set_unicode_string(unicode_string);
+
+  // 4. Let iterator.[[SegmentIteratorPosition]] be 0.
+  // 5. Let iterator.[[SegmentIteratorBreakType]] be an implementation-dependent
+  // string representing a break at the edge of a string.
+  // step 4 and 5 are stored inside break_iterator.
+
+  return segment_iterator;
+}
+
+// ecma402 #sec-segment-iterator-prototype-breakType
+Handle<Object> JSSegmentIterator::BreakType() const {
+  icu::BreakIterator* break_iterator = icu_break_iterator()->raw();
+  int32_t rule_status = break_iterator->getRuleStatus();
+  switch (granularity()) {
+    case JSSegmenter::Granularity::GRAPHEME:
+      return GetReadOnlyRoots().undefined_value_handle();
+    case JSSegmenter::Granularity::WORD:
+      if (rule_status >= UBRK_WORD_NONE && rule_status < UBRK_WORD_NONE_LIMIT) {
+        // "words" that do not fit into any of other categories. Includes spaces
+        // and most punctuation.
+        return GetReadOnlyRoots().none_string_handle();
+      }
+      if ((rule_status >= UBRK_WORD_NUMBER &&
+           rule_status < UBRK_WORD_NUMBER_LIMIT) ||
+          (rule_status >= UBRK_WORD_LETTER &&
+           rule_status < UBRK_WORD_LETTER_LIMIT) ||
+          (rule_status >= UBRK_WORD_KANA &&
+           rule_status < UBRK_WORD_KANA_LIMIT) ||
+          (rule_status >= UBRK_WORD_IDEO &&
+           rule_status < UBRK_WORD_IDEO_LIMIT)) {
+        // words that appear to be numbers, letters, kana characters,
+        // ideographic characters, etc
+        return GetReadOnlyRoots().word_string_handle();
+      }
+      return GetReadOnlyRoots().undefined_value_handle();
+    case JSSegmenter::Granularity::LINE:
+      if (rule_status >= UBRK_LINE_SOFT && rule_status < UBRK_LINE_SOFT_LIMIT) {
+        // soft line breaks, positions at which a line break is acceptable but
+        // not required
+        return GetReadOnlyRoots().soft_string_handle();
+      }
+      if ((rule_status >= UBRK_LINE_HARD &&
+           rule_status < UBRK_LINE_HARD_LIMIT)) {
+        // hard, or mandatory line breaks
+        return GetReadOnlyRoots().hard_string_handle();
+      }
+      return GetReadOnlyRoots().undefined_value_handle();
+    case JSSegmenter::Granularity::SENTENCE:
+      if (rule_status >= UBRK_SENTENCE_TERM &&
+          rule_status < UBRK_SENTENCE_TERM_LIMIT) {
+        // sentences ending with a sentence terminator ('.', '?', '!', etc.)
+        // character, possibly followed by a hard separator (CR, LF, PS, etc.)
+        return GetReadOnlyRoots().term_string_handle();
+      }
+      if ((rule_status >= UBRK_SENTENCE_SEP &&
+           rule_status < UBRK_SENTENCE_SEP_LIMIT)) {
+        // sentences that do not contain an ending sentence terminator ('.',
+        // '?', '!', etc.) character, but are ended only by a hard separator
+        // (CR, LF, PS, etc.) hard, or mandatory line breaks
+        return GetReadOnlyRoots().sep_string_handle();
+      }
+      return GetReadOnlyRoots().undefined_value_handle();
+    case JSSegmenter::Granularity::COUNT:
+      UNREACHABLE();
+  }
+}
+
+// ecma402 #sec-segment-iterator-prototype-position
+Handle<Object> JSSegmentIterator::Position(
+    Isolate* isolate, Handle<JSSegmentIterator> segment_iterator) {
+  icu::BreakIterator* icu_break_iterator =
+      segment_iterator->icu_break_iterator()->raw();
+  CHECK_NOT_NULL(icu_break_iterator);
+  return isolate->factory()->NewNumberFromInt(icu_break_iterator->current());
+}
+
+namespace {
+
+Handle<JSReceiver> CreateResultForNext(Isolate* isolate, Handle<String> segment,
+                                       Handle<Object> break_type) {
+  Factory* factory = isolate->factory();
+  // Step 10-13 of %SegmentIteratorPrototype%.next( )
+  // ecma402 #sec-segment-iterator-prototype-next
+  // 10. Let result be ! ObjectCreate(%ObjectPrototype%).
+  Handle<JSObject> result = factory->NewJSObject(isolate->object_function());
+
+  // 11. Perform ! CreateDataProperty(result "segment", segment).
+  CHECK(JSReceiver::CreateDataProperty(
+            isolate, result, factory->segment_string(), segment, kDontThrow)
+            .FromJust());
+
+  // 12. Perform ! CreateDataProperty(result, "breakType", breakType).
+  CHECK(JSReceiver::CreateDataProperty(isolate, result,
+                                       factory->breakType_string(), break_type,
+                                       kDontThrow)
+            .FromJust());
+
+  // 13. Return CreateIterResultObject(result, false).
+  return factory->NewJSIteratorResult(result, false);
+}
+
+}  // namespace
+
+// ecma402 #sec-segment-iterator-prototype-next
+MaybeHandle<JSReceiver> JSSegmentIterator::Next(
+    Isolate* isolate, Handle<JSSegmentIterator> segment_iterator) {
+  Factory* factory = isolate->factory();
+  icu::BreakIterator* icu_break_iterator =
+      segment_iterator->icu_break_iterator()->raw();
+  // 3. Let _previousPosition be iterator.[[SegmentIteratorPosition]].
+  int32_t prev = icu_break_iterator->current();
+  // 4. Let done be AdvanceSegmentIterator(iterator, forwards).
+  int32_t position = icu_break_iterator->next();
+  if (position == icu::BreakIterator::DONE) {
+    // 5. If done is true, return CreateIterResultObject(undefined, true).
+    return factory->NewJSIteratorResult(isolate->factory()->undefined_value(),
+                                        true);
+  }
+
+  // 8. Let segment be the substring of string from previousPosition to
+  // newPosition, inclusive of previousPosition and exclusive of newPosition.
+  Handle<String> segment;
+  ASSIGN_RETURN_ON_EXCEPTION(
+      isolate, segment, segment_iterator->GetSegment(isolate, prev, position),
+      JSReceiver);
+  Handle<Object> break_type = segment_iterator->BreakType();
+  return CreateResultForNext(isolate, segment, break_type);
+}
+
+// ecma402 #sec-segment-iterator-prototype-following
+Maybe<bool> JSSegmentIterator::Following(
+    Isolate* isolate, Handle<JSSegmentIterator> segment_iterator,
+    Handle<Object> from_obj) {
+  Factory* factory = isolate->factory();
+  icu::BreakIterator* icu_break_iterator =
+      segment_iterator->icu_break_iterator()->raw();
+  // 3. If from is not undefined,
+  if (!from_obj->IsUndefined()) {
+    // a. Let from be ? ToIndex(from).
+    uint32_t from;
+    if (!from_obj->ToArrayIndex(&from)) {
+      THROW_NEW_ERROR_RETURN_VALUE(
+          isolate,
+          NewRangeError(MessageTemplate::kParameterOfFunctionOutOfRange,
+                        factory->NewStringFromStaticChars("from"),
+                        factory->NewStringFromStaticChars("following"),
+                        from_obj),
+          Nothing<bool>());
+    }
+    // b. If from ≥ iterator.[[SegmentIteratorString]], throw a RangeError
+    // exception.
+    // c. Let iterator.[[SegmentIteratorPosition]] be from.
+    if (icu_break_iterator->following(from) == icu::BreakIterator::DONE) {
+      THROW_NEW_ERROR_RETURN_VALUE(
+          isolate,
+          NewRangeError(MessageTemplate::kParameterOfFunctionOutOfRange,
+                        factory->NewStringFromStaticChars("from"),
+                        factory->NewStringFromStaticChars("following"),
+                        from_obj),
+          Nothing<bool>());
+    }
+    return Just(false);
+  }
+  // 4. return AdvanceSegmentIterator(iterator, forward).
+  // 4. .... or if direction is backwards and position is 0, return true.
+  // 4. If direction is forwards and position is the length of string ... return
+  // true.
+  return Just(icu_break_iterator->next() == icu::BreakIterator::DONE);
+}
+
+// ecma402 #sec-segment-iterator-prototype-preceding
+Maybe<bool> JSSegmentIterator::Preceding(
+    Isolate* isolate, Handle<JSSegmentIterator> segment_iterator,
+    Handle<Object> from_obj) {
+  Factory* factory = isolate->factory();
+  icu::BreakIterator* icu_break_iterator =
+      segment_iterator->icu_break_iterator()->raw();
+  // 3. If from is not undefined,
+  if (!from_obj->IsUndefined()) {
+    // a. Let from be ? ToIndex(from).
+    uint32_t from;
+    if (!from_obj->ToArrayIndex(&from)) {
+      THROW_NEW_ERROR_RETURN_VALUE(
+          isolate,
+          NewRangeError(MessageTemplate::kParameterOfFunctionOutOfRange,
+                        factory->NewStringFromStaticChars("from"),
+                        factory->NewStringFromStaticChars("following"),
+                        from_obj),
+          Nothing<bool>());
+    }
+    // b. If from > iterator.[[SegmentIteratorString]] or from = 0, throw a
+    // RangeError exception.
+    // c. Let iterator.[[SegmentIteratorPosition]] be from.
+    uint32_t text_len =
+        static_cast<uint32_t>(icu_break_iterator->getText().getLength());
+    if (from > text_len ||
+        icu_break_iterator->preceding(from) == icu::BreakIterator::DONE) {
+      THROW_NEW_ERROR_RETURN_VALUE(
+          isolate,
+          NewRangeError(MessageTemplate::kParameterOfFunctionOutOfRange,
+                        factory->NewStringFromStaticChars("from"),
+                        factory->NewStringFromStaticChars("preceding"),
+                        from_obj),
+          Nothing<bool>());
+    }
+    return Just(false);
+  }
+  // 4. return AdvanceSegmentIterator(iterator, backwards).
+  // 4. .... or if direction is backwards and position is 0, return true.
+  return Just(icu_break_iterator->previous() == icu::BreakIterator::DONE);
+}
+
+}  // namespace internal
+}  // namespace v8

src/objects/js-segment-iterator.h

+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef V8_INTL_SUPPORT
+#error Internationalization is expected to be enabled.
+#endif  // V8_INTL_SUPPORT
+
+#ifndef V8_OBJECTS_JS_SEGMENT_ITERATOR_H_
+#define V8_OBJECTS_JS_SEGMENT_ITERATOR_H_
+
+#include "src/heap/factory.h"
+#include "src/isolate.h"
+#include "src/objects.h"
+#include "src/objects/js-segmenter.h"
+#include "src/objects/managed.h"
+#include "unicode/uversion.h"
+
+// Has to be the last include (doesn't have include guards):
+#include "src/objects/object-macros.h"
+
+namespace U_ICU_NAMESPACE {
+class BreakIterator;
+class UnicodeString;
+}  // namespace U_ICU_NAMESPACE
+
+namespace v8 {
+namespace internal {
+
+class JSSegmentIterator : public JSObject {
+ public:
+  // ecma402 #sec-CreateSegmentIterator
+  V8_WARN_UNUSED_RESULT static MaybeHandle<JSSegmentIterator> Create(
+      Isolate* isolate, icu::BreakIterator* icu_break_iterator,
+      JSSegmenter::Granularity granularity, Handle<String> string);
+
+  // ecma402 #sec-segment-iterator-prototype-next
+  V8_WARN_UNUSED_RESULT static MaybeHandle<JSReceiver> Next(
+      Isolate* isolate, Handle<JSSegmentIterator> segment_iterator_holder);
+
+  // ecma402 #sec-segment-iterator-prototype-following
+  static Maybe<bool> Following(
+      Isolate* isolate, Handle<JSSegmentIterator> segment_iterator_holder,
+      Handle<Object> from);
+
+  // ecma402 #sec-segment-iterator-prototype-preceding
+  static Maybe<bool> Preceding(
+      Isolate* isolate, Handle<JSSegmentIterator> segment_iterator_holder,
+      Handle<Object> from);
+
+  // ecma402 #sec-segment-iterator-prototype-position
+  static Handle<Object> Position(
+      Isolate* isolate, Handle<JSSegmentIterator> segment_iterator_holder);
+
+  Handle<String> GranularityAsString() const;
+
+  // ecma402 #sec-segment-iterator-prototype-breakType
+  Handle<Object> BreakType() const;
+
+  V8_WARN_UNUSED_RESULT MaybeHandle<String> GetSegment(Isolate* isolate,
+                                                       int32_t start,
+                                                       int32_t end) const;
+
+  DECL_CAST(JSSegmentIterator)
+
+  // SegmentIterator accessors.
+  DECL_ACCESSORS(icu_break_iterator, Managed<icu::BreakIterator>)
+  DECL_ACCESSORS(unicode_string, Managed<icu::UnicodeString>)
+
+  DECL_PRINTER(JSSegmentIterator)
+  DECL_VERIFIER(JSSegmentIterator)
+
+  inline void set_granularity(JSSegmenter::Granularity granularity);
+  inline JSSegmenter::Granularity granularity() const;
+
+// Bit positions in |flags|.
+#define FLAGS_BIT_FIELDS(V, _) \
+  V(GranularityBits, JSSegmenter::Granularity, 3, _)
+  DEFINE_BIT_FIELDS(FLAGS_BIT_FIELDS)
+#undef FLAGS_BIT_FIELDS
+
+  STATIC_ASSERT(JSSegmenter::Granularity::GRAPHEME <= GranularityBits::kMax);
+  STATIC_ASSERT(JSSegmenter::Granularity::WORD <= GranularityBits::kMax);
+  STATIC_ASSERT(JSSegmenter::Granularity::SENTENCE <= GranularityBits::kMax);
+  STATIC_ASSERT(JSSegmenter::Granularity::LINE <= GranularityBits::kMax);
+
+  // [flags] Bit field containing various flags about the function.
+  DECL_INT_ACCESSORS(flags)
+
+// Layout description.
+#define SEGMENTER_FIELDS(V)                \
+  /* Pointer fields. */                    \
+  V(kICUBreakIteratorOffset, kPointerSize) \
+  V(kUnicodeStringOffset, kPointerSize)    \
+  V(kFlagsOffset, kPointerSize)            \
+  /* Total Size */                         \
+  V(kSize, 0)
+
+  DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize, SEGMENTER_FIELDS)
+#undef SEGMENTER_FIELDS
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(JSSegmentIterator);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#include "src/objects/object-macros-undef.h"
+
+#endif  // V8_OBJECTS_JS_SEGMENT_ITERATOR_H_

src/objects/js-segmenter.cc

@@ -156,13 +156,21 @@ MaybeHandle<JSSegmenter> JSSegmenter::Initialize(
       icu_break_iterator.reset(
           icu::BreakIterator::createSentenceInstance(icu_locale, status));
       break;
-    case Granularity::LINE:
-      icu_break_iterator.reset(
-          icu::BreakIterator::createLineInstance(icu_locale, status));
+    case Granularity::LINE: {
       // 15. If granularity is "line",
       // a. Set segmenter.[[SegmenterLineBreakStyle]] to r.[[lb]].
-      // TBW
+      const char* key = uloc_toLegacyKey("lb");
+      CHECK_NOT_NULL(key);
+      const char* value =
+          uloc_toLegacyType(key, segmenter_holder->LineBreakStyleAsCString());
+      CHECK_NOT_NULL(value);
+      UErrorCode status = U_ZERO_ERROR;
+      icu_locale.setKeywordValue(key, value, status);
+      CHECK(U_SUCCESS(status));
+      icu_break_iterator.reset(
+          icu::BreakIterator::createLineInstance(icu_locale, status));
       break;
+    }
     case Granularity::COUNT:
       UNREACHABLE();
   }
@@ -194,6 +202,20 @@ Handle<JSObject> JSSegmenter::ResolvedOptions(
   return result;
 }
 
+const char* JSSegmenter::LineBreakStyleAsCString() const {
+  switch (line_break_style()) {
+    case LineBreakStyle::STRICT:
+      return "strict";
+    case LineBreakStyle::NORMAL:
+      return "normal";
+    case LineBreakStyle::LOOSE:
+      return "loose";
+    case LineBreakStyle::COUNT:
+    case LineBreakStyle::NOTSET:
+      UNREACHABLE();
+  }
+}
+
 Handle<String> JSSegmenter::LineBreakStyleAsString() const {
   switch (line_break_style()) {
     case LineBreakStyle::STRICT:

src/objects/js-segmenter.h

@@ -37,6 +37,7 @@ class JSSegmenter : public JSObject {
       Isolate* isolate, Handle<JSSegmenter> segmenter_holder);
 
   Handle<String> LineBreakStyleAsString() const;
+  const char* LineBreakStyleAsCString() const;
   Handle<String> GranularityAsString() const;
 
   DECL_CAST(JSSegmenter)

test/intl/intl.status

@@ -29,36 +29,6 @@
 [ALWAYS, {
   # TODO(jochen): The following test is flaky.
   'overrides/caching': [PASS, FAIL],
-
-  # https://bugs.chromium.org/p/v8/issues/detail?id=6891
-  'segmenter/segment': [FAIL],
-  'segmenter/segment-grapheme': [FAIL],
-  'segmenter/segment-grapheme-following': [FAIL],
-  'segmenter/segment-grapheme-iterable': [FAIL],
-  'segmenter/segment-grapheme-next': [FAIL],
-  'segmenter/segment-grapheme-preceding': [FAIL],
-  'segmenter/segment-iterator': [FAIL],
-  'segmenter/segment-iterator-breakType': [FAIL],
-  'segmenter/segment-iterator-following': [FAIL],
-  'segmenter/segment-iterator-next': [FAIL],
-  'segmenter/segment-iterator-position': [FAIL],
-  'segmenter/segment-iterator-preceding': [FAIL],
-  'segmenter/segment-line': [FAIL],
-  'segmenter/segment-line-following': [FAIL],
-  'segmenter/segment-line-following-modes': [FAIL],
-  'segmenter/segment-line-iterable': [FAIL],
-  'segmenter/segment-line-next': [FAIL],
-  'segmenter/segment-line-preceding': [FAIL],
-  'segmenter/segment-sentence': [FAIL],
-  'segmenter/segment-sentence-following': [FAIL],
-  'segmenter/segment-sentence-iterable': [FAIL],
-  'segmenter/segment-sentence-next': [FAIL],
-  'segmenter/segment-sentence-preceding': [FAIL],
-  'segmenter/segment-word': [FAIL],
-  'segmenter/segment-word-following': [FAIL],
-  'segmenter/segment-word-iterable': [FAIL],
-  'segmenter/segment-word-next': [FAIL],
-  'segmenter/segment-word-preceding': [FAIL],
 }],  # ALWAYS
 
 ['variant == no_wasm_traps', {

test/intl/segmenter/segment-iterator-following.js

@@ -10,6 +10,11 @@ const iter = segmenter.segment(text);
 
 assertEquals("function", typeof iter.following);
 
+assertThrows(() => iter.following("ABC"), RangeError);
+assertThrows(() => iter.following(null), RangeError);
+assertThrows(() => iter.following(1.4), RangeError);
+assertThrows(() => iter.following(-3), RangeError);
+
 // 1.5.3.2 %SegmentIteratorPrototype%.following( [ from ] )
 // 3.b If from >= iterator.[[SegmentIteratorString]], throw a RangeError exception.
 assertDoesNotThrow(() => iter.following(text.length - 1));

test/intl/segmenter/segment-iterator-ownPropertyDescriptor.js

+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-intl-segmenter
+
+let seg = new Intl.Segmenter();
+let descriptor = Object.getOwnPropertyDescriptor(
+    Intl.Segmenter, "supportedLocalesOf");
+assertTrue(descriptor.writable);
+assertFalse(descriptor.enumerable);
+assertTrue(descriptor.configurable);
+
+// ecma402 #sec-Intl.Segmenter.prototype
+// Intl.Segmenter.prototype
+// The value of Intl.Segmenter.prototype is %SegmenterPrototype%.
+// This property has the attributes
+// { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.
+descriptor = Object.getOwnPropertyDescriptor(Intl.Segmenter, "prototype");
+assertFalse(descriptor.writable);
+assertFalse(descriptor.enumerable);
+assertFalse(descriptor.configurable);
+
+for (let func of ["segment", "resolvedOptions"]) {
+  let descriptor = Object.getOwnPropertyDescriptor(
+      Intl.Segmenter.prototype, func);
+  assertTrue(descriptor.writable);
+  assertFalse(descriptor.enumerable);
+  assertTrue(descriptor.configurable);
+}
+
+let prototype = Object.getPrototypeOf(seg.segment('text'));
+for (let func of ["next", "following", "preceding"]) {
+  let descriptor = Object.getOwnPropertyDescriptor(prototype, func);
+  assertTrue(descriptor.writable);
+  assertFalse(descriptor.enumerable);
+  assertTrue(descriptor.configurable);
+}

test/intl/segmenter/segment-iterator-preceding.js

@@ -10,6 +10,11 @@ const iter = segmenter.segment(text);
 
 assertEquals("function", typeof iter.preceding);
 
+assertThrows(() => iter.preceding("ABC"), RangeError);
+assertThrows(() => iter.preceding(null), RangeError);
+assertThrows(() => iter.preceding(1.4), RangeError);
+assertThrows(() => iter.preceding(-3), RangeError);
+
 // 1.5.3.3 %SegmentIteratorPrototype%.preceding( [ from ] )
 // 3.b If ... from = 0, throw a RangeError exception.
 assertThrows(() => iter.preceding(0), RangeError);

test/intl/segmenter/segment-iterator.js

@@ -4,7 +4,6 @@
 
 // Flags: --harmony-intl-segmenter
 
-let descriptor;
 const text = "Hello World, Test 123! Foo Bar. How are you?";
 for (const granularity of ["grapheme", "word", "sentence", "line"]) {
   const segmenter = new Intl.Segmenter("en", { granularity });

test/intl/segmenter/segment.js

@@ -5,3 +5,35 @@
 // Flags: --harmony-intl-segmenter
 
 assertEquals("function", typeof Intl.Segmenter.prototype.segment);
+assertEquals(1, Intl.Segmenter.prototype.segment.length);
+
+let seg = new Intl.Segmenter("en", {granularity: "word"})
+let res;
+
+// test with 0 args
+assertDoesNotThrow(() => res = seg.segment())
+// test with 1 arg
+assertDoesNotThrow(() => res = seg.segment("hello"))
+assertEquals("hello", res.next().value.segment);
+// test with 2 args
+assertDoesNotThrow(() => res = seg.segment("hello world"))
+assertEquals("hello", res.next().value.segment);
+
+// test with other types
+assertDoesNotThrow(() => res = seg.segment(undefined))
+assertEquals("undefined", res.next().value.segment);
+assertDoesNotThrow(() => res = seg.segment(null))
+assertEquals("null", res.next().value.segment);
+assertDoesNotThrow(() => res = seg.segment(true))
+assertEquals("true", res.next().value.segment);
+assertDoesNotThrow(() => res = seg.segment(false))
+assertEquals("false", res.next().value.segment);
+assertDoesNotThrow(() => res = seg.segment(1234))
+assertEquals("1234", res.next().value.segment);
+assertDoesNotThrow(() => res = seg.segment(3.1415926))
+assertEquals("3.1415926", res.next().value.segment);
+assertDoesNotThrow(() => res = seg.segment(["hello","world"]))
+assertEquals("hello", res.next().value.segment);
+assertDoesNotThrow(() => res = seg.segment({k: 'v'}))
+assertEquals("[", res.next().value.segment);
+assertThrows(() => res = seg.segment(Symbol()), TypeError)

tools/v8heapconst.py

@@ -172,15 +172,16 @@ INSTANCE_TYPES = {
   1093: "JS_INTL_NUMBER_FORMAT_TYPE",
   1094: "JS_INTL_PLURAL_RULES_TYPE",
   1095: "JS_INTL_RELATIVE_TIME_FORMAT_TYPE",
-  1096: "JS_INTL_SEGMENTER_TYPE",
-  1097: "WASM_EXCEPTION_TYPE",
-  1098: "WASM_GLOBAL_TYPE",
-  1099: "WASM_INSTANCE_TYPE",
-  1100: "WASM_MEMORY_TYPE",
-  1101: "WASM_MODULE_TYPE",
-  1102: "WASM_TABLE_TYPE",
-  1103: "JS_BOUND_FUNCTION_TYPE",
-  1104: "JS_FUNCTION_TYPE",
+  1096: "JS_INTL_SEGMENT_ITERATOR_TYPE",
+  1097: "JS_INTL_SEGMENTER_TYPE",
+  1098: "WASM_EXCEPTION_TYPE",
+  1099: "WASM_GLOBAL_TYPE",
+  1100: "WASM_INSTANCE_TYPE",
+  1101: "WASM_MEMORY_TYPE",
+  1102: "WASM_MODULE_TYPE",
+  1103: "WASM_TABLE_TYPE",
+  1104: "JS_BOUND_FUNCTION_TYPE",
+  1105: "JS_FUNCTION_TYPE",
 }
 
 # List of known V8 maps.
@@ -295,41 +296,41 @@ KNOWN_MAPS = {
   ("RO_SPACE", 0x02699): (171, "Tuple2Map"),
   ("RO_SPACE", 0x02739): (173, "ArrayBoilerplateDescriptionMap"),
   ("RO_SPACE", 0x02a79): (161, "InterceptorInfoMap"),
-  ("RO_SPACE", 0x04f61): (153, "AccessCheckInfoMap"),
-  ("RO_SPACE", 0x04fb1): (154, "AccessorInfoMap"),
-  ("RO_SPACE", 0x05001): (155, "AccessorPairMap"),
-  ("RO_SPACE", 0x05051): (156, "AliasedArgumentsEntryMap"),
-  ("RO_SPACE", 0x050a1): (157, "AllocationMementoMap"),
-  ("RO_SPACE", 0x050f1): (158, "AsyncGeneratorRequestMap"),
-  ("RO_SPACE", 0x05141): (159, "DebugInfoMap"),
-  ("RO_SPACE", 0x05191): (160, "FunctionTemplateInfoMap"),
-  ("RO_SPACE", 0x051e1): (162, "InterpreterDataMap"),
-  ("RO_SPACE", 0x05231): (163, "ModuleInfoEntryMap"),
-  ("RO_SPACE", 0x05281): (164, "ModuleMap"),
-  ("RO_SPACE", 0x052d1): (165, "ObjectTemplateInfoMap"),
-  ("RO_SPACE", 0x05321): (166, "PromiseCapabilityMap"),
-  ("RO_SPACE", 0x05371): (167, "PromiseReactionMap"),
-  ("RO_SPACE", 0x053c1): (168, "PrototypeInfoMap"),
-  ("RO_SPACE", 0x05411): (169, "ScriptMap"),
-  ("RO_SPACE", 0x05461): (170, "StackFrameInfoMap"),
-  ("RO_SPACE", 0x054b1): (172, "Tuple3Map"),
-  ("RO_SPACE", 0x05501): (174, "WasmDebugInfoMap"),
-  ("RO_SPACE", 0x05551): (175, "WasmExportedFunctionDataMap"),
-  ("RO_SPACE", 0x055a1): (176, "CallableTaskMap"),
-  ("RO_SPACE", 0x055f1): (177, "CallbackTaskMap"),
-  ("RO_SPACE", 0x05641): (178, "PromiseFulfillReactionJobTaskMap"),
-  ("RO_SPACE", 0x05691): (179, "PromiseRejectReactionJobTaskMap"),
-  ("RO_SPACE", 0x056e1): (180, "PromiseResolveThenableJobTaskMap"),
-  ("RO_SPACE", 0x05731): (181, "MicrotaskQueueMap"),
-  ("RO_SPACE", 0x05781): (182, "AllocationSiteWithWeakNextMap"),
-  ("RO_SPACE", 0x057d1): (182, "AllocationSiteWithoutWeakNextMap"),
-  ("RO_SPACE", 0x05821): (214, "LoadHandler1Map"),
-  ("RO_SPACE", 0x05871): (214, "LoadHandler2Map"),
-  ("RO_SPACE", 0x058c1): (214, "LoadHandler3Map"),
-  ("RO_SPACE", 0x05911): (221, "StoreHandler0Map"),
-  ("RO_SPACE", 0x05961): (221, "StoreHandler1Map"),
-  ("RO_SPACE", 0x059b1): (221, "StoreHandler2Map"),
-  ("RO_SPACE", 0x05a01): (221, "StoreHandler3Map"),
+  ("RO_SPACE", 0x05031): (153, "AccessCheckInfoMap"),
+  ("RO_SPACE", 0x05081): (154, "AccessorInfoMap"),
+  ("RO_SPACE", 0x050d1): (155, "AccessorPairMap"),
+  ("RO_SPACE", 0x05121): (156, "AliasedArgumentsEntryMap"),
+  ("RO_SPACE", 0x05171): (157, "AllocationMementoMap"),
+  ("RO_SPACE", 0x051c1): (158, "AsyncGeneratorRequestMap"),
+  ("RO_SPACE", 0x05211): (159, "DebugInfoMap"),
+  ("RO_SPACE", 0x05261): (160, "FunctionTemplateInfoMap"),
+  ("RO_SPACE", 0x052b1): (162, "InterpreterDataMap"),
+  ("RO_SPACE", 0x05301): (163, "ModuleInfoEntryMap"),
+  ("RO_SPACE", 0x05351): (164, "ModuleMap"),
+  ("RO_SPACE", 0x053a1): (165, "ObjectTemplateInfoMap"),
+  ("RO_SPACE", 0x053f1): (166, "PromiseCapabilityMap"),
+  ("RO_SPACE", 0x05441): (167, "PromiseReactionMap"),
+  ("RO_SPACE", 0x05491): (168, "PrototypeInfoMap"),
+  ("RO_SPACE", 0x054e1): (169, "ScriptMap"),
+  ("RO_SPACE", 0x05531): (170, "StackFrameInfoMap"),
+  ("RO_SPACE", 0x05581): (172, "Tuple3Map"),
+  ("RO_SPACE", 0x055d1): (174, "WasmDebugInfoMap"),
+  ("RO_SPACE", 0x05621): (175, "WasmExportedFunctionDataMap"),
+  ("RO_SPACE", 0x05671): (176, "CallableTaskMap"),
+  ("RO_SPACE", 0x056c1): (177, "CallbackTaskMap"),
+  ("RO_SPACE", 0x05711): (178, "PromiseFulfillReactionJobTaskMap"),
+  ("RO_SPACE", 0x05761): (179, "PromiseRejectReactionJobTaskMap"),
+  ("RO_SPACE", 0x057b1): (180, "PromiseResolveThenableJobTaskMap"),
+  ("RO_SPACE", 0x05801): (181, "MicrotaskQueueMap"),
+  ("RO_SPACE", 0x05851): (182, "AllocationSiteWithWeakNextMap"),
+  ("RO_SPACE", 0x058a1): (182, "AllocationSiteWithoutWeakNextMap"),
+  ("RO_SPACE", 0x058f1): (214, "LoadHandler1Map"),
+  ("RO_SPACE", 0x05941): (214, "LoadHandler2Map"),
+  ("RO_SPACE", 0x05991): (214, "LoadHandler3Map"),
+  ("RO_SPACE", 0x059e1): (221, "StoreHandler0Map"),
+  ("RO_SPACE", 0x05a31): (221, "StoreHandler1Map"),
+  ("RO_SPACE", 0x05a81): (221, "StoreHandler2Map"),
+  ("RO_SPACE", 0x05ad1): (221, "StoreHandler3Map"),
   ("MAP_SPACE", 0x00139): (1057, "ExternalMap"),
   ("MAP_SPACE", 0x00189): (1073, "JSMessageObjectMap"),
 }