Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1071 insertions, 0 deletions

diff --git a/js/src/builtin/String.js b/js/src/builtin/String.js
new file mode 100644
index 0000000000..efeb65360e
--- /dev/null
+++ b/js/src/builtin/String.js
@@ -0,0 +1,1071 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function StringProtoHasNoMatch() {
+    var ObjectProto = GetBuiltinPrototype("Object");
+    var StringProto = GetBuiltinPrototype("String");
+    if (!ObjectHasPrototype(StringProto, ObjectProto))
+        return false;
+    return !(std_match in StringProto);
+}
+
+function IsStringMatchOptimizable() {
+    var RegExpProto = GetBuiltinPrototype("RegExp");
+    // If RegExpPrototypeOptimizable succeeds, `exec` and `@@match` are
+    // guaranteed to be data properties.
+    return RegExpPrototypeOptimizable(RegExpProto) &&
+           RegExpProto.exec === RegExp_prototype_Exec &&
+           RegExpProto[std_match] === RegExpMatch;
+}
+
+function ThrowIncompatibleMethod(name, thisv) {
+    ThrowTypeError(JSMSG_INCOMPATIBLE_PROTO, "String", name, ToString(thisv));
+}
+
+// ES 2016 draft Mar 25, 2016 21.1.3.11.
+function String_match(regexp) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("match", this);
+
+    // Step 2.
+    var isPatternString = (typeof regexp === "string");
+    if (!(isPatternString && StringProtoHasNoMatch()) && regexp !== undefined && regexp !== null) {
+        // Step 2.a.
+        var matcher = GetMethod(regexp, std_match);
+
+        // Step 2.b.
+        if (matcher !== undefined)
+            return callContentFunction(matcher, regexp, this);
+    }
+
+    // Step 3.
+    var S = ToString(this);
+
+    if (isPatternString && IsStringMatchOptimizable()) {
+        var flatResult = FlatStringMatch(S, regexp);
+        if (flatResult !== undefined)
+            return flatResult;
+    }
+
+    // Step 4.
+    var rx = RegExpCreate(regexp);
+
+    // Step 5 (optimized case).
+    if (IsStringMatchOptimizable())
+        return RegExpMatcher(rx, S, 0);
+
+    // Step 5.
+    return callContentFunction(GetMethod(rx, std_match), rx, S);
+}
+
+
+// String.prototype.matchAll proposal.
+//
+// String.prototype.matchAll ( regexp )
+function String_matchAll(regexp) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("matchAll", this);
+
+    // Step 2.
+    if (regexp !== undefined && regexp !== null) {
+        // Steps 2.a-b.
+        if (IsRegExp(regexp)) {
+            // Step 2.b.i.
+            var flags = regexp.flags;
+
+            // Step 2.b.ii.
+            if (flags === undefined || flags === null) {
+                ThrowTypeError(JSMSG_FLAGS_UNDEFINED_OR_NULL);
+            }
+
+            // Step 2.b.iii.
+            if (!callFunction(std_String_includes, ToString(flags), "g")) {
+                ThrowTypeError(JSMSG_REQUIRES_GLOBAL_REGEXP, "matchAll");
+            }
+        }
+
+        // Step 2.c.
+        var matcher = GetMethod(regexp, std_matchAll);
+
+        // Step 2.d.
+        if (matcher !== undefined)
+            return callContentFunction(matcher, regexp, this);
+    }
+
+    // Step 3.
+    var string = ToString(this);
+
+    // Step 4.
+    var rx = RegExpCreate(regexp, "g");
+
+    // Step 5.
+    return callContentFunction(GetMethod(rx, std_matchAll), rx, string);
+}
+
+/**
+ * A helper function implementing the logic for both String.prototype.padStart
+ * and String.prototype.padEnd as described in ES7 Draft March 29, 2016
+ */
+function String_pad(maxLength, fillString, padEnd) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod(padEnd ? "padEnd" : "padStart", this);
+
+    // Step 2.
+    let str = ToString(this);
+
+    // Steps 3-4.
+    let intMaxLength = ToLength(maxLength);
+    let strLen = str.length;
+
+    // Step 5.
+    if (intMaxLength <= strLen)
+        return str;
+
+    // Steps 6-7.
+    assert(fillString !== undefined, "never called when fillString is undefined");
+    let filler = ToString(fillString);
+
+    // Step 8.
+    if (filler === "")
+        return str;
+
+    // Throw an error if the final string length exceeds the maximum string
+    // length. Perform this check early so we can use int32 operations below.
+    if (intMaxLength > MAX_STRING_LENGTH)
+        ThrowRangeError(JSMSG_RESULTING_STRING_TOO_LARGE);
+
+    // Step 9.
+    let fillLen = intMaxLength - strLen;
+
+    // Step 10.
+    // Perform an int32 division to ensure String_repeat is not called with a
+    // double to avoid repeated bailouts in ToInteger.
+    let truncatedStringFiller = callFunction(String_repeat, filler,
+                                             (fillLen / filler.length) | 0);
+
+    truncatedStringFiller += Substring(filler, 0, fillLen % filler.length);
+
+    // Step 11.
+    if (padEnd === true)
+        return str + truncatedStringFiller;
+    return truncatedStringFiller + str;
+}
+
+function String_pad_start(maxLength, fillString = " ") {
+    return callFunction(String_pad, this, maxLength, fillString, false);
+}
+
+function String_pad_end(maxLength, fillString = " ") {
+    return callFunction(String_pad, this, maxLength, fillString, true);
+}
+
+function StringProtoHasNoReplace() {
+    var ObjectProto = GetBuiltinPrototype("Object");
+    var StringProto = GetBuiltinPrototype("String");
+    if (!ObjectHasPrototype(StringProto, ObjectProto))
+        return false;
+    return !(std_replace in StringProto);
+}
+
+// A thin wrapper to call SubstringKernel with int32-typed arguments.
+// Caller should check the range of |from| and |length|.
+function Substring(str, from, length) {
+    assert(typeof str === "string", "|str| should be a string");
+    assert(from | 0 === from, "coercing |from| into int32 should not change the value");
+    assert(length | 0 === length, "coercing |length| into int32 should not change the value");
+
+    return SubstringKernel(str, from | 0, length | 0);
+}
+
+// ES 2016 draft Mar 25, 2016 21.1.3.14.
+function String_replace(searchValue, replaceValue) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("replace", this);
+
+    // Step 2.
+    if (!(typeof searchValue === "string" && StringProtoHasNoReplace()) &&
+        searchValue !== undefined && searchValue !== null)
+    {
+        // Step 2.a.
+        var replacer = GetMethod(searchValue, std_replace);
+
+        // Step 2.b.
+        if (replacer !== undefined)
+            return callContentFunction(replacer, searchValue, this, replaceValue);
+    }
+
+    // Step 3.
+    var string = ToString(this);
+
+    // Step 4.
+    var searchString = ToString(searchValue);
+
+    if (typeof replaceValue === "string") {
+        // Steps 6-12: Optimized for string case.
+        return StringReplaceString(string, searchString, replaceValue);
+    }
+
+    // Step 5.
+    if (!IsCallable(replaceValue)) {
+        // Steps 6-12.
+        return StringReplaceString(string, searchString, ToString(replaceValue));
+    }
+
+    // Step 7.
+    var pos = callFunction(std_String_indexOf, string, searchString);
+    if (pos === -1)
+        return string;
+
+    // Step 8.
+    var replStr = ToString(callContentFunction(replaceValue, undefined, searchString, pos, string));
+
+    // Step 10.
+    var tailPos = pos + searchString.length;
+
+    // Step 11.
+    var newString;
+    if (pos === 0)
+        newString = "";
+    else
+        newString = Substring(string, 0, pos);
+
+    newString += replStr;
+    var stringLength = string.length;
+    if (tailPos < stringLength)
+        newString += Substring(string, tailPos, stringLength - tailPos);
+
+    // Step 12.
+    return newString;
+}
+
+// String.prototype.replaceAll (Stage 3 proposal)
+// https://tc39.es/proposal-string-replaceall/
+//
+// String.prototype.replaceAll ( searchValue, replaceValue )
+function String_replaceAll(searchValue, replaceValue) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("replaceAll", this);
+
+    // Step 2.
+    if (searchValue !== undefined && searchValue !== null) {
+        // Steps 2.a-b.
+        if (IsRegExp(searchValue)) {
+            // Step 2.b.i.
+            var flags = searchValue.flags;
+
+            // Step 2.b.ii.
+            if (flags === undefined || flags === null) {
+                ThrowTypeError(JSMSG_FLAGS_UNDEFINED_OR_NULL);
+            }
+
+            // Step 2.b.iii.
+            if (!callFunction(std_String_includes, ToString(flags), "g")) {
+                ThrowTypeError(JSMSG_REQUIRES_GLOBAL_REGEXP, "replaceAll");
+            }
+        }
+
+        // Step 2.c.
+        var replacer = GetMethod(searchValue, std_replace);
+
+        // Step 2.b.
+        if (replacer !== undefined) {
+            return callContentFunction(replacer, searchValue, this, replaceValue);
+        }
+    }
+
+    // Step 3.
+    var string = ToString(this);
+
+    // Step 4.
+    var searchString = ToString(searchValue);
+
+    // Steps 5-6.
+    if (!IsCallable(replaceValue)) {
+        // Steps 7-16.
+        return StringReplaceAllString(string, searchString, ToString(replaceValue));
+    }
+
+    // Step 7.
+    var searchLength = searchString.length;
+
+    // Step 8.
+    var advanceBy = std_Math_max(1, searchLength);
+
+    // Step 9 (not needed in this implementation).
+
+    // Step 12.
+    var endOfLastMatch = 0;
+
+    // Step 13.
+    var result = "";
+
+    // Steps 10-11, 14.
+    var position = 0;
+    while (true) {
+        // Steps 10-11.
+        //
+        // StringIndexOf doesn't clamp the |position| argument to the input
+        // string length, i.e. |StringIndexOf("abc", "", 4)| returns -1,
+        // whereas |"abc".indexOf("", 4)| returns 3. That means we need to
+        // exit the loop when |nextPosition| is smaller than |position| and
+        // not just when |nextPosition| is -1.
+        var nextPosition = callFunction(std_String_indexOf, string, searchString, position);
+        if (nextPosition < position) {
+            break;
+        }
+        position = nextPosition;
+
+        // Step 14.a.
+        var replacement = ToString(callContentFunction(replaceValue, undefined, searchString,
+                                                       position, string));
+
+        // Step 14.b (not applicable).
+
+        // Step 14.c.
+        var stringSlice = Substring(string, endOfLastMatch, position - endOfLastMatch);
+
+        // Step 14.d.
+        result += stringSlice + replacement;
+
+        // Step 14.e.
+        endOfLastMatch = position + searchLength;
+
+        // Step 11.b.
+        position += advanceBy;
+    }
+
+    // Step 15.
+    if (endOfLastMatch < string.length) {
+        // Step 15.a.
+        result += Substring(string, endOfLastMatch, string.length - endOfLastMatch);
+    }
+
+    // Step 16.
+    return result;
+}
+
+function StringProtoHasNoSearch() {
+    var ObjectProto = GetBuiltinPrototype("Object");
+    var StringProto = GetBuiltinPrototype("String");
+    if (!ObjectHasPrototype(StringProto, ObjectProto))
+        return false;
+    return !(std_search in StringProto);
+}
+
+function IsStringSearchOptimizable() {
+    var RegExpProto = GetBuiltinPrototype("RegExp");
+    // If RegExpPrototypeOptimizable succeeds, `exec` and `@@search` are
+    // guaranteed to be data properties.
+    return RegExpPrototypeOptimizable(RegExpProto) &&
+           RegExpProto.exec === RegExp_prototype_Exec &&
+           RegExpProto[std_search] === RegExpSearch;
+}
+
+// ES 2016 draft Mar 25, 2016 21.1.3.15.
+function String_search(regexp) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("search", this);
+
+    // Step 2.
+    var isPatternString = (typeof regexp === "string");
+    if (!(isPatternString && StringProtoHasNoSearch()) && regexp !== undefined && regexp !== null) {
+        // Step 2.a.
+        var searcher = GetMethod(regexp, std_search);
+
+        // Step 2.b.
+        if (searcher !== undefined)
+            return callContentFunction(searcher, regexp, this);
+    }
+
+    // Step 3.
+    var string = ToString(this);
+
+    if (isPatternString && IsStringSearchOptimizable()) {
+        var flatResult = FlatStringSearch(string, regexp);
+        if (flatResult !== -2)
+            return flatResult;
+    }
+
+    // Step 4.
+    var rx = RegExpCreate(regexp);
+
+    // Step 5.
+    return callContentFunction(GetMethod(rx, std_search), rx, string);
+}
+
+function StringProtoHasNoSplit() {
+    var ObjectProto = GetBuiltinPrototype("Object");
+    var StringProto = GetBuiltinPrototype("String");
+    if (!ObjectHasPrototype(StringProto, ObjectProto))
+        return false;
+    return !(std_split in StringProto);
+}
+
+// ES 2016 draft Mar 25, 2016 21.1.3.17.
+function String_split(separator, limit) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("split", this);
+
+    // Optimized path for string.split(string), especially when both strings
+    // are constants.  Following sequence of if's cannot be put together in
+    // order that IonMonkey sees the constant if present (bug 1246141).
+    if (typeof this === "string") {
+        if (StringProtoHasNoSplit()) {
+            if (typeof separator === "string") {
+                if (limit === undefined) {
+                    // inlineConstantStringSplitString needs both arguments to
+                    // be MConstant, so pass them directly.
+                    return StringSplitString(this, separator);
+                }
+            }
+        }
+    }
+
+    // Step 2.
+    if (!(typeof separator == "string" && StringProtoHasNoSplit()) &&
+        separator !== undefined && separator !== null)
+    {
+        // Step 2.a.
+        var splitter = GetMethod(separator, std_split);
+
+        // Step 2.b.
+        if (splitter !== undefined)
+            return callContentFunction(splitter, separator, this, limit);
+    }
+
+    // Step 3.
+    var S = ToString(this);
+
+    // Step 6.
+    var R;
+    if (limit !== undefined) {
+        var lim = limit >>> 0;
+
+        // Step 9.
+        R = ToString(separator);
+
+        // Step 10.
+        if (lim === 0)
+            return [];
+
+        // Step 11.
+        if (separator === undefined)
+            return [S];
+
+        // Steps 4, 8, 12-18.
+        return StringSplitStringLimit(S, R, lim);
+    }
+
+    // Step 9.
+    R = ToString(separator);
+
+    // Step 11.
+    if (separator === undefined)
+        return [S];
+
+    // Optimized path.
+    // Steps 4, 8, 12-18.
+    return StringSplitString(S, R);
+}
+
+// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9
+// 21.1.3.22 String.prototype.substring ( start, end )
+function String_substring(start, end) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("substring", this);
+
+    // Step 2.
+    var str = ToString(this);
+
+    // Step 3.
+    var len = str.length;
+
+    // Step 4.
+    var intStart = ToInteger(start);
+
+    // Step 5.
+    var intEnd = (end === undefined) ? len : ToInteger(end);
+
+    // Step 6.
+    var finalStart = std_Math_min(std_Math_max(intStart, 0), len);
+
+    // Step 7.
+    var finalEnd = std_Math_min(std_Math_max(intEnd, 0), len);
+
+    // Steps 8-9.
+    var from, to;
+    if (finalStart < finalEnd) {
+        from = finalStart;
+        to = finalEnd;
+    } else {
+        from = finalEnd;
+        to = finalStart;
+    }
+
+    // Step 10.
+    // While |from| and |to - from| are bounded to the length of |str| and this
+    // and thus definitely in the int32 range, they can still be typed as
+    // double. Eagerly truncate since SubstringKernel only accepts int32.
+    return SubstringKernel(str, from | 0, (to - from) | 0);
+}
+
+// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9
+// B.2.3.1 String.prototype.substr ( start, length )
+function String_substr(start, length) {
+    // Steps 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("substr", this);
+
+    // Step 2.
+    var str = ToString(this);
+
+    // Step 3.
+    var intStart = ToInteger(start);
+
+    // Steps 4-5.
+    var size = str.length;
+    // Use |size| instead of +Infinity to avoid performing calculations with
+    // doubles. (The result is the same either way.)
+    var end = (length === undefined) ? size : ToInteger(length);
+
+    // Step 6.
+    if (intStart < 0)
+        intStart = std_Math_max(intStart + size, 0);
+
+    // Step 7.
+    var resultLength = std_Math_min(std_Math_max(end, 0), size - intStart);
+
+    // Step 8.
+    if (resultLength <= 0)
+        return "";
+
+    // Step 9.
+    // While |intStart| and |resultLength| are bounded to the length of |str|
+    // and thus definitely in the int32 range, they can still be typed as
+    // double. Eagerly truncate since SubstringKernel only accepts int32.
+    return SubstringKernel(str, intStart | 0, resultLength | 0);
+}
+
+// ES2021 draft rev 12a546b92275a0e2f834017db2727bb9c6f6c8fd
+// 21.1.3.4 String.prototype.concat ( ...args )
+// Note: String.prototype.concat.length is 1.
+function String_concat(arg1) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("concat", this);
+
+    // Step 2.
+    var str = ToString(this);
+
+    // Specialize for the most common number of arguments for better inlining.
+    if (arguments.length === 0) {
+        return str;
+    }
+    if (arguments.length === 1) {
+        return str + ToString(arguments[0]);
+    }
+    if (arguments.length === 2) {
+        return str + ToString(arguments[0]) + ToString(arguments[1]);
+    }
+
+    // Step 3. (implicit)
+    // Step 4.
+    var result = str;
+
+    // Step 5.
+    for (var i = 0; i < arguments.length; i++) {
+        // Steps 5.a-b.
+        var nextString = ToString(arguments[i]);
+        // Step 5.c.
+        result += nextString;
+    }
+
+    // Step 6.
+    return result;
+}
+
+// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9
+// 21.1.3.19 String.prototype.slice ( start, end )
+function String_slice(start, end) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("slice", this);
+
+    // Step 2.
+    var str = ToString(this);
+
+    // Step 3.
+    var len = str.length;
+
+    // Step 4.
+    var intStart = ToInteger(start);
+
+    // Step 5.
+    var intEnd = (end === undefined) ? len : ToInteger(end);
+
+    // Step 6.
+    var from = (intStart < 0) ? std_Math_max(len + intStart, 0) : std_Math_min(intStart, len);
+
+    // Step 7.
+    var to = (intEnd < 0) ? std_Math_max(len + intEnd, 0) : std_Math_min(intEnd, len);
+
+    // Step 8.
+    var span = std_Math_max(to - from, 0);
+
+    // Step 9.
+    // While |from| and |span| are bounded to the length of |str|
+    // and thus definitely in the int32 range, they can still be typed as
+    // double. Eagerly truncate since SubstringKernel only accepts int32.
+    return SubstringKernel(str, from | 0, span | 0);
+}
+
+// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9
+// 21.1.3.3 String.prototype.codePointAt ( pos )
+function String_codePointAt(pos) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("codePointAt", this);
+
+    // Step 2.
+    var S = ToString(this);
+
+    // Step 3.
+    var position = ToInteger(pos);
+
+    // Step 4.
+    var size = S.length;
+
+    // Step 5.
+    if (position < 0 || position >= size)
+        return undefined;
+
+    // Steps 6-7.
+    var first = callFunction(std_String_charCodeAt, S, position);
+    if (first < 0xD800 || first > 0xDBFF || position + 1 === size)
+        return first;
+
+    // Steps 8-9.
+    var second = callFunction(std_String_charCodeAt, S, position + 1);
+    if (second < 0xDC00 || second > 0xDFFF)
+        return first;
+
+    // Step 10.
+    return (first - 0xD800) * 0x400 + (second - 0xDC00) + 0x10000;
+}
+
+// ES2020 draft rev dc1e21c454bd316810be1c0e7af0131a2d7f38e9
+// 21.1.3.16 String.prototype.repeat ( count )
+function String_repeat(count) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("repeat", this);
+
+    // Step 2.
+    var S = ToString(this);
+
+    // Step 3.
+    var n = ToInteger(count);
+
+    // Step 4.
+    if (n < 0)
+        ThrowRangeError(JSMSG_NEGATIVE_REPETITION_COUNT);
+
+    // Step 5.
+    // Inverted condition to handle |Infinity * 0 = NaN| correctly.
+    if (!(n * S.length <= MAX_STRING_LENGTH))
+        ThrowRangeError(JSMSG_RESULTING_STRING_TOO_LARGE);
+
+    // Communicate |n|'s possible range to the compiler. We actually use
+    // MAX_STRING_LENGTH + 1 as range because that's a valid bit mask. That's
+    // fine because it's only used as optimization hint.
+    assert(TO_INT32(MAX_STRING_LENGTH + 1) == MAX_STRING_LENGTH + 1,
+           "MAX_STRING_LENGTH + 1 must fit in int32");
+    assert(((MAX_STRING_LENGTH + 1) & (MAX_STRING_LENGTH + 2)) === 0,
+           "MAX_STRING_LENGTH + 1 can be used as a bitmask");
+    n = n & (MAX_STRING_LENGTH + 1);
+
+    // Steps 6-7.
+    var T = "";
+    for (;;) {
+        if (n & 1)
+            T += S;
+        n >>= 1;
+        if (n)
+            S += S;
+        else
+            break;
+    }
+    return T;
+}
+
+// ES6 draft specification, section 21.1.3.27, version 2013-09-27.
+function String_iterator() {
+    // Step 1.
+    if (this === undefined || this === null) {
+        ThrowTypeError(JSMSG_INCOMPATIBLE_PROTO2, "String", "Symbol.iterator",
+                       ToString(this));
+    }
+
+    // Step 2.
+    var S = ToString(this);
+
+    // Step 3.
+    var iterator = NewStringIterator();
+    UnsafeSetReservedSlot(iterator, ITERATOR_SLOT_TARGET, S);
+    UnsafeSetReservedSlot(iterator, ITERATOR_SLOT_NEXT_INDEX, 0);
+    return iterator;
+}
+
+function StringIteratorNext() {
+    var obj;
+    if (!IsObject(this) || (obj = GuardToStringIterator(this)) === null) {
+        return callFunction(CallStringIteratorMethodIfWrapped, this,
+                            "StringIteratorNext");
+    }
+
+    var S = UnsafeGetStringFromReservedSlot(obj, ITERATOR_SLOT_TARGET);
+    // We know that JSString::MAX_LENGTH <= INT32_MAX (and assert this in
+    // SelfHostring.cpp) so our current index can never be anything other than
+    // an Int32Value.
+    var index = UnsafeGetInt32FromReservedSlot(obj, ITERATOR_SLOT_NEXT_INDEX);
+    var size = S.length;
+    var result = { value: undefined, done: false };
+
+    if (index >= size) {
+        result.done = true;
+        return result;
+    }
+
+    var charCount = 1;
+    var first = callFunction(std_String_charCodeAt, S, index);
+    if (first >= 0xD800 && first <= 0xDBFF && index + 1 < size) {
+        var second = callFunction(std_String_charCodeAt, S, index + 1);
+        if (second >= 0xDC00 && second <= 0xDFFF) {
+            first = (first - 0xD800) * 0x400 + (second - 0xDC00) + 0x10000;
+            charCount = 2;
+        }
+    }
+
+    UnsafeSetReservedSlot(obj, ITERATOR_SLOT_NEXT_INDEX, index + charCount);
+
+    // Communicate |first|'s possible range to the compiler.
+    result.value = callFunction(std_String_fromCodePoint, null, first & 0x1fffff);
+
+    return result;
+}
+
+#if JS_HAS_INTL_API
+var collatorCache = new Record();
+
+/**
+ * Compare this String against that String, using the locale and collation
+ * options provided.
+ *
+ * Spec: ECMAScript Internationalization API Specification, 13.1.1.
+ */
+function String_localeCompare(that) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("localeCompare", this);
+
+    // Steps 2-3.
+    var S = ToString(this);
+    var That = ToString(that);
+
+    // Steps 4-5.
+    var locales = arguments.length > 1 ? arguments[1] : undefined;
+    var options = arguments.length > 2 ? arguments[2] : undefined;
+
+    // Step 6.
+    var collator;
+    if (locales === undefined && options === undefined) {
+        // This cache only optimizes for the old ES5 localeCompare without
+        // locales and options.
+        if (!IsRuntimeDefaultLocale(collatorCache.runtimeDefaultLocale)) {
+            collatorCache.collator = intl_Collator(locales, options);
+            collatorCache.runtimeDefaultLocale = RuntimeDefaultLocale();
+        }
+        collator = collatorCache.collator;
+    } else {
+        collator = intl_Collator(locales, options);
+    }
+
+    // Step 7.
+    return intl_CompareStrings(collator, S, That);
+}
+
+/**
+ * 13.1.2 String.prototype.toLocaleLowerCase ( [ locales ] )
+ *
+ * ES2017 Intl draft rev 94045d234762ad107a3d09bb6f7381a65f1a2f9b
+ */
+function String_toLocaleLowerCase() {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("toLocaleLowerCase", this);
+
+    // Step 2.
+    var string = ToString(this);
+
+    // Handle the common cases (no locales argument or a single string
+    // argument) first.
+    var locales = arguments.length > 0 ? arguments[0] : undefined;
+    var requestedLocale;
+    if (locales === undefined) {
+        // Steps 3, 6.
+        requestedLocale = undefined;
+    } else if (typeof locales === "string") {
+        // Steps 3, 5.
+        requestedLocale = intl_ValidateAndCanonicalizeLanguageTag(locales, false);
+    } else {
+        // Step 3.
+        var requestedLocales = CanonicalizeLocaleList(locales);
+
+        // Steps 4-6.
+        requestedLocale = requestedLocales.length > 0 ? requestedLocales[0] : undefined;
+    }
+
+    // Trivial case: When the input is empty, directly return the empty string.
+    if (string.length === 0)
+        return "";
+
+    if (requestedLocale === undefined)
+        requestedLocale = DefaultLocale();
+
+    // Steps 7-16.
+    return intl_toLocaleLowerCase(string, requestedLocale);
+}
+
+/**
+ * 13.1.3 String.prototype.toLocaleUpperCase ( [ locales ] )
+ *
+ * ES2017 Intl draft rev 94045d234762ad107a3d09bb6f7381a65f1a2f9b
+ */
+function String_toLocaleUpperCase() {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("toLocaleUpperCase", this);
+
+    // Step 2.
+    var string = ToString(this);
+
+    // Handle the common cases (no locales argument or a single string
+    // argument) first.
+    var locales = arguments.length > 0 ? arguments[0] : undefined;
+    var requestedLocale;
+    if (locales === undefined) {
+        // Steps 3, 6.
+        requestedLocale = undefined;
+    } else if (typeof locales === "string") {
+        // Steps 3, 5.
+        requestedLocale = intl_ValidateAndCanonicalizeLanguageTag(locales, false);
+    } else {
+        // Step 3.
+        var requestedLocales = CanonicalizeLocaleList(locales);
+
+        // Steps 4-6.
+        requestedLocale = requestedLocales.length > 0 ? requestedLocales[0] : undefined;
+    }
+
+    // Trivial case: When the input is empty, directly return the empty string.
+    if (string.length === 0)
+        return "";
+
+    if (requestedLocale === undefined)
+        requestedLocale = DefaultLocale();
+
+    // Steps 7-16.
+    return intl_toLocaleUpperCase(string, requestedLocale);
+}
+#endif  // JS_HAS_INTL_API
+
+// ES2018 draft rev 8fadde42cf6a9879b4ab0cb6142b31c4ee501667
+// 21.1.2.4 String.raw ( template, ...substitutions )
+function String_static_raw(callSite/*, ...substitutions*/) {
+    // Steps 1-2 (not applicable).
+
+    // Step 3.
+    var cooked = ToObject(callSite);
+
+    // Step 4.
+    var raw = ToObject(cooked.raw);
+
+    // Step 5.
+    var literalSegments = ToLength(raw.length);
+
+    // Step 6.
+    if (literalSegments === 0)
+        return "";
+
+    // Special case for |String.raw `<literal>`| callers to avoid falling into
+    // the loop code below.
+    if (literalSegments === 1)
+        return ToString(raw[0]);
+
+    // Steps 7-9 were reordered to use the arguments object instead of a rest
+    // parameter, because the former is currently more optimized.
+    //
+    // String.raw intersperses the substitution elements between the literal
+    // segments, i.e. a substitution is added iff there are still pending
+    // literal segments. Furthermore by moving the access to |raw[0]| outside
+    // of the loop, we can use |nextIndex| to index into both, the |raw| array
+    // and the arguments object.
+
+    // Steps 7 (implicit) and 9.a-c.
+    var resultString = ToString(raw[0]);
+
+    // Steps 8-9, 9.d, and 9.i.
+    for (var nextIndex = 1; nextIndex < literalSegments; nextIndex++) {
+        // Steps 9.e-h.
+        if (nextIndex < arguments.length)
+            resultString += ToString(arguments[nextIndex]);
+
+        // Steps 9.a-c.
+        resultString += ToString(raw[nextIndex]);
+    }
+
+    // Step 9.d.i.
+    return resultString;
+}
+
+// https://github.com/tc39/proposal-relative-indexing-method
+// String.prototype.at ( index )
+function String_at(index) {
+    // Step 1.
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("at", this);
+
+    // Step 2.
+    var string = ToString(this);
+
+    // Step 3.
+    var len = string.length;
+
+    // Step 4.
+    var relativeIndex = ToInteger(index);
+
+    // Steps 5-6.
+    var k;
+    if (relativeIndex >= 0) {
+        k = relativeIndex;
+    } else {
+        k = len + relativeIndex;
+    }
+
+    // Step 7.
+    if (k < 0 || k >= len) {
+        return undefined;
+    }
+
+    // Step 8.
+    return string[k];
+}
+
+// ES6 draft 2014-04-27 B.2.3.3
+function String_big() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("big", this);
+    return "<big>" + ToString(this) + "</big>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.4
+function String_blink() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("blink", this);
+    return "<blink>" + ToString(this) + "</blink>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.5
+function String_bold() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("bold", this);
+    return "<b>" + ToString(this) + "</b>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.6
+function String_fixed() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("fixed", this);
+    return "<tt>" + ToString(this) + "</tt>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.9
+function String_italics() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("italics", this);
+    return "<i>" + ToString(this) + "</i>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.11
+function String_small() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("small", this);
+    return "<small>" + ToString(this) + "</small>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.12
+function String_strike() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("strike", this);
+    return "<strike>" + ToString(this) + "</strike>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.13
+function String_sub() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("sub", this);
+    return "<sub>" + ToString(this) + "</sub>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.14
+function String_sup() {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("sup", this);
+    return "<sup>" + ToString(this) + "</sup>";
+}
+
+function EscapeAttributeValue(v) {
+    var inputStr = ToString(v);
+    return StringReplaceAllString(inputStr, '"', "&quot;");
+}
+
+// ES6 draft 2014-04-27 B.2.3.2
+function String_anchor(name) {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("anchor", this);
+    var S = ToString(this);
+    return '<a name="' + EscapeAttributeValue(name) + '">' + S + "</a>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.7
+function String_fontcolor(color) {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("fontcolor", this);
+    var S = ToString(this);
+    return '<font color="' + EscapeAttributeValue(color) + '">' + S + "</font>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.8
+function String_fontsize(size) {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("fontsize", this);
+    var S = ToString(this);
+    return '<font size="' + EscapeAttributeValue(size) + '">' + S + "</font>";
+}
+
+// ES6 draft 2014-04-27 B.2.3.10
+function String_link(url) {
+    if (this === undefined || this === null)
+        ThrowIncompatibleMethod("link", this);
+    var S = ToString(this);
+    return '<a href="' + EscapeAttributeValue(url) + '">' + S + "</a>";
+}