The Tor Browser: js/src/jsstr.cpp@6474c204b198 (annotated)

js/src/jsstr.cpp@6474c204b198 (annotated)

js/src/jsstr.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * 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/. */
 /*
  * JS string type implementation.
  *
  * In order to avoid unnecessary js_LockGCThing/js_UnlockGCThing calls, these
  * native methods store strings (possibly newborn) converted from their 'this'
  * parameter and arguments on the stack: 'this' conversions at argv[-1], arg
  * conversions at their index (argv[0], argv[1]).  This is a legitimate method
  * of rooting things that might lose their newborn root due to subsequent GC
  * allocations in the same native method.
  */
 #include "jsstr.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/Casting.h"
 #include "mozilla/CheckedInt.h"
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/PodOperations.h"
 #include <ctype.h>
 #include <string.h>
 #include "jsapi.h"
 #include "jsarray.h"
 #include "jsatom.h"
 #include "jsbool.h"
 #include "jscntxt.h"
 #include "jsgc.h"
 #include "jsnum.h"
 #include "jsobj.h"
 #include "jsopcode.h"
 #include "jstypes.h"
 #include "jsutil.h"
 #include "builtin/Intl.h"
 #include "builtin/RegExp.h"
 #if ENABLE_INTL_API
 #include "unicode/unorm.h"
 #endif
 #include "vm/GlobalObject.h"
 #include "vm/Interpreter.h"
 #include "vm/NumericConversions.h"
 #include "vm/Opcodes.h"
 #include "vm/RegExpObject.h"
 #include "vm/RegExpStatics.h"
 #include "vm/ScopeObject.h"
 #include "vm/StringBuffer.h"
 #include "jsinferinlines.h"
 #include "vm/Interpreter-inl.h"
 #include "vm/String-inl.h"
 #include "vm/StringObject-inl.h"
 using namespace js;
 using namespace js::gc;
 using namespace js::types;
 using namespace js::unicode;
 using mozilla::CheckedInt;
 using mozilla::IsNaN;
 using mozilla::IsNegativeZero;
 using mozilla::PodCopy;
 using mozilla::PodEqual;
 using mozilla::SafeCast;
 typedef Handle<JSLinearString*> HandleLinearString;
 static JSLinearString *
 ArgToRootedString(JSContext *cx, CallArgs &args, unsigned argno)
 {
     if (argno >= args.length())
         return cx->names().undefined;
     JSString *str = ToString<CanGC>(cx, args[argno]);
     if (!str)
         return nullptr;
     args[argno].setString(str);
     return str->ensureLinear(cx);
 }
 /*
  * Forward declarations for URI encode/decode and helper routines
  */
 static bool
 str_decodeURI(JSContext *cx, unsigned argc, Value *vp);
 static bool
 str_decodeURI_Component(JSContext *cx, unsigned argc, Value *vp);
 static bool
 str_encodeURI(JSContext *cx, unsigned argc, Value *vp);
 static bool
 str_encodeURI_Component(JSContext *cx, unsigned argc, Value *vp);
 /*
  * Global string methods
  */
 /* ES5 B.2.1 */
 static bool
 str_escape(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     static const char digits[] = {'0', '1', '2', '3', '4', '5', '6', '7',
                                   '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
     JSLinearString *str = ArgToRootedString(cx, args, 0);
     if (!str)
         return false;
     size_t length = str->length();
     const jschar *chars = str->chars();
     static const uint8_t shouldPassThrough[256] = {
 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
 ,0,0,0,0,0,0,0,0,0,1,1,0,1,1,1,       /*    !"#$%&'()*+,-./  */
 ,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,       /*   0123456789:;<=>?  */
 ,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,       /*   @ABCDEFGHIJKLMNO  */
 ,1,1,1,1,1,1,1,1,1,1,0,0,0,0,1,       /*   PQRSTUVWXYZ[\]^_  */
 ,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,       /*   `abcdefghijklmno  */
 ,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,     /*   pqrstuvwxyz{\}~  DEL */
     };
     /* In step 7, exactly 69 characters should pass through unencoded. */
 #ifdef DEBUG
     size_t count = 0;
     for (size_t i = 0; i < sizeof(shouldPassThrough); i++) {
         if (shouldPassThrough[i]) {
             count++;
         }
     }
     JS_ASSERT(count == 69);
 #endif
     /* Take a first pass and see how big the result string will need to be. */
     size_t newlength = length;
     for (size_t i = 0; i < length; i++) {
         jschar ch = chars[i];
         if (ch < 128 && shouldPassThrough[ch])
             continue;
         /* The character will be encoded as %XX or %uXXXX. */
         newlength += (ch < 256) ? 2 : 5;
         /*
          * This overflow test works because newlength is incremented by at
          * most 5 on each iteration.
          */
         if (newlength < length) {
             js_ReportAllocationOverflow(cx);
             return false;
         }
     }
     if (newlength >= ~(size_t)0 / sizeof(jschar)) {
         js_ReportAllocationOverflow(cx);
         return false;
     }
     jschar *newchars = cx->pod_malloc<jschar>(newlength + 1);
     if (!newchars)
         return false;
     size_t i, ni;
     for (i = 0, ni = 0; i < length; i++) {
         jschar ch = chars[i];
         if (ch < 128 && shouldPassThrough[ch]) {
             newchars[ni++] = ch;
         } else if (ch < 256) {
             newchars[ni++] = '%';
             newchars[ni++] = digits[ch >> 4];
             newchars[ni++] = digits[ch & 0xF];
         } else {
             newchars[ni++] = '%';
             newchars[ni++] = 'u';
             newchars[ni++] = digits[ch >> 12];
             newchars[ni++] = digits[(ch & 0xF00) >> 8];
             newchars[ni++] = digits[(ch & 0xF0) >> 4];
             newchars[ni++] = digits[ch & 0xF];
         }
     }
     JS_ASSERT(ni == newlength);
     newchars[newlength] = 0;
     JSString *retstr = js_NewString<CanGC>(cx, newchars, newlength);
     if (!retstr) {
         js_free(newchars);
         return false;
     }
     args.rval().setString(retstr);
     return true;
 }
 static inline bool
 Unhex4(const jschar *chars, jschar *result)
 {
     jschar a = chars[0],
            b = chars[1],
            c = chars[2],
            d = chars[3];
     if (!(JS7_ISHEX(a) && JS7_ISHEX(b) && JS7_ISHEX(c) && JS7_ISHEX(d)))
         return false;
     *result = (((((JS7_UNHEX(a) << 4) + JS7_UNHEX(b)) << 4) + JS7_UNHEX(c)) << 4) + JS7_UNHEX(d);
     return true;
 }
 static inline bool
 Unhex2(const jschar *chars, jschar *result)
 {
     jschar a = chars[0],
            b = chars[1];
     if (!(JS7_ISHEX(a) && JS7_ISHEX(b)))
         return false;
     *result = (JS7_UNHEX(a) << 4) + JS7_UNHEX(b);
     return true;
 }
 /* ES5 B.2.2 */
 static bool
 str_unescape(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     /* Step 1. */
     JSLinearString *str = ArgToRootedString(cx, args, 0);
     if (!str)
         return false;
     /*
      * NB: use signed integers for length/index to allow simple length
      * comparisons without unsigned-underflow hazards.
      */
     JS_STATIC_ASSERT(JSString::MAX_LENGTH <= INT_MAX);
     /* Step 2. */
     int length = str->length();
     const jschar *chars = str->chars();
     /* Step 3. */
     StringBuffer sb(cx);
     /*
      * Note that the spec algorithm has been optimized to avoid building
      * a string in the case where no escapes are present.
      */
     /* Step 4. */
     int k = 0;
     bool building = false;
     while (true) {
         /* Step 5. */
         if (k == length) {
             JSLinearString *result;
             if (building) {
                 result = sb.finishString();
                 if (!result)
                     return false;
             } else {
                 result = str;
             }
             args.rval().setString(result);
             return true;
         }
         /* Step 6. */
         jschar c = chars[k];
         /* Step 7. */
         if (c != '%')
             goto step_18;
         /* Step 8. */
         if (k > length - 6)
             goto step_14;
         /* Step 9. */
         if (chars[k + 1] != 'u')
             goto step_14;
 #define ENSURE_BUILDING                             \
     JS_BEGIN_MACRO                                  \
         if (!building) {                            \
             building = true;                        \
             if (!sb.reserve(length))                \
                 return false;                       \
             sb.infallibleAppend(chars, chars + k);  \
         }                                           \
     JS_END_MACRO
         /* Step 10-13. */
         if (Unhex4(&chars[k + 2], &c)) {
             ENSURE_BUILDING;
             k += 5;
             goto step_18;
         }
       step_14:
         /* Step 14. */
         if (k > length - 3)
             goto step_18;
         /* Step 15-17. */
         if (Unhex2(&chars[k + 1], &c)) {
             ENSURE_BUILDING;
             k += 2;
         }
       step_18:
         if (building)
             sb.infallibleAppend(c);
         /* Step 19. */
         k += 1;
     }
 #undef ENSURE_BUILDING
 }
 #if JS_HAS_UNEVAL
 static bool
 str_uneval(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     JSString *str = ValueToSource(cx, args.get(0));
     if (!str)
         return false;
     args.rval().setString(str);
     return true;
 }
 #endif
 static const JSFunctionSpec string_functions[] = {
     JS_FN(js_escape_str,             str_escape,                1,0),
     JS_FN(js_unescape_str,           str_unescape,              1,0),
 #if JS_HAS_UNEVAL
     JS_FN(js_uneval_str,             str_uneval,                1,0),
 #endif
     JS_FN(js_decodeURI_str,          str_decodeURI,             1,0),
     JS_FN(js_encodeURI_str,          str_encodeURI,             1,0),
     JS_FN(js_decodeURIComponent_str, str_decodeURI_Component,   1,0),
     JS_FN(js_encodeURIComponent_str, str_encodeURI_Component,   1,0),
     JS_FS_END
 };
 const jschar      js_empty_ucstr[]  = {0};
 const JSSubString js_EmptySubString = {0, js_empty_ucstr};
 static const unsigned STRING_ELEMENT_ATTRS = JSPROP_ENUMERATE | JSPROP_READONLY | JSPROP_PERMANENT;
 static bool
 str_enumerate(JSContext *cx, HandleObject obj)
 {
     RootedString str(cx, obj->as<StringObject>().unbox());
     RootedValue value(cx);
     for (size_t i = 0, length = str->length(); i < length; i++) {
         JSString *str1 = js_NewDependentString(cx, str, i, 1);
         if (!str1)
             return false;
         value.setString(str1);
         if (!JSObject::defineElement(cx, obj, i, value,
                                      JS_PropertyStub, JS_StrictPropertyStub,
                                      STRING_ELEMENT_ATTRS))
         {
             return false;
         }
     }
     return true;
 }
 bool
 js::str_resolve(JSContext *cx, HandleObject obj, HandleId id, MutableHandleObject objp)
 {
     if (!JSID_IS_INT(id))
         return true;
     RootedString str(cx, obj->as<StringObject>().unbox());
     int32_t slot = JSID_TO_INT(id);
     if ((size_t)slot < str->length()) {
         JSString *str1 = cx->staticStrings().getUnitStringForElement(cx, str, size_t(slot));
         if (!str1)
             return false;
         RootedValue value(cx, StringValue(str1));
         if (!JSObject::defineElement(cx, obj, uint32_t(slot), value, nullptr, nullptr,
                                      STRING_ELEMENT_ATTRS))
         {
             return false;
         }
         objp.set(obj);
     }
     return true;
 }
 const Class StringObject::class_ = {
     js_String_str,
     JSCLASS_HAS_RESERVED_SLOTS(StringObject::RESERVED_SLOTS) |
     JSCLASS_NEW_RESOLVE | JSCLASS_HAS_CACHED_PROTO(JSProto_String),
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     str_enumerate,
     (JSResolveOp)str_resolve,
     JS_ConvertStub
 };
 /*
  * Returns a JSString * for the |this| value associated with 'call', or throws
  * a TypeError if |this| is null or undefined.  This algorithm is the same as
  * calling CheckObjectCoercible(this), then returning ToString(this), as all
  * String.prototype.* methods do (other than toString and valueOf).
  */
 static MOZ_ALWAYS_INLINE JSString *
 ThisToStringForStringProto(JSContext *cx, CallReceiver call)
 {
     JS_CHECK_RECURSION(cx, return nullptr);
     if (call.thisv().isString())
         return call.thisv().toString();
     if (call.thisv().isObject()) {
         RootedObject obj(cx, &call.thisv().toObject());
         if (obj->is<StringObject>()) {
             Rooted<jsid> id(cx, NameToId(cx->names().toString));
             if (ClassMethodIsNative(cx, obj, &StringObject::class_, id, js_str_toString)) {
                 JSString *str = obj->as<StringObject>().unbox();
                 call.setThis(StringValue(str));
                 return str;
             }
         }
     } else if (call.thisv().isNullOrUndefined()) {
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_CANT_CONVERT_TO,
                              call.thisv().isNull() ? "null" : "undefined", "object");
         return nullptr;
     }
     JSString *str = ToStringSlow<CanGC>(cx, call.thisv());
     if (!str)
         return nullptr;
     call.setThis(StringValue(str));
     return str;
 }
 MOZ_ALWAYS_INLINE bool
 IsString(HandleValue v)
 {
     return v.isString() || (v.isObject() && v.toObject().is<StringObject>());
 }
 #if JS_HAS_TOSOURCE
 /*
  * String.prototype.quote is generic (as are most string methods), unlike
  * toSource, toString, and valueOf.
  */
 static bool
 str_quote(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     str = js_QuoteString(cx, str, '"');
     if (!str)
         return false;
     args.rval().setString(str);
     return true;
 }
 MOZ_ALWAYS_INLINE bool
 str_toSource_impl(JSContext *cx, CallArgs args)
 {
     JS_ASSERT(IsString(args.thisv()));
     Rooted<JSString*> str(cx, ToString<CanGC>(cx, args.thisv()));
     if (!str)
         return false;
     str = js_QuoteString(cx, str, '"');
     if (!str)
         return false;
     StringBuffer sb(cx);
     if (!sb.append("(new String(") || !sb.append(str) || !sb.append("))"))
         return false;
     str = sb.finishString();
     if (!str)
         return false;
     args.rval().setString(str);
     return true;
 }
 static bool
 str_toSource(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     return CallNonGenericMethod<IsString, str_toSource_impl>(cx, args);
 }
 #endif /* JS_HAS_TOSOURCE */
 MOZ_ALWAYS_INLINE bool
 str_toString_impl(JSContext *cx, CallArgs args)
 {
     JS_ASSERT(IsString(args.thisv()));
     args.rval().setString(args.thisv().isString()
                               ? args.thisv().toString()
                               : args.thisv().toObject().as<StringObject>().unbox());
     return true;
 }
 bool
 js_str_toString(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     return CallNonGenericMethod<IsString, str_toString_impl>(cx, args);
 }
 /*
  * Java-like string native methods.
  */
 static MOZ_ALWAYS_INLINE bool
 ValueToIntegerRange(JSContext *cx, HandleValue v, int32_t *out)
 {
     if (v.isInt32()) {
         *out = v.toInt32();
     } else {
         double d;
         if (!ToInteger(cx, v, &d))
             return false;
         if (d > INT32_MAX)
             *out = INT32_MAX;
         else if (d < INT32_MIN)
             *out = INT32_MIN;
         else
             *out = int32_t(d);
     }
     return true;
 }
 static JSString *
 DoSubstr(JSContext *cx, JSString *str, size_t begin, size_t len)
 {
     /*
      * Optimization for one level deep ropes.
      * This is common for the following pattern:
      *
      * while() {
      *   text = text.substr(0, x) + "bla" + text.substr(x)
      *   test.charCodeAt(x + 1)
      * }
      */
     if (str->isRope()) {
         JSRope *rope = &str->asRope();
         /* Substring is totally in leftChild of rope. */
         if (begin + len <= rope->leftChild()->length()) {
             str = rope->leftChild();
             return js_NewDependentString(cx, str, begin, len);
         }
         /* Substring is totally in rightChild of rope. */
         if (begin >= rope->leftChild()->length()) {
             str = rope->rightChild();
             begin -= rope->leftChild()->length();
             return js_NewDependentString(cx, str, begin, len);
         }
         /*
          * Requested substring is partly in the left and partly in right child.
          * Create a rope of substrings for both childs.
          */
         JS_ASSERT (begin < rope->leftChild()->length() &&
                    begin + len > rope->leftChild()->length());
         size_t lhsLength = rope->leftChild()->length() - begin;
         size_t rhsLength = begin + len - rope->leftChild()->length();
         Rooted<JSRope *> ropeRoot(cx, rope);
         RootedString lhs(cx, js_NewDependentString(cx, ropeRoot->leftChild(),
                                                    begin, lhsLength));
         if (!lhs)
             return nullptr;
         RootedString rhs(cx, js_NewDependentString(cx, ropeRoot->rightChild(), 0, rhsLength));
         if (!rhs)
             return nullptr;
         return JSRope::new_<CanGC>(cx, lhs, rhs, len);
     }
     return js_NewDependentString(cx, str, begin, len);
 }
 static bool
 str_substring(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     JSString *str = ThisToStringForStringProto(cx, args);
     if (!str)
         return false;
     int32_t length, begin, end;
     if (args.length() > 0) {
         end = length = int32_t(str->length());
         if (args[0].isInt32()) {
             begin = args[0].toInt32();
         } else {
             RootedString strRoot(cx, str);
             if (!ValueToIntegerRange(cx, args[0], &begin))
                 return false;
             str = strRoot;
         }
         if (begin < 0)
             begin = 0;
         else if (begin > length)
             begin = length;
         if (args.hasDefined(1)) {
             if (args[1].isInt32()) {
                 end = args[1].toInt32();
             } else {
                 RootedString strRoot(cx, str);
                 if (!ValueToIntegerRange(cx, args[1], &end))
                     return false;
                 str = strRoot;
             }
             if (end > length) {
                 end = length;
             } else {
                 if (end < 0)
                     end = 0;
                 if (end < begin) {
                     int32_t tmp = begin;
                     begin = end;
                     end = tmp;
                 }
             }
         }
         str = DoSubstr(cx, str, size_t(begin), size_t(end - begin));
         if (!str)
             return false;
     }
     args.rval().setString(str);
     return true;
 }
 JSString* JS_FASTCALL
 js_toLowerCase(JSContext *cx, JSString *str)
 {
     size_t n = str->length();
     const jschar *s = str->getChars(cx);
     if (!s)
         return nullptr;
     jschar *news = cx->pod_malloc<jschar>(n + 1);
     if (!news)
         return nullptr;
     for (size_t i = 0; i < n; i++)
         news[i] = unicode::ToLowerCase(s[i]);
     news[n] = 0;
     str = js_NewString<CanGC>(cx, news, n);
     if (!str) {
         js_free(news);
         return nullptr;
     }
     return str;
 }
 static inline bool
 ToLowerCaseHelper(JSContext *cx, CallReceiver call)
 {
     RootedString str(cx, ThisToStringForStringProto(cx, call));
     if (!str)
         return false;
     str = js_toLowerCase(cx, str);
     if (!str)
         return false;
     call.rval().setString(str);
     return true;
 }
 static bool
 str_toLowerCase(JSContext *cx, unsigned argc, Value *vp)
 {
     return ToLowerCaseHelper(cx, CallArgsFromVp(argc, vp));
 }
 static bool
 str_toLocaleLowerCase(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     /*
      * Forcefully ignore the first (or any) argument and return toLowerCase(),
      * ECMA has reserved that argument, presumably for defining the locale.
      */
     if (cx->runtime()->localeCallbacks && cx->runtime()->localeCallbacks->localeToLowerCase) {
         RootedString str(cx, ThisToStringForStringProto(cx, args));
         if (!str)
             return false;
         RootedValue result(cx);
         if (!cx->runtime()->localeCallbacks->localeToLowerCase(cx, str, &result))
             return false;
         args.rval().set(result);
         return true;
     }
     return ToLowerCaseHelper(cx, args);
 }
 JSString* JS_FASTCALL
 js_toUpperCase(JSContext *cx, JSString *str)
 {
     size_t n = str->length();
     const jschar *s = str->getChars(cx);
     if (!s)
         return nullptr;
     jschar *news = cx->pod_malloc<jschar>(n + 1);
     if (!news)
         return nullptr;
     for (size_t i = 0; i < n; i++)
         news[i] = unicode::ToUpperCase(s[i]);
     news[n] = 0;
     str = js_NewString<CanGC>(cx, news, n);
     if (!str) {
         js_free(news);
         return nullptr;
     }
     return str;
 }
 static bool
 ToUpperCaseHelper(JSContext *cx, CallReceiver call)
 {
     RootedString str(cx, ThisToStringForStringProto(cx, call));
     if (!str)
         return false;
     str = js_toUpperCase(cx, str);
     if (!str)
         return false;
     call.rval().setString(str);
     return true;
 }
 static bool
 str_toUpperCase(JSContext *cx, unsigned argc, Value *vp)
 {
     return ToUpperCaseHelper(cx, CallArgsFromVp(argc, vp));
 }
 static bool
 str_toLocaleUpperCase(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     /*
      * Forcefully ignore the first (or any) argument and return toUpperCase(),
      * ECMA has reserved that argument, presumably for defining the locale.
      */
     if (cx->runtime()->localeCallbacks && cx->runtime()->localeCallbacks->localeToUpperCase) {
         RootedString str(cx, ThisToStringForStringProto(cx, args));
         if (!str)
             return false;
         RootedValue result(cx);
         if (!cx->runtime()->localeCallbacks->localeToUpperCase(cx, str, &result))
             return false;
         args.rval().set(result);
         return true;
     }
     return ToUpperCaseHelper(cx, args);
 }
 #if !EXPOSE_INTL_API
 static bool
 str_localeCompare(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     RootedString thatStr(cx, ToString<CanGC>(cx, args.get(0)));
     if (!thatStr)
         return false;
     if (cx->runtime()->localeCallbacks && cx->runtime()->localeCallbacks->localeCompare) {
         RootedValue result(cx);
         if (!cx->runtime()->localeCallbacks->localeCompare(cx, str, thatStr, &result))
             return false;
         args.rval().set(result);
         return true;
     }
     int32_t result;
     if (!CompareStrings(cx, str, thatStr, &result))
         return false;
     args.rval().setInt32(result);
     return true;
 }
 #endif
 #if EXPOSE_INTL_API
 static const size_t SB_LENGTH = 32;
 /* ES6 20140210 draft 21.1.3.12. */
 static bool
 str_normalize(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     // Steps 1-3.
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     // Step 4.
     UNormalizationMode form;
     if (!args.hasDefined(0)) {
         form = UNORM_NFC;
     } else {
         // Steps 5-6.
         Rooted<JSLinearString*> formStr(cx, ArgToRootedString(cx, args, 0));
         if (!formStr)
             return false;
         // Step 7.
         if (formStr == cx->names().NFC) {
             form = UNORM_NFC;
         } else if (formStr == cx->names().NFD) {
             form = UNORM_NFD;
         } else if (formStr == cx->names().NFKC) {
             form = UNORM_NFKC;
         } else if (formStr == cx->names().NFKD) {
             form = UNORM_NFKD;
         } else {
             JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr,
                                  JSMSG_INVALID_NORMALIZE_FORM);
             return false;
         }
     }
     // Step 8.
     Rooted<JSFlatString*> flatStr(cx, str->ensureFlat(cx));
     if (!flatStr)
         return false;
     const UChar *srcChars = JSCharToUChar(flatStr->chars());
     int32_t srcLen = SafeCast<int32_t>(flatStr->length());
     StringBuffer chars(cx);
     if (!chars.resize(SB_LENGTH))
         return false;
     UErrorCode status = U_ZERO_ERROR;
     int32_t size = unorm_normalize(srcChars, srcLen, form, 0,
                                    JSCharToUChar(chars.begin()), SB_LENGTH,
                                    &status);
     if (status == U_BUFFER_OVERFLOW_ERROR) {
         if (!chars.resize(size))
             return false;
         status = U_ZERO_ERROR;
 #ifdef DEBUG
         int32_t finalSize =
 #endif
         unorm_normalize(srcChars, srcLen, form, 0,
                         JSCharToUChar(chars.begin()), size,
                         &status);
         MOZ_ASSERT(size == finalSize || U_FAILURE(status), "unorm_normalize behaved inconsistently");
     }
     if (U_FAILURE(status))
         return false;
     // Trim any unused characters.
     if (!chars.resize(size))
         return false;
     RootedString ns(cx, chars.finishString());
     if (!ns)
         return false;
     // Step 9.
     args.rval().setString(ns);
     return true;
 }
 #endif
 bool
 js_str_charAt(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString str(cx);
     size_t i;
     if (args.thisv().isString() && args.length() != 0 && args[0].isInt32()) {
         str = args.thisv().toString();
         i = size_t(args[0].toInt32());
         if (i >= str->length())
             goto out_of_range;
     } else {
         str = ThisToStringForStringProto(cx, args);
         if (!str)
             return false;
         double d = 0.0;
         if (args.length() > 0 && !ToInteger(cx, args[0], &d))
             return false;
         if (d < 0 || str->length() <= d)
             goto out_of_range;
         i = size_t(d);
     }
     str = cx->staticStrings().getUnitStringForElement(cx, str, i);
     if (!str)
         return false;
     args.rval().setString(str);
     return true;
   out_of_range:
     args.rval().setString(cx->runtime()->emptyString);
     return true;
 }
 bool
 js_str_charCodeAt(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString str(cx);
     size_t i;
     if (args.thisv().isString() && args.length() != 0 && args[0].isInt32()) {
         str = args.thisv().toString();
         i = size_t(args[0].toInt32());
         if (i >= str->length())
             goto out_of_range;
     } else {
         str = ThisToStringForStringProto(cx, args);
         if (!str)
             return false;
         double d = 0.0;
         if (args.length() > 0 && !ToInteger(cx, args[0], &d))
             return false;
         if (d < 0 || str->length() <= d)
             goto out_of_range;
         i = size_t(d);
     }
     jschar c;
     if (!str->getChar(cx, i, &c))
         return false;
     args.rval().setInt32(c);
     return true;
 out_of_range:
     args.rval().setNaN();
     return true;
 }
 /*
  * Boyer-Moore-Horspool superlinear search for pat:patlen in text:textlen.
  * The patlen argument must be positive and no greater than sBMHPatLenMax.
  *
  * Return the index of pat in text, or -1 if not found.
  */
 static const uint32_t sBMHCharSetSize = 256; /* ISO-Latin-1 */
 static const uint32_t sBMHPatLenMax   = 255; /* skip table element is uint8_t */
 static const int      sBMHBadPattern  = -2;  /* return value if pat is not ISO-Latin-1 */
 int
 js_BoyerMooreHorspool(const jschar *text, uint32_t textlen,
                       const jschar *pat, uint32_t patlen)
 {
     uint8_t skip[sBMHCharSetSize];
     JS_ASSERT(0 < patlen && patlen <= sBMHPatLenMax);
     for (uint32_t i = 0; i < sBMHCharSetSize; i++)
         skip[i] = (uint8_t)patlen;
     uint32_t m = patlen - 1;
     for (uint32_t i = 0; i < m; i++) {
         jschar c = pat[i];
         if (c >= sBMHCharSetSize)
             return sBMHBadPattern;
         skip[c] = (uint8_t)(m - i);
     }
     jschar c;
     for (uint32_t k = m;
          k < textlen;
          k += ((c = text[k]) >= sBMHCharSetSize) ? patlen : skip[c]) {
         for (uint32_t i = k, j = m; ; i--, j--) {
             if (text[i] != pat[j])
                 break;
             if (j == 0)
                 return static_cast<int>(i);  /* safe: max string size */
         }
     }
     return -1;
 }
 struct MemCmp {
     typedef uint32_t Extent;
     static MOZ_ALWAYS_INLINE Extent computeExtent(const jschar *, uint32_t patlen) {
         return (patlen - 1) * sizeof(jschar);
     }
     static MOZ_ALWAYS_INLINE bool match(const jschar *p, const jschar *t, Extent extent) {
         return memcmp(p, t, extent) == 0;
     }
 };
 struct ManualCmp {
     typedef const jschar *Extent;
     static MOZ_ALWAYS_INLINE Extent computeExtent(const jschar *pat, uint32_t patlen) {
         return pat + patlen;
     }
     static MOZ_ALWAYS_INLINE bool match(const jschar *p, const jschar *t, Extent extent) {
         for (; p != extent; ++p, ++t) {
             if (*p != *t)
                 return false;
         }
         return true;
     }
 };
 template <class InnerMatch>
 static int
 UnrolledMatch(const jschar *text, uint32_t textlen, const jschar *pat, uint32_t patlen)
 {
     JS_ASSERT(patlen > 0 && textlen > 0);
     const jschar *textend = text + textlen - (patlen - 1);
     const jschar p0 = *pat;
     const jschar *const patNext = pat + 1;
     const typename InnerMatch::Extent extent = InnerMatch::computeExtent(pat, patlen);
     uint8_t fixup;
     const jschar *t = text;
     switch ((textend - t) & 7) {
       case 0: if (*t++ == p0) { fixup = 8; goto match; }
       case 7: if (*t++ == p0) { fixup = 7; goto match; }
       case 6: if (*t++ == p0) { fixup = 6; goto match; }
       case 5: if (*t++ == p0) { fixup = 5; goto match; }
       case 4: if (*t++ == p0) { fixup = 4; goto match; }
       case 3: if (*t++ == p0) { fixup = 3; goto match; }
       case 2: if (*t++ == p0) { fixup = 2; goto match; }
       case 1: if (*t++ == p0) { fixup = 1; goto match; }
     }
     while (t != textend) {
       if (t[0] == p0) { t += 1; fixup = 8; goto match; }
       if (t[1] == p0) { t += 2; fixup = 7; goto match; }
       if (t[2] == p0) { t += 3; fixup = 6; goto match; }
       if (t[3] == p0) { t += 4; fixup = 5; goto match; }
       if (t[4] == p0) { t += 5; fixup = 4; goto match; }
       if (t[5] == p0) { t += 6; fixup = 3; goto match; }
       if (t[6] == p0) { t += 7; fixup = 2; goto match; }
       if (t[7] == p0) { t += 8; fixup = 1; goto match; }
         t += 8;
         continue;
         do {
             if (*t++ == p0) {
               match:
                 if (!InnerMatch::match(patNext, t, extent))
                     goto failed_match;
                 return t - text - 1;
             }
           failed_match:;
         } while (--fixup > 0);
     }
     return -1;
 }
 static MOZ_ALWAYS_INLINE int
 StringMatch(const jschar *text, uint32_t textlen,
             const jschar *pat, uint32_t patlen)
 {
     if (patlen == 0)
         return 0;
     if (textlen < patlen)
         return -1;
 #if defined(__i386__) || defined(_M_IX86) || defined(__i386)
     /*
      * Given enough registers, the unrolled loop below is faster than the
      * following loop. 32-bit x86 does not have enough registers.
      */
     if (patlen == 1) {
         const jschar p0 = *pat;
         for (const jschar *c = text, *end = text + textlen; c != end; ++c) {
             if (*c == p0)
                 return c - text;
         }
         return -1;
     }
 #endif
     /*
      * If the text or pattern string is short, BMH will be more expensive than
      * the basic linear scan due to initialization cost and a more complex loop
      * body. While the correct threshold is input-dependent, we can make a few
      * conservative observations:
      *  - When |textlen| is "big enough", the initialization time will be
      *    proportionally small, so the worst-case slowdown is minimized.
      *  - When |patlen| is "too small", even the best case for BMH will be
      *    slower than a simple scan for large |textlen| due to the more complex
      *    loop body of BMH.
      * From this, the values for "big enough" and "too small" are determined
      * empirically. See bug 526348.
      */
     if (textlen >= 512 && patlen >= 11 && patlen <= sBMHPatLenMax) {
         int index = js_BoyerMooreHorspool(text, textlen, pat, patlen);
         if (index != sBMHBadPattern)
             return index;
     }
     /*
      * For big patterns with large potential overlap we want the SIMD-optimized
      * speed of memcmp. For small patterns, a simple loop is faster.
      *
      * FIXME: Linux memcmp performance is sad and the manual loop is faster.
      */
     return
 #if !defined(__linux__)
            patlen > 128 ? UnrolledMatch<MemCmp>(text, textlen, pat, patlen)
                         :
 #endif
                           UnrolledMatch<ManualCmp>(text, textlen, pat, patlen);
 }
 static const size_t sRopeMatchThresholdRatioLog2 = 5;
 bool
 js::StringHasPattern(const jschar *text, uint32_t textlen,
                      const jschar *pat, uint32_t patlen)
 {
     return StringMatch(text, textlen, pat, patlen) != -1;
 }
 // When an algorithm does not need a string represented as a single linear
 // array of characters, this range utility may be used to traverse the string a
 // sequence of linear arrays of characters. This avoids flattening ropes.
 class StringSegmentRange
 {
     // If malloc() shows up in any profiles from this vector, we can add a new
     // StackAllocPolicy which stashes a reusable freed-at-gc buffer in the cx.
     AutoStringVector stack;
     Rooted<JSLinearString*> cur;
     bool settle(JSString *str) {
         while (str->isRope()) {
             JSRope &rope = str->asRope();
             if (!stack.append(rope.rightChild()))
                 return false;
             str = rope.leftChild();
         }
         cur = &str->asLinear();
         return true;
     }
   public:
     StringSegmentRange(JSContext *cx)
       : stack(cx), cur(cx)
     {}
     MOZ_WARN_UNUSED_RESULT bool init(JSString *str) {
         JS_ASSERT(stack.empty());
         return settle(str);
     }
     bool empty() const {
         return cur == nullptr;
     }
     JSLinearString *front() const {
         JS_ASSERT(!cur->isRope());
         return cur;
     }
     MOZ_WARN_UNUSED_RESULT bool popFront() {
         JS_ASSERT(!empty());
         if (stack.empty()) {
             cur = nullptr;
             return true;
         }
         return settle(stack.popCopy());
     }
 };
 /*
  * RopeMatch takes the text to search and the pattern to search for in the text.
  * RopeMatch returns false on OOM and otherwise returns the match index through
  * the 'match' outparam (-1 for not found).
  */
 static bool
 RopeMatch(JSContext *cx, JSString *textstr, const jschar *pat, uint32_t patlen, int *match)
 {
     JS_ASSERT(textstr->isRope());
     if (patlen == 0) {
         *match = 0;
         return true;
     }
     if (textstr->length() < patlen) {
         *match = -1;
         return true;
     }
     /*
      * List of leaf nodes in the rope. If we run out of memory when trying to
      * append to this list, we can still fall back to StringMatch, so use the
      * system allocator so we don't report OOM in that case.
      */
     Vector<JSLinearString *, 16, SystemAllocPolicy> strs;
     /*
      * We don't want to do rope matching if there is a poor node-to-char ratio,
      * since this means spending a lot of time in the match loop below. We also
      * need to build the list of leaf nodes. Do both here: iterate over the
      * nodes so long as there are not too many.
      */
     {
         size_t textstrlen = textstr->length();
         size_t threshold = textstrlen >> sRopeMatchThresholdRatioLog2;
         StringSegmentRange r(cx);
         if (!r.init(textstr))
             return false;
         while (!r.empty()) {
             if (threshold-- == 0 || !strs.append(r.front())) {
                 const jschar *chars = textstr->getChars(cx);
                 if (!chars)
                     return false;
                 *match = StringMatch(chars, textstrlen, pat, patlen);
                 return true;
             }
             if (!r.popFront())
                 return false;
         }
     }
     /* Absolute offset from the beginning of the logical string textstr. */
     int pos = 0;
     for (JSLinearString **outerp = strs.begin(); outerp != strs.end(); ++outerp) {
         /* Try to find a match within 'outer'. */
         JSLinearString *outer = *outerp;
         const jschar *chars = outer->chars();
         size_t len = outer->length();
         int matchResult = StringMatch(chars, len, pat, patlen);
         if (matchResult != -1) {
             /* Matched! */
             *match = pos + matchResult;
             return true;
         }
         /* Try to find a match starting in 'outer' and running into other nodes. */
         const jschar *const text = chars + (patlen > len ? 0 : len - patlen + 1);
         const jschar *const textend = chars + len;
         const jschar p0 = *pat;
         const jschar *const p1 = pat + 1;
         const jschar *const patend = pat + patlen;
         for (const jschar *t = text; t != textend; ) {
             if (*t++ != p0)
                 continue;
             JSLinearString **innerp = outerp;
             const jschar *ttend = textend;
             for (const jschar *pp = p1, *tt = t; pp != patend; ++pp, ++tt) {
                 while (tt == ttend) {
                     if (++innerp == strs.end()) {
                         *match = -1;
                         return true;
                     }
                     JSLinearString *inner = *innerp;
                     tt = inner->chars();
                     ttend = tt + inner->length();
                 }
                 if (*pp != *tt)
                     goto break_continue;
             }
             /* Matched! */
             *match = pos + (t - chars) - 1;  /* -1 because of *t++ above */
             return true;
           break_continue:;
         }
         pos += len;
     }
     *match = -1;
     return true;
 }
 /* ES6 20121026 draft 15.5.4.24. */
 static bool
 str_contains(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     // Steps 1, 2, and 3
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     // Steps 4 and 5
     Rooted<JSLinearString*> searchStr(cx, ArgToRootedString(cx, args, 0));
     if (!searchStr)
         return false;
     // Steps 6 and 7
     uint32_t pos = 0;
     if (args.hasDefined(1)) {
         if (args[1].isInt32()) {
             int i = args[1].toInt32();
             pos = (i < 0) ? 0U : uint32_t(i);
         } else {
             double d;
             if (!ToInteger(cx, args[1], &d))
                 return false;
             pos = uint32_t(Min(Max(d, 0.0), double(UINT32_MAX)));
         }
     }
     // Step 8
     uint32_t textLen = str->length();
     const jschar *textChars = str->getChars(cx);
     if (!textChars)
         return false;
     // Step 9
     uint32_t start = Min(Max(pos, 0U), textLen);
     // Step 10
     uint32_t searchLen = searchStr->length();
     const jschar *searchChars = searchStr->chars();
     // Step 11
     textChars += start;
     textLen -= start;
     int match = StringMatch(textChars, textLen, searchChars, searchLen);
     args.rval().setBoolean(match != -1);
     return true;
 }
 /* ES6 20120927 draft 15.5.4.7. */
 static bool
 str_indexOf(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     // Steps 1, 2, and 3
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     // Steps 4 and 5
     Rooted<JSLinearString*> searchStr(cx, ArgToRootedString(cx, args, 0));
     if (!searchStr)
         return false;
     // Steps 6 and 7
     uint32_t pos = 0;
     if (args.hasDefined(1)) {
         if (args[1].isInt32()) {
             int i = args[1].toInt32();
             pos = (i < 0) ? 0U : uint32_t(i);
         } else {
             double d;
             if (!ToInteger(cx, args[1], &d))
                 return false;
             pos = uint32_t(Min(Max(d, 0.0), double(UINT32_MAX)));
         }
     }
    // Step 8
     uint32_t textLen = str->length();
     const jschar *textChars = str->getChars(cx);
     if (!textChars)
         return false;
     // Step 9
     uint32_t start = Min(Max(pos, 0U), textLen);
     // Step 10
     uint32_t searchLen = searchStr->length();
     const jschar *searchChars = searchStr->chars();
     // Step 11
     textChars += start;
     textLen -= start;
     int match = StringMatch(textChars, textLen, searchChars, searchLen);
     args.rval().setInt32((match == -1) ? -1 : start + match);
     return true;
 }
 static bool
 str_lastIndexOf(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString textstr(cx, ThisToStringForStringProto(cx, args));
     if (!textstr)
         return false;
     size_t textlen = textstr->length();
     Rooted<JSLinearString*> patstr(cx, ArgToRootedString(cx, args, 0));
     if (!patstr)
         return false;
     size_t patlen = patstr->length();
     int i = textlen - patlen; // Start searching here
     if (i < 0) {
         args.rval().setInt32(-1);
         return true;
     }
     if (args.length() > 1) {
         if (args[1].isInt32()) {
             int j = args[1].toInt32();
             if (j <= 0)
                 i = 0;
             else if (j < i)
                 i = j;
         } else {
             double d;
             if (!ToNumber(cx, args[1], &d))
                 return false;
             if (!IsNaN(d)) {
                 d = ToInteger(d);
                 if (d <= 0)
                     i = 0;
                 else if (d < i)
                     i = (int)d;
             }
         }
     }
     if (patlen == 0) {
         args.rval().setInt32(i);
         return true;
     }
     const jschar *text = textstr->getChars(cx);
     if (!text)
         return false;
     const jschar *pat = patstr->chars();
     const jschar *t = text + i;
     const jschar *textend = text - 1;
     const jschar p0 = *pat;
     const jschar *patNext = pat + 1;
     const jschar *patEnd = pat + patlen;
     for (; t != textend; --t) {
         if (*t == p0) {
             const jschar *t1 = t + 1;
             for (const jschar *p1 = patNext; p1 != patEnd; ++p1, ++t1) {
                 if (*t1 != *p1)
                     goto break_continue;
             }
             args.rval().setInt32(t - text);
             return true;
         }
       break_continue:;
     }
     args.rval().setInt32(-1);
     return true;
 }
 /* ES6 20131108 draft 21.1.3.18. */
 static bool
 str_startsWith(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     // Steps 1, 2, and 3
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     // Step 4
     if (args.get(0).isObject() && IsObjectWithClass(args[0], ESClass_RegExp, cx)) {
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_INVALID_ARG_TYPE,
                              "first", "", "Regular Expression");
         return false;
     }
     // Steps 5 and 6
     Rooted<JSLinearString*> searchStr(cx, ArgToRootedString(cx, args, 0));
     if (!searchStr)
         return false;
     // Steps 7 and 8
     uint32_t pos = 0;
     if (args.hasDefined(1)) {
         if (args[1].isInt32()) {
             int i = args[1].toInt32();
             pos = (i < 0) ? 0U : uint32_t(i);
         } else {
             double d;
             if (!ToInteger(cx, args[1], &d))
                 return false;
             pos = uint32_t(Min(Max(d, 0.0), double(UINT32_MAX)));
         }
     }
     // Step 9
     uint32_t textLen = str->length();
     const jschar *textChars = str->getChars(cx);
     if (!textChars)
         return false;
     // Step 10
     uint32_t start = Min(Max(pos, 0U), textLen);
     // Step 11
     uint32_t searchLen = searchStr->length();
     const jschar *searchChars = searchStr->chars();
     // Step 12
     if (searchLen + start < searchLen || searchLen + start > textLen) {
         args.rval().setBoolean(false);
         return true;
     }
     // Steps 13 and 14
     args.rval().setBoolean(PodEqual(textChars + start, searchChars, searchLen));
     return true;
 }
 /* ES6 20131108 draft 21.1.3.7. */
 static bool
 str_endsWith(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     // Steps 1, 2, and 3
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     // Step 4
     if (args.get(0).isObject() && IsObjectWithClass(args[0], ESClass_RegExp, cx)) {
         JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_INVALID_ARG_TYPE,
                              "first", "", "Regular Expression");
         return false;
     }
     // Steps 5 and 6
     Rooted<JSLinearString *> searchStr(cx, ArgToRootedString(cx, args, 0));
     if (!searchStr)
         return false;
     // Step 7
     uint32_t textLen = str->length();
     const jschar *textChars = str->getChars(cx);
     if (!textChars)
         return false;
     // Steps 8 and 9
     uint32_t pos = textLen;
     if (args.hasDefined(1)) {
         if (args[1].isInt32()) {
             int i = args[1].toInt32();
             pos = (i < 0) ? 0U : uint32_t(i);
         } else {
             double d;
             if (!ToInteger(cx, args[1], &d))
                 return false;
             pos = uint32_t(Min(Max(d, 0.0), double(UINT32_MAX)));
         }
     }
     // Step 10
     uint32_t end = Min(Max(pos, 0U), textLen);
     // Step 11
     uint32_t searchLen = searchStr->length();
     const jschar *searchChars = searchStr->chars();
     // Step 13 (reordered)
     if (searchLen > end) {
         args.rval().setBoolean(false);
         return true;
     }
     // Step 12
     uint32_t start = end - searchLen;
     // Steps 14 and 15
     args.rval().setBoolean(PodEqual(textChars + start, searchChars, searchLen));
     return true;
 }
 static bool
 js_TrimString(JSContext *cx, Value *vp, bool trimLeft, bool trimRight)
 {
     CallReceiver call = CallReceiverFromVp(vp);
     RootedString str(cx, ThisToStringForStringProto(cx, call));
     if (!str)
         return false;
     size_t length = str->length();
     const jschar *chars = str->getChars(cx);
     if (!chars)
         return false;
     size_t begin = 0;
     size_t end = length;
     if (trimLeft) {
         while (begin < length && unicode::IsSpace(chars[begin]))
             ++begin;
     }
     if (trimRight) {
         while (end > begin && unicode::IsSpace(chars[end - 1]))
             --end;
     }
     str = js_NewDependentString(cx, str, begin, end - begin);
     if (!str)
         return false;
     call.rval().setString(str);
     return true;
 }
 static bool
 str_trim(JSContext *cx, unsigned argc, Value *vp)
 {
     return js_TrimString(cx, vp, true, true);
 }
 static bool
 str_trimLeft(JSContext *cx, unsigned argc, Value *vp)
 {
     return js_TrimString(cx, vp, true, false);
 }
 static bool
 str_trimRight(JSContext *cx, unsigned argc, Value *vp)
 {
     return js_TrimString(cx, vp, false, true);
 }
 /*
  * Perl-inspired string functions.
  */
 namespace {
 /* Result of a successfully performed flat match. */
 class FlatMatch
 {
     RootedAtom patstr;
     const jschar *pat;
     size_t       patlen;
     int32_t      match_;
     friend class StringRegExpGuard;
   public:
     FlatMatch(JSContext *cx) : patstr(cx) {}
     JSLinearString *pattern() const { return patstr; }
     size_t patternLength() const { return patlen; }
     /*
      * Note: The match is -1 when the match is performed successfully,
      * but no match is found.
      */
     int32_t match() const { return match_; }
 };
 } /* anonymous namespace */
 static inline bool
 IsRegExpMetaChar(jschar c)
 {
     switch (c) {
       /* Taken from the PatternCharacter production in 15.10.1. */
       case '^': case '$': case '\\': case '.': case '*': case '+':
       case '?': case '(': case ')': case '[': case ']': case '{':
       case '}': case '|':
         return true;
       default:
         return false;
     }
 }
 static inline bool
 HasRegExpMetaChars(const jschar *chars, size_t length)
 {
     for (size_t i = 0; i < length; ++i) {
         if (IsRegExpMetaChar(chars[i]))
             return true;
     }
     return false;
 }
 namespace {
 /*
  * StringRegExpGuard factors logic out of String regexp operations.
  *
  * |optarg| indicates in which argument position RegExp flags will be found, if
  * present. This is a Mozilla extension and not part of any ECMA spec.
  */
 class MOZ_STACK_CLASS StringRegExpGuard
 {
     RegExpGuard re_;
     FlatMatch   fm;
     RootedObject obj_;
     /*
      * Upper bound on the number of characters we are willing to potentially
      * waste on searching for RegExp meta-characters.
      */
     static const size_t MAX_FLAT_PAT_LEN = 256;
     static JSAtom *
     flattenPattern(JSContext *cx, JSAtom *patstr)
     {
         StringBuffer sb(cx);
         if (!sb.reserve(patstr->length()))
             return nullptr;
         static const jschar ESCAPE_CHAR = '\\';
         const jschar *chars = patstr->chars();
         size_t len = patstr->length();
         for (const jschar *it = chars; it != chars + len; ++it) {
             if (IsRegExpMetaChar(*it)) {
                 if (!sb.append(ESCAPE_CHAR) || !sb.append(*it))
                     return nullptr;
             } else {
                 if (!sb.append(*it))
                     return nullptr;
             }
         }
         return sb.finishAtom();
     }
   public:
     StringRegExpGuard(JSContext *cx)
       : re_(cx), fm(cx), obj_(cx)
     { }
     /* init must succeed in order to call tryFlatMatch or normalizeRegExp. */
     bool init(JSContext *cx, CallArgs args, bool convertVoid = false)
     {
         if (args.length() != 0 && IsObjectWithClass(args[0], ESClass_RegExp, cx))
             return init(cx, &args[0].toObject());
         if (convertVoid && !args.hasDefined(0)) {
             fm.patstr = cx->runtime()->emptyString;
             return true;
         }
         JSString *arg = ArgToRootedString(cx, args, 0);
         if (!arg)
             return false;
         fm.patstr = AtomizeString(cx, arg);
         if (!fm.patstr)
             return false;
         return true;
     }
     bool init(JSContext *cx, JSObject *regexp) {
         obj_ = regexp;
         JS_ASSERT(ObjectClassIs(obj_, ESClass_RegExp, cx));
         if (!RegExpToShared(cx, obj_, &re_))
             return false;
         return true;
     }
     bool init(JSContext *cx, HandleString pattern) {
         fm.patstr = AtomizeString(cx, pattern);
         if (!fm.patstr)
             return false;
         return true;
     }
     /*
      * Attempt to match |patstr| to |textstr|. A flags argument, metachars in
      * the pattern string, or a lengthy pattern string can thwart this process.
      *
      * |checkMetaChars| looks for regexp metachars in the pattern string.
      *
      * Return whether flat matching could be used.
      *
      * N.B. tryFlatMatch returns nullptr on OOM, so the caller must check
      * cx->isExceptionPending().
      */
     const FlatMatch *
     tryFlatMatch(JSContext *cx, JSString *textstr, unsigned optarg, unsigned argc,
                  bool checkMetaChars = true)
     {
         if (re_.initialized())
             return nullptr;
         fm.pat = fm.patstr->chars();
         fm.patlen = fm.patstr->length();
         if (optarg < argc)
             return nullptr;
         if (checkMetaChars &&
             (fm.patlen > MAX_FLAT_PAT_LEN || HasRegExpMetaChars(fm.pat, fm.patlen))) {
             return nullptr;
         }
         /*
          * textstr could be a rope, so we want to avoid flattening it for as
          * long as possible.
          */
         if (textstr->isRope()) {
             if (!RopeMatch(cx, textstr, fm.pat, fm.patlen, &fm.match_))
                 return nullptr;
         } else {
             const jschar *text = textstr->asLinear().chars();
             size_t textlen = textstr->length();
             fm.match_ = StringMatch(text, textlen, fm.pat, fm.patlen);
         }
         return &fm;
     }
     /* If the pattern is not already a regular expression, make it so. */
     bool normalizeRegExp(JSContext *cx, bool flat, unsigned optarg, CallArgs args)
     {
         if (re_.initialized())
             return true;
         /* Build RegExp from pattern string. */
         RootedString opt(cx);
         if (optarg < args.length()) {
             opt = ToString<CanGC>(cx, args[optarg]);
             if (!opt)
                 return false;
         } else {
             opt = nullptr;
         }
         Rooted<JSAtom *> patstr(cx);
         if (flat) {
             patstr = flattenPattern(cx, fm.patstr);
             if (!patstr)
                 return false;
         } else {
             patstr = fm.patstr;
         }
         JS_ASSERT(patstr);
         return cx->compartment()->regExps.get(cx, patstr, opt, &re_);
     }
     bool zeroLastIndex(JSContext *cx) {
         if (!regExpIsObject())
             return true;
         // Use a fast path for same-global RegExp objects with writable
         // lastIndex.
         if (obj_->is<RegExpObject>() && obj_->nativeLookup(cx, cx->names().lastIndex)->writable()) {
             obj_->as<RegExpObject>().zeroLastIndex();
             return true;
         }
         // Handle everything else generically (including throwing if .lastIndex is non-writable).
         RootedValue zero(cx, Int32Value(0));
         return JSObject::setProperty(cx, obj_, obj_, cx->names().lastIndex, &zero, true);
     }
     RegExpShared &regExp() { return *re_; }
     bool regExpIsObject() { return obj_ != nullptr; }
     HandleObject regExpObject() {
         JS_ASSERT(regExpIsObject());
         return obj_;
     }
   private:
     StringRegExpGuard(const StringRegExpGuard &) MOZ_DELETE;
     void operator=(const StringRegExpGuard &) MOZ_DELETE;
 };
 } /* anonymous namespace */
 static bool
 DoMatchLocal(JSContext *cx, CallArgs args, RegExpStatics *res, Handle<JSLinearString*> input,
              RegExpShared &re)
 {
     size_t charsLen = input->length();
     const jschar *chars = input->chars();
     size_t i = 0;
     ScopedMatchPairs matches(&cx->tempLifoAlloc());
     RegExpRunStatus status = re.execute(cx, chars, charsLen, &i, matches);
     if (status == RegExpRunStatus_Error)
         return false;
     if (status == RegExpRunStatus_Success_NotFound) {
         args.rval().setNull();
         return true;
     }
     if (!res->updateFromMatchPairs(cx, input, matches))
         return false;
     RootedValue rval(cx);
     if (!CreateRegExpMatchResult(cx, input, matches, &rval))
         return false;
     args.rval().set(rval);
     return true;
 }
 /* ES5 15.5.4.10 step 8. */
 static bool
 DoMatchGlobal(JSContext *cx, CallArgs args, RegExpStatics *res, Handle<JSLinearString*> input,
               StringRegExpGuard &g)
 {
     // Step 8a.
     //
     // This single zeroing of "lastIndex" covers all "lastIndex" changes in the
     // rest of String.prototype.match, particularly in steps 8f(i) and
     // 8f(iii)(2)(a).  Here's why.
     //
     // The inputs to the calls to RegExp.prototype.exec are a RegExp object
     // whose .global is true and a string.  The only side effect of a call in
     // these circumstances is that the RegExp's .lastIndex will be modified to
     // the next starting index after the discovered match (or to 0 if there's
     // no remaining match).  Because .lastIndex is a non-configurable data
     // property and no script-controllable code executes after step 8a, passing
     // step 8a implies *every* .lastIndex set succeeds.  String.prototype.match
     // calls RegExp.prototype.exec repeatedly, and the last call doesn't match,
     // so the final value of .lastIndex is 0: exactly the state after step 8a
     // succeeds.  No spec step lets script observe intermediate .lastIndex
     // values.
     //
     // The arrays returned by RegExp.prototype.exec always have a string at
     // index 0, for which [[Get]]s have no side effects.
     //
     // Filling in a new array using [[DefineOwnProperty]] is unobservable.
     //
     // This is a tricky point, because after this set, our implementation *can*
     // fail.  The key is that script can't distinguish these failure modes from
     // one where, in spec terms, we fail immediately after step 8a.  That *in
     // reality* we might have done extra matching work, or created a partial
     // results array to return, or hit an interrupt, is irrelevant.  The
     // script can't tell we did any of those things but didn't update
     // .lastIndex.  Thus we can optimize steps 8b onward however we want,
     // including eliminating intermediate .lastIndex sets, as long as we don't
     // add ways for script to observe the intermediate states.
     //
     // In short: it's okay to cheat (by setting .lastIndex to 0, once) because
     // we can't get caught.
     if (!g.zeroLastIndex(cx))
         return false;
     // Step 8b.
     AutoValueVector elements(cx);
     size_t lastSuccessfulStart = 0;
     // The loop variables from steps 8c-e aren't needed, as we use different
     // techniques from the spec to implement step 8f's loop.
     // Step 8f.
     MatchPair match;
     size_t charsLen = input->length();
     const jschar *chars = input->chars();
     RegExpShared &re = g.regExp();
     for (size_t searchIndex = 0; searchIndex <= charsLen; ) {
         if (!CheckForInterrupt(cx))
             return false;
         // Steps 8f(i-ii), minus "lastIndex" updates (see above).
         size_t nextSearchIndex = searchIndex;
         RegExpRunStatus status = re.executeMatchOnly(cx, chars, charsLen, &nextSearchIndex, match);
         if (status == RegExpRunStatus_Error)
             return false;
         // Step 8f(ii).
         if (status == RegExpRunStatus_Success_NotFound)
             break;
         lastSuccessfulStart = searchIndex;
         // Steps 8f(iii)(1-3).
         searchIndex = match.isEmpty() ? nextSearchIndex + 1 : nextSearchIndex;
         // Step 8f(iii)(4-5).
         JSLinearString *str = js_NewDependentString(cx, input, match.start, match.length());
         if (!str)
             return false;
         if (!elements.append(StringValue(str)))
             return false;
     }
     // Step 8g.
     if (elements.empty()) {
         args.rval().setNull();
         return true;
     }
     // The last *successful* match updates the RegExpStatics. (Interestingly,
     // this implies that String.prototype.match's semantics aren't those
     // implied by the RegExp.prototype.exec calls in the ES5 algorithm.)
     res->updateLazily(cx, input, &re, lastSuccessfulStart);
     // Steps 8b, 8f(iii)(5-6), 8h.
     JSObject *array = NewDenseCopiedArray(cx, elements.length(), elements.begin());
     if (!array)
         return false;
     args.rval().setObject(*array);
     return true;
 }
 static bool
 BuildFlatMatchArray(JSContext *cx, HandleString textstr, const FlatMatch &fm, CallArgs *args)
 {
     if (fm.match() < 0) {
         args->rval().setNull();
         return true;
     }
     /* For this non-global match, produce a RegExp.exec-style array. */
     RootedObject obj(cx, NewDenseEmptyArray(cx));
     if (!obj)
         return false;
     RootedValue patternVal(cx, StringValue(fm.pattern()));
     RootedValue matchVal(cx, Int32Value(fm.match()));
     RootedValue textVal(cx, StringValue(textstr));
     if (!JSObject::defineElement(cx, obj, 0, patternVal) ||
         !JSObject::defineProperty(cx, obj, cx->names().index, matchVal) ||
         !JSObject::defineProperty(cx, obj, cx->names().input, textVal))
     {
         return false;
     }
     args->rval().setObject(*obj);
     return true;
 }
 /* ES5 15.5.4.10. */
 bool
 js::str_match(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     /* Steps 1-2. */
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     /* Steps 3-4, plus the trailing-argument "flags" extension. */
     StringRegExpGuard g(cx);
     if (!g.init(cx, args, true))
         return false;
     /* Fast path when the search pattern can be searched for as a string. */
     if (const FlatMatch *fm = g.tryFlatMatch(cx, str, 1, args.length()))
         return BuildFlatMatchArray(cx, str, *fm, &args);
     /* Return if there was an error in tryFlatMatch. */
     if (cx->isExceptionPending())
         return false;
     /* Create regular-expression internals as needed to perform the match. */
     if (!g.normalizeRegExp(cx, false, 1, args))
         return false;
     RegExpStatics *res = cx->global()->getRegExpStatics();
     Rooted<JSLinearString*> linearStr(cx, str->ensureLinear(cx));
     if (!linearStr)
         return false;
     /* Steps 5-6, 7. */
     if (!g.regExp().global())
         return DoMatchLocal(cx, args, res, linearStr, g.regExp());
     /* Steps 6, 8. */
     return DoMatchGlobal(cx, args, res, linearStr, g);
 }
 bool
 js::str_search(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     StringRegExpGuard g(cx);
     if (!g.init(cx, args, true))
         return false;
     if (const FlatMatch *fm = g.tryFlatMatch(cx, str, 1, args.length())) {
         args.rval().setInt32(fm->match());
         return true;
     }
     if (cx->isExceptionPending())  /* from tryFlatMatch */
         return false;
     if (!g.normalizeRegExp(cx, false, 1, args))
         return false;
     Rooted<JSLinearString*> linearStr(cx, str->ensureLinear(cx));
     if (!linearStr)
         return false;
     const jschar *chars = linearStr->chars();
     size_t length = linearStr->length();
     RegExpStatics *res = cx->global()->getRegExpStatics();
     /* Per ECMAv5 15.5.4.12 (5) The last index property is ignored and left unchanged. */
     size_t i = 0;
     MatchPair match;
     RegExpRunStatus status = g.regExp().executeMatchOnly(cx, chars, length, &i, match);
     if (status == RegExpRunStatus_Error)
         return false;
     if (status == RegExpRunStatus_Success)
         res->updateLazily(cx, linearStr, &g.regExp(), 0);
     JS_ASSERT_IF(status == RegExpRunStatus_Success_NotFound, match.start == -1);
     args.rval().setInt32(match.start);
     return true;
 }
 // Utility for building a rope (lazy concatenation) of strings.
 class RopeBuilder {
     JSContext *cx;
     RootedString res;
     RopeBuilder(const RopeBuilder &other) MOZ_DELETE;
     void operator=(const RopeBuilder &other) MOZ_DELETE;
   public:
     RopeBuilder(JSContext *cx)
       : cx(cx), res(cx, cx->runtime()->emptyString)
     {}
     inline bool append(HandleString str) {
         res = ConcatStrings<CanGC>(cx, res, str);
         return !!res;
     }
     inline JSString *result() {
         return res;
     }
 };
 namespace {
 struct ReplaceData
 {
     ReplaceData(JSContext *cx)
       : str(cx), g(cx), lambda(cx), elembase(cx), repstr(cx),
         fig(cx, NullValue()), sb(cx)
     {}
     inline void setReplacementString(JSLinearString *string) {
         JS_ASSERT(string);
         lambda = nullptr;
         elembase = nullptr;
         repstr = string;
         /* We're about to store pointers into the middle of our string. */
         dollarEnd = repstr->chars() + repstr->length();
         dollar = js_strchr_limit(repstr->chars(), '$', dollarEnd);
     }
     inline void setReplacementFunction(JSObject *func) {
         JS_ASSERT(func);
         lambda = func;
         elembase = nullptr;
         repstr = nullptr;
         dollar = dollarEnd = nullptr;
     }
     RootedString       str;            /* 'this' parameter object as a string */
     StringRegExpGuard  g;              /* regexp parameter object and private data */
     RootedObject       lambda;         /* replacement function object or null */
     RootedObject       elembase;       /* object for function(a){return b[a]} replace */
     Rooted<JSLinearString*> repstr; /* replacement string */
     const jschar       *dollar;        /* null or pointer to first $ in repstr */
     const jschar       *dollarEnd;     /* limit pointer for js_strchr_limit */
     int                leftIndex;      /* left context index in str->chars */
     JSSubString        dollarStr;      /* for "$$" InterpretDollar result */
     bool               calledBack;     /* record whether callback has been called */
     FastInvokeGuard    fig;            /* used for lambda calls, also holds arguments */
     StringBuffer       sb;             /* buffer built during DoMatch */
 };
 } /* anonymous namespace */
 static bool
 ReplaceRegExp(JSContext *cx, RegExpStatics *res, ReplaceData &rdata);
 static bool
 DoMatchForReplaceLocal(JSContext *cx, RegExpStatics *res, Handle<JSLinearString*> linearStr,
                        RegExpShared &re, ReplaceData &rdata)
 {
     size_t charsLen = linearStr->length();
     size_t i = 0;
     ScopedMatchPairs matches(&cx->tempLifoAlloc());
     RegExpRunStatus status = re.execute(cx, linearStr->chars(), charsLen, &i, matches);
     if (status == RegExpRunStatus_Error)
         return false;
     if (status == RegExpRunStatus_Success_NotFound)
         return true;
     if (!res->updateFromMatchPairs(cx, linearStr, matches))
         return false;
     return ReplaceRegExp(cx, res, rdata);
 }
 static bool
 DoMatchForReplaceGlobal(JSContext *cx, RegExpStatics *res, Handle<JSLinearString*> linearStr,
                         RegExpShared &re, ReplaceData &rdata)
 {
     size_t charsLen = linearStr->length();
     ScopedMatchPairs matches(&cx->tempLifoAlloc());
     for (size_t count = 0, i = 0; i <= charsLen; ++count) {
         if (!CheckForInterrupt(cx))
             return false;
         RegExpRunStatus status = re.execute(cx, linearStr->chars(), charsLen, &i, matches);
         if (status == RegExpRunStatus_Error)
             return false;
         if (status == RegExpRunStatus_Success_NotFound)
             break;
         if (!res->updateFromMatchPairs(cx, linearStr, matches))
             return false;
         if (!ReplaceRegExp(cx, res, rdata))
             return false;
         if (!res->matched())
             ++i;
     }
     return true;
 }
 static bool
 InterpretDollar(RegExpStatics *res, const jschar *dp, const jschar *ep,
                 ReplaceData &rdata, JSSubString *out, size_t *skip)
 {
     JS_ASSERT(*dp == '$');
     /* If there is only a dollar, bail now */
     if (dp + 1 >= ep)
         return false;
     /* Interpret all Perl match-induced dollar variables. */
     jschar dc = dp[1];
     if (JS7_ISDEC(dc)) {
         /* ECMA-262 Edition 3: 1-9 or 01-99 */
         unsigned num = JS7_UNDEC(dc);
         if (num > res->getMatches().parenCount())
             return false;
         const jschar *cp = dp + 2;
         if (cp < ep && (dc = *cp, JS7_ISDEC(dc))) {
             unsigned tmp = 10 * num + JS7_UNDEC(dc);
             if (tmp <= res->getMatches().parenCount()) {
                 cp++;
                 num = tmp;
             }
         }
         if (num == 0)
             return false;
         *skip = cp - dp;
         JS_ASSERT(num <= res->getMatches().parenCount());
         /*
          * Note: we index to get the paren with the (1-indexed) pair
          * number, as opposed to a (0-indexed) paren number.
          */
         res->getParen(num, out);
         return true;
     }
     *skip = 2;
     switch (dc) {
       case '$':
         rdata.dollarStr.chars = dp;
         rdata.dollarStr.length = 1;
         *out = rdata.dollarStr;
         return true;
       case '&':
         res->getLastMatch(out);
         return true;
       case '+':
         res->getLastParen(out);
         return true;
       case '`':
         res->getLeftContext(out);
         return true;
       case '\'':
         res->getRightContext(out);
         return true;
     }
     return false;
 }
 static bool
 FindReplaceLength(JSContext *cx, RegExpStatics *res, ReplaceData &rdata, size_t *sizep)
 {
     if (rdata.elembase) {
         /*
          * The base object is used when replace was passed a lambda which looks like
          * 'function(a) { return b[a]; }' for the base object b.  b will not change
          * in the course of the replace unless we end up making a scripted call due
          * to accessing a scripted getter or a value with a scripted toString.
          */
         JS_ASSERT(rdata.lambda);
         JS_ASSERT(!rdata.elembase->getOps()->lookupProperty);
         JS_ASSERT(!rdata.elembase->getOps()->getProperty);
         RootedValue match(cx);
         if (!res->createLastMatch(cx, &match))
             return false;
         JSAtom *atom = ToAtom<CanGC>(cx, match);
         if (!atom)
             return false;
         RootedValue v(cx);
         if (HasDataProperty(cx, rdata.elembase, AtomToId(atom), v.address()) && v.isString()) {
             rdata.repstr = v.toString()->ensureLinear(cx);
             if (!rdata.repstr)
                 return false;
             *sizep = rdata.repstr->length();
             return true;
         }
         /*
          * Couldn't handle this property, fall through and despecialize to the
          * general lambda case.
          */
         rdata.elembase = nullptr;
     }
     if (rdata.lambda) {
         RootedObject lambda(cx, rdata.lambda);
         PreserveRegExpStatics staticsGuard(cx, res);
         if (!staticsGuard.init(cx))
             return false;
         /*
          * In the lambda case, not only do we find the replacement string's
          * length, we compute repstr and return it via rdata for use within
          * DoReplace.  The lambda is called with arguments ($&, $1, $2, ...,
          * index, input), i.e., all the properties of a regexp match array.
          * For $&, etc., we must create string jsvals from cx->regExpStatics.
          * We grab up stack space to keep the newborn strings GC-rooted.
          */
         unsigned p = res->getMatches().parenCount();
         unsigned argc = 1 + p + 2;
         InvokeArgs &args = rdata.fig.args();
         if (!args.init(argc))
             return false;
         args.setCallee(ObjectValue(*lambda));
         args.setThis(UndefinedValue());
         /* Push $&, $1, $2, ... */
         unsigned argi = 0;
         if (!res->createLastMatch(cx, args[argi++]))
             return false;
         for (size_t i = 0; i < res->getMatches().parenCount(); ++i) {
             if (!res->createParen(cx, i + 1, args[argi++]))
                 return false;
         }
         /* Push match index and input string. */
         args[argi++].setInt32(res->getMatches()[0].start);
         args[argi].setString(rdata.str);
         if (!rdata.fig.invoke(cx))
             return false;
         /* root repstr: rdata is on the stack, so scanned by conservative gc. */
         JSString *repstr = ToString<CanGC>(cx, args.rval());
         if (!repstr)
             return false;
         rdata.repstr = repstr->ensureLinear(cx);
         if (!rdata.repstr)
             return false;
         *sizep = rdata.repstr->length();
         return true;
     }
     JSString *repstr = rdata.repstr;
     CheckedInt<uint32_t> replen = repstr->length();
     for (const jschar *dp = rdata.dollar, *ep = rdata.dollarEnd; dp;
          dp = js_strchr_limit(dp, '$', ep)) {
         JSSubString sub;
         size_t skip;
         if (InterpretDollar(res, dp, ep, rdata, &sub, &skip)) {
             if (sub.length > skip)
                 replen += sub.length - skip;
             else
                 replen -= skip - sub.length;
             dp += skip;
         } else {
             dp++;
         }
     }
     if (!replen.isValid()) {
         js_ReportAllocationOverflow(cx);
         return false;
     }
     *sizep = replen.value();
     return true;
 }
 /*
  * Precondition: |rdata.sb| already has necessary growth space reserved (as
  * derived from FindReplaceLength).
  */
 static void
 DoReplace(RegExpStatics *res, ReplaceData &rdata)
 {
     JSLinearString *repstr = rdata.repstr;
     const jschar *cp;
     const jschar *bp = cp = repstr->chars();
     const jschar *dp = rdata.dollar;
     const jschar *ep = rdata.dollarEnd;
     for (; dp; dp = js_strchr_limit(dp, '$', ep)) {
         /* Move one of the constant portions of the replacement value. */
         size_t len = dp - cp;
         rdata.sb.infallibleAppend(cp, len);
         cp = dp;
         JSSubString sub;
         size_t skip;
         if (InterpretDollar(res, dp, ep, rdata, &sub, &skip)) {
             len = sub.length;
             rdata.sb.infallibleAppend(sub.chars, len);
             cp += skip;
             dp += skip;
         } else {
             dp++;
         }
     }
     rdata.sb.infallibleAppend(cp, repstr->length() - (cp - bp));
 }
 static bool
 ReplaceRegExp(JSContext *cx, RegExpStatics *res, ReplaceData &rdata)
 {
     const MatchPair &match = res->getMatches()[0];
     JS_ASSERT(!match.isUndefined());
     JS_ASSERT(match.limit >= match.start && match.limit >= 0);
     rdata.calledBack = true;
     size_t leftoff = rdata.leftIndex;
     size_t leftlen = match.start - leftoff;
     rdata.leftIndex = match.limit;
     size_t replen = 0;  /* silence 'unused' warning */
     if (!FindReplaceLength(cx, res, rdata, &replen))
         return false;
     CheckedInt<uint32_t> newlen(rdata.sb.length());
     newlen += leftlen;
     newlen += replen;
     if (!newlen.isValid()) {
         js_ReportAllocationOverflow(cx);
         return false;
     }
     if (!rdata.sb.reserve(newlen.value()))
         return false;
     JSLinearString &str = rdata.str->asLinear();  /* flattened for regexp */
     const jschar *left = str.chars() + leftoff;
     rdata.sb.infallibleAppend(left, leftlen); /* skipped-over portion of the search value */
     DoReplace(res, rdata);
     return true;
 }
 static bool
 BuildFlatReplacement(JSContext *cx, HandleString textstr, HandleString repstr,
                      const FlatMatch &fm, MutableHandleValue rval)
 {
     RopeBuilder builder(cx);
     size_t match = fm.match();
     size_t matchEnd = match + fm.patternLength();
     if (textstr->isRope()) {
         /*
          * If we are replacing over a rope, avoid flattening it by iterating
          * through it, building a new rope.
          */
         StringSegmentRange r(cx);
         if (!r.init(textstr))
             return false;
         size_t pos = 0;
         while (!r.empty()) {
             RootedString str(cx, r.front());
             size_t len = str->length();
             size_t strEnd = pos + len;
             if (pos < matchEnd && strEnd > match) {
                 /*
                  * We need to special-case any part of the rope that overlaps
                  * with the replacement string.
                  */
                 if (match >= pos) {
                     /*
                      * If this part of the rope overlaps with the left side of
                      * the pattern, then it must be the only one to overlap with
                      * the first character in the pattern, so we include the
                      * replacement string here.
                      */
                     RootedString leftSide(cx, js_NewDependentString(cx, str, 0, match - pos));
                     if (!leftSide ||
                         !builder.append(leftSide) ||
                         !builder.append(repstr)) {
                         return false;
                     }
                 }
                 /*
                  * If str runs off the end of the matched string, append the
                  * last part of str.
                  */
                 if (strEnd > matchEnd) {
                     RootedString rightSide(cx, js_NewDependentString(cx, str, matchEnd - pos,
                                                                      strEnd - matchEnd));
                     if (!rightSide || !builder.append(rightSide))
                         return false;
                 }
             } else {
                 if (!builder.append(str))
                     return false;
             }
             pos += str->length();
             if (!r.popFront())
                 return false;
         }
     } else {
         RootedString leftSide(cx, js_NewDependentString(cx, textstr, 0, match));
         if (!leftSide)
             return false;
         RootedString rightSide(cx);
         rightSide = js_NewDependentString(cx, textstr, match + fm.patternLength(),
                                           textstr->length() - match - fm.patternLength());
         if (!rightSide ||
             !builder.append(leftSide) ||
             !builder.append(repstr) ||
             !builder.append(rightSide)) {
             return false;
         }
     }
     rval.setString(builder.result());
     return true;
 }
 /*
  * Perform a linear-scan dollar substitution on the replacement text,
  * constructing a result string that looks like:
  *
  *      newstring = string[:matchStart] + dollarSub(replaceValue) + string[matchLimit:]
  */
 static inline bool
 BuildDollarReplacement(JSContext *cx, JSString *textstrArg, JSLinearString *repstr,
                        const jschar *firstDollar, const FlatMatch &fm, MutableHandleValue rval)
 {
     Rooted<JSLinearString*> textstr(cx, textstrArg->ensureLinear(cx));
     if (!textstr)
         return false;
     JS_ASSERT(repstr->chars() <= firstDollar && firstDollar < repstr->chars() + repstr->length());
     size_t matchStart = fm.match();
     size_t matchLimit = matchStart + fm.patternLength();
     /*
      * Most probably:
      *
      *      len(newstr) >= len(orig) - len(match) + len(replacement)
      *
      * Note that dollar vars _could_ make the resulting text smaller than this.
      */
     StringBuffer newReplaceChars(cx);
     if (!newReplaceChars.reserve(textstr->length() - fm.patternLength() + repstr->length()))
         return false;
     /* Move the pre-dollar chunk in bulk. */
     newReplaceChars.infallibleAppend(repstr->chars(), firstDollar);
     /* Move the rest char-by-char, interpreting dollars as we encounter them. */
 #define ENSURE(__cond) if (!(__cond)) return false;
     const jschar *repstrLimit = repstr->chars() + repstr->length();
     for (const jschar *it = firstDollar; it < repstrLimit; ++it) {
         if (*it != '$' || it == repstrLimit - 1) {
             ENSURE(newReplaceChars.append(*it));
             continue;
         }
         switch (*(it + 1)) {
           case '$': /* Eat one of the dollars. */
             ENSURE(newReplaceChars.append(*it));
             break;
           case '&':
             ENSURE(newReplaceChars.append(textstr->chars() + matchStart,
                                           textstr->chars() + matchLimit));
             break;
           case '`':
             ENSURE(newReplaceChars.append(textstr->chars(), textstr->chars() + matchStart));
             break;
           case '\'':
             ENSURE(newReplaceChars.append(textstr->chars() + matchLimit,
                                           textstr->chars() + textstr->length()));
             break;
           default: /* The dollar we saw was not special (no matter what its mother told it). */
             ENSURE(newReplaceChars.append(*it));
             continue;
         }
         ++it; /* We always eat an extra char in the above switch. */
     }
     RootedString leftSide(cx, js_NewDependentString(cx, textstr, 0, matchStart));
     ENSURE(leftSide);
     RootedString newReplace(cx, newReplaceChars.finishString());
     ENSURE(newReplace);
     JS_ASSERT(textstr->length() >= matchLimit);
     RootedString rightSide(cx, js_NewDependentString(cx, textstr, matchLimit,
                                                         textstr->length() - matchLimit));
     ENSURE(rightSide);
     RopeBuilder builder(cx);
     ENSURE(builder.append(leftSide) &&
            builder.append(newReplace) &&
            builder.append(rightSide));
 #undef ENSURE
     rval.setString(builder.result());
     return true;
 }
 struct StringRange
 {
     size_t start;
     size_t length;
     StringRange(size_t s, size_t l)
       : start(s), length(l)
     { }
 };
 static inline JSFatInlineString *
 FlattenSubstrings(JSContext *cx, const jschar *chars,
                   const StringRange *ranges, size_t rangesLen, size_t outputLen)
 {
     JS_ASSERT(JSFatInlineString::lengthFits(outputLen));
     JSFatInlineString *str = js_NewGCFatInlineString<CanGC>(cx);
     if (!str)
         return nullptr;
     jschar *buf = str->init(outputLen);
     size_t pos = 0;
     for (size_t i = 0; i < rangesLen; i++) {
         PodCopy(buf + pos, chars + ranges[i].start, ranges[i].length);
         pos += ranges[i].length;
     }
     JS_ASSERT(pos == outputLen);
     buf[outputLen] = 0;
     return str;
 }
 static JSString *
 AppendSubstrings(JSContext *cx, Handle<JSFlatString*> flatStr,
                  const StringRange *ranges, size_t rangesLen)
 {
     JS_ASSERT(rangesLen);
     /* For single substrings, construct a dependent string. */
     if (rangesLen == 1)
         return js_NewDependentString(cx, flatStr, ranges[0].start, ranges[0].length);
     const jschar *chars = flatStr->getChars(cx);
     if (!chars)
         return nullptr;
     /* Collect substrings into a rope */
     size_t i = 0;
     RopeBuilder rope(cx);
     RootedString part(cx, nullptr);
     while (i < rangesLen) {
         /* Find maximum range that fits in JSFatInlineString */
         size_t substrLen = 0;
         size_t end = i;
         for (; end < rangesLen; end++) {
             if (substrLen + ranges[end].length > JSFatInlineString::MAX_FAT_INLINE_LENGTH)
                 break;
             substrLen += ranges[end].length;
         }
         if (i == end) {
             /* Not even one range fits JSFatInlineString, use DependentString */
             const StringRange &sr = ranges[i++];
             part = js_NewDependentString(cx, flatStr, sr.start, sr.length);
         } else {
             /* Copy the ranges (linearly) into a JSFatInlineString */
             part = FlattenSubstrings(cx, chars, ranges + i, end - i, substrLen);
             i = end;
         }
         if (!part)
             return nullptr;
         /* Appending to the rope permanently roots the substring. */
         if (!rope.append(part))
             return nullptr;
     }
     return rope.result();
 }
 static bool
 StrReplaceRegexpRemove(JSContext *cx, HandleString str, RegExpShared &re, MutableHandleValue rval)
 {
     Rooted<JSFlatString*> flatStr(cx, str->ensureFlat(cx));
     if (!flatStr)
         return false;
     Vector<StringRange, 16, SystemAllocPolicy> ranges;
     size_t charsLen = flatStr->length();
     MatchPair match;
     size_t startIndex = 0; /* Index used for iterating through the string. */
     size_t lastIndex = 0;  /* Index after last successful match. */
     size_t lazyIndex = 0;  /* Index before last successful match. */
     /* Accumulate StringRanges for unmatched substrings. */
     while (startIndex <= charsLen) {
         if (!CheckForInterrupt(cx))
             return false;
         RegExpRunStatus status =
             re.executeMatchOnly(cx, flatStr->chars(), charsLen, &startIndex, match);
         if (status == RegExpRunStatus_Error)
             return false;
         if (status == RegExpRunStatus_Success_NotFound)
             break;
         /* Include the latest unmatched substring. */
         if (size_t(match.start) > lastIndex) {
             if (!ranges.append(StringRange(lastIndex, match.start - lastIndex)))
                 return false;
         }
         lazyIndex = lastIndex;
         lastIndex = startIndex;
         if (match.isEmpty())
             startIndex++;
         /* Non-global removal executes at most once. */
         if (!re.global())
             break;
     }
     /* If unmatched, return the input string. */
     if (!lastIndex) {
         if (startIndex > 0)
             cx->global()->getRegExpStatics()->updateLazily(cx, flatStr, &re, lazyIndex);
         rval.setString(str);
         return true;
     }
     /* The last successful match updates the RegExpStatics. */
     cx->global()->getRegExpStatics()->updateLazily(cx, flatStr, &re, lazyIndex);
     /* Include any remaining part of the string. */
     if (lastIndex < charsLen) {
         if (!ranges.append(StringRange(lastIndex, charsLen - lastIndex)))
             return false;
     }
     /* Handle the empty string before calling .begin(). */
     if (ranges.empty()) {
         rval.setString(cx->runtime()->emptyString);
         return true;
     }
     JSString *result = AppendSubstrings(cx, flatStr, ranges.begin(), ranges.length());
     if (!result)
         return false;
     rval.setString(result);
     return true;
 }
 static inline bool
 StrReplaceRegExp(JSContext *cx, ReplaceData &rdata, MutableHandleValue rval)
 {
     rdata.leftIndex = 0;
     rdata.calledBack = false;
     RegExpStatics *res = cx->global()->getRegExpStatics();
     RegExpShared &re = rdata.g.regExp();
     // The spec doesn't describe this function very clearly, so we go ahead and
     // assume that when the input to String.prototype.replace is a global
     // RegExp, calling the replacer function (assuming one was provided) takes
     // place only after the matching is done. See the comment at the beginning
     // of DoMatchGlobal explaining why we can zero the the RegExp object's
     // lastIndex property here.
     if (re.global() && !rdata.g.zeroLastIndex(cx))
         return false;
     /* Optimize removal. */
     if (rdata.repstr && rdata.repstr->length() == 0) {
         JS_ASSERT(!rdata.lambda && !rdata.elembase && !rdata.dollar);
         return StrReplaceRegexpRemove(cx, rdata.str, re, rval);
     }
     Rooted<JSLinearString*> linearStr(cx, rdata.str->ensureLinear(cx));
     if (!linearStr)
         return false;
     if (re.global()) {
         if (!DoMatchForReplaceGlobal(cx, res, linearStr, re, rdata))
             return false;
     } else {
         if (!DoMatchForReplaceLocal(cx, res, linearStr, re, rdata))
             return false;
     }
     if (!rdata.calledBack) {
         /* Didn't match, so the string is unmodified. */
         rval.setString(rdata.str);
         return true;
     }
     JSSubString sub;
     res->getRightContext(&sub);
     if (!rdata.sb.append(sub.chars, sub.length))
         return false;
     JSString *retstr = rdata.sb.finishString();
     if (!retstr)
         return false;
     rval.setString(retstr);
     return true;
 }
 static inline bool
 str_replace_regexp(JSContext *cx, CallArgs args, ReplaceData &rdata)
 {
     if (!rdata.g.normalizeRegExp(cx, true, 2, args))
         return false;
     return StrReplaceRegExp(cx, rdata, args.rval());
 }
 bool
 js::str_replace_regexp_raw(JSContext *cx, HandleString string, HandleObject regexp,
                        HandleString replacement, MutableHandleValue rval)
 {
     /* Optimize removal, so we don't have to create ReplaceData */
     if (replacement->length() == 0) {
         StringRegExpGuard guard(cx);
         if (!guard.init(cx, regexp))
             return false;
         RegExpShared &re = guard.regExp();
         return StrReplaceRegexpRemove(cx, string, re, rval);
     }
     ReplaceData rdata(cx);
     rdata.str = string;
     JSLinearString *repl = replacement->ensureLinear(cx);
     if (!repl)
         return false;
     rdata.setReplacementString(repl);
     if (!rdata.g.init(cx, regexp))
         return false;
     return StrReplaceRegExp(cx, rdata, rval);
 }
 static inline bool
 StrReplaceString(JSContext *cx, ReplaceData &rdata, const FlatMatch &fm, MutableHandleValue rval)
 {
     /*
      * Note: we could optimize the text.length == pattern.length case if we wanted,
      * even in the presence of dollar metachars.
      */
     if (rdata.dollar)
         return BuildDollarReplacement(cx, rdata.str, rdata.repstr, rdata.dollar, fm, rval);
     return BuildFlatReplacement(cx, rdata.str, rdata.repstr, fm, rval);
 }
 static const uint32_t ReplaceOptArg = 2;
 bool
 js::str_replace_string_raw(JSContext *cx, HandleString string, HandleString pattern,
                           HandleString replacement, MutableHandleValue rval)
 {
     ReplaceData rdata(cx);
     rdata.str = string;
     JSLinearString *repl = replacement->ensureLinear(cx);
     if (!repl)
         return false;
     rdata.setReplacementString(repl);
     if (!rdata.g.init(cx, pattern))
         return false;
     const FlatMatch *fm = rdata.g.tryFlatMatch(cx, rdata.str, ReplaceOptArg, ReplaceOptArg, false);
     if (fm->match() < 0) {
         rval.setString(string);
         return true;
     }
     return StrReplaceString(cx, rdata, *fm, rval);
 }
 static inline bool
 str_replace_flat_lambda(JSContext *cx, CallArgs outerArgs, ReplaceData &rdata, const FlatMatch &fm)
 {
     RootedString matchStr(cx, js_NewDependentString(cx, rdata.str, fm.match(), fm.patternLength()));
     if (!matchStr)
         return false;
     /* lambda(matchStr, matchStart, textstr) */
     static const uint32_t lambdaArgc = 3;
     if (!rdata.fig.args().init(lambdaArgc))
         return false;
     CallArgs &args = rdata.fig.args();
     args.setCallee(ObjectValue(*rdata.lambda));
     args.setThis(UndefinedValue());
     Value *sp = args.array();
     sp[0].setString(matchStr);
     sp[1].setInt32(fm.match());
     sp[2].setString(rdata.str);
     if (!rdata.fig.invoke(cx))
         return false;
     RootedString repstr(cx, ToString<CanGC>(cx, args.rval()));
     if (!repstr)
         return false;
     RootedString leftSide(cx, js_NewDependentString(cx, rdata.str, 0, fm.match()));
     if (!leftSide)
         return false;
     size_t matchLimit = fm.match() + fm.patternLength();
     RootedString rightSide(cx, js_NewDependentString(cx, rdata.str, matchLimit,
                                                         rdata.str->length() - matchLimit));
     if (!rightSide)
         return false;
     RopeBuilder builder(cx);
     if (!(builder.append(leftSide) &&
           builder.append(repstr) &&
           builder.append(rightSide))) {
         return false;
     }
     outerArgs.rval().setString(builder.result());
     return true;
 }
 /*
  * Pattern match the script to check if it is is indexing into a particular
  * object, e.g. 'function(a) { return b[a]; }'. Avoid calling the script in
  * such cases, which are used by javascript packers (particularly the popular
  * Dean Edwards packer) to efficiently encode large scripts. We only handle the
  * code patterns generated by such packers here.
  */
 static bool
 LambdaIsGetElem(JSContext *cx, JSObject &lambda, MutableHandleObject pobj)
 {
     if (!lambda.is<JSFunction>())
         return true;
     RootedFunction fun(cx, &lambda.as<JSFunction>());
     if (!fun->isInterpreted())
         return true;
     JSScript *script = fun->getOrCreateScript(cx);
     if (!script)
         return false;
     jsbytecode *pc = script->code();
     /*
      * JSOP_GETALIASEDVAR tells us exactly where to find the base object 'b'.
      * Rule out the (unlikely) possibility of a heavyweight function since it
      * would make our scope walk off by 1.
      */
     if (JSOp(*pc) != JSOP_GETALIASEDVAR || fun->isHeavyweight())
         return true;
     ScopeCoordinate sc(pc);
     ScopeObject *scope = &fun->environment()->as<ScopeObject>();
     for (unsigned i = 0; i < sc.hops(); ++i)
         scope = &scope->enclosingScope().as<ScopeObject>();
     Value b = scope->aliasedVar(sc);
     pc += JSOP_GETALIASEDVAR_LENGTH;
     /* Look for 'a' to be the lambda's first argument. */
     if (JSOp(*pc) != JSOP_GETARG || GET_ARGNO(pc) != 0)
         return true;
     pc += JSOP_GETARG_LENGTH;
     /* 'b[a]' */
     if (JSOp(*pc) != JSOP_GETELEM)
         return true;
     pc += JSOP_GETELEM_LENGTH;
     /* 'return b[a]' */
     if (JSOp(*pc) != JSOP_RETURN)
         return true;
     /* 'b' must behave like a normal object. */
     if (!b.isObject())
         return true;
     JSObject &bobj = b.toObject();
     const Class *clasp = bobj.getClass();
     if (!clasp->isNative() || clasp->ops.lookupProperty || clasp->ops.getProperty)
         return true;
     pobj.set(&bobj);
     return true;
 }
 bool
 js::str_replace(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     ReplaceData rdata(cx);
     rdata.str = ThisToStringForStringProto(cx, args);
     if (!rdata.str)
         return false;
     if (!rdata.g.init(cx, args))
         return false;
     /* Extract replacement string/function. */
     if (args.length() >= ReplaceOptArg && js_IsCallable(args[1])) {
         rdata.setReplacementFunction(&args[1].toObject());
         if (!LambdaIsGetElem(cx, *rdata.lambda, &rdata.elembase))
             return false;
     } else {
         JSLinearString *string = ArgToRootedString(cx, args, 1);
         if (!string)
             return false;
         rdata.setReplacementString(string);
     }
     rdata.fig.initFunction(ObjectOrNullValue(rdata.lambda));
     /*
      * Unlike its |String.prototype| brethren, |replace| doesn't convert
      * its input to a regular expression. (Even if it contains metachars.)
      *
      * However, if the user invokes our (non-standard) |flags| argument
      * extension then we revert to creating a regular expression. Note that
      * this is observable behavior through the side-effect mutation of the
      * |RegExp| statics.
      */
     const FlatMatch *fm = rdata.g.tryFlatMatch(cx, rdata.str, ReplaceOptArg, args.length(), false);
     if (!fm) {
         if (cx->isExceptionPending())  /* oom in RopeMatch in tryFlatMatch */
             return false;
         return str_replace_regexp(cx, args, rdata);
     }
     if (fm->match() < 0) {
         args.rval().setString(rdata.str);
         return true;
     }
     if (rdata.lambda)
         return str_replace_flat_lambda(cx, args, rdata, *fm);
     return StrReplaceString(cx, rdata, *fm, args.rval());
 }
 namespace {
 class SplitMatchResult {
     size_t endIndex_;
     size_t length_;
   public:
     void setFailure() {
         JS_STATIC_ASSERT(SIZE_MAX > JSString::MAX_LENGTH);
         endIndex_ = SIZE_MAX;
     }
     bool isFailure() const {
         return endIndex_ == SIZE_MAX;
     }
     size_t endIndex() const {
         JS_ASSERT(!isFailure());
         return endIndex_;
     }
     size_t length() const {
         JS_ASSERT(!isFailure());
         return length_;
     }
     void setResult(size_t length, size_t endIndex) {
         length_ = length;
         endIndex_ = endIndex;
     }
 };
 } /* anonymous namespace */
 template<class Matcher>
 static ArrayObject *
 SplitHelper(JSContext *cx, Handle<JSLinearString*> str, uint32_t limit, const Matcher &splitMatch,
             Handle<TypeObject*> type)
 {
     size_t strLength = str->length();
     SplitMatchResult result;
     /* Step 11. */
     if (strLength == 0) {
         if (!splitMatch(cx, str, 0, &result))
             return nullptr;
         /*
          * NB: Unlike in the non-empty string case, it's perfectly fine
          *     (indeed the spec requires it) if we match at the end of the
          *     string.  Thus these cases should hold:
          *
          *   var a = "".split("");
          *   assertEq(a.length, 0);
          *   var b = "".split(/.?/);
          *   assertEq(b.length, 0);
          */
         if (!result.isFailure())
             return NewDenseEmptyArray(cx);
         RootedValue v(cx, StringValue(str));
         return NewDenseCopiedArray(cx, 1, v.address());
     }
     /* Step 12. */
     size_t lastEndIndex = 0;
     size_t index = 0;
     /* Step 13. */
     AutoValueVector splits(cx);
     while (index < strLength) {
         /* Step 13(a). */
         if (!splitMatch(cx, str, index, &result))
             return nullptr;
         /*
          * Step 13(b).
          *
          * Our match algorithm differs from the spec in that it returns the
          * next index at which a match happens.  If no match happens we're
          * done.
          *
          * But what if the match is at the end of the string (and the string is
          * not empty)?  Per 13(c)(ii) this shouldn't be a match, so we have to
          * specially exclude it.  Thus this case should hold:
          *
          *   var a = "abc".split(/\b/);
          *   assertEq(a.length, 1);
          *   assertEq(a[0], "abc");
          */
         if (result.isFailure())
             break;
         /* Step 13(c)(i). */
         size_t sepLength = result.length();
         size_t endIndex = result.endIndex();
         if (sepLength == 0 && endIndex == strLength)
             break;
         /* Step 13(c)(ii). */
         if (endIndex == lastEndIndex) {
             index++;
             continue;
         }
         /* Step 13(c)(iii). */
         JS_ASSERT(lastEndIndex < endIndex);
         JS_ASSERT(sepLength <= strLength);
         JS_ASSERT(lastEndIndex + sepLength <= endIndex);
         /* Steps 13(c)(iii)(1-3). */
         size_t subLength = size_t(endIndex - sepLength - lastEndIndex);
         JSString *sub = js_NewDependentString(cx, str, lastEndIndex, subLength);
         if (!sub || !splits.append(StringValue(sub)))
             return nullptr;
         /* Step 13(c)(iii)(4). */
         if (splits.length() == limit)
             return NewDenseCopiedArray(cx, splits.length(), splits.begin());
         /* Step 13(c)(iii)(5). */
         lastEndIndex = endIndex;
         /* Step 13(c)(iii)(6-7). */
         if (Matcher::returnsCaptures) {
             RegExpStatics *res = cx->global()->getRegExpStatics();
             const MatchPairs &matches = res->getMatches();
             for (size_t i = 0; i < matches.parenCount(); i++) {
                 /* Steps 13(c)(iii)(7)(a-c). */
                 if (!matches[i + 1].isUndefined()) {
                     JSSubString parsub;
                     res->getParen(i + 1, &parsub);
                     sub = js_NewStringCopyN<CanGC>(cx, parsub.chars, parsub.length);
                     if (!sub || !splits.append(StringValue(sub)))
                         return nullptr;
                 } else {
                     /* Only string entries have been accounted for so far. */
                     AddTypePropertyId(cx, type, JSID_VOID, UndefinedValue());
                     if (!splits.append(UndefinedValue()))
                         return nullptr;
                 }
                 /* Step 13(c)(iii)(7)(d). */
                 if (splits.length() == limit)
                     return NewDenseCopiedArray(cx, splits.length(), splits.begin());
             }
         }
         /* Step 13(c)(iii)(8). */
         index = lastEndIndex;
     }
     /* Steps 14-15. */
     JSString *sub = js_NewDependentString(cx, str, lastEndIndex, strLength - lastEndIndex);
     if (!sub || !splits.append(StringValue(sub)))
         return nullptr;
     /* Step 16. */
     return NewDenseCopiedArray(cx, splits.length(), splits.begin());
 }
 // Fast-path for splitting a string into a character array via split("").
 static ArrayObject *
 CharSplitHelper(JSContext *cx, Handle<JSLinearString*> str, uint32_t limit)
 {
     size_t strLength = str->length();
     if (strLength == 0)
         return NewDenseEmptyArray(cx);
     js::StaticStrings &staticStrings = cx->staticStrings();
     uint32_t resultlen = (limit < strLength ? limit : strLength);
     AutoValueVector splits(cx);
     if (!splits.reserve(resultlen))
         return nullptr;
     for (size_t i = 0; i < resultlen; ++i) {
         JSString *sub = staticStrings.getUnitStringForElement(cx, str, i);
         if (!sub)
             return nullptr;
         splits.infallibleAppend(StringValue(sub));
     }
     return NewDenseCopiedArray(cx, splits.length(), splits.begin());
 }
 namespace {
 /*
  * The SplitMatch operation from ES5 15.5.4.14 is implemented using different
  * paths for regular expression and string separators.
  *
  * The algorithm differs from the spec in that the we return the next index at
  * which a match happens.
  */
 class SplitRegExpMatcher
 {
     RegExpShared &re;
     RegExpStatics *res;
   public:
     SplitRegExpMatcher(RegExpShared &re, RegExpStatics *res) : re(re), res(res) {}
     static const bool returnsCaptures = true;
     bool operator()(JSContext *cx, Handle<JSLinearString*> str, size_t index,
                     SplitMatchResult *result) const
     {
         const jschar *chars = str->chars();
         size_t length = str->length();
         ScopedMatchPairs matches(&cx->tempLifoAlloc());
         RegExpRunStatus status = re.execute(cx, chars, length, &index, matches);
         if (status == RegExpRunStatus_Error)
             return false;
         if (status == RegExpRunStatus_Success_NotFound) {
             result->setFailure();
             return true;
         }
         if (!res->updateFromMatchPairs(cx, str, matches))
             return false;
         JSSubString sep;
         res->getLastMatch(&sep);
         result->setResult(sep.length, index);
         return true;
     }
 };
 class SplitStringMatcher
 {
     Rooted<JSLinearString*> sep;
   public:
     SplitStringMatcher(JSContext *cx, HandleLinearString sep)
       : sep(cx, sep)
     {}
     static const bool returnsCaptures = false;
     bool operator()(JSContext *cx, JSLinearString *str, size_t index, SplitMatchResult *res) const
     {
         JS_ASSERT(index == 0 || index < str->length());
         const jschar *chars = str->chars();
         int match = StringMatch(chars + index, str->length() - index,
                                 sep->chars(), sep->length());
         if (match == -1)
             res->setFailure();
         else
             res->setResult(sep->length(), index + match + sep->length());
         return true;
     }
 };
 } /* anonymous namespace */
 /* ES5 15.5.4.14 */
 bool
 js::str_split(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     /* Steps 1-2. */
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     RootedTypeObject type(cx, GetTypeCallerInitObject(cx, JSProto_Array));
     if (!type)
         return false;
     AddTypePropertyId(cx, type, JSID_VOID, Type::StringType());
     /* Step 5: Use the second argument as the split limit, if given. */
     uint32_t limit;
     if (args.hasDefined(1)) {
         double d;
         if (!ToNumber(cx, args[1], &d))
             return false;
         limit = ToUint32(d);
     } else {
         limit = UINT32_MAX;
     }
     /* Step 8. */
     RegExpGuard re(cx);
     RootedLinearString sepstr(cx);
     bool sepDefined = args.hasDefined(0);
     if (sepDefined) {
         if (IsObjectWithClass(args[0], ESClass_RegExp, cx)) {
             RootedObject obj(cx, &args[0].toObject());
             if (!RegExpToShared(cx, obj, &re))
                 return false;
         } else {
             sepstr = ArgToRootedString(cx, args, 0);
             if (!sepstr)
                 return false;
         }
     }
     /* Step 9. */
     if (limit == 0) {
         JSObject *aobj = NewDenseEmptyArray(cx);
         if (!aobj)
             return false;
         aobj->setType(type);
         args.rval().setObject(*aobj);
         return true;
     }
     /* Step 10. */
     if (!sepDefined) {
         RootedValue v(cx, StringValue(str));
         JSObject *aobj = NewDenseCopiedArray(cx, 1, v.address());
         if (!aobj)
             return false;
         aobj->setType(type);
         args.rval().setObject(*aobj);
         return true;
     }
     Rooted<JSLinearString*> linearStr(cx, str->ensureLinear(cx));
     if (!linearStr)
         return false;
     /* Steps 11-15. */
     RootedObject aobj(cx);
     if (!re.initialized()) {
         if (sepstr->length() == 0) {
             aobj = CharSplitHelper(cx, linearStr, limit);
         } else {
             SplitStringMatcher matcher(cx, sepstr);
             aobj = SplitHelper(cx, linearStr, limit, matcher, type);
         }
     } else {
         SplitRegExpMatcher matcher(*re, cx->global()->getRegExpStatics());
         aobj = SplitHelper(cx, linearStr, limit, matcher, type);
     }
     if (!aobj)
         return false;
     /* Step 16. */
     aobj->setType(type);
     args.rval().setObject(*aobj);
     return true;
 }
 JSObject *
 js::str_split_string(JSContext *cx, HandleTypeObject type, HandleString str, HandleString sep)
 {
     Rooted<JSLinearString*> linearStr(cx, str->ensureLinear(cx));
     if (!linearStr)
         return nullptr;
     Rooted<JSLinearString*> linearSep(cx, sep->ensureLinear(cx));
     if (!linearSep)
         return nullptr;
     uint32_t limit = UINT32_MAX;
     RootedObject aobj(cx);
     if (linearSep->length() == 0) {
         aobj = CharSplitHelper(cx, linearStr, limit);
     } else {
         SplitStringMatcher matcher(cx, linearSep);
         aobj = SplitHelper(cx, linearStr, limit, matcher, type);
     }
     if (!aobj)
         return nullptr;
     aobj->setType(type);
     return aobj;
 }
 static bool
 str_substr(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     int32_t length, len, begin;
     if (args.length() > 0) {
         length = int32_t(str->length());
         if (!ValueToIntegerRange(cx, args[0], &begin))
             return false;
         if (begin >= length) {
             args.rval().setString(cx->runtime()->emptyString);
             return true;
         }
         if (begin < 0) {
             begin += length; /* length + INT_MIN will always be less than 0 */
             if (begin < 0)
                 begin = 0;
         }
         if (args.hasDefined(1)) {
             if (!ValueToIntegerRange(cx, args[1], &len))
                 return false;
             if (len <= 0) {
                 args.rval().setString(cx->runtime()->emptyString);
                 return true;
             }
             if (uint32_t(length) < uint32_t(begin + len))
                 len = length - begin;
         } else {
             len = length - begin;
         }
         str = DoSubstr(cx, str, size_t(begin), size_t(len));
         if (!str)
             return false;
     }
     args.rval().setString(str);
     return true;
 }
 /*
  * Python-esque sequence operations.
  */
 static bool
 str_concat(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     JSString *str = ThisToStringForStringProto(cx, args);
     if (!str)
         return false;
     for (unsigned i = 0; i < args.length(); i++) {
         JSString *argStr = ToString<NoGC>(cx, args[i]);
         if (!argStr) {
             RootedString strRoot(cx, str);
             argStr = ToString<CanGC>(cx, args[i]);
             if (!argStr)
                 return false;
             str = strRoot;
         }
         JSString *next = ConcatStrings<NoGC>(cx, str, argStr);
         if (next) {
             str = next;
         } else {
             RootedString strRoot(cx, str), argStrRoot(cx, argStr);
             str = ConcatStrings<CanGC>(cx, strRoot, argStrRoot);
             if (!str)
                 return false;
         }
     }
     args.rval().setString(str);
     return true;
 }
 static bool
 str_slice(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 1 && args.thisv().isString() && args[0].isInt32()) {
         JSString *str = args.thisv().toString();
         size_t begin = args[0].toInt32();
         size_t end = str->length();
         if (begin <= end) {
             size_t length = end - begin;
             if (length == 0) {
                 str = cx->runtime()->emptyString;
             } else {
                 str = (length == 1)
                       ? cx->staticStrings().getUnitStringForElement(cx, str, begin)
                       : js_NewDependentString(cx, str, begin, length);
                 if (!str)
                     return false;
             }
             args.rval().setString(str);
             return true;
         }
     }
     RootedString str(cx, ThisToStringForStringProto(cx, args));
     if (!str)
         return false;
     if (args.length() != 0) {
         double begin, end, length;
         if (!ToInteger(cx, args[0], &begin))
             return false;
         length = str->length();
         if (begin < 0) {
             begin += length;
             if (begin < 0)
                 begin = 0;
         } else if (begin > length) {
             begin = length;
         }
         if (args.hasDefined(1)) {
             if (!ToInteger(cx, args[1], &end))
                 return false;
             if (end < 0) {
                 end += length;
                 if (end < 0)
                     end = 0;
             } else if (end > length) {
                 end = length;
             }
             if (end < begin)
                 end = begin;
         } else {
             end = length;
         }
         str = js_NewDependentString(cx, str,
                                     (size_t)begin,
                                     (size_t)(end - begin));
         if (!str)
             return false;
     }
     args.rval().setString(str);
     return true;
 }
 #if JS_HAS_STR_HTML_HELPERS
 /*
  * HTML composition aids.
  */
 static bool
 tagify(JSContext *cx, const char *begin, HandleLinearString param, const char *end,
        CallReceiver call)
 {
     JSString *thisstr = ThisToStringForStringProto(cx, call);
     if (!thisstr)
         return false;
     JSLinearString *str = thisstr->ensureLinear(cx);
     if (!str)
         return false;
     if (!end)
         end = begin;
     size_t beglen = strlen(begin);
     size_t taglen = 1 + beglen + 1;                     /* '<begin' + '>' */
     if (param) {
         size_t numChars = param->length();
         const jschar *parchars = param->chars();
         for (size_t i = 0, parlen = numChars; i < parlen; ++i) {
             if (parchars[i] == '"')
                 numChars += 5;                          /* len(&quot;) - len(") */
         }
         taglen += 2 + numChars + 1;                     /* '="param"' */
     }
     size_t endlen = strlen(end);
     taglen += str->length() + 2 + endlen + 1;           /* 'str</end>' */
     StringBuffer sb(cx);
     if (!sb.reserve(taglen))
         return false;
     sb.infallibleAppend('<');
     MOZ_ALWAYS_TRUE(sb.appendInflated(begin, beglen));
     if (param) {
         sb.infallibleAppend('=');
         sb.infallibleAppend('"');
         const jschar *parchars = param->chars();
         for (size_t i = 0, parlen = param->length(); i < parlen; ++i) {
             if (parchars[i] != '"') {
                 sb.infallibleAppend(parchars[i]);
             } else {
                 MOZ_ALWAYS_TRUE(sb.append("&quot;"));
             }
         }
         sb.infallibleAppend('"');
     }
     sb.infallibleAppend('>');
     MOZ_ALWAYS_TRUE(sb.append(str));
     sb.infallibleAppend('<');
     sb.infallibleAppend('/');
     MOZ_ALWAYS_TRUE(sb.appendInflated(end, endlen));
     sb.infallibleAppend('>');
     JSFlatString *retstr = sb.finishString();
     if (!retstr)
         return false;
     call.rval().setString(retstr);
     return true;
 }
 static bool
 tagify_value(JSContext *cx, CallArgs args, const char *begin, const char *end)
 {
     RootedLinearString param(cx, ArgToRootedString(cx, args, 0));
     if (!param)
         return false;
     return tagify(cx, begin, param, end, args);
 }
 static bool
 str_bold(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "b", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_italics(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "i", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_fixed(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "tt", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_fontsize(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify_value(cx, CallArgsFromVp(argc, vp), "font size", "font");
 }
 static bool
 str_fontcolor(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify_value(cx, CallArgsFromVp(argc, vp), "font color", "font");
 }
 static bool
 str_link(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify_value(cx, CallArgsFromVp(argc, vp), "a href", "a");
 }
 static bool
 str_anchor(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify_value(cx, CallArgsFromVp(argc, vp), "a name", "a");
 }
 static bool
 str_strike(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "strike", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_small(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "small", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_big(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "big", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_blink(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "blink", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_sup(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "sup", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 static bool
 str_sub(JSContext *cx, unsigned argc, Value *vp)
 {
     return tagify(cx, "sub", NullPtr(), nullptr, CallReceiverFromVp(vp));
 }
 #endif /* JS_HAS_STR_HTML_HELPERS */
 static const JSFunctionSpec string_methods[] = {
 #if JS_HAS_TOSOURCE
     JS_FN("quote",             str_quote,             0,JSFUN_GENERIC_NATIVE),
     JS_FN(js_toSource_str,     str_toSource,          0,0),
 #endif
     /* Java-like methods. */
     JS_FN(js_toString_str,     js_str_toString,       0,0),
     JS_FN(js_valueOf_str,      js_str_toString,       0,0),
     JS_FN("substring",         str_substring,         2,JSFUN_GENERIC_NATIVE),
     JS_FN("toLowerCase",       str_toLowerCase,       0,JSFUN_GENERIC_NATIVE),
     JS_FN("toUpperCase",       str_toUpperCase,       0,JSFUN_GENERIC_NATIVE),
     JS_FN("charAt",            js_str_charAt,         1,JSFUN_GENERIC_NATIVE),
     JS_FN("charCodeAt",        js_str_charCodeAt,     1,JSFUN_GENERIC_NATIVE),
     JS_SELF_HOSTED_FN("codePointAt", "String_codePointAt", 1,0),
     JS_FN("contains",          str_contains,          1,JSFUN_GENERIC_NATIVE),
     JS_FN("indexOf",           str_indexOf,           1,JSFUN_GENERIC_NATIVE),
     JS_FN("lastIndexOf",       str_lastIndexOf,       1,JSFUN_GENERIC_NATIVE),
     JS_FN("startsWith",        str_startsWith,        1,JSFUN_GENERIC_NATIVE),
     JS_FN("endsWith",          str_endsWith,          1,JSFUN_GENERIC_NATIVE),
     JS_FN("trim",              str_trim,              0,JSFUN_GENERIC_NATIVE),
     JS_FN("trimLeft",          str_trimLeft,          0,JSFUN_GENERIC_NATIVE),
     JS_FN("trimRight",         str_trimRight,         0,JSFUN_GENERIC_NATIVE),
     JS_FN("toLocaleLowerCase", str_toLocaleLowerCase, 0,JSFUN_GENERIC_NATIVE),
     JS_FN("toLocaleUpperCase", str_toLocaleUpperCase, 0,JSFUN_GENERIC_NATIVE),
 #if EXPOSE_INTL_API
     JS_SELF_HOSTED_FN("localeCompare", "String_localeCompare", 1,0),
 #else
     JS_FN("localeCompare",     str_localeCompare,     1,JSFUN_GENERIC_NATIVE),
 #endif
     JS_SELF_HOSTED_FN("repeat", "String_repeat",      1,0),
 #if EXPOSE_INTL_API
     JS_FN("normalize",         str_normalize,         0,JSFUN_GENERIC_NATIVE),
 #endif
     /* Perl-ish methods (search is actually Python-esque). */
     JS_FN("match",             str_match,             1,JSFUN_GENERIC_NATIVE),
     JS_FN("search",            str_search,            1,JSFUN_GENERIC_NATIVE),
     JS_FN("replace",           str_replace,           2,JSFUN_GENERIC_NATIVE),
     JS_FN("split",             str_split,             2,JSFUN_GENERIC_NATIVE),
     JS_FN("substr",            str_substr,            2,JSFUN_GENERIC_NATIVE),
     /* Python-esque sequence methods. */
     JS_FN("concat",            str_concat,            1,JSFUN_GENERIC_NATIVE),
     JS_FN("slice",             str_slice,             2,JSFUN_GENERIC_NATIVE),
     /* HTML string methods. */
 #if JS_HAS_STR_HTML_HELPERS
     JS_FN("bold",              str_bold,              0,0),
     JS_FN("italics",           str_italics,           0,0),
     JS_FN("fixed",             str_fixed,             0,0),
     JS_FN("fontsize",          str_fontsize,          1,0),
     JS_FN("fontcolor",         str_fontcolor,         1,0),
     JS_FN("link",              str_link,              1,0),
     JS_FN("anchor",            str_anchor,            1,0),
     JS_FN("strike",            str_strike,            0,0),
     JS_FN("small",             str_small,             0,0),
     JS_FN("big",               str_big,               0,0),
     JS_FN("blink",             str_blink,             0,0),
     JS_FN("sup",               str_sup,               0,0),
     JS_FN("sub",               str_sub,               0,0),
 #endif
     JS_SELF_HOSTED_FN("@@iterator", "String_iterator", 0,0),
     JS_FS_END
 };
 bool
 js_String(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     RootedString str(cx);
     if (args.length() > 0) {
         str = ToString<CanGC>(cx, args[0]);
         if (!str)
             return false;
     } else {
         str = cx->runtime()->emptyString;
     }
     if (args.isConstructing()) {
         StringObject *strobj = StringObject::create(cx, str);
         if (!strobj)
             return false;
         args.rval().setObject(*strobj);
         return true;
     }
     args.rval().setString(str);
     return true;
 }
 bool
 js::str_fromCharCode(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     JS_ASSERT(args.length() <= ARGS_LENGTH_MAX);
     if (args.length() == 1) {
         uint16_t code;
         if (!ToUint16(cx, args[0], &code))
             return false;
         if (StaticStrings::hasUnit(code)) {
             args.rval().setString(cx->staticStrings().getUnit(code));
             return true;
         }
         args[0].setInt32(code);
     }
     jschar *chars = cx->pod_malloc<jschar>(args.length() + 1);
     if (!chars)
         return false;
     for (unsigned i = 0; i < args.length(); i++) {
         uint16_t code;
         if (!ToUint16(cx, args[i], &code)) {
             js_free(chars);
             return false;
         }
         chars[i] = (jschar)code;
     }
     chars[args.length()] = 0;
     JSString *str = js_NewString<CanGC>(cx, chars, args.length());
     if (!str) {
         js_free(chars);
         return false;
     }
     args.rval().setString(str);
     return true;
 }
 static const JSFunctionSpec string_static_methods[] = {
     JS_FN("fromCharCode", js::str_fromCharCode, 1, 0),
     JS_SELF_HOSTED_FN("fromCodePoint", "String_static_fromCodePoint", 0,0),
     // This must be at the end because of bug 853075: functions listed after
     // self-hosted methods aren't available in self-hosted code.
 #if EXPOSE_INTL_API
     JS_SELF_HOSTED_FN("localeCompare", "String_static_localeCompare", 2,0),
 #endif
     JS_FS_END
 };
 /* static */ Shape *
 StringObject::assignInitialShape(ExclusiveContext *cx, Handle<StringObject*> obj)
 {
     JS_ASSERT(obj->nativeEmpty());
     return obj->addDataProperty(cx, cx->names().length, LENGTH_SLOT,
                                 JSPROP_PERMANENT | JSPROP_READONLY);
 }
 JSObject *
 js_InitStringClass(JSContext *cx, HandleObject obj)
 {
     JS_ASSERT(obj->isNative());
     Rooted<GlobalObject*> global(cx, &obj->as<GlobalObject>());
     Rooted<JSString*> empty(cx, cx->runtime()->emptyString);
     RootedObject proto(cx, global->createBlankPrototype(cx, &StringObject::class_));
     if (!proto || !proto->as<StringObject>().init(cx, empty))
         return nullptr;
     /* Now create the String function. */
     RootedFunction ctor(cx);
     ctor = global->createConstructor(cx, js_String, cx->names().String, 1);
     if (!ctor)
         return nullptr;
     if (!LinkConstructorAndPrototype(cx, ctor, proto))
         return nullptr;
     if (!DefinePropertiesAndBrand(cx, proto, nullptr, string_methods) ||
         !DefinePropertiesAndBrand(cx, ctor, nullptr, string_static_methods))
     {
         return nullptr;
     }
     if (!GlobalObject::initBuiltinConstructor(cx, global, JSProto_String, ctor, proto))
         return nullptr;
     /*
      * Define escape/unescape, the URI encode/decode functions, and maybe
      * uneval on the global object.
      */
     if (!JS_DefineFunctions(cx, global, string_functions))
         return nullptr;
     return proto;
 }
 template <AllowGC allowGC>
 JSFlatString *
 js_NewString(ThreadSafeContext *cx, jschar *chars, size_t length)
 {
     if (length == 1) {
         jschar c = chars[0];
         if (StaticStrings::hasUnit(c)) {
             // Free |chars| because we're taking possession of it, but it's no
             // longer needed because we use the static string instead.
             js_free(chars);
             return cx->staticStrings().getUnit(c);
         }
     }
     return JSFlatString::new_<allowGC>(cx, chars, length);
 }
 template JSFlatString *
 js_NewString<CanGC>(ThreadSafeContext *cx, jschar *chars, size_t length);
 template JSFlatString *
 js_NewString<NoGC>(ThreadSafeContext *cx, jschar *chars, size_t length);
 JSLinearString *
 js_NewDependentString(JSContext *cx, JSString *baseArg, size_t start, size_t length)
 {
     if (length == 0)
         return cx->emptyString();
     JSLinearString *base = baseArg->ensureLinear(cx);
     if (!base)
         return nullptr;
     if (start == 0 && length == base->length())
         return base;
     const jschar *chars = base->chars() + start;
     if (JSLinearString *staticStr = cx->staticStrings().lookup(chars, length))
         return staticStr;
     return JSDependentString::new_(cx, base, chars, length);
 }
 template <AllowGC allowGC>
 JSFlatString *
 js_NewStringCopyN(ExclusiveContext *cx, const jschar *s, size_t n)
 {
     if (JSFatInlineString::lengthFits(n))
         return NewFatInlineString<allowGC>(cx, TwoByteChars(s, n));
     jschar *news = cx->pod_malloc<jschar>(n + 1);
     if (!news)
         return nullptr;
     js_strncpy(news, s, n);
     news[n] = 0;
     JSFlatString *str = js_NewString<allowGC>(cx, news, n);
     if (!str)
         js_free(news);
     return str;
 }
 template JSFlatString *
 js_NewStringCopyN<CanGC>(ExclusiveContext *cx, const jschar *s, size_t n);
 template JSFlatString *
 js_NewStringCopyN<NoGC>(ExclusiveContext *cx, const jschar *s, size_t n);
 template <AllowGC allowGC>
 JSFlatString *
 js_NewStringCopyN(ThreadSafeContext *cx, const char *s, size_t n)
 {
     if (JSFatInlineString::lengthFits(n))
         return NewFatInlineString<allowGC>(cx, JS::Latin1Chars(s, n));
     jschar *chars = InflateString(cx, s, &n);
     if (!chars)
         return nullptr;
     JSFlatString *str = js_NewString<allowGC>(cx, chars, n);
     if (!str)
         js_free(chars);
     return str;
 }
 template JSFlatString *
 js_NewStringCopyN<CanGC>(ThreadSafeContext *cx, const char *s, size_t n);
 template JSFlatString *
 js_NewStringCopyN<NoGC>(ThreadSafeContext *cx, const char *s, size_t n);
 template <AllowGC allowGC>
 JSFlatString *
 js_NewStringCopyZ(ExclusiveContext *cx, const jschar *s)
 {
     size_t n = js_strlen(s);
     if (JSFatInlineString::lengthFits(n))
         return NewFatInlineString<allowGC>(cx, TwoByteChars(s, n));
     size_t m = (n + 1) * sizeof(jschar);
     jschar *news = (jschar *) cx->malloc_(m);
     if (!news)
         return nullptr;
     js_memcpy(news, s, m);
     JSFlatString *str = js_NewString<allowGC>(cx, news, n);
     if (!str)
         js_free(news);
     return str;
 }
 template JSFlatString *
 js_NewStringCopyZ<CanGC>(ExclusiveContext *cx, const jschar *s);
 template JSFlatString *
 js_NewStringCopyZ<NoGC>(ExclusiveContext *cx, const jschar *s);
 template <AllowGC allowGC>
 JSFlatString *
 js_NewStringCopyZ(ThreadSafeContext *cx, const char *s)
 {
     return js_NewStringCopyN<allowGC>(cx, s, strlen(s));
 }
 template JSFlatString *
 js_NewStringCopyZ<CanGC>(ThreadSafeContext *cx, const char *s);
 template JSFlatString *
 js_NewStringCopyZ<NoGC>(ThreadSafeContext *cx, const char *s);
 const char *
 js_ValueToPrintable(JSContext *cx, const Value &vArg, JSAutoByteString *bytes, bool asSource)
 {
     RootedValue v(cx, vArg);
     JSString *str;
     if (asSource)
         str = ValueToSource(cx, v);
     else
         str = ToString<CanGC>(cx, v);
     if (!str)
         return nullptr;
     str = js_QuoteString(cx, str, 0);
     if (!str)
         return nullptr;
     return bytes->encodeLatin1(cx, str);
 }
 template <AllowGC allowGC>
 JSString *
 js::ToStringSlow(ExclusiveContext *cx, typename MaybeRooted<Value, allowGC>::HandleType arg)
 {
     /* As with ToObjectSlow, callers must verify that |arg| isn't a string. */
     JS_ASSERT(!arg.isString());
     Value v = arg;
     if (!v.isPrimitive()) {
         if (!cx->shouldBeJSContext() || !allowGC)
             return nullptr;
         RootedValue v2(cx, v);
         if (!ToPrimitive(cx->asJSContext(), JSTYPE_STRING, &v2))
             return nullptr;
         v = v2;
     }
     JSString *str;
     if (v.isString()) {
         str = v.toString();
     } else if (v.isInt32()) {
         str = Int32ToString<allowGC>(cx, v.toInt32());
     } else if (v.isDouble()) {
         str = NumberToString<allowGC>(cx, v.toDouble());
     } else if (v.isBoolean()) {
         str = js_BooleanToString(cx, v.toBoolean());
     } else if (v.isNull()) {
         str = cx->names().null;
     } else {
         str = cx->names().undefined;
     }
     return str;
 }
 template JSString *
 js::ToStringSlow<CanGC>(ExclusiveContext *cx, HandleValue arg);
 template JSString *
 js::ToStringSlow<NoGC>(ExclusiveContext *cx, Value arg);
 JS_PUBLIC_API(JSString *)
 js::ToStringSlow(JSContext *cx, HandleValue v)
 {
     return ToStringSlow<CanGC>(cx, v);
 }
 JSString *
 js::ValueToSource(JSContext *cx, HandleValue v)
 {
     JS_CHECK_RECURSION(cx, return nullptr);
     assertSameCompartment(cx, v);
     if (v.isUndefined())
         return cx->names().void0;
     if (v.isString())
         return StringToSource(cx, v.toString());
     if (v.isPrimitive()) {
         /* Special case to preserve negative zero, _contra_ toString. */
         if (v.isDouble() && IsNegativeZero(v.toDouble())) {
             /* NB: _ucNstr rather than _ucstr to indicate non-terminated. */
             static const jschar js_negzero_ucNstr[] = {'-', '0'};
             return js_NewStringCopyN<CanGC>(cx, js_negzero_ucNstr, 2);
         }
         return ToString<CanGC>(cx, v);
     }
     RootedValue fval(cx);
     RootedObject obj(cx, &v.toObject());
     if (!JSObject::getProperty(cx, obj, obj, cx->names().toSource, &fval))
         return nullptr;
     if (js_IsCallable(fval)) {
         RootedValue rval(cx);
         if (!Invoke(cx, ObjectValue(*obj), fval, 0, nullptr, &rval))
             return nullptr;
         return ToString<CanGC>(cx, rval);
     }
     return ObjectToSource(cx, obj);
 }
 JSString *
 js::StringToSource(JSContext *cx, JSString *str)
 {
     return js_QuoteString(cx, str, '"');
 }
 bool
 js::EqualStrings(JSContext *cx, JSString *str1, JSString *str2, bool *result)
 {
     if (str1 == str2) {
         *result = true;
         return true;
     }
     size_t length1 = str1->length();
     if (length1 != str2->length()) {
         *result = false;
         return true;
     }
     JSLinearString *linear1 = str1->ensureLinear(cx);
     if (!linear1)
         return false;
     JSLinearString *linear2 = str2->ensureLinear(cx);
     if (!linear2)
         return false;
     *result = PodEqual(linear1->chars(), linear2->chars(), length1);
     return true;
 }
 bool
 js::EqualStrings(JSLinearString *str1, JSLinearString *str2)
 {
     if (str1 == str2)
         return true;
     size_t length1 = str1->length();
     if (length1 != str2->length())
         return false;
     return PodEqual(str1->chars(), str2->chars(), length1);
 }
 static bool
 CompareStringsImpl(JSContext *cx, JSString *str1, JSString *str2, int32_t *result)
 {
     JS_ASSERT(str1);
     JS_ASSERT(str2);
     if (str1 == str2) {
         *result = 0;
         return true;
     }
     const jschar *s1 = str1->getChars(cx);
     if (!s1)
         return false;
     const jschar *s2 = str2->getChars(cx);
     if (!s2)
         return false;
     *result = CompareChars(s1, str1->length(), s2, str2->length());
     return true;
 }
 bool
 js::CompareStrings(JSContext *cx, JSString *str1, JSString *str2, int32_t *result)
 {
     return CompareStringsImpl(cx, str1, str2, result);
 }
 int32_t
 js::CompareAtoms(JSAtom *atom1, JSAtom *atom2)
 {
     return CompareChars(atom1->chars(), atom1->length(), atom2->chars(), atom2->length());
 }
 bool
 js::StringEqualsAscii(JSLinearString *str, const char *asciiBytes)
 {
     size_t length = strlen(asciiBytes);
 #ifdef DEBUG
     for (size_t i = 0; i != length; ++i)
         JS_ASSERT(unsigned(asciiBytes[i]) <= 127);
 #endif
     if (length != str->length())
         return false;
     const jschar *chars = str->chars();
     for (size_t i = 0; i != length; ++i) {
         if (unsigned(asciiBytes[i]) != unsigned(chars[i]))
             return false;
     }
     return true;
 }
 size_t
 js_strlen(const jschar *s)
 {
     const jschar *t;
     for (t = s; *t != 0; t++)
         continue;
     return (size_t)(t - s);
 }
 int32_t
 js_strcmp(const jschar *lhs, const jschar *rhs)
 {
     while (true) {
         if (*lhs != *rhs)
             return int32_t(*lhs) - int32_t(*rhs);
         if (*lhs == 0)
             return 0;
         ++lhs, ++rhs;
     }
 }
 jschar *
 js_strdup(js::ThreadSafeContext *cx, const jschar *s)
 {
     size_t n = js_strlen(s);
     jschar *ret = cx->pod_malloc<jschar>(n + 1);
     if (!ret)
         return nullptr;
     js_strncpy(ret, s, n);
     ret[n] = '\0';
     return ret;
 }
 jschar *
 js_strchr_limit(const jschar *s, jschar c, const jschar *limit)
 {
     while (s < limit) {
         if (*s == c)
             return (jschar *)s;
         s++;
     }
     return nullptr;
 }
 jschar *
 js::InflateString(ThreadSafeContext *cx, const char *bytes, size_t *lengthp)
 {
     size_t nchars;
     jschar *chars;
     size_t nbytes = *lengthp;
     nchars = nbytes;
     chars = cx->pod_malloc<jschar>(nchars + 1);
     if (!chars)
         goto bad;
     for (size_t i = 0; i < nchars; i++)
         chars[i] = (unsigned char) bytes[i];
     *lengthp = nchars;
     chars[nchars] = 0;
     return chars;
   bad:
     // For compatibility with callers of JS_DecodeBytes we must zero lengthp
     // on errors.
     *lengthp = 0;
     return nullptr;
 }
 bool
 js::DeflateStringToBuffer(JSContext *maybecx, const jschar *src, size_t srclen,
                           char *dst, size_t *dstlenp)
 {
     size_t dstlen = *dstlenp;
     if (srclen > dstlen) {
         for (size_t i = 0; i < dstlen; i++)
             dst[i] = (char) src[i];
         if (maybecx) {
             AutoSuppressGC suppress(maybecx);
             JS_ReportErrorNumber(maybecx, js_GetErrorMessage, nullptr,
                                  JSMSG_BUFFER_TOO_SMALL);
         }
         return false;
     }
     for (size_t i = 0; i < srclen; i++)
         dst[i] = (char) src[i];
     *dstlenp = srclen;
     return true;
 }
 #define ____ false
 /*
  * Identifier start chars:
  * -      36:    $
  * -  65..90: A..Z
  * -      95:    _
  * - 97..122: a..z
  */
 const bool js_isidstart[] = {
 /*       0     1     2     3     4     5     6     7     8     9  */
 /*  0 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  1 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  2 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  3 */ ____, ____, ____, ____, ____, ____, true, ____, ____, ____,
 /*  4 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  5 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  6 */ ____, ____, ____, ____, ____, true, true, true, true, true,
 /*  7 */ true, true, true, true, true, true, true, true, true, true,
 /*  8 */ true, true, true, true, true, true, true, true, true, true,
 /*  9 */ true, ____, ____, ____, ____, true, ____, true, true, true,
 /* 10 */ true, true, true, true, true, true, true, true, true, true,
 /* 11 */ true, true, true, true, true, true, true, true, true, true,
 /* 12 */ true, true, true, ____, ____, ____, ____, ____
 };
 /*
  * Identifier chars:
  * -      36:    $
  * -  48..57: 0..9
  * -  65..90: A..Z
  * -      95:    _
  * - 97..122: a..z
  */
 const bool js_isident[] = {
 /*       0     1     2     3     4     5     6     7     8     9  */
 /*  0 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  1 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  2 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  3 */ ____, ____, ____, ____, ____, ____, true, ____, ____, ____,
 /*  4 */ ____, ____, ____, ____, ____, ____, ____, ____, true, true,
 /*  5 */ true, true, true, true, true, true, true, true, ____, ____,
 /*  6 */ ____, ____, ____, ____, ____, true, true, true, true, true,
 /*  7 */ true, true, true, true, true, true, true, true, true, true,
 /*  8 */ true, true, true, true, true, true, true, true, true, true,
 /*  9 */ true, ____, ____, ____, ____, true, ____, true, true, true,
 /* 10 */ true, true, true, true, true, true, true, true, true, true,
 /* 11 */ true, true, true, true, true, true, true, true, true, true,
 /* 12 */ true, true, true, ____, ____, ____, ____, ____
 };
 /* Whitespace chars: '\t', '\n', '\v', '\f', '\r', ' '. */
 const bool js_isspace[] = {
 /*       0     1     2     3     4     5     6     7     8     9  */
 /*  0 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, true,
 /*  1 */ true, true, true, true, ____, ____, ____, ____, ____, ____,
 /*  2 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  3 */ ____, ____, true, ____, ____, ____, ____, ____, ____, ____,
 /*  4 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  5 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  6 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  7 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  8 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  9 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /* 10 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /* 11 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /* 12 */ ____, ____, ____, ____, ____, ____, ____, ____
 };
 /*
  * Uri reserved chars + #:
  * - 35: #
  * - 36: $
  * - 38: &
  * - 43: +
  * - 44: ,
  * - 47: /
  * - 58: :
  * - 59: ;
  * - 61: =
  * - 63: ?
  * - 64: @
  */
 static const bool js_isUriReservedPlusPound[] = {
 /*       0     1     2     3     4     5     6     7     8     9  */
 /*  0 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  1 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  2 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  3 */ ____, ____, ____, ____, ____, true, true, ____, true, ____,
 /*  4 */ ____, ____, ____, true, true, ____, ____, true, ____, ____,
 /*  5 */ ____, ____, ____, ____, ____, ____, ____, ____, true, true,
 /*  6 */ ____, true, ____, true, true, ____, ____, ____, ____, ____,
 /*  7 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  8 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  9 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /* 10 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /* 11 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /* 12 */ ____, ____, ____, ____, ____, ____, ____, ____
 };
 /*
  * Uri unescaped chars:
  * -      33: !
  * -      39: '
  * -      40: (
  * -      41: )
  * -      42: *
  * -      45: -
  * -      46: .
  * -  48..57: 0-9
  * -  65..90: A-Z
  * -      95: _
  * - 97..122: a-z
  * -     126: ~
  */
 static const bool js_isUriUnescaped[] = {
 /*       0     1     2     3     4     5     6     7     8     9  */
 /*  0 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  1 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  2 */ ____, ____, ____, ____, ____, ____, ____, ____, ____, ____,
 /*  3 */ ____, ____, ____, true, ____, ____, ____, ____, ____, true,
 /*  4 */ true, true, true, ____, ____, true, true, ____, true, true,
 /*  5 */ true, true, true, true, true, true, true, true, ____, ____,
 /*  6 */ ____, ____, ____, ____, ____, true, true, true, true, true,
 /*  7 */ true, true, true, true, true, true, true, true, true, true,
 /*  8 */ true, true, true, true, true, true, true, true, true, true,
 /*  9 */ true, ____, ____, ____, ____, true, ____, true, true, true,
 /* 10 */ true, true, true, true, true, true, true, true, true, true,
 /* 11 */ true, true, true, true, true, true, true, true, true, true,
 /* 12 */ true, true, true, ____, ____, ____, true, ____
 };
 #undef ____
 #define URI_CHUNK 64U
 static inline bool
 TransferBufferToString(StringBuffer &sb, MutableHandleValue rval)
 {
     JSString *str = sb.finishString();
     if (!str)
         return false;
     rval.setString(str);
     return true;
 }
 /*
  * ECMA 3, 15.1.3 URI Handling Function Properties
  *
  * The following are implementations of the algorithms
  * given in the ECMA specification for the hidden functions
  * 'Encode' and 'Decode'.
  */
 static bool
 Encode(JSContext *cx, Handle<JSLinearString*> str, const bool *unescapedSet,
        const bool *unescapedSet2, MutableHandleValue rval)
 {
     static const char HexDigits[] = "0123456789ABCDEF"; /* NB: uppercase */
     size_t length = str->length();
     if (length == 0) {
         rval.setString(cx->runtime()->emptyString);
         return true;
     }
     const jschar *chars = str->chars();
     StringBuffer sb(cx);
     if (!sb.reserve(length))
         return false;
     jschar hexBuf[4];
     hexBuf[0] = '%';
     hexBuf[3] = 0;
     for (size_t k = 0; k < length; k++) {
         jschar c = chars[k];
         if (c < 128 && (unescapedSet[c] || (unescapedSet2 && unescapedSet2[c]))) {
             if (!sb.append(c))
                 return false;
         } else {
             if ((c >= 0xDC00) && (c <= 0xDFFF)) {
                 JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_BAD_URI, nullptr);
                 return false;
             }
             uint32_t v;
             if (c < 0xD800 || c > 0xDBFF) {
                 v = c;
             } else {
                 k++;
                 if (k == length) {
                     JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr,
                                      JSMSG_BAD_URI, nullptr);
                     return false;
                 }
                 jschar c2 = chars[k];
                 if ((c2 < 0xDC00) || (c2 > 0xDFFF)) {
                     JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr,
                                      JSMSG_BAD_URI, nullptr);
                     return false;
                 }
                 v = ((c - 0xD800) << 10) + (c2 - 0xDC00) + 0x10000;
             }
             uint8_t utf8buf[4];
             size_t L = js_OneUcs4ToUtf8Char(utf8buf, v);
             for (size_t j = 0; j < L; j++) {
                 hexBuf[1] = HexDigits[utf8buf[j] >> 4];
                 hexBuf[2] = HexDigits[utf8buf[j] & 0xf];
                 if (!sb.append(hexBuf, 3))
                     return false;
             }
         }
     }
     return TransferBufferToString(sb, rval);
 }
 static bool
 Decode(JSContext *cx, Handle<JSLinearString*> str, const bool *reservedSet, MutableHandleValue rval)
 {
     size_t length = str->length();
     if (length == 0) {
         rval.setString(cx->runtime()->emptyString);
         return true;
     }
     const jschar *chars = str->chars();
     StringBuffer sb(cx);
     for (size_t k = 0; k < length; k++) {
         jschar c = chars[k];
         if (c == '%') {
             size_t start = k;
             if ((k + 2) >= length)
                 goto report_bad_uri;
             if (!JS7_ISHEX(chars[k+1]) || !JS7_ISHEX(chars[k+2]))
                 goto report_bad_uri;
             uint32_t B = JS7_UNHEX(chars[k+1]) * 16 + JS7_UNHEX(chars[k+2]);
             k += 2;
             if (!(B & 0x80)) {
                 c = (jschar)B;
             } else {
                 int n = 1;
                 while (B & (0x80 >> n))
                     n++;
                 if (n == 1 || n > 4)
                     goto report_bad_uri;
                 uint8_t octets[4];
                 octets[0] = (uint8_t)B;
                 if (k + 3 * (n - 1) >= length)
                     goto report_bad_uri;
                 for (int j = 1; j < n; j++) {
                     k++;
                     if (chars[k] != '%')
                         goto report_bad_uri;
                     if (!JS7_ISHEX(chars[k+1]) || !JS7_ISHEX(chars[k+2]))
                         goto report_bad_uri;
                     B = JS7_UNHEX(chars[k+1]) * 16 + JS7_UNHEX(chars[k+2]);
                     if ((B & 0xC0) != 0x80)
                         goto report_bad_uri;
                     k += 2;
                     octets[j] = (char)B;
                 }
                 uint32_t v = JS::Utf8ToOneUcs4Char(octets, n);
                 if (v >= 0x10000) {
                     v -= 0x10000;
                     if (v > 0xFFFFF)
                         goto report_bad_uri;
                     c = (jschar)((v & 0x3FF) + 0xDC00);
                     jschar H = (jschar)((v >> 10) + 0xD800);
                     if (!sb.append(H))
                         return false;
                 } else {
                     c = (jschar)v;
                 }
             }
             if (c < 128 && reservedSet && reservedSet[c]) {
                 if (!sb.append(chars + start, k - start + 1))
                     return false;
             } else {
                 if (!sb.append(c))
                     return false;
             }
         } else {
             if (!sb.append(c))
                 return false;
         }
     }
     return TransferBufferToString(sb, rval);
   report_bad_uri:
     JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_BAD_URI);
     /* FALL THROUGH */
     return false;
 }
 static bool
 str_decodeURI(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     Rooted<JSLinearString*> str(cx, ArgToRootedString(cx, args, 0));
     if (!str)
         return false;
     return Decode(cx, str, js_isUriReservedPlusPound, args.rval());
 }
 static bool
 str_decodeURI_Component(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     Rooted<JSLinearString*> str(cx, ArgToRootedString(cx, args, 0));
     if (!str)
         return false;
     return Decode(cx, str, nullptr, args.rval());
 }
 static bool
 str_encodeURI(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     Rooted<JSLinearString*> str(cx, ArgToRootedString(cx, args, 0));
     if (!str)
         return false;
     return Encode(cx, str, js_isUriUnescaped, js_isUriReservedPlusPound, args.rval());
 }
 static bool
 str_encodeURI_Component(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     Rooted<JSLinearString*> str(cx, ArgToRootedString(cx, args, 0));
     if (!str)
         return false;
     return Encode(cx, str, js_isUriUnescaped, nullptr, args.rval());
 }
 /*
  * Convert one UCS-4 char and write it into a UTF-8 buffer, which must be at
  * least 4 bytes long.  Return the number of UTF-8 bytes of data written.
  */
 int
 js_OneUcs4ToUtf8Char(uint8_t *utf8Buffer, uint32_t ucs4Char)
 {
     int utf8Length = 1;
     JS_ASSERT(ucs4Char <= 0x10FFFF);
     if (ucs4Char < 0x80) {
         *utf8Buffer = (uint8_t)ucs4Char;
     } else {
         int i;
         uint32_t a = ucs4Char >> 11;
         utf8Length = 2;
         while (a) {
             a >>= 5;
             utf8Length++;
         }
         i = utf8Length;
         while (--i) {
             utf8Buffer[i] = (uint8_t)((ucs4Char & 0x3F) | 0x80);
             ucs4Char >>= 6;
         }
         *utf8Buffer = (uint8_t)(0x100 - (1 << (8-utf8Length)) + ucs4Char);
     }
     return utf8Length;
 }
 size_t
 js::PutEscapedStringImpl(char *buffer, size_t bufferSize, FILE *fp, JSLinearString *str,
                          uint32_t quote)
 {
     return PutEscapedStringImpl(buffer, bufferSize, fp, str->chars(),
                                 str->length(), quote);
 }
 size_t
 js::PutEscapedStringImpl(char *buffer, size_t bufferSize, FILE *fp, const jschar *chars,
                          size_t length, uint32_t quote)
 {
     enum {
         STOP, FIRST_QUOTE, LAST_QUOTE, CHARS, ESCAPE_START, ESCAPE_MORE
     } state;
     JS_ASSERT(quote == 0 || quote == '\'' || quote == '"');
     JS_ASSERT_IF(!buffer, bufferSize == 0);
     JS_ASSERT_IF(fp, !buffer);
     if (bufferSize == 0)
         buffer = nullptr;
     else
         bufferSize--;
     const jschar *charsEnd = chars + length;
     size_t n = 0;
     state = FIRST_QUOTE;
     unsigned shift = 0;
     unsigned hex = 0;
     unsigned u = 0;
     char c = 0;  /* to quell GCC warnings */
     for (;;) {
         switch (state) {
           case STOP:
             goto stop;
           case FIRST_QUOTE:
             state = CHARS;
             goto do_quote;
           case LAST_QUOTE:
             state = STOP;
           do_quote:
             if (quote == 0)
                 continue;
             c = (char)quote;
             break;
           case CHARS:
             if (chars == charsEnd) {
                 state = LAST_QUOTE;
                 continue;
             }
             u = *chars++;
             if (u < ' ') {
                 if (u != 0) {
                     const char *escape = strchr(js_EscapeMap, (int)u);
                     if (escape) {
                         u = escape[1];
                         goto do_escape;
                     }
                 }
                 goto do_hex_escape;
             }
             if (u < 127) {
                 if (u == quote || u == '\\')
                     goto do_escape;
                 c = (char)u;
             } else if (u < 0x100) {
                 goto do_hex_escape;
             } else {
                 shift = 16;
                 hex = u;
                 u = 'u';
                 goto do_escape;
             }
             break;
           do_hex_escape:
             shift = 8;
             hex = u;
             u = 'x';
           do_escape:
             c = '\\';
             state = ESCAPE_START;
             break;
           case ESCAPE_START:
             JS_ASSERT(' ' <= u && u < 127);
             c = (char)u;
             state = ESCAPE_MORE;
             break;
           case ESCAPE_MORE:
             if (shift == 0) {
                 state = CHARS;
                 continue;
             }
             shift -= 4;
             u = 0xF & (hex >> shift);
             c = (char)(u + (u < 10 ? '0' : 'A' - 10));
             break;
         }
         if (buffer) {
             JS_ASSERT(n <= bufferSize);
             if (n != bufferSize) {
                 buffer[n] = c;
             } else {
                 buffer[n] = '\0';
                 buffer = nullptr;
             }
         } else if (fp) {
             if (fputc(c, fp) < 0)
                 return size_t(-1);
         }
         n++;
     }
   stop:
     if (buffer)
         buffer[n] = '\0';
     return n;
 }

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js/src/jsstr.cpp@6474c204b198 (annotated)

js/src/jsstr.cpp