C++ JSLinearString类代码示例

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;

    if (base->hasTwoByteChars()) {
        AutoCheckCannotGC nogc;
        const char16_t* chars = base->twoByteChars(nogc) + start;
        if (JSLinearString* staticStr = cx->staticStrings().lookup(chars, length))
            return staticStr;
    } else {
        AutoCheckCannotGC nogc;
        const Latin1Char* chars = base->latin1Chars(nogc) + start;
        if (JSLinearString* staticStr = cx->staticStrings().lookup(chars, length))
            return staticStr;
    }

    return JSDependentString::new_(cx, base, start, length);
}

bool
js::ParseRegExpFlags(JSContext* cx, JSString* flagStr, RegExpFlag* flagsOut)
{
    JSLinearString* linear = flagStr->ensureLinear(cx);
    if (!linear)
        return false;

    size_t len = linear->length();

    bool ok;
    char16_t lastParsed;
    if (linear->hasLatin1Chars()) {
        AutoCheckCannotGC nogc;
        ok = ::ParseRegExpFlags(linear->latin1Chars(nogc), len, flagsOut, &lastParsed);
    } else {
        AutoCheckCannotGC nogc;
        ok = ::ParseRegExpFlags(linear->twoByteChars(nogc), len, flagsOut, &lastParsed);
    }

    if (!ok) {
        char charBuf[2];
        charBuf[0] = char(lastParsed);
        charBuf[1] = '\0';
        JS_ReportErrorFlagsAndNumber(cx, JSREPORT_ERROR, GetErrorMessage, nullptr,
                                     JSMSG_BAD_REGEXP_FLAG, charBuf);
        return false;
    }

    return true;
}

JSBool
js_json_parse(JSContext *cx, uintN argc, Value *vp)
{
    JSString *s = NULL;
    Value *argv = vp + 2;
    AutoValueRooter reviver(cx);

    if (!JS_ConvertArguments(cx, argc, Jsvalify(argv), "S / v", &s, reviver.addr()))
        return JS_FALSE;

    JSLinearString *linearStr = s->ensureLinear(cx);
    if (!linearStr)
        return JS_FALSE;

    JSONParser *jp = js_BeginJSONParse(cx, vp);
    JSBool ok = jp != NULL;
    if (ok) {
        const jschar *chars = linearStr->chars();
        size_t length = linearStr->length();
        ok = js_ConsumeJSONText(cx, jp, chars, length);
        ok &= !!js_FinishJSONParse(cx, jp, reviver.value());
    }

    return ok;
}

JSFlatString *
RegExpObject::toString(JSContext *cx) const
{
    JSLinearString *src = getSource();
    StringBuffer sb(cx);
    if (size_t len = src->length()) {
        if (!sb.reserve(len + 2))
            return NULL;
        sb.infallibleAppend('/');
        sb.infallibleAppend(src->chars(), len);
        sb.infallibleAppend('/');
    } else {
        if (!sb.append("/(?:)/"))
            return NULL;
    }
    if (global() && !sb.append('g'))
        return NULL;
    if (ignoreCase() && !sb.append('i'))
        return NULL;
    if (multiline() && !sb.append('m'))
        return NULL;
    if (sticky() && !sb.append('y'))
        return NULL;

    return sb.finishString();
}

static bool
Quote(JSContext* cx, StringBuffer& sb, JSString* str)
{
    JSLinearString* linear = str->ensureLinear(cx);
    if (!linear)
        return false;

    return linear->hasLatin1Chars()
           ? Quote<Latin1Char>(sb, linear)
           : Quote<char16_t>(sb, linear);
}

void
CopyChars(Latin1Char* dest, const JSLinearString& str)
{
    AutoCheckCannotGC nogc;
    if (str.hasLatin1Chars()) {
        PodCopy(dest, str.latin1Chars(nogc), str.length());
    } else {
        /*
         * When we flatten a TwoByte rope, we turn child ropes (including Latin1
         * ropes) into TwoByte dependent strings. If one of these strings is
         * also part of another Latin1 rope tree, we can have a Latin1 rope with
         * a TwoByte descendent and we end up here when we flatten it. Although
         * the chars are stored as TwoByte, we know they must be in the Latin1
         * range, so we can safely deflate here.
         */
        size_t len = str.length();
        const char16_t* chars = str.twoByteChars(nogc);
        for (size_t i = 0; i < len; i++) {
            MOZ_ASSERT(chars[i] <= JSString::MAX_LATIN1_CHAR);
            dest[i] = chars[i];
        }
    }
}

/* ES5 15.12.2. */
JSBool
js_json_parse(JSContext *cx, unsigned argc, Value *vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    /* Step 1. */
    JSLinearString *linear;
    if (argc >= 1) {
        JSString *str = ToString(cx, args[0]);
        if (!str)
            return false;
        linear = str->ensureLinear(cx);
        if (!linear)
            return false;
    } else {
        linear = cx->names().undefined;
    }
    JS::Anchor<JSString *> anchor(linear);

    RootedValue reviver(cx, (argc >= 2) ? args[1] : UndefinedValue());

    /* Steps 2-5. */
    return ParseJSONWithReviver(cx, linear->chars(), linear->length(), reviver, args.rval());
}

bool
js::intl_isDefaultTimeZone(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    MOZ_ASSERT(args.length() == 1);
    MOZ_ASSERT(args[0].isString() || args[0].isUndefined());

    // |undefined| is the default value when the Intl runtime caches haven't
    // yet been initialized. Handle it the same way as a cache miss.
    if (args[0].isUndefined()) {
        args.rval().setBoolean(false);
        return true;
    }

    // The current default might be stale, because JS::ResetTimeZone() doesn't
    // immediately update ICU's default time zone. So perform an update if
    // needed.
    js::ResyncICUDefaultTimeZone();

    Vector<char16_t, INITIAL_CHAR_BUFFER_SIZE> chars(cx);
    int32_t size = CallICU(cx, ucal_getDefaultTimeZone, chars);
    if (size < 0)
        return false;

    JSLinearString* str = args[0].toString()->ensureLinear(cx);
    if (!str)
        return false;

    bool equals;
    if (str->length() == size_t(size)) {
        JS::AutoCheckCannotGC nogc;
        equals = str->hasLatin1Chars()
                 ? EqualChars(str->latin1Chars(nogc), chars.begin(), str->length())
                 : EqualChars(str->twoByteChars(nogc), chars.begin(), str->length());
    } else {
        equals = false;
    }

    args.rval().setBoolean(equals);
    return true;
}

JSAtom *
js::AtomizeString(ExclusiveContext *cx, JSString *str,
                  js::InternBehavior ib /* = js::DoNotInternAtom */)
{
    if (str->isAtom()) {
        JSAtom &atom = str->asAtom();
        /* N.B. static atoms are effectively always interned. */
        if (ib != InternAtom || js::StaticStrings::isStatic(&atom))
            return &atom;

        AtomHasher::Lookup lookup(&atom);

        /* Likewise, permanent atoms are always interned. */
        MOZ_ASSERT(cx->isPermanentAtomsInitialized());
        AtomSet::Ptr p = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
        if (p)
            return &atom;

        AutoLockForExclusiveAccess lock(cx);

        p = cx->atoms().lookup(lookup);
        MOZ_ASSERT(p); /* Non-static atom must exist in atom state set. */
        MOZ_ASSERT(p->asPtr() == &atom);
        MOZ_ASSERT(ib == InternAtom);
        p->setTagged(bool(ib));
        return &atom;
    }

    JSLinearString *linear = str->ensureLinear(cx);
    if (!linear)
        return nullptr;

    JS::AutoCheckCannotGC nogc;
    return linear->hasLatin1Chars()
           ? AtomizeAndCopyChars(cx, linear->latin1Chars(nogc), linear->length(), ib)
           : AtomizeAndCopyChars(cx, linear->twoByteChars(nogc), linear->length(), ib);
}

//.........这里部分代码省略.........
                            return false;
                    }
                } else {
                    bool shouldAdd = item.isString();
                    if (!shouldAdd) {
                        ESClass cls;
                        if (!GetClassOfValue(cx, item, &cls))
                            return false;

                        shouldAdd = cls == ESClass::String || cls == ESClass::Number;
                    }

                    if (shouldAdd) {
                        /* Step 4b(iii)(5)(f). */
                        if (!ValueToId<CanGC>(cx, item, &id))
                            return false;
                    } else {
                        /* Step 4b(iii)(5)(g). */
                        continue;
                    }
                }

                /* Step 4b(iii)(5)(g). */
                auto p = idSet.lookupForAdd(id);
                if (!p) {
                    /* Step 4b(iii)(5)(g)(i). */
                    if (!idSet.add(p, id) || !propertyList.append(id))
                        return false;
                }
            }
        } else {
            replacer = nullptr;
        }
    }

    /* Step 5. */
    if (space.isObject()) {
        RootedObject spaceObj(cx, &space.toObject());

        ESClass cls;
        if (!GetBuiltinClass(cx, spaceObj, &cls))
            return false;

        if (cls == ESClass::Number) {
            double d;
            if (!ToNumber(cx, space, &d))
                return false;
            space = NumberValue(d);
        } else if (cls == ESClass::String) {
            JSString* str = ToStringSlow<CanGC>(cx, space);
            if (!str)
                return false;
            space = StringValue(str);
        }
    }

    StringBuffer gap(cx);

    if (space.isNumber()) {
        /* Step 6. */
        double d;
        MOZ_ALWAYS_TRUE(ToInteger(cx, space, &d));
        d = Min(10.0, d);
        if (d >= 1 && !gap.appendN(' ', uint32_t(d)))
            return false;
    } else if (space.isString()) {
        /* Step 7. */
        JSLinearString* str = space.toString()->ensureLinear(cx);
        if (!str)
            return false;
        size_t len = Min(size_t(10), str->length());
        if (!gap.appendSubstring(str, 0, len))
            return false;
    } else {
        /* Step 8. */
        MOZ_ASSERT(gap.empty());
    }

    /* Step 9. */
    RootedPlainObject wrapper(cx, NewBuiltinClassInstance<PlainObject>(cx));
    if (!wrapper)
        return false;

    /* Steps 10-11. */
    RootedId emptyId(cx, NameToId(cx->names().empty));
    if (!NativeDefineProperty(cx, wrapper, emptyId, vp, nullptr, nullptr, JSPROP_ENUMERATE))
        return false;

    /* Step 12. */
    StringifyContext scx(cx, sb, gap, replacer, propertyList,
                         stringifyBehavior == StringifyBehavior::RestrictedSafe);
    if (!scx.init())
        return false;
    if (!PreprocessValue(cx, wrapper, HandleId(emptyId), vp, &scx))
        return false;
    if (IsFilteredValue(vp))
        return true;

    return Str(cx, vp, &scx);
}

JSAtom *
js_AtomizeString(JSContext *cx, JSString *strArg, uintN flags)
{
    JS_ASSERT(!(flags & ~(ATOM_PINNED|ATOM_INTERNED|ATOM_TMPSTR|ATOM_NOCOPY)));
    JS_ASSERT_IF(flags & ATOM_NOCOPY, flags & ATOM_TMPSTR);

    if (strArg->isAtomized())
        return STRING_TO_ATOM(strArg);

    JSLinearString *str = strArg->ensureLinear(cx);
    if (!str)
        return NULL;

    const jschar *chars = str->chars();
    size_t length = str->length();

    JSString *staticStr = JSString::lookupStaticString(chars, length);
    if (staticStr)
        return STRING_TO_ATOM(staticStr);

    JSAtomState *state = &cx->runtime->atomState;
    AtomSet &atoms = state->atoms;

    AutoLockAtomsCompartment lock(cx);
    AtomSet::AddPtr p = atoms.lookupForAdd(str);

    /* Hashing the string should have flattened it if it was a rope. */
    JS_ASSERT(str->isFlat() || str->isDependent());

    JSLinearString *key;
    if (p) {
        key = AtomEntryToKey(*p);
    } else {
        /*
         * Ensure that any atomized string lives only in the default
         * compartment.
         */
        bool needNewString = !!(flags & ATOM_TMPSTR) ||
                             str->asCell()->compartment() != cx->runtime->atomsCompartment;

        /*
         * Unless str is already comes from the default compartment and flat,
         * we have to relookup the key as the last ditch GC invoked from the
         * string allocation or OOM handling may unlock the default
         * compartment lock.
         */
        if (!needNewString && str->isFlat()) {
            str->flatClearExtensible();
            key = str;
            atoms.add(p, StringToInitialAtomEntry(key));
        } else {
            if (needNewString) {
                SwitchToCompartment sc(cx, cx->runtime->atomsCompartment);
                if (flags & ATOM_NOCOPY) {
                    key = js_NewString(cx, const_cast<jschar *>(str->flatChars()), length);
                    if (!key)
                        return NULL;

                    /* Finish handing off chars to the GC'ed key string. */
                    JS_ASSERT(flags & ATOM_TMPSTR);
                    str->u.chars = NULL;
                } else {
                    key = js_NewStringCopyN(cx, chars, length);
                    if (!key)
                        return NULL;
                }
            } else {
                JS_ASSERT(str->isDependent());
                if (!str->undepend(cx))
                    return NULL;
                key = str;
            }

            if (!atoms.relookupOrAdd(p, key, StringToInitialAtomEntry(key))) {
                JS_ReportOutOfMemory(cx); /* SystemAllocPolicy does not report */
                return NULL;
            }
        }
        key->flatSetAtomized();
    }

    AddAtomEntryFlags(*p, flags & (ATOM_PINNED | ATOM_INTERNED));

    JSAtom *atom = STRING_TO_ATOM(key);
    return atom;
}

//.........这里部分代码省略.........

        /* Unwrap the object, but don't unwrap outer windows. */
        obj = UnwrapObject(&vp->toObject(), /* stopAtOuter = */ true, &flags);

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);

        if (cx->runtime->preWrapObjectCallback) {
            obj = cx->runtime->preWrapObjectCallback(cx, global, obj, flags);
            if (!obj)
                return false;
        }

        if (obj->compartment() == this)
            return WrapForSameCompartment(cx, obj, vp);
        vp->setObject(*obj);

#ifdef DEBUG
        {
            JSObject *outer = GetOuterObject(cx, obj);
            JS_ASSERT(outer && outer == obj);
        }
#endif
    }

    RootedValue key(cx, *vp);

    /* If we already have a wrapper for this value, use it. */
    if (WrapperMap::Ptr p = crossCompartmentWrappers.lookup(key)) {
        *vp = p->value;
        if (vp->isObject()) {
            RootedObject obj(cx, &vp->toObject());
            JS_ASSERT(obj->isCrossCompartmentWrapper());
            JS_ASSERT(obj->getParent() == global);
        }
        return true;
    }

    if (vp->isString()) {
        RootedValue orig(cx, *vp);
        JSLinearString *str = vp->toString()->ensureLinear(cx);
        if (!str)
            return false;
        JSString *wrapped = js_NewStringCopyN(cx, str->chars(), str->length());
        if (!wrapped)
            return false;
        vp->setString(wrapped);
        if (!putWrapper(orig, *vp))
            return false;

        if (str->compartment()->isGCMarking()) {
            /*
             * All string wrappers are dropped when collection starts, but we
             * just created a new one.  Mark the wrapped string to stop it being
             * finalized, because if it was then the pointer in this
             * compartment's wrapper map would be left dangling.
             */
            JSString *tmp = str;
            MarkStringUnbarriered(&rt->gcMarker, &tmp, "wrapped string");
            JS_ASSERT(tmp == str);
        }

        return true;
    }

    RootedObject obj(cx, &vp->toObject());

    JSObject *proto = Proxy::LazyProto;
    if (existing) {
        /* Is it possible to reuse |existing|? */
        if (!existing->getTaggedProto().isLazy() ||
            existing->getClass() != &ObjectProxyClass ||
            existing->getParent() != global ||
            obj->isCallable())
        {
            existing = NULL;
        }
    }

    /*
     * We hand in the original wrapped object into the wrap hook to allow
     * the wrap hook to reason over what wrappers are currently applied
     * to the object.
     */
    RootedObject wrapper(cx);
    wrapper = cx->runtime->wrapObjectCallback(cx, existing, obj, proto, global, flags);
    if (!wrapper)
        return false;

    // We maintain the invariant that the key in the cross-compartment wrapper
    // map is always directly wrapped by the value.
    JS_ASSERT(Wrapper::wrappedObject(wrapper) == &key.get().toObject());

    vp->setObject(*wrapper);

    if (!putWrapper(key, *vp))
        return false;

    return true;
}

JSString*
js::ConcatStrings(ExclusiveContext* cx,
                  typename MaybeRooted<JSString*, allowGC>::HandleType left,
                  typename MaybeRooted<JSString*, allowGC>::HandleType right)
{
    MOZ_ASSERT_IF(!left->isAtom(), cx->isInsideCurrentZone(left));
    MOZ_ASSERT_IF(!right->isAtom(), cx->isInsideCurrentZone(right));

    size_t leftLen = left->length();
    if (leftLen == 0)
        return right;

    size_t rightLen = right->length();
    if (rightLen == 0)
        return left;

    size_t wholeLength = leftLen + rightLen;
    if (!JSString::validateLength(cx, wholeLength))
        return nullptr;

    bool isLatin1 = left->hasLatin1Chars() && right->hasLatin1Chars();
    bool canUseInline = isLatin1
                        ? JSInlineString::lengthFits<Latin1Char>(wholeLength)
                        : JSInlineString::lengthFits<char16_t>(wholeLength);
    if (canUseInline && cx->isJSContext()) {
        Latin1Char* latin1Buf = nullptr;  // initialize to silence GCC warning
        char16_t* twoByteBuf = nullptr;  // initialize to silence GCC warning
        JSInlineString* str = isLatin1
            ? AllocateInlineString<allowGC>(cx, wholeLength, &latin1Buf)
            : AllocateInlineString<allowGC>(cx, wholeLength, &twoByteBuf);
        if (!str)
            return nullptr;

        AutoCheckCannotGC nogc;
        JSLinearString* leftLinear = left->ensureLinear(cx);
        if (!leftLinear)
            return nullptr;
        JSLinearString* rightLinear = right->ensureLinear(cx);
        if (!rightLinear)
            return nullptr;

        if (isLatin1) {
            PodCopy(latin1Buf, leftLinear->latin1Chars(nogc), leftLen);
            PodCopy(latin1Buf + leftLen, rightLinear->latin1Chars(nogc), rightLen);
            latin1Buf[wholeLength] = 0;
        } else {
            if (leftLinear->hasTwoByteChars())
                PodCopy(twoByteBuf, leftLinear->twoByteChars(nogc), leftLen);
            else
                CopyAndInflateChars(twoByteBuf, leftLinear->latin1Chars(nogc), leftLen);
            if (rightLinear->hasTwoByteChars())
                PodCopy(twoByteBuf + leftLen, rightLinear->twoByteChars(nogc), rightLen);
            else
                CopyAndInflateChars(twoByteBuf + leftLen, rightLinear->latin1Chars(nogc), rightLen);
            twoByteBuf[wholeLength] = 0;
        }

        return str;
    }

    return JSRope::new_<allowGC>(cx, left, right, wholeLength);
}

//.........这里部分代码省略.........
            RootedValue v(cx);
            for (; i < len; i++) {
                if (!CheckForInterrupt(cx))
                    return false;

                /* Step 4b(iv)(2). */
                if (!GetElement(cx, replacer, replacer, i, &v))
                    return false;

                RootedId id(cx);
                if (v.isNumber()) {
                    /* Step 4b(iv)(4). */
                    int32_t n;
                    if (v.isNumber() && ValueFitsInInt32(v, &n) && INT_FITS_IN_JSID(n)) {
                        id = INT_TO_JSID(n);
                    } else {
                        if (!ValueToId<CanGC>(cx, v, &id))
                            return false;
                    }
                } else if (v.isString() ||
                           IsObjectWithClass(v, ESClass_String, cx) ||
                           IsObjectWithClass(v, ESClass_Number, cx))
                {
                    /* Step 4b(iv)(3), 4b(iv)(5). */
                    if (!ValueToId<CanGC>(cx, v, &id))
                        return false;
                } else {
                    continue;
                }

                /* Step 4b(iv)(6). */
                HashSet<jsid, JsidHasher>::AddPtr p = idSet.lookupForAdd(id);
                if (!p) {
                    /* Step 4b(iv)(6)(a). */
                    if (!idSet.add(p, id) || !propertyList.append(id))
                        return false;
                }
            }
        } else {
            replacer = nullptr;
        }
    }

    /* Step 5. */
    if (space.isObject()) {
        RootedObject spaceObj(cx, &space.toObject());
        if (ObjectClassIs(spaceObj, ESClass_Number, cx)) {
            double d;
            if (!ToNumber(cx, space, &d))
                return false;
            space = NumberValue(d);
        } else if (ObjectClassIs(spaceObj, ESClass_String, cx)) {
            JSString* str = ToStringSlow<CanGC>(cx, space);
            if (!str)
                return false;
            space = StringValue(str);
        }
    }

    StringBuffer gap(cx);

    if (space.isNumber()) {
        /* Step 6. */
        double d;
        JS_ALWAYS_TRUE(ToInteger(cx, space, &d));
        d = Min(10.0, d);
        if (d >= 1 && !gap.appendN(' ', uint32_t(d)))
            return false;
    } else if (space.isString()) {
        /* Step 7. */
        JSLinearString* str = space.toString()->ensureLinear(cx);
        if (!str)
            return false;
        size_t len = Min(size_t(10), str->length());
        if (!gap.appendSubstring(str, 0, len))
            return false;
    } else {
        /* Step 8. */
        MOZ_ASSERT(gap.empty());
    }

    /* Step 9. */
    RootedPlainObject wrapper(cx, NewBuiltinClassInstance<PlainObject>(cx));
    if (!wrapper)
        return false;

    /* Step 10. */
    RootedId emptyId(cx, NameToId(cx->names().empty));
    if (!NativeDefineProperty(cx, wrapper, emptyId, vp, nullptr, nullptr, JSPROP_ENUMERATE))
        return false;

    /* Step 11. */
    StringifyContext scx(cx, sb, gap, replacer, propertyList);
    if (!PreprocessValue(cx, wrapper, HandleId(emptyId), vp, &scx))
        return false;
    if (IsFilteredValue(vp))
        return true;

    return Str(cx, vp, &scx);
}