C++ Ptr::asPtr方法代码示例

MOZ_ALWAYS_INLINE
static JSAtom *
AtomizeAndCopyChars(ExclusiveContext *cx, const CharT *tbchars, size_t length, InternBehavior ib)
{
    if (JSAtom *s = cx->staticStrings().lookup(tbchars, length))
         return s;

    AtomHasher::Lookup lookup(tbchars, length);

    // Note: when this function is called while the permanent atoms table is
    // being initialized (in initializeAtoms()), |permanentAtoms| is not yet
    // initialized so this lookup is always skipped. Only once
    // transformToPermanentAtoms() is called does |permanentAtoms| get
    // initialized and then this lookup will go ahead.
    if (cx->isPermanentAtomsInitialized()) {
        AtomSet::Ptr pp = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
        if (pp)
            return pp->asPtr();
    }

    AutoLockForExclusiveAccess lock(cx);

    AtomSet& atoms = cx->atoms();
    AtomSet::AddPtr p = atoms.lookupForAdd(lookup);
    if (p) {
        JSAtom *atom = p->asPtr();
        p->setTagged(bool(ib));
        return atom;
    }

    AutoCompartment ac(cx, cx->atomsCompartment());

    JSFlatString *flat = NewStringCopyN<NoGC>(cx, tbchars, length);
    if (!flat) {
        // Grudgingly forgo last-ditch GC. The alternative would be to release
        // the lock, manually GC here, and retry from the top. If you fix this,
        // please also fix or comment the similar case in Symbol::new_.
        ReportOutOfMemory(cx);
        return nullptr;
    }

    JSAtom *atom = flat->morphAtomizedStringIntoAtom();

    // We have held the lock since looking up p, and the operations we've done
    // since then can't GC; therefore the atoms table has not been modified and
    // p is still valid.
    if (!atoms.add(p, AtomStateEntry(atom, bool(ib)))) {
        ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
        return nullptr;
    }

    return atom;
}

/* |tbchars| must not point into an inline or short string. */
MOZ_ALWAYS_INLINE
static JSAtom *
AtomizeAndCopyChars(ExclusiveContext *cx, const jschar *tbchars, size_t length, InternBehavior ib)
{
    if (JSAtom *s = cx->staticStrings().lookup(tbchars, length))
         return s;

    AtomHasher::Lookup lookup(tbchars, length);

    AtomSet::Ptr pp = cx->permanentAtoms().readonlyThreadsafeLookup(lookup);
    if (pp)
        return pp->asPtr();

    /*
     * If a GC occurs at js_NewStringCopy then |p| will still have the correct
     * hash, allowing us to avoid rehashing it. Even though the hash is
     * unchanged, we need to re-lookup the table position because a last-ditch
     * GC will potentially free some table entries.
     */

    AutoLockForExclusiveAccess lock(cx);

    AtomSet& atoms = cx->atoms();
    AtomSet::AddPtr p = atoms.lookupForAdd(lookup);
    if (p) {
        JSAtom *atom = p->asPtr();
        p->setTagged(bool(ib));
        return atom;
    }

    AutoCompartment ac(cx, cx->atomsCompartment());

    JSFlatString *flat = js_NewStringCopyN<NoGC>(cx, tbchars, length);
    if (!flat) {
        js_ReportOutOfMemory(cx);
        return nullptr;
    }

    JSAtom *atom = flat->morphAtomizedStringIntoAtom();

    if (!atoms.relookupOrAdd(p, lookup, AtomStateEntry(atom, bool(ib)))) {
        js_ReportOutOfMemory(cx); /* SystemAllocPolicy does not report OOM. */
        return nullptr;
    }

    return atom;
}

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;

        AutoLockForExclusiveAccess lock(cx);

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

    const jschar *chars;
    if (str->isLinear()) {
        chars = str->asLinear().chars();
    } else {
        if (!cx->shouldBeJSContext())
            return NULL;
        chars = str->getChars(cx->asJSContext());
        if (!chars)
            return NULL;
    }

    if (JSAtom *atom = AtomizeAndCopyChars<NoGC>(cx, chars, str->length(), ib))
        return atom;

    if (!cx->isJSContext() || !allowGC)
        return NULL;

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

    JS_ASSERT(linear->length() <= JSString::MAX_LENGTH);
    return AtomizeAndCopyChars<CanGC>(cx, linear->chars(), linear->length(), ib);
}

UnrootedAtom
js::AtomizeString(JSContext *cx, JSString *str, js::InternBehavior ib /* = js::DoNotInternAtom */)
{
    AssertCanGC();

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

        AtomSet::Ptr p = cx->runtime->atoms.lookup(AtomHasher::Lookup(&atom));
        JS_ASSERT(p); /* Non-static atom must exist in atom state set. */
        JS_ASSERT(p->asPtr() == &atom);
        JS_ASSERT(ib == InternAtom);
        p->setTagged(bool(ib));
        return &atom;
    }

    const jschar *chars = str->getChars(cx);
    if (!chars)
        return NULL;

    if (JSAtom *atom = AtomizeAndCopyChars<NoGC>(cx, chars, str->length(), ib))
        return atom;

    if (!allowGC)
        return NULL;

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

    JS_ASSERT(linear->length() <= JSString::MAX_LENGTH);
    return AtomizeAndCopyChars<CanGC>(cx, linear->chars(), linear->length(), ib);
}