scriptableobject.java

這是一個javascript 的 interpreter是了解 web browser的好材料

    /**
     * Removes the indexed property from the object.
     *
     * If the property is not found, or it has the PERMANENT attribute,
     * no action is taken.
     *
     * @param index the numeric index for the property
     */
    public void delete(int index)
    {
        checkNotSealed(null, index);
        accessSlot(null, index, SLOT_REMOVE);
    }

    /**
     * Sets the value of the named const property, creating it if need be.
     *
     * If the property was created using defineProperty, the
     * appropriate setter method is called. <p>
     *
     * If the property's attributes include READONLY, no action is
     * taken.
     * This method will actually set the property in the start
     * object.
     *
     * @param name the name of the property
     * @param start the object whose property is being set
     * @param value value to set the property to
     */
    public void putConst(String name, Scriptable start, Object value)
    {
        if (putImpl(name, 0, start, value, READONLY))
            return;

        if (start == this) throw Kit.codeBug();
        if (start instanceof ConstProperties)
            ((ConstProperties)start).putConst(name, start, value);
        else
            start.put(name, start, value);
    }

    public void defineConst(String name, Scriptable start)
    {
        if (putImpl(name, 0, start, Undefined.instance, UNINITIALIZED_CONST))
            return;

        if (start == this) throw Kit.codeBug();
        if (start instanceof ConstProperties)
            ((ConstProperties)start).defineConst(name, start);
    }
    /**
     * Returns true if the named property is defined as a const on this object.
     * @param name
     * @return true if the named property is defined as a const, false
     * otherwise.
     */
    public boolean isConst(String name)
    {
        Slot slot = getSlot(name, 0, SLOT_QUERY);
        if (slot == null) {
            return false;
        }
        return (slot.getAttributes() & (PERMANENT|READONLY)) ==
                                       (PERMANENT|READONLY);

    }
    /**
     * @deprecated Use {@link #getAttributes(String name)}. The engine always
     * ignored the start argument.
     */
    public final int getAttributes(String name, Scriptable start)
    {
        return getAttributes(name);
    }

    /**
     * @deprecated Use {@link #getAttributes(int index)}. The engine always
     * ignored the start argument.
     */
    public final int getAttributes(int index, Scriptable start)
    {
        return getAttributes(index);
    }

    /**
     * @deprecated Use {@link #setAttributes(String name, int attributes)}.
     * The engine always ignored the start argument.
     */
    public final void setAttributes(String name, Scriptable start,
                                    int attributes)
    {
        setAttributes(name, attributes);
    }

    /**
     * @deprecated Use {@link #setAttributes(int index, int attributes)}.
     * The engine always ignored the start argument.
     */
    public void setAttributes(int index, Scriptable start,
                              int attributes)
    {
        setAttributes(index, attributes);
    }

    /**
     * Get the attributes of a named property.
     *
     * The property is specified by <code>name</code>
     * as defined for <code>has</code>.<p>
     *
     * @param name the identifier for the property
     * @return the bitset of attributes
     * @exception EvaluatorException if the named property is not found
     * @see org.mozilla.javascript.ScriptableObject#has(String, Scriptable)
     * @see org.mozilla.javascript.ScriptableObject#READONLY
     * @see org.mozilla.javascript.ScriptableObject#DONTENUM
     * @see org.mozilla.javascript.ScriptableObject#PERMANENT
     * @see org.mozilla.javascript.ScriptableObject#EMPTY
     */
    public int getAttributes(String name)
    {
        return findAttributeSlot(name, 0, SLOT_QUERY).getAttributes();
    }

    /**
     * Get the attributes of an indexed property.
     *
     * @param index the numeric index for the property
     * @exception EvaluatorException if the named property is not found
     *            is not found
     * @return the bitset of attributes
     * @see org.mozilla.javascript.ScriptableObject#has(String, Scriptable)
     * @see org.mozilla.javascript.ScriptableObject#READONLY
     * @see org.mozilla.javascript.ScriptableObject#DONTENUM
     * @see org.mozilla.javascript.ScriptableObject#PERMANENT
     * @see org.mozilla.javascript.ScriptableObject#EMPTY
     */
    public int getAttributes(int index)
    {
        return findAttributeSlot(null, index, SLOT_QUERY).getAttributes();
    }

    /**
     * Set the attributes of a named property.
     *
     * The property is specified by <code>name</code>
     * as defined for <code>has</code>.<p>
     *
     * The possible attributes are READONLY, DONTENUM,
     * and PERMANENT. Combinations of attributes
     * are expressed by the bitwise OR of attributes.
     * EMPTY is the state of no attributes set. Any unused
     * bits are reserved for future use.
     *
     * @param name the name of the property
     * @param attributes the bitset of attributes
     * @exception EvaluatorException if the named property is not found
     * @see org.mozilla.javascript.Scriptable#has(String, Scriptable)
     * @see org.mozilla.javascript.ScriptableObject#READONLY
     * @see org.mozilla.javascript.ScriptableObject#DONTENUM
     * @see org.mozilla.javascript.ScriptableObject#PERMANENT
     * @see org.mozilla.javascript.ScriptableObject#EMPTY
     */
    public void setAttributes(String name, int attributes)
    {
        checkNotSealed(name, 0);
        findAttributeSlot(name, 0, SLOT_MODIFY).setAttributes(attributes);
    }

    /**
     * Set the attributes of an indexed property.
     *
     * @param index the numeric index for the property
     * @param attributes the bitset of attributes
     * @exception EvaluatorException if the named property is not found
     * @see org.mozilla.javascript.Scriptable#has(String, Scriptable)
     * @see org.mozilla.javascript.ScriptableObject#READONLY
     * @see org.mozilla.javascript.ScriptableObject#DONTENUM
     * @see org.mozilla.javascript.ScriptableObject#PERMANENT
     * @see org.mozilla.javascript.ScriptableObject#EMPTY
     */
    public void setAttributes(int index, int attributes)
    {
        checkNotSealed(null, index);
        findAttributeSlot(null, index, SLOT_MODIFY).setAttributes(attributes);
    }

    /**
     * XXX: write docs.
     */
    public void setGetterOrSetter(String name, int index,
                                  Callable getterOrSeter, boolean isSetter)
    {
        if (name != null && index != 0)
            throw new IllegalArgumentException(name);

        checkNotSealed(name, index);
        GetterSlot gslot = (GetterSlot)getSlot(name, index,
                                               SLOT_MODIFY_GETTER_SETTER);
        gslot.checkNotReadonly();
        if (isSetter) {
            gslot.setter = getterOrSeter;
        } else {
            gslot.getter = getterOrSeter;
        }
        gslot.value = Undefined.instance;
    }
    
    /**
     * Get the getter or setter for a given property. Used by __lookupGetter__
     * and __lookupSetter__.
     * 
     * @param name Name of the object. If nonnull, index must be 0.
     * @param index Index of the object. If nonzero, name must be null.
     * @param isSetter If true, return the setter, otherwise return the getter.
     * @exception IllegalArgumentException if both name and index are nonnull
     *            and nonzero respectively.
     * @return Null if the property does not exist. Otherwise returns either 
     *         the getter or the setter for the property, depending on 
     *         the value of isSetter (may be undefined if unset).
     */
    public Object getGetterOrSetter(String name, int index, boolean isSetter)
    {
        if (name != null && index != 0)
            throw new IllegalArgumentException(name);
        Slot slot = getSlot(name, index, SLOT_QUERY);
        if (slot == null)
            return null;
        if (slot instanceof GetterSlot) {
            GetterSlot gslot = (GetterSlot)slot;
            Object result = isSetter ? gslot.setter : gslot.getter;
            return result != null ? result : Undefined.instance;
        } else
            return Undefined.instance;
    }

    /**
     * Returns whether a property is a getter or a setter
     * @param name property name
     * @param index property index
     * @param setter true to check for a setter, false for a getter
     * @return whether the property is a getter or a setter
     */
    protected boolean isGetterOrSetter(String name, int index, boolean setter) {
        Slot slot = getSlot(name, index, SLOT_QUERY);
        if (slot instanceof GetterSlot) {
            if (setter && ((GetterSlot)slot).setter != null) return true;
            if (!setter && ((GetterSlot)slot).getter != null) return true;
        }
        return false;
    }

    void addLazilyInitializedValue(String name, int index,
                                   LazilyLoadedCtor init, int attributes)
    {
        if (name != null && index != 0)
            throw new IllegalArgumentException(name);
        checkNotSealed(name, index);
        GetterSlot gslot = (GetterSlot)getSlot(name, index,
                                               SLOT_MODIFY_GETTER_SETTER);
        gslot.setAttributes(attributes);
        gslot.getter = null;
        gslot.setter = null;
        gslot.value = init;
    }

    /**
     * Returns the prototype of the object.
     */
    public Scriptable getPrototype()
    {
        return prototypeObject;
    }

    /**
     * Sets the prototype of the object.
     */
    public void setPrototype(Scriptable m)
    {
        prototypeObject = m;
    }

    /**
     * Returns the parent (enclosing) scope of the object.
     */
    public Scriptable getParentScope()
    {
        return parentScopeObject;
    }

    /**
     * Sets the parent (enclosing) scope of the object.
     */
    public void setParentScope(Scriptable m)
    {
        parentScopeObject = m;
    }

    /**
     * Returns an array of ids for the properties of the object.
     *
     * <p>Any properties with the attribute DONTENUM are not listed. <p>
     *
     * @return an array of java.lang.Objects with an entry for every
     * listed property. Properties accessed via an integer index will
     * have a corresponding
     * Integer entry in the returned array. Properties accessed by
     * a String will have a String entry in the returned array.
     */
    public Object[] getIds() {
        return getIds(false);
    }

    /**
     * Returns an array of ids for the properties of the object.
     *
     * <p>All properties, even those with attribute DONTENUM, are listed. <p>
     *
     * @return an array of java.lang.Objects with an entry for every
     * listed property. Properties accessed via an integer index will
     * have a corresponding
     * Integer entry in the returned array. Properties accessed by
     * a String will have a String entry in the returned array.
     */
    public Object[] getAllIds() {
        return getIds(true);
    }

    /**
     * Implements the [[DefaultValue]] internal method.
     *
     * <p>Note that the toPrimitive conversion is a no-op for
     * every type other than Object, for which [[DefaultValue]]
     * is called. See ECMA 9.1.<p>
     *
     * A <code>hint</code> of null means "no hint".
     *
     * @param typeHint the type hint
     * @return the default value for the object
     *
     * See ECMA 8.6.2.6.
     */
    public Object getDefaultValue(Class typeHint)
    {
        return getDefaultValue(this, typeHint);
    }
    
    public static Object getDefaultValue(Scriptable object, Class typeHint)