scriptableobject.java

java中比较著名的js引擎当属mozilla开源的rhino

     * @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
     * @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)
    {
        Slot slot = getNamedSlot(name);
        if (slot == null) {
            throw Context.reportRuntimeError1("msg.prop.not.found", name);
        }
        return slot.attributes;
    }

    /**
     * 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
     * @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)
    {
        Slot slot = getSlot(null, index);
        if (slot == null) {
            throw Context.reportRuntimeError1("msg.prop.not.found",
                                              String.valueOf(index));
        }
        return slot.attributes;
    }

    /**
     * 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
     * @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)
    {
        checkValidAttributes(attributes);
        Slot slot = getNamedSlot(name);
        if (slot == null) {
            throw Context.reportRuntimeError1("msg.prop.not.found", name);
        }
        slot.attributes = (short) 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
     * @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)
    {
        checkValidAttributes(attributes);
        Slot slot = getSlot(null, index);
        if (slot == null) {
            throw Context.reportRuntimeError1("msg.prop.not.found",
                                              String.valueOf(index));
        }
        slot.attributes = (short) attributes;
    }

    /**
     * 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)
    {
        Context cx = null;
        for (int i=0; i < 2; i++) {
            boolean tryToString;
            if (typeHint == ScriptRuntime.StringClass) {
                tryToString = (i == 0);
            } else {
                tryToString = (i == 1);
            }

            String methodName;
            Object[] args;
            if (tryToString) {
                methodName = "toString";
                args = ScriptRuntime.emptyArgs;
            } else {
                methodName = "valueOf";
                args = new Object[1];
                String hint;
                if (typeHint == null) {
                    hint = "undefined";
                } else if (typeHint == ScriptRuntime.StringClass) {
                    hint = "string";
                } else if (typeHint == ScriptRuntime.ScriptableClass) {
                    hint = "object";
                } else if (typeHint == ScriptRuntime.FunctionClass) {
                    hint = "function";
                } else if (typeHint == ScriptRuntime.BooleanClass
                           || typeHint == Boolean.TYPE)
                {
                    hint = "boolean";
                } else if (typeHint == ScriptRuntime.NumberClass ||
                         typeHint == ScriptRuntime.ByteClass ||
                         typeHint == Byte.TYPE ||
                         typeHint == ScriptRuntime.ShortClass ||
                         typeHint == Short.TYPE ||
                         typeHint == ScriptRuntime.IntegerClass ||
                         typeHint == Integer.TYPE ||
                         typeHint == ScriptRuntime.FloatClass ||
                         typeHint == Float.TYPE ||
                         typeHint == ScriptRuntime.DoubleClass ||
                         typeHint == Double.TYPE)
                {
                    hint = "number";
                } else {
                    throw Context.reportRuntimeError1(
                        "msg.invalid.type", typeHint.toString());
                }
                args[0] = hint;
            }
            Object v = getProperty(this, methodName);
            if (!(v instanceof Function))
                continue;
            Function fun = (Function) v;
            if (cx == null)
                cx = Context.getContext();
            v = fun.call(cx, fun.getParentScope(), this, args);
            if (v != null) {
                if (!(v instanceof Scriptable)) {
                    return v;
                }
                if (typeHint == ScriptRuntime.ScriptableClass
                    || typeHint == ScriptRuntime.FunctionClass)
                {
                    return v;
                }
                if (tryToString && v instanceof Wrapper) {
                    // Let a wrapped java.lang.String pass for a primitive
                    // string.
                    Object u = ((Wrapper)v).unwrap();
                    if (u instanceof String)
                        return u;
                }
            }
        }
        // fall through to error
        String arg = (typeHint == null) ? "undefined" : typeHint.getName();
        throw ScriptRuntime.typeError1("msg.default.value", arg);
    }

    /**
     * Implements the instanceof operator.
     *
     * <p>This operator has been proposed to ECMA.
     *
     * @param instance The value that appeared on the LHS of the instanceof
     *              operator
     * @return true if "this" appears in value's prototype chain
     *
     */
    public boolean hasInstance(Scriptable instance) {
        // Default for JS objects (other than Function) is to do prototype
        // chasing.  This will be overridden in NativeFunction and non-JS
        // objects.

        return ScriptRuntime.jsDelegatesTo(instance, this);
    }

    /**
     * Custom <tt>==</tt> operator.
     * Must return {@link Scriptable#NOT_FOUND} if this object does not
     * have custom equality operator for the given value,
     * <tt>Boolean.TRUE</tt> if this object is equivalent to <tt>value</tt>,
     * <tt>Boolean.FALSE</tt> if this object is not equivalent to
     * <tt>value</tt>.
     * <p>
     * The default implementation returns Boolean.TRUE
     * if <tt>this == value</tt> or {@link Scriptable#NOT_FOUND} otherwise.
     * It indicates that by default custom equality is available only if
     * <tt>value</tt> is <tt>this</tt> in which case true is returned.
     */
    protected Object equivalentValues(Object value)
    {
        return (this == value) ? Boolean.TRUE : Scriptable.NOT_FOUND;
    }

    /**
     * Defines JavaScript objects from a Java class that implements Scriptable.
     *
     * If the given class has a method
     * <pre>
     * static void init(Context cx, Scriptable scope, boolean sealed);</pre>
     *
     * or its compatibility form
     * <pre>
     * static void init(Scriptable scope);</pre>
     *
     * then it is invoked and no further initialization is done.<p>
     *
     * However, if no such a method is found, then the class's constructors and
     * methods are used to initialize a class in the following manner.<p>
     *
     * First, the zero-parameter constructor of the class is called to
     * create the prototype. If no such constructor exists,
     * a {@link EvaluatorException} is thrown. <p>
     *
     * Next, all methods are scanned for special prefixes that indicate that they
     * have special meaning for defining JavaScript objects.
     * These special prefixes are
     * <ul>
     * <li><code>jsFunction_</code> for a JavaScript function
     * <li><code>jsStaticFunction_</code> for a JavaScript function that
     *           is a property of the constructor
     * <li><code>jsGet_</code> for a getter of a JavaScript property
     * <li><code>jsSet_</code> for a setter of a JavaScript property
     * <li><code>jsConstructor</code> for a JavaScript function that
     *           is the constructor
     * </ul><p>
     *
     * If the method's name begins with "jsFunction_", a JavaScript function
     * is created with a name formed from the rest of the Java method name
     * following "jsFunction_". So a Java method named "jsFunction_foo" will
     * define a JavaScript method "foo". Calling this JavaScript function
     * will cause the Java method to be called. The parameters of the method
     * must be of number and types as defined by the FunctionObject class.
     * The JavaScript function is then added as a property
     * of the prototype. <p>
     *
     * If the method's name begins with "jsStaticFunction_", it is handled
     * similarly except that the resulting JavaScript function is added as a
     * property of the constructor object. The Java method must be static.
     *
     * If the method's name begins with "jsGet_" or "jsSet_", the method is
     * considered to define a property. Accesses to the defined property
     * will result in calls to these getter and setter methods. If no
     * setter is defined, the property is defined as READONLY.<p>
     *
     * If the method's name is "jsConstructor", the method is
     * considered to define the body of the constructor. Only one
     * method of this name may be defined.
     * If no method is found that can serve as constructor, a Java
     * constructor will be selected to serve as the JavaScript
     * constructor in the following manner. If the class has only one
     * Java constructor, that constructor is used to define
     * the JavaScript constructor. If the the class has two constructors,
     * one must be the zero-argument constructor (otherwise an
     * {@link EvaluatorException} would have already been thrown
     * when the prototype was to be created). In this case
     * the Java constructor with one or more parameters will be used