scriptableobject.java

java中比较著名的js引擎当属mozilla开源的rhino

/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Rhino code, released
 * May 6, 1999.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1997-1999
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Norris Boyd
 *   Igor Bukanov
 *   Roger Lawrence
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License Version 2 or later (the "GPL"), in which
 * case the provisions of the GPL are applicable instead of those above. If
 * you wish to allow use of your version of this file only under the terms of
 * the GPL and not to allow others to use your version of this file under the
 * MPL, indicate your decision by deleting the provisions above and replacing
 * them with the notice and other provisions required by the GPL. If you do
 * not delete the provisions above, a recipient may use your version of this
 * file under either the MPL or the GPL.
 *
 * ***** END LICENSE BLOCK ***** */

// API class

package org.mozilla.javascript;

import java.lang.reflect.*;
import java.util.Hashtable;
import java.io.*;
import org.mozilla.javascript.debug.DebuggableObject;

/**
 * This is the default implementation of the Scriptable interface. This
 * class provides convenient default behavior that makes it easier to
 * define host objects.
 * <p>
 * Various properties and methods of JavaScript objects can be conveniently
 * defined using methods of ScriptableObject.
 * <p>
 * Classes extending ScriptableObject must define the getClassName method.
 *
 * @see org.mozilla.javascript.Scriptable
 * @author Norris Boyd
 */

public abstract class ScriptableObject implements Scriptable, Serializable,
                                                  DebuggableObject
{

    /**
     * The empty property attribute.
     *
     * Used by getAttributes() and setAttributes().
     *
     * @see org.mozilla.javascript.ScriptableObject#getAttributes
     * @see org.mozilla.javascript.ScriptableObject#setAttributes
     */
    public static final int EMPTY =     0x00;

    /**
     * Property attribute indicating assignment to this property is ignored.
     *
     * @see org.mozilla.javascript.ScriptableObject#put
     * @see org.mozilla.javascript.ScriptableObject#getAttributes
     * @see org.mozilla.javascript.ScriptableObject#setAttributes
     */
    public static final int READONLY =  0x01;

    /**
     * Property attribute indicating property is not enumerated.
     *
     * Only enumerated properties will be returned by getIds().
     *
     * @see org.mozilla.javascript.ScriptableObject#getIds
     * @see org.mozilla.javascript.ScriptableObject#getAttributes
     * @see org.mozilla.javascript.ScriptableObject#setAttributes
     */
    public static final int DONTENUM =  0x02;

    /**
     * Property attribute indicating property cannot be deleted.
     *
     * @see org.mozilla.javascript.ScriptableObject#delete
     * @see org.mozilla.javascript.ScriptableObject#getAttributes
     * @see org.mozilla.javascript.ScriptableObject#setAttributes
     */
    public static final int PERMANENT = 0x04;

    static void checkValidAttributes(int attributes)
    {
        final int mask = READONLY | DONTENUM | PERMANENT;
        if ((attributes & ~mask) != 0) {
            throw new IllegalArgumentException(String.valueOf(attributes));
        }
    }

    public ScriptableObject()
    {
    }

    public ScriptableObject(Scriptable scope, Scriptable prototype)
    {
        if (scope == null)
            throw new IllegalArgumentException();

        parentScopeObject = scope;
        prototypeObject = prototype;
    }

    /**
     * Return the name of the class.
     *
     * This is typically the same name as the constructor.
     * Classes extending ScriptableObject must implement this abstract
     * method.
     */
    public abstract String getClassName();

    /**
     * Returns true if the named property is defined.
     *
     * @param name the name of the property
     * @param start the object in which the lookup began
     * @return true if and only if the property was found in the object
     */
    public boolean has(String name, Scriptable start)
    {
        return null != getNamedSlot(name);
    }

    /**
     * Returns true if the property index is defined.
     *
     * @param index the numeric index for the property
     * @param start the object in which the lookup began
     * @return true if and only if the property was found in the object
     */
    public boolean has(int index, Scriptable start)
    {
        return null != getSlot(null, index);
    }

    /**
     * Returns the value of the named property or NOT_FOUND.
     *
     * If the property was created using defineProperty, the
     * appropriate getter method is called.
     *
     * @param name the name of the property
     * @param start the object in which the lookup began
     * @return the value of the property (may be null), or NOT_FOUND
     */
    public Object get(String name, Scriptable start)
    {
        Slot slot = getNamedSlot(name);
        if (slot == null) {
            return Scriptable.NOT_FOUND;
        }
        if (slot instanceof GetterSlot) {
            GetterSlot gslot = (GetterSlot)slot;
            if (gslot.getter != null) {
                return getByGetter(gslot, start);
            }
        }

        return slot.value;
    }

    /**
     * Returns the value of the indexed property or NOT_FOUND.
     *
     * @param index the numeric index for the property
     * @param start the object in which the lookup began
     * @return the value of the property (may be null), or NOT_FOUND
     */
    public Object get(int index, Scriptable start)
    {
        Slot slot = getSlot(null, index);
        if (slot == null) {
            return Scriptable.NOT_FOUND;
        }
        return slot.value;
    }

    /**
     * Sets the value of the named 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 put(String name, Scriptable start, Object value)
    {
        Slot slot = lastAccess; // Get local copy
        if (name != slot.stringKey || slot.wasDeleted != 0) {
            int hash = name.hashCode();
            slot = getSlot(name, hash);
            if (slot == null) {
                if (start != this) {
                    start.put(name, start, value);
                    return;
                }
                slot = addSlot(name, hash, null);
            }
            // Note: cache is not updated in put
        }
        if (start == this && isSealed()) {
            throw Context.reportRuntimeError1("msg.modify.sealed", name);
        }
        if ((slot.attributes & ScriptableObject.READONLY) != 0) {
            return;
        }
        if (slot instanceof GetterSlot) {
            GetterSlot gslot = (GetterSlot)slot;
            if (gslot.setter != null) {
                setBySetter(gslot, start, value);
            }
            return;
        }
        if (this == start) {
            slot.value = value;
        } else {
            start.put(name, start, value);
        }
    }

    /**
     * Sets the value of the indexed property, creating it if need be.
     *
     * @param index the numeric index for the property
     * @param start the object whose property is being set
     * @param value value to set the property to
     */
    public void put(int index, Scriptable start, Object value)
    {
        Slot slot = getSlot(null, index);
        if (slot == null) {
            if (start != this) {
                start.put(index, start, value);
                return;
            }
            slot = addSlot(null, index, null);
        }
        if (start == this && isSealed()) {
            throw Context.reportRuntimeError1("msg.modify.sealed",
                                              Integer.toString(index));
        }
        if ((slot.attributes & ScriptableObject.READONLY) != 0) {
            return;
        }
        if (this == start) {
            slot.value = value;
        } else {
            start.put(index, start, value);
        }
    }

    /**
     * Removes a named property from the object.
     *
     * If the property is not found, or it has the PERMANENT attribute,
     * no action is taken.
     *
     * @param name the name of the property
     */
    public void delete(String name) {
        removeSlot(name, name.hashCode());
    }

    /**
     * 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) {
        removeSlot(null, index);
    }

    /**
     * @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>
     *