functionfactory.java

sunxacml源码

/*
 * @(#)FunctionFactory.java
 *
 * Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
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 *
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 * the design, construction, operation or maintenance of any nuclear facility.
 */

package com.sun.xacml.cond;

import com.sun.xacml.ParsingException;
import com.sun.xacml.PolicyMetaData;
import com.sun.xacml.UnknownIdentifierException;

import java.net.URI;

import java.util.HashMap;
import java.util.Set;

import org.w3c.dom.Node;


/**
 * Factory used to create all functions. There are three kinds of factories:
 * general, condition, and target. These provide functions that can be used
 * anywhere, only in a condition's root and only in a target (respectively).
 * <p>
 * Note that all functions, except for abstract functions, are singletons, so
 * any instance that is added to a factory will be the same one returned
 * from the create methods. This is done because most functions don't have
 * state, so there is no need to have more than one, or to spend the time
 * creating multiple instances that all do the same thing.
 *
 * @since 1.0
 * @author Marco Barreno
 * @author Seth Proctor
 */
public abstract class FunctionFactory
{

    // the proxies used to get the default factorys
    private static FunctionFactoryProxy defaultFactoryProxy;

    // the map of registered factories
    private static HashMap registeredFactories;

    /**
     * static intialiazer that sets up the default factory proxies and
     * registers the standard namespaces
     */
    static {
        FunctionFactoryProxy proxy = new FunctionFactoryProxy() {
                public FunctionFactory getTargetFactory() {
                    return StandardFunctionFactory.getTargetFactory();
                }
                public FunctionFactory getConditionFactory() {
                    return StandardFunctionFactory.getConditionFactory();
                }
                public FunctionFactory getGeneralFactory() {
                    return StandardFunctionFactory.getGeneralFactory();
                }
            };

        registeredFactories = new HashMap();
        registeredFactories.put(PolicyMetaData.XACML_1_0_IDENTIFIER, proxy);
        registeredFactories.put(PolicyMetaData.XACML_2_0_IDENTIFIER, proxy);

        defaultFactoryProxy = proxy;
    };

    /**
     * Default constructor. Used only by subclasses.
     */
    protected FunctionFactory() {

    }

    /**
     * Returns the default FunctionFactory that will only provide those
     * functions that are usable in Target matching.
     *
     * @return a <code>FunctionFactory</code> for target functions
     */
    public static final FunctionFactory getTargetInstance() {
        return defaultFactoryProxy.getTargetFactory();
    }

    /**
     * Returns a factory based on the given identifier. You may register
     * as many factories as you like, and then retrieve them through this
     * interface, but a factory may only be registered once using a given
     * identifier. By default, the standard XACML 1.0 and 2.0 identifiers
     * are regsietered to provide the standard factory.
     *
     * @param identifier the identifier for a factory
     *
     * @return a <code>FunctionFactory</code> that supports Target functions
     *
     * @throws UnknownIdentifierException if the given identifier isn't
     *                                    registered
     */
    public static final FunctionFactory getTargetInstance(String identifier)
        throws UnknownIdentifierException
    {
        return getRegisteredProxy(identifier).getTargetFactory();
    }

    /**
     * Returns the default FuntionFactory that will only provide those
     * functions that are usable in the root of the Condition. These Functions
     * are a superset of the Target functions.
     *
     * @return a <code>FunctionFactory</code> for condition functions
     */
    public static final FunctionFactory getConditionInstance() {
        return defaultFactoryProxy.getConditionFactory();
    }

    /**
     * Returns a factory based on the given identifier. You may register
     * as many factories as you like, and then retrieve them through this
     * interface, but a factory may only be registered once using a given
     * identifier. By default, the standard XACML 1.0 and 2.0 identifiers
     * are regsietered to provide the standard factory.
     *
     * @param identifier the identifier for a factory
     *
     * @return a <code>FunctionFactory</code> that supports Condition functions
     *
     * @throws UnknownIdentifierException if the given identifier isn't
     *                                    registered
     */
    public static final FunctionFactory getConditionInstance(String identifier)
        throws UnknownIdentifierException
    {
        return getRegisteredProxy(identifier).getConditionFactory();
    }

    /**
     * Returns the default FunctionFactory that provides access to all the
     * functions. These Functions are a superset of the Condition functions.
     *
     * @return a <code>FunctionFactory</code> for all functions
     */
    public static final FunctionFactory getGeneralInstance() {
        return defaultFactoryProxy.getGeneralFactory();
    }

    /**
     * Returns a factory based on the given identifier. You may register
     * as many factories as you like, and then retrieve them through this
     * interface, but a factory may only be registered once using a given
     * identifier. By default, the standard XACML 1.0 and 2.0 identifiers
     * are regsietered to provide the standard factory.
     *
     * @param identifier the identifier for a factory
     *
     * @return a <code>FunctionFactory</code> that supports General functions
     *
     * @throws UnknownIdentifierException if the given identifier isn't
     *                                    registered
     */
    public static final FunctionFactory getGeneralInstance(String identifier)
        throws UnknownIdentifierException
    {
        return getRegisteredProxy(identifier).getGeneralFactory();
    }

    /**
     * Returns the default FunctionFactoryProxy that provides access to all
     * the functions.
     *
     * @return a <code>FunctionFactoryProxy</code> for all functions
     */
    public static final FunctionFactoryProxy getInstance() {
        return defaultFactoryProxy;
    }

    /**
     * Returns a factory based on the given identifier. You may register
     * as many factories as you like, and then retrieve them through this
     * interface, but a factory may only be registered once using a given
     * identifier. By default, the standard XACML 1.0 and 2.0 identifiers
     * are regsietered to provide the standard factory.
     *
     * @param identifier the identifier for a factory
     *
     * @return a <code>FunctionFactoryProxy</code>
     *
     * @throws UnknownIdentifierException if the given identifier isn't
     *                                    registered
     */
    public static final FunctionFactoryProxy getInstance(String identifier)
        throws UnknownIdentifierException
    {
        return getRegisteredProxy(identifier);
    }

    /**
     * Private helper that resolves the proxy for the given identifier, or
     * throws an exception if no proxy is registered for that identifier.
     */
    private static FunctionFactoryProxy getRegisteredProxy(String identifier)
        throws UnknownIdentifierException
    {
        FunctionFactoryProxy proxy =
            (FunctionFactoryProxy)(registeredFactories.get(identifier));

        if (proxy == null)
            throw new UnknownIdentifierException("Uknown FunctionFactory " +
                                                 "identifier: " + identifier);

        return proxy;
    }

    /**
     * Sets the default factory. This does not register the factory proxy as
     * an identifiable factory.
     *
     * @param proxy the <code>FunctionFactoryProxy</code> to set as the new
     *              default factory proxy
     */
    public static final void setDefaultFactory(FunctionFactoryProxy proxy) {
        defaultFactoryProxy = proxy;
    }

    /**
     * Registers the given factory proxy with the given identifier. If the
     * identifier is already used, then this throws an exception. If the
     * identifier is not already used, then it will always be bound to the
     * given proxy.
     *
     * @param identifier the identifier for the proxy
     * @param proxy the <code>FunctionFactoryProxy</code> to register with
     *              the given identifier
     *
     * @throws IllegalArgumentException if the identifier is already used
     */
    public static final void registerFactory(String identifier,
                                             FunctionFactoryProxy proxy)
        throws IllegalArgumentException