org.xacml4j.v30.spi.pdp.RequestContextHandlerChain.java Source code

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Here is the source code for org.xacml4j.v30.spi.pdp.RequestContextHandlerChain.java

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package org.xacml4j.v30.spi.pdp;

/*
 * #%L
 * Xacml4J Core Engine Implementation
 * %%
 * Copyright (C) 2009 - 2014 Xacml4J.org
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-3.0.html>.
 * #L%
 */

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;

import org.xacml4j.v30.RequestContext;
import org.xacml4j.v30.Result;
import org.xacml4j.v30.pdp.PolicyDecisionPointContext;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Sets;

/**
 * A chain of {@link RequestContextHandler}
 * implementations implemented as {@link RequestContextHandler}
 *
 * @author Giedrius Trumpickas
 */
public class RequestContextHandlerChain implements RequestContextHandler {
    private List<RequestContextHandler> handlers;

    public RequestContextHandlerChain(Iterable<RequestContextHandler> handlers) {
        this.handlers = new CopyOnWriteArrayList<RequestContextHandler>();
        Iterables.addAll(this.handlers, handlers);
        RequestContextHandler prev = null;
        for (RequestContextHandler h : handlers) {
            if (prev == null) {
                prev = h;
                continue;
            }
            prev.setNext(h);
            prev = h;
        }
    }

    public RequestContextHandlerChain(RequestContextHandler... handlers) {
        this(Arrays.asList(handlers));
    }

    @Override
    public Collection<String> getFeatures() {
        Set<String> features = Sets.newLinkedHashSet();
        for (RequestContextHandler h : handlers) {
            features.addAll(h.getFeatures());
        }
        return features;
    }

    @Override
    public final Collection<Result> handle(RequestContext req, PolicyDecisionPointContext context) {
        if (handlers.isEmpty()) {
            return ImmutableList.of(context.requestDecision(req));
        }
        return postProcessResults(req, handlers.get(0).handle(req, context));
    }

    /**
     * @exception IllegalStateException if this handler
     * has no handlers in the internal list or handler
     * was already set for last handler in the list
     */
    @Override
    public final void setNext(RequestContextHandler handler) {
        Preconditions.checkState(!handlers.isEmpty());
        handlers.get(handlers.size() - 1).setNext(handler);
    }

    /**
     * A hook to perform post-processing of
     * decision results
     *
     * @param req a decision request
     * @param results a collection of decision results
     * @return a collection of decision results
     */
    protected Collection<Result> postProcessResults(RequestContext req, Collection<Result> results) {
        return results;
    }
}