nl.tue.gale.ae.processor.view.NextView.java Source code

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Here is the source code for nl.tue.gale.ae.processor.view.NextView.java

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/*
    
   This file is part of GALE (Generic Adaptation Language and Engine).
    
GALE 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.
    
GALE 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 Lesser General Public License for 
more details.
    
You should have received a copy of the GNU Lesser General Public License
along with GALE. If not, see <http://www.gnu.org/licenses/>.
    
 */
/**
 * NextView.java
 * Last modified: $Date$
 * In revision:   $Revision$
 * Modified by:   $Author$
 *
 * Copyright (c) 2008-2011 Eindhoven University of Technology.
 * All Rights Reserved.
 *
 * This software is proprietary information of the Eindhoven University
 * of Technology. It may be used according to the GNU LGPL license.
 */
package nl.tue.gale.ae.processor.view;

import java.util.Arrays;

import nl.tue.gale.ae.GaleContext;
import nl.tue.gale.ae.Resource;
import nl.tue.gale.common.GaleUtil;
import nl.tue.gale.common.cache.CacheSession;
import nl.tue.gale.common.uri.URIs;
import nl.tue.gale.um.data.EntityValue;

import org.dom4j.Element;

public class NextView extends AbstractView {
    private static final int loopMax = 200;

    private String defaultExpr = "${#suitability}";

    public void setDefaultExpr(String defaultExpr) {
        this.defaultExpr = defaultExpr;
    }

    public Element getXml(Resource resource, Object... params) {
        GaleContext gale = GaleContext.of(resource);
        String expr = GaleUtil.getParam(params, "expr");
        if (expr == null)
            expr = defaultExpr;
        String label = GaleUtil.getParam(params, "label");
        String done = GaleUtil.getParam(params, "done");
        if (done == null)
            done = "end of course";

        TreeNodes nodes = new TreeNodes(gale);
        TreeNode startNode = nodes.get(gale.concept().getUriString());
        TreeNode currentNode = nextNode(startNode, nodes);
        int loop = 0;
        while (currentNode != null && !startNode.equals(currentNode) && loop < loopMax) {
            CacheSession<EntityValue> session = gale.openUmSession();
            session.setBaseUri(URIs.of(currentNode.getConcept()));
            Boolean exprResult = (Boolean) gale.eval(session, expr);
            if (exprResult)
                break;
            currentNode = nextNode(currentNode, nodes);
            loop++;
        }
        if (loop == loopMax)
            return GaleUtil.createHTMLElement("span").addText(done + " (loop)");
        Element span = GaleUtil.createHTMLElement("span");
        if (currentNode == null || startNode.equals(currentNode)) {
            span.addText(done);
            return span;
        }
        if (label != null)
            span.addText(label);
        Element a = GaleUtil.createNSElement("a", GaleUtil.adaptns);
        span.add(a);
        a.addAttribute("href", currentNode.getConcept());
        a.addText(gale.dm().get(URIs.of(currentNode.getConcept())).getTitle());
        return span;
    }

    // depth first algorithm
    private TreeNode nextNode(TreeNode currentNode, TreeNodes nodes) {
        // try first child
        if (currentNode.getChildren().length > 0)
            return nodes.get(currentNode.getChildren()[0]);
        // try next sibling, then parent's next sibling, etc...
        int loop = 0;
        while (currentNode != null && loop < loopMax) {
            String parent = (currentNode.getParents().length == 0 ? null : currentNode.getParents()[0]);
            if (parent == null)
                return currentNode;
            TreeNode parentNode = nodes.get(parent);
            int index = Arrays.asList(parentNode.getChildren()).indexOf(currentNode.getConcept());
            if ((index + 1) < parentNode.getChildren().length)
                return nodes.get(parentNode.getChildren()[index + 1]);
            currentNode = parentNode;
            loop++;
        }
        if (loop == loopMax)
            throw new IllegalArgumentException("parent relations form a loop");
        return null;
    }
}