src.main.java.com.eva.properties.Switch Maven / Gradle / Ivy

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/*
 * $Id: Switch.java 109 2007-03-24 14:55:03Z max $
 * 
 * Copyright (c) 2006-2007 Maximilian Antoni. All rights reserved.
 * 
 * This software is licensed as described in the file LICENSE.txt, which you
 * should have received as part of this distribution. The terms are also
 * available at http://www.maxantoni.de/projects/eva-properties/license.txt.
 */
package com.eva.properties;

import java.io.File;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.logging.Level;

/**
 * wrapps a list of alternatives. If the first alternative evaluates to
 * null, throws an exception or is a file that doesn't exist,
 * the next alternative is tried. If no alternative is found, null
 * is returned.
 * 
 * @author Max Antoni
 * @version $Revision: 109 $
 */
public class Switch implements Replaceable {
    private Collection alternatives;
    
    /**
     * creates an empty switch.
     */
    public Switch() {
        super();
        alternatives = new ArrayList();
    }
    
    /**
     * creates a switch with the given alternatives.
     * 
     * @param inAlternatives the alternatives.
     */
    public Switch(Collection inAlternatives) {
        super();
        alternatives = inAlternatives;
    }
    
    /**
     * adds the given alternative to this switch.
     * 
     * @param inAlternative the alternative.
     */
    public void add(Object inAlternative) {
        alternatives.add(inAlternative);
    }
    
    /* 
     * @see java.lang.Object#toString()
     */
    public String toString() {
        Writer writer = new Writer();
        write(writer);
        return writer.toString();
    }

    /* 
     * @see com.eva.properties.Replaceable#write(com.eva.properties.Writer)
     */
    public void write(Writer inoutWriter) {
        inoutWriter.append("(\n");
        inoutWriter.increaseIndentation();
        for(Iterator i = alternatives.iterator(); i.hasNext();) {
            inoutWriter.write(i.next());
        }
        inoutWriter.decreaseIndentation();
        inoutWriter.appendIndentation();
        inoutWriter.append(")\n");
    }

    /* 
     * @see com.eva.properties.Replaceable#replace(com.eva.properties.Context)
     */
    public Object replace(Context inContext) throws PropertiesException {
        for(Iterator i = alternatives.iterator(); i.hasNext();) {
            Object value;
            try {
                value = inContext.replace(i.next());
            }
            catch(PropertiesException e) {
                if(Log.instance().isLoggable(Level.FINE)) {
                    Log.instance().fine(e.getMessage());
                }
                continue;
            }
            if(value == null) {
                continue;
            }
            if(value instanceof File && !((File) value).exists()) {
                if(Log.instance().isLoggable(Level.FINE)) {
                    Log.instance().fine("Properties: "
                            + ((File) value).getAbsolutePath()
                            + " does not exist.");
                }
                continue;
            }
            if(value == Null.INSTANCE) {
                continue;
            }
            if(value == NoProperties.INSTANCE) {
                continue;
            }
            return value;
        }
        return null;
    }

    /*
     * @see com.eva.properties.Replaceable#copy(com.eva.properties.Properties)
     */
    public Replaceable copy(Properties inParent) {
        Collection newAlternatives = new ArrayList();
        for(Iterator i = alternatives.iterator(); i.hasNext();) {
            Object value = i.next();
            if(value instanceof Properties) {
                newAlternatives.add(((Properties) value).copy(inParent));
            }
            else if(value instanceof Replaceable) {
                newAlternatives.add(((Replaceable) value).copy(inParent));
            }
            else {
                newAlternatives.add(value);
            }
        }
        return new Switch(newAlternatives);
    }
    
}