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'DatabeneScript' is an open source software library for resolving Java-like script expressions, written by Volker Bergmann.

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/*
 * (c) Copyright 2009-2011 by Volker Bergmann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted under the terms of the
 * GNU General Public License.
 *
 * For redistributing this software or a derivative work under a license other
 * than the GPL-compatible Free Software License as defined by the Free
 * Software Foundation or approved by OSI, you must first obtain a commercial
 * license to this software product from Volker Bergmann.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package org.databene.script;

import java.util.HashSet;
import java.util.Set;

import org.databene.commons.ArrayFormat;
import org.databene.commons.ArrayUtil;
import org.databene.commons.ConfigurationError;
import org.databene.commons.Context;
import org.databene.commons.ObjectNotFoundException;
import org.databene.commons.accessor.FeatureAccessor;
import org.databene.commons.bean.DefaultClassProvider;
import org.databene.script.expression.DynamicExpression;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * {@link Expression} implementation that evaluates a qualified name as attributes of an object reference or 
 * static fields of a Java class.

 * 

 * Created at 08.10.2009 07:18:53
 * @since 0.6.0
 * @author Volker Bergmann
 */

public class QNExpression extends DynamicExpression {

	private static final Logger LOGGER = LoggerFactory.getLogger(DatabeneScriptParser.class);
	
	private static Set noClasses = new HashSet(1000);

	private String[] qnParts;
	
	public QNExpression(String[] qnParts) {
	    this.qnParts = qnParts;
    }

    public Object evaluate(Context context) {
    	try {
    		return resolveNamePart(qnParts, qnParts.length, context);
    	} catch (ObjectNotFoundException e) {
    		throw new ObjectNotFoundException("Unable to resolve " + ArrayFormat.format(".", qnParts));
    	}
    }

    public static Object resolveNamePart(String[] qnParts, int qnLength, Context context) {
    	String objectOrClassName = ArrayFormat.formatPart(".", 0, qnLength, qnParts);
    	if (context.contains(objectOrClassName)) {
    		return context.get(objectOrClassName);
    	} else {
    		if (!noClasses.contains(objectOrClassName)) {
	    		try {
	    			return DefaultClassProvider.resolveByObjectOrDefaultInstance(objectOrClassName, context);
	    		} catch (ConfigurationError e) {
	    		}
    		}
			LOGGER.debug("Class not found: " + objectOrClassName);
			noClasses.add(objectOrClassName);
			if (qnLength > 1) {
    			return readField(qnParts, qnLength - 1, qnParts[qnLength - 1], context);
			} else
				throw new ObjectNotFoundException("'" + objectOrClassName + "' is not defined");
    	}
    }

    private static Object readField(String[] qnParts, int qnLength, String fieldName, Context context) {
    	return FeatureAccessor.getValue(resolveNamePart(qnParts, qnLength, context), fieldName);
    }

	public BeanSpec resolve(Context context) {
        String qn = ArrayFormat.format(".", qnParts);
        if (context.contains(qn)) {
        	return BeanSpec.createReference(context.get(qn));
        } else {
        	if (!noClasses.contains(qn)) {
	    		try {
	    			Class bean = DefaultClassProvider.resolveByObjectOrDefaultInstance(qn, context);
					return BeanSpec.createConstruction(bean);
	    		} catch (ConfigurationError e) {
	    		}
        	}
			LOGGER.debug("Class not found: " + qn);
			noClasses.add(qn);
	    	Object bean = readField(qnParts, qnParts.length - 1, ArrayUtil.lastElementOf(qnParts), context);
			return BeanSpec.createReference(bean);
        }
	}
    
    @Override
    public String toString() {
        return ArrayFormat.format(".", qnParts);
    }

}

    

    

    

            

    

            



    
    






    
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