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package org.codehaus.plexus.interpolation;

/*
 * Copyright 2007 The Codehaus Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.codehaus.plexus.interpolation.reflection.ReflectionValueExtractor;

/**
 * Wraps an object, providing reflective access to the object graph of which the
 * supplied object is the root. Expressions like 'child.name' will translate into
 * 'rootObject.getChild().getName()' for non-boolean properties, and
 * 'rootObject.getChild().isName()' for boolean properties.
 */
public class ObjectBasedValueSource
    extends AbstractValueSource
{

    private final Object root;

    /**
     * Construct a new value source, using the supplied object as the root from
     * which to start, and using expressions split at the dot ('.') to navigate
     * the object graph beneath this root.
     * @param root the root of the graph.
     */
    public ObjectBasedValueSource( Object root )
    {
        super( true );
        this.root = root;
    }

    /**
     * 

Split the expression into parts, tokenized on the dot ('.') character. Then, * starting at the root object contained in this value source, apply each part * to the object graph below this root, using either 'getXXX()' or 'isXXX()' * accessor types to resolve the value for each successive expression part. * Finally, return the result of the last expression part's resolution.

* *

NOTE: The object-graph nagivation actually takes place via the * {@link ReflectionValueExtractor} class.

*/ public Object getValue( String expression ) { if ( expression == null || expression.trim().length() < 1 ) { return null; } try { return ReflectionValueExtractor.evaluate( expression, root, false ); } catch ( Exception e ) { addFeedback( "Failed to extract \'" + expression + "\' from: " + root, e ); } return null; } }




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