br.com.caelum.vraptor.http.route.JavaEvaluator.java Source code

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Here is the source code for br.com.caelum.vraptor.http.route.JavaEvaluator.java

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/***
 * Copyright (c) 2009 Caelum - www.caelum.com.br/opensource
 * All rights reserved.
 *
 * 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.
 */

package br.com.caelum.vraptor.http.route;

import java.lang.reflect.Array;
import java.util.Collection;

import javax.enterprise.context.ApplicationScoped;

import net.vidageek.mirror.dsl.Mirror;
import br.com.caelum.vraptor.VRaptorException;

import com.google.common.collect.Iterables;

/**
 * Evaluates expressions in order to access values.
 *
 * @author guilherme silveira
 *
 */
@ApplicationScoped
public class JavaEvaluator implements Evaluator {

    @Override
    public Object get(Object root, String path) {
        if (root == null) {
            return null;
        }
        String[] paths = path.split("[\\]\\.]");
        Object current = root;
        for (int i = 1; i < paths.length; i++) {
            try {
                current = navigate(current, paths[i]);
            } catch (Exception e) {
                throw new VRaptorException("Unable to evaluate expression " + path, e);
            }
            if (current == null) {
                return "";
            }
        }
        return current;
    }

    private Object navigate(Object current, String path) {
        int index = path.indexOf("[");
        int position = -1;
        if (index != -1) {
            position = Integer.parseInt(path.substring(index + 1));
            path = path.substring(0, index);
        }
        Object instance = new Mirror().on(current).invoke().getterFor(path);
        if (index != -1) {
            instance = access(instance, position);
        }
        return instance;
    }

    private Object access(Object current, int position) {
        if (current.getClass().isArray()) {
            return Array.get(current, position);
        } else if (Collection.class.isAssignableFrom(current.getClass())) {
            return Iterables.get((Collection<?>) current, position);
        }
        throw new VRaptorException("Unable to access position of a" + current.getClass().getName() + ".");
    }
}