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Tools to assist in the reading of configuration/preferences files in various formats
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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.configuration2.beanutils;

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

import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.DynaClass;
import org.apache.commons.configuration2.Configuration;
import org.apache.commons.configuration2.ConfigurationMap;
import org.apache.commons.configuration2.SubsetConfiguration;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * The {@code ConfigurationDynaBean} dynamically reads and writes configurations properties from a wrapped
 * configuration-collection {@link org.apache.commons.configuration2.Configuration} instance. It also implements a
 * {@link java.util.Map} interface so that it can be used in JSP 2.0 Expression Language expressions.
 *
 * 
 * The {@code ConfigurationDynaBean} maps nested and mapped properties to the appropriate {@code Configuration} subset
 * using the {@link org.apache.commons.configuration2.Configuration#subset} method. Similarly, indexed properties
 * reference lists of configuration properties using the
 * {@link org.apache.commons.configuration2.Configuration#getList(String)} method. Setting an indexed property is
 * supported, too.
 * 
 *
 * 
 * Note: Some of the methods expect that a dot (".") is used as property delimiter for the wrapped
 * configuration. This is true for most of the default configurations. Hierarchical configurations, for which a specific
 * expression engine is set, may cause problems.
 * 
 *
 * @since 1.0-rc1
 */
public class ConfigurationDynaBean extends ConfigurationMap implements DynaBean {

    /** Constant for the property delimiter. */
    private static final String PROPERTY_DELIMITER = ".";

    /** The logger. */
    private static final Log LOG = LogFactory.getLog(ConfigurationDynaBean.class);

    /**
     * Constructs a new instance of {@code ConfigurationDynaBean} and sets the configuration this bean is associated with.
     *
     * @param configuration the configuration
     */
    public ConfigurationDynaBean(final Configuration configuration) {
        super(configuration);
        if (LOG.isTraceEnabled()) {
            LOG.trace("ConfigurationDynaBean(" + configuration + ")");
        }
    }

    /**
     * Checks whether the given name references an indexed property. This implementation tests for properties of type list or
     * array. If the property does not exist, an exception is thrown.
     *
     * @param name the name of the property to check
     * @return a flag whether this is an indexed property
     * @throws IllegalArgumentException if the property does not exist
     */
    private boolean checkIndexedProperty(final String name) {
        final Object property = getConfiguration().getProperty(name);

        if (property == null) {
            throw new IllegalArgumentException("Property '" + name + "' does not exist.");
        }

        return property instanceof List || property.getClass().isArray();
    }

    @Override
    public boolean contains(final String name, final String key) {
        final Configuration subset = getConfiguration().subset(name);
        if (subset == null) {
            throw new IllegalArgumentException("Mapped property '" + name + "' does not exist.");
        }

        return subset.containsKey(key);
    }

    @Override
    public Object get(final String name) {
        if (LOG.isTraceEnabled()) {
            LOG.trace("get(" + name + ")");
        }

        // get configuration property
        Object result = getConfiguration().getProperty(name);
        if (result == null) {
            // otherwise attempt to create bean from configuration subset
            final Configuration subset = new SubsetConfiguration(getConfiguration(), name, PROPERTY_DELIMITER);
            if (!subset.isEmpty()) {
                result = new ConfigurationDynaBean(subset);
            }
        }

        if (LOG.isDebugEnabled()) {
            LOG.debug(name + "=[" + result + "]");
        }

        if (result == null) {
            throw new IllegalArgumentException("Property '" + name + "' does not exist.");
        }
        return result;
    }

    @Override
    public Object get(final String name, final int index) {
        if (!checkIndexedProperty(name)) {
            throw new IllegalArgumentException("Property '" + name + "' is not indexed.");
        }

        final List