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/*
 * Based on JUEL 2.2.1 code, 2006-2009 Odysseus Software GmbH
 *
 * 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 org.activiti.engine.impl.juel;

import java.beans.FeatureDescriptor;
import java.util.Iterator;

import org.activiti.engine.impl.bpmn.data.ItemInstance;
import org.activiti.engine.impl.javax.el.ArrayELResolver;
import org.activiti.engine.impl.javax.el.BeanELResolver;
import org.activiti.engine.impl.javax.el.CompositeELResolver;
import org.activiti.engine.impl.javax.el.DynamicBeanPropertyELResolver;
import org.activiti.engine.impl.javax.el.ELContext;
import org.activiti.engine.impl.javax.el.ELResolver;
import org.activiti.engine.impl.javax.el.ListELResolver;
import org.activiti.engine.impl.javax.el.MapELResolver;
import org.activiti.engine.impl.javax.el.ResourceBundleELResolver;

/**
 * Simple resolver implementation. This resolver handles root properties (top-level identifiers). Resolving "real" properties ( base != null) is delegated to a resolver specified at
 * construction time.
 * 
 * @author Christoph Beck
 */
public class SimpleResolver extends ELResolver {
  private static final ELResolver DEFAULT_RESOLVER_READ_ONLY = new CompositeELResolver() {
    {
      add(new ArrayELResolver(true));
      add(new ListELResolver(true));
      add(new MapELResolver(true));
      add(new ResourceBundleELResolver());
      add(new DynamicBeanPropertyELResolver(true, ItemInstance.class, "getFieldValue", "setFieldValue"));
      add(new BeanELResolver(true));
    }
  };
  private static final ELResolver DEFAULT_RESOLVER_READ_WRITE = new CompositeELResolver() {
    {
      add(new ArrayELResolver(false));
      add(new ListELResolver(false));
      add(new MapELResolver(false));
      add(new ResourceBundleELResolver());
      add(new DynamicBeanPropertyELResolver(false, ItemInstance.class, "getFieldValue", "setFieldValue"));
      add(new BeanELResolver(false));
    }
  };

  private final RootPropertyResolver root;
  private final CompositeELResolver delegate;

  /**
   * Create a resolver capable of resolving top-level identifiers. Everything else is passed to the supplied delegate.
   */
  public SimpleResolver(ELResolver resolver, boolean readOnly) {
    delegate = new CompositeELResolver();
    delegate.add(root = new RootPropertyResolver(readOnly));
    delegate.add(resolver);
  }

  /**
   * Create a read/write resolver capable of resolving top-level identifiers. Everything else is passed to the supplied delegate.
   */
  public SimpleResolver(ELResolver resolver) {
    this(resolver, false);
  }

  /**
   * Create a resolver capable of resolving top-level identifiers, array values, list values, map values, resource values and bean properties.
   */
  public SimpleResolver(boolean readOnly) {
    this(readOnly ? DEFAULT_RESOLVER_READ_ONLY : DEFAULT_RESOLVER_READ_WRITE, readOnly);
  }

  /**
   * Create a read/write resolver capable of resolving top-level identifiers, array values, list values, map values, resource values and bean properties.
   */
  public SimpleResolver() {
    this(DEFAULT_RESOLVER_READ_WRITE, false);
  }

  /**
   * Answer our root resolver which provides an API to access top-level properties.
   * 
   * @return root property resolver
   */
  public RootPropertyResolver getRootPropertyResolver() {
    return root;
  }

  @Override
  public Class getCommonPropertyType(ELContext context, Object base) {
    return delegate.getCommonPropertyType(context, base);
  }

  @Override
  public Iterator getFeatureDescriptors(ELContext context, Object base) {
    return delegate.getFeatureDescriptors(context, base);
  }

  @Override
  public Class getType(ELContext context, Object base, Object property) {
    return delegate.getType(context, base, property);
  }

  @Override
  public Object getValue(ELContext context, Object base, Object property) {
    return delegate.getValue(context, base, property);
  }

  @Override
  public boolean isReadOnly(ELContext context, Object base, Object property) {
    return delegate.isReadOnly(context, base, property);
  }

  @Override
  public void setValue(ELContext context, Object base, Object property, Object value) {
    delegate.setValue(context, base, property, value);
  }

  @Override
  public Object invoke(ELContext context, Object base, Object method, Class[] paramTypes, Object[] params) {
    return delegate.invoke(context, base, method, paramTypes, params);
  }
}