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/*
 * Copyright 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 de.odysseus.el.tree.impl.ast;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import javax.el.ELContext;

import de.odysseus.el.tree.Bindings;
import de.odysseus.el.tree.ExpressionNode;

public abstract class AstNode implements ExpressionNode {
	/**
	 * evaluate and return the (optionally coerced) result.
	 */
	public final Object getValue(Bindings bindings, ELContext context, Class type) {
		Object value = eval(bindings, context);
		if (type != null) {
			value = bindings.convert(value, type);
		}
		return value;
	}

	public abstract void appendStructure(StringBuilder builder, Bindings bindings);

	public abstract Object eval(Bindings bindings, ELContext context);
  
	public final String getStructuralId(Bindings bindings) {
		StringBuilder builder = new StringBuilder();
		appendStructure(builder, bindings);
		return builder.toString();
	}

	/**
	 * Find accessible method. Searches the inheritance tree of the class declaring
	 * the method until it finds a method that can be invoked.
	 * @param method method
	 * @return accessible method or null
	 */
	private static Method findPublicAccessibleMethod(Method method) {
		if (method == null || !Modifier.isPublic(method.getModifiers())) {
			return null;
		}
		if (method.isAccessible() || Modifier.isPublic(method.getDeclaringClass().getModifiers())) {
			return method;
		}
		for (Class cls : method.getDeclaringClass().getInterfaces()) {
			Method mth = null;
			try {
				mth = findPublicAccessibleMethod(cls.getMethod(method.getName(), method.getParameterTypes()));
				if (mth != null) {
					return mth;
				}
			} catch (NoSuchMethodException ignore) {
				// do nothing
			}
		}
		Class cls = method.getDeclaringClass().getSuperclass();
		if (cls != null) {
			Method mth = null;
			try {
				mth = findPublicAccessibleMethod(cls.getMethod(method.getName(), method.getParameterTypes()));
				if (mth != null) {
					return mth;
				}
			} catch (NoSuchMethodException ignore) {
				// do nothing
			}
		}
		return null;
	}

	protected Method findAccessibleMethod(Method method) {
		Method result = findPublicAccessibleMethod(method);
		if (result == null && method != null && Modifier.isPublic(method.getModifiers())) {
			result = method;
			try {
				method.setAccessible(true);
			} catch (SecurityException e) {
				result = null; 
			}
		}
		return result;
	}
}