ParameterizedDataProvider.java

/*
 * Copyright 2010, Andrew M Gibson
 *
 * www.andygibson.net
 *
 * This file is part of DataValve.
 *
 * DataValve is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * DataValve is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 * 
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with DataValve.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package org.fluttercode.datavalve.provider;

import java.util.List;
import java.util.Map;

import org.fluttercode.datavalve.DataProvider;
import org.fluttercode.datavalve.ParameterResolver;

/**
 * Extends the {@link DataProvider} interface to include parameterization of
 * the dataset. This introduces methods that allows you to define parameters and
 * also attach {@link ParameterResolver} instances to extend the parameter
 * resolution beyond key-value pairs.
 * 
 * @author Andy Gibson
 * 
 * @param <T> The type of objects returned from this query
 */
public interface ParameterizedDataProvider<T> extends DataProvider<T> {

	/**
	 * Returns the map holding local parameters that are by default used in
	 * parameter resolution.
	 * 
	 * @return The map holding local parameters
	 */
	public abstract Map<String, Object> getParameters();

	/**
	 * Set the parameter map for this dataset.
	 * 
	 * @param parameters
	 *            The parameter map to assign to this dataset
	 */
	public abstract void setParameters(Map<String, Object> parameters);

	/**
	 * Helper method to add a new parameter value to the dataset.
	 * 
	 * @param name
	 *            Name of new parameter
	 * @param value
	 *            Value of new parameter
	 */
	public abstract void addParameter(String name, Object value);

	/**
	 * Adds a new parameter resolver to the dataset. This resolver will be
	 * called if the resolvers preceeding it are unable to resolve the
	 * expression.
	 * 
	 * @param resolver
	 *            the new {@link ParameterResolver} to add to this dataset.
	 */
	public void addParameterResolver(ParameterResolver resolver);

	/**
	 * Resolves the parameter defined by <code>name</code>. The name may include
	 * various decorations to indicate what type of expression it is (i.e.
	 * #{name} for EL expressions. This method should use the
	 * {@link ParameterResolver} instances attached to this dataset to resolve
	 * the parameter name to a value. This method should return the first
	 * non-null value that is return from an attached resolver.
	 * 
	 * @param name
	 *            of the parameter to resolve
	 * @return the value of this parameter (null if not found)
	 */
	public Object resolveParameter(String name);

	
	public List<ParameterResolver> getParameterResolvers();
	
	public void setParameterResolvers(List<ParameterResolver> parameterResolvers);
	
}