FilterAdapter.java

/**
 * Copyright (c) Codice Foundation
 * <p>
 * This 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 any later version.
 * <p>
 * This program 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. A copy of the GNU Lesser General Public License
 * is distributed along with this program and can be found at
 * <http://www.gnu.org/licenses/lgpl.html>.
 */
package ddf.catalog.filter;

import org.opengis.filter.Filter;

import ddf.catalog.source.UnsupportedQueryException;

/**
 * {@code FilterAdapter} visits a {@link Filter} and invokes {@link FilterDelegate} methods with
 * normalized, typed values. A large part of implementing a {@link org.opengis.filter.FilterVisitor} is handling
 * expressions, type casting literals, and supporting custom filter logic like {@code FuzzyFunction}
 * s. The {@code FilterAdapter} handles all of this common boilerplate functionality. Furthermore,
 * sources using the {@code FilterAdapter} will receive future enhancements and ensure basic
 * compatibility with Endpoints that use the {@code FilterBuilder}.
 * <p>
 * To use the {@code FilterAdapter}, a {@code FilterDelegate} for the source is required. Here is an
 * example using a text base filter delegate.
 *
 * <pre>
 * FilterDelegate<String> delegate = new FilterToTextDelegate();
 *
 * FilterAdapter adapter = new FilterAdapterImpl();
 *
 * String result = adapter.adapt(filter, delegate);
 * </pre>
 *
 * A reference implementation is provided with the DDF Core in the Filter Proxy bundle.
 *
 * @author ddf.isgs@lmco.com
 *
 * @see FilterDelegate
 */
public interface FilterAdapter {

    /**
     * Visit {@code Filter} nodes and invoke {@code FilterDelegate} methods with normalized input.
     *
     * @param filter
     *            OGC Filter to visit
     * @param filterDelegate
     *            delegate to invoke will visiting
     * @return result of adapted filter output
     * @throws UnsupportedQueryException
     */
    public <T> T adapt(Filter filter, FilterDelegate<T> filterDelegate)
            throws UnsupportedQueryException;

}