Expression.java

/* Copyright 2013 The jeo project. All rights reserved.
 *
 * 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 io.jeo.filter;

/**
 * Derives a value from a given input.
 *  
 * @author Justin Deoliveira, OpenGeo
 */
public interface Expression {

    /**
     * Returns the value of the given expression for the specified input.
     */
    Object evaluate(Object obj);

    /**
     * Applies a visitor to the expression.
     */
    <R> R accept(FilterVisitor<R> visitor, Object obj);
}