Expression.java

/*
* Copyright 2016 Nabarun Mondal
* 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 com.noga.njexl.lang;


/**
 * Represents a single JEXL expression.
 * <p>
 * This simple interface provides access to the underlying expression through
 * {@link Expression#getExpression()}.
 * </p>
 *
 * <p>
 * An expression is different than a script - it is simply a reference of
 * an expression.
 * </p>
 *
 * @since 1.0
 */
public interface Expression {
    /**
     * Evaluates the expression with the variables contained in the
     * supplied {@link JexlContext}.
     *
     * @param context A JexlContext containing variables.
     * @return The result of this evaluation
     * @throws JexlException on any error
     */
    Object evaluate(JexlContext context);

    /**
     * Returns the JEXL expression this Expression was created with.
     *
     * @return The JEXL expression to be evaluated
     */
    String getExpression();

    /**
     * Returns the JEXL expression by reconstructing it from the parsed tree.
     * @return the JEXL expression
     */
    String dump();
}