/*
 * Copyright (c) 1997, 2020 Oracle and/or its affiliates and others.
 * All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * 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 jakarta.servlet.jsp.el;

/**
 * <p>
 * The abstract class for a prepared expression.
 * </p>
 *
 * <p>
 * An instance of an Expression can be obtained via from an ExpressionEvaluator instance.
 * </p>
 *
 * <p>
 * An Expression may or not have done a syntactic parse of the expression. A client invoking the evaluate() method
 * should be ready for the case where ELParseException exceptions are raised.
 * </p>
 *
 * @deprecated As of JSP 2.1, replaced by {@link jakarta.el.ValueExpression}
 * @since JSP 2.0
 */
@Deprecated
public abstract class Expression {

    /**
     * Evaluates an expression that was previously prepared. In some implementations preparing an expression involves
     * full syntactic validation, but others may not do so. Evaluating the expression may raise an ELParseException as
     * well as other ELExceptions due to run-time evaluation.
     *
     * @param vResolver A VariableResolver instance that can be used at runtime to resolve the name of implicit objects
     *                  into Objects.
     * @return The result of the expression evaluation.
     *
     * @exception ELException Thrown if the expression evaluation failed.
     */
    public abstract Object evaluate(VariableResolver vResolver) throws ELException;
}
