| /* |
| * 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 javax.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> |
| * |
| * @since 2.0 |
| */ |
| 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; |
| } |
| |