001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.jexl2; 018 019 /** 020 * Manages variables which can be referenced in a JEXL expression. 021 * 022 * @since 1.0 023 * @version $Id: JexlContext.java 885553 2009-11-30 19:28:40Z henrib $ 024 */ 025 public interface JexlContext { 026 /** 027 * Gets the value of a variable. 028 * @param name the variable's name 029 * @return the value 030 */ 031 Object get(String name); 032 033 /** 034 * Sets the value of a variable. 035 * @param name the variable's name 036 * @param value the variable's value 037 */ 038 void set(String name, Object value); 039 040 /** 041 * Checks whether a variable is defined in this context. 042 * <p>A variable may be defined with a null value; this method checks whether the 043 * value is null or if the variable is undefined.</p> 044 * @param name the variable's name 045 * @return true if it exists, false otherwise 046 */ 047 boolean has(String name); 048 }