1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.jxpath; 19 20 import java.io.Serializable; 21 22 /** 23 * Variables provide access to a global set of values accessible via XPath. XPath can reference variables using the {@code "$varname"} syntax. To use a custom 24 * implementation of this interface, pass it to {@link JXPathContext#setVariables JXPathContext.setVariables()} 25 */ 26 public interface Variables extends Serializable { 27 28 /** 29 * Defines a new variable with the specified value or modifies the value of an existing variable. May throw UnsupportedOperationException. 30 * 31 * @param name variable name 32 * @param value to declare 33 */ 34 void declareVariable(String name, Object value); 35 36 /** 37 * Returns the value of the specified variable. 38 * 39 * @param name variable name 40 * @return Object value 41 * @throws IllegalArgumentException if there is no such variable. 42 */ 43 Object getVariable(String name); 44 45 /** 46 * Returns true if the specified variable is declared. 47 * 48 * @param name variable name 49 * @return boolean 50 */ 51 boolean isDeclaredVariable(String name); 52 53 /** 54 * Removes an existing variable. May throw UnsupportedOperationException. 55 * 56 * @param name is a variable name without the "$" sign 57 */ 58 void undeclareVariable(String name); 59 }