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.scxml; 018 019 import java.util.Map; 020 021 /** 022 * A Context or "scope" for storing variables; usually tied to 023 * a SCXML root or State object. 024 */ 025 public interface Context { 026 /** 027 * Assigns a new value to an existing variable or creates a new one. 028 * The method searches the chain of parent Contexts for variable 029 * existence. 030 * 031 * @param name The variable name 032 * @param value The variable value 033 */ 034 void set(String name, Object value); 035 036 /** 037 * Assigns a new value to an existing variable or creates a new one. 038 * The method allows to shaddow a variable of the same name up the 039 * Context chain. 040 * 041 * @param name The variable name 042 * @param value The variable value 043 */ 044 void setLocal(String name, Object value); 045 046 /** 047 * Get the value of this variable; delegating to parent. 048 * 049 * @param name The name of the variable 050 * @return The value (or null) 051 */ 052 Object get(String name); 053 054 /** 055 * Check if this variable exists, delegating to parent. 056 * 057 * @param name The name of the variable 058 * @return Whether a variable with the name exists in this Context 059 */ 060 boolean has(String name); 061 062 /** 063 * Get the Map of all variables in this Context. 064 * 065 * @return Local variable entries Map 066 * To get variables in parent Context, call getParent().getVars(). 067 * @see #getParent() 068 */ 069 Map getVars(); 070 071 /** 072 * Clear this Context. 073 */ 074 void reset(); 075 076 /** 077 * Get the parent Context, may be null. 078 * 079 * @return The parent Context in a chained Context environment 080 */ 081 Context getParent(); 082 083 }