1 /* 2 * Copyright (c) 2002, 2003, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package com.sun.corba.se.spi.orbutil.fsm; 27 28 /** 29 * 30 * @author Ken Cavanaugh 31 */ 32 public interface Guard 33 { 34 public static final class Complement extends GuardBase { 35 private Guard guard ; 36 37 public Complement( GuardBase guard ) 38 { 39 super( "not(" + guard.getName() + ")" ) ; 40 this.guard = guard ; 41 } 42 43 public Result evaluate( FSM fsm, Input in ) 44 { 45 return guard.evaluate( fsm, in ).complement() ; 46 } 47 } 48 49 public static final class Result { 50 private String name ; 51 52 private Result( String name ) 53 { 54 this.name = name ; 55 } 56 57 public static Result convert( boolean res ) 58 { 59 return res ? ENABLED : DISABLED ; 60 } 61 62 public Result complement() 63 { 64 if (this == ENABLED) 65 return DISABLED ; 66 else if (this == DISABLED) 67 return ENABLED ; 68 else 69 return DEFERED ; 70 } 71 72 public String toString() 73 { 74 return "Guard.Result[" + name + "]" ; 75 } 76 77 public static final Result ENABLED = new Result( "ENABLED" ) ; 78 public static final Result DISABLED = new Result( "DISABLED" ) ; 79 public static final Result DEFERED = new Result( "DEFERED" ) ; 80 } 81 82 /** Called by the state engine to determine whether a 83 * transition is enabled, defered, or disabled. 84 * The result is interpreted as follows: 85 * <ul> 86 * <li>ENABLED if the transition is ready to proceed 87 * <li>DISABLED if the transition is not ready to proceed 88 * <li>DEFERED if the action associated with the transition 89 * is to be deferred. This means that the input will not be 90 * acted upon, but rather it will be saved for later execution. 91 * Typically this is implemented using a CondVar wait, and the 92 * blocked thread represents the defered input. The defered 93 * input is retried when the thread runs again. 94 * </ul> 95 * 96 * @param fsm is the state machine causing this action. 97 * @param in is the input that caused the transition. 98 */ 99 public Result evaluate( FSM fsm, Input in ) ; 100 } 101 102 // end of Action.java