001 /*
002 * Copyright 1999-2001,2004 The Apache Software Foundation.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package org.apache.commons.workflow.core;
018
019
020 import java.util.EmptyStackException;
021 import org.apache.commons.workflow.Block;
022 import org.apache.commons.workflow.BlockState;
023 import org.apache.commons.workflow.Context;
024 import org.apache.commons.workflow.Descriptor;
025 import org.apache.commons.workflow.Iterator;
026 import org.apache.commons.workflow.Step;
027 import org.apache.commons.workflow.StepException;
028 import org.apache.commons.workflow.base.BaseBlock;
029
030
031 /**
032 * <p>Repeatedly evaluate the properties specified by the associated
033 * Descriptors, and execute the nested Steps if and only if
034 * <strong>ANY</strong> of them evaluate to a negative result.
035 * To avoid non-deterministic evaluation
036 * stack behavior, all of the specified Descriptors are always
037 * evaluated exactly once.</p>
038 *
039 * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
040 * @author Craig R. McClanahan
041 */
042
043 public class WhileNotStep extends WhileStep {
044
045
046 // ----------------------------------------------------------= Constructors
047
048
049 /**
050 * Construct a default instance of this Step.
051 */
052 public WhileNotStep() {
053
054 super();
055
056 }
057
058
059 /**
060 * Construct an instance of this Step with the specified identifier.
061 *
062 * @param id Step identifier
063 */
064 public WhileNotStep(String id) {
065
066 this(id, null);
067
068 }
069
070
071 /**
072 * Construct a fully configured instance of this Step.
073 *
074 * @param id Step identifier of this step
075 * @param descriptor Initial descriptor to be added
076 */
077 public WhileNotStep(String id, Descriptor descriptor) {
078
079 super();
080 setId(id);
081 if (descriptor != null)
082 addDescriptor(descriptor);
083
084 }
085
086
087 // --------------------------------------------------------- Public Methods
088
089
090 /**
091 * Render a string representation of this Step.
092 */
093 public String toString() {
094
095 StringBuffer sb = new StringBuffer("<core:whileAny");
096 if (getId() != null) {
097 sb.append(" id=\"");
098 sb.append(getId());
099 sb.append("\"");
100 }
101 sb.append(">");
102 Descriptor descriptors[] = findDescriptors();
103 for (int i = 0; i < descriptors.length; i++)
104 sb.append(descriptors[i]);
105 Step steps[] = getSteps();
106 for (int i = 0; i < steps.length; i++)
107 sb.append(steps[i]);
108 sb.append("</core:whileAny>");
109 return (sb.toString());
110
111 }
112
113
114 // ------------------------------------------------------ Protected Methods
115
116
117 /**
118 * Evaluate the condition specified by the Descriptors associated with
119 * this Block, and return the resulting boolean value.
120 *
121 * @param context Context within which to evaluate the descriptors
122 */
123 protected boolean evaluate(Context context) {
124
125 boolean condition = true;
126 Descriptor descriptors[] = findDescriptors();
127 for (int i = 0; i < descriptors.length; i++) {
128 if (descriptors[i] == null)
129 continue;
130 if (!descriptors[i].positive(context))
131 condition = false;
132 }
133 return (!condition);
134
135 }
136
137
138 }