001 /* $Id: VariableAttributes.java 992060 2010-09-02 19:09:47Z simonetripodi $
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one or more
004 * contributor license agreements. See the NOTICE file distributed with
005 * this work for additional information regarding copyright ownership.
006 * The ASF licenses this file to You under the Apache License, Version 2.0
007 * (the "License"); you may not use this file except in compliance with
008 * the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019
020 package org.apache.commons.digester.substitution;
021
022 import org.xml.sax.Attributes;
023
024 import java.util.ArrayList;
025
026
027 /**
028 * <p>Wrapper for an org.xml.sax.Attributes object which expands any
029 * "variables" referenced in the attribute value via ${foo} or similar.
030 * This is only done when something actually asks for the attribute value,
031 * thereby imposing no performance penalty if the attribute is not used.</p>
032 *
033 * @since 1.6
034 */
035
036 public class VariableAttributes implements Attributes {
037
038 // list of mapped attributes.
039 private ArrayList<String> values = new ArrayList<String>(10);
040
041 private Attributes attrs;
042 private VariableExpander expander;
043
044 // ------------------- Public Methods
045
046 /**
047 * Specify which attributes class this object is a proxy for.
048 */
049 public void init(Attributes attrs, VariableExpander expander) {
050 this.attrs = attrs;
051 this.expander = expander;
052
053 // I hope this doesn't release the memory for this array; for
054 // efficiency, this should just mark the array as being size 0.
055 values.clear();
056 }
057
058 public String getValue(int index) {
059 if (index >= values.size()) {
060 // Expand the values array with null elements, so the later
061 // call to set(index, s) works ok.
062 //
063 // Unfortunately, there is no easy way to set the size of
064 // an arraylist; we must repeatedly add null elements to it..
065 values.ensureCapacity(index+1);
066 for(int i = values.size(); i<= index; ++i) {
067 values.add(null);
068 }
069 }
070
071 String s = values.get(index);
072
073 if (s == null) {
074 // we have never been asked for this value before.
075 // get the real attribute value and perform substitution
076 // on it.
077 s = attrs.getValue(index);
078 if (s != null) {
079 s = expander.expand(s);
080 values.set(index, s);
081 }
082 }
083
084 return s;
085 }
086
087 public String getValue(String qname) {
088 int index = attrs.getIndex(qname);
089 if (index == -1) {
090 return null;
091 }
092 return getValue(index);
093 }
094
095 public String getValue(String uri, String localname) {
096 int index = attrs.getIndex(uri, localname);
097 if (index == -1) {
098 return null;
099 }
100 return getValue(index);
101 }
102
103 // plain proxy methods follow : nothing interesting :-)
104 public int getIndex(String qname) {
105 return attrs.getIndex(qname);
106 }
107
108 public int getIndex(String uri, String localpart) {
109 return attrs.getIndex(uri, localpart);
110 }
111
112 public int getLength() {
113 return attrs.getLength();
114 }
115
116 public String getLocalName(int index) {
117 return attrs.getLocalName(index);
118 }
119
120 public String getQName(int index) {
121 return attrs.getQName(index);
122 }
123
124 public String getType(int index) {
125 return attrs.getType(index);
126 }
127
128 public String getType(String qname) {
129 return attrs.getType(qname);
130 }
131
132 public String getType(String uri, String localname) {
133 return attrs.getType(uri, localname);
134 }
135
136 public String getURI(int index) {
137 return attrs.getURI(index);
138 }
139
140 }