1 package org.apache.commons.digester3.substitution;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.Map;
23 import java.util.ArrayList;
24
25 /**
26 * <p>
27 * Expands variable references from multiple sources.
28 * </p>
29 *
30 * @since 1.6
31 */
32 public class MultiVariableExpander
33 implements VariableExpander
34 {
35
36 private int nEntries = 0;
37
38 private final ArrayList<String> markers = new ArrayList<String>( 2 );
39
40 private final ArrayList<Map<String, Object>> sources = new ArrayList<Map<String, Object>>( 2 );
41
42 /**
43 * Add a new variables source, identified by the input marker
44 *
45 * @param marker The input variables marker
46 * @param source The variables source
47 */
48 public void addSource( String marker, Map<String, Object> source )
49 {
50 ++nEntries;
51 markers.add( marker );
52 sources.add( source );
53 }
54
55 /**
56 * {@inheritDoc}
57 */
58 public String expand( String param )
59 {
60 for ( int i = 0; i < nEntries; ++i )
61 {
62 param = expand( param, markers.get( i ), sources.get( i ) );
63 }
64 return param;
65 }
66
67 /**
68 * Replace any occurrences within the string of the form "marker{key}" with the value from source[key].
69 * <p>
70 * Commonly, the variable marker is "$", in which case variables are indicated by ${key} in the string.
71 * <p>
72 * Returns the string after performing all substitutions.
73 * <p>
74 * If no substitutions were made, the input string object is returned (not a copy).
75 *
76 * @param str The input string containing placeholders
77 * @param marker The input variables marker
78 * @param source The variables source
79 * @return The input string where variables have been expanded by replacing values found in source
80 */
81 public String expand( String str, String marker, Map<String, Object> source )
82 {
83 String startMark = marker + "{";
84 int markLen = startMark.length();
85
86 int index = 0;
87 for ( ;; )
88 {
89 index = str.indexOf( startMark, index );
90 if ( index == -1 )
91 {
92 return str;
93 }
94
95 int startIndex = index + markLen;
96 if ( startIndex > str.length() )
97 {
98 throw new IllegalArgumentException( "var expression starts at end of string" );
99 }
100
101 int endIndex = str.indexOf( "}", index + markLen );
102 if ( endIndex == -1 )
103 {
104 throw new IllegalArgumentException( "var expression starts but does not end" );
105 }
106
107 String key = str.substring( index + markLen, endIndex );
108 Object value = source.get( key );
109 if ( value == null )
110 {
111 throw new IllegalArgumentException( "parameter [" + key + "] is not defined." );
112 }
113 String varValue = value.toString();
114
115 str = str.substring( 0, index ) + varValue + str.substring( endIndex + 1 );
116 index += varValue.length();
117 }
118 }
119
120 }