1 package org.apache.torque.generator.template.velocity;
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.io.BufferedReader;
23 import java.io.ByteArrayInputStream;
24 import java.io.ByteArrayOutputStream;
25 import java.io.IOException;
26 import java.io.InputStream;
27 import java.io.InputStreamReader;
28 import java.io.OutputStreamWriter;
29 import java.io.Writer;
30
31 import org.apache.torque.generator.template.TemplateFilter;
32
33 /**
34 * A Filter for velocity templates. It has the effect of beautifying the output
35 * of the velocity outlet.
36 */
37 public class VelocityTemplateFilter implements TemplateFilter
38 {
39 /**
40 * With which String tabs should be replaced
41 */
42 private static final String TAB_REPLACEMENT = " ";
43
44 /**
45 * This method filters the template and replaces some
46 * unwanted characters. For example it removes leading
47 * spaces in front of velocity commands and replaces
48 * tabs with spaces to prevent bounces in different
49 * code editors with different tab-width-setting.
50 *
51 * @param resource the input stream to filter.
52 * @param encoding the encoding to use, or null for the system encoding.
53 *
54 * @return the filtered input stream.
55 *
56 * @throws IOException if creating, reading or writing to a stream fails.
57 */
58 public InputStream filter(InputStream resource, String encoding)
59 throws IOException
60 {
61 InputStreamReader streamReader;
62 if (encoding == null)
63 {
64 streamReader = new InputStreamReader(resource);
65 }
66 else
67 {
68 streamReader = new InputStreamReader(resource, encoding);
69 }
70 BufferedReader bufferedReader = new BufferedReader(streamReader);
71 ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
72 Writer outputStreamWriter = null;
73 if (encoding == null)
74 {
75 outputStreamWriter = new OutputStreamWriter(outputStream);
76 }
77 else
78 {
79 outputStreamWriter = new OutputStreamWriter(outputStream, encoding);
80 }
81
82 boolean onlySpacesInLineSoFar = true;
83 StringBuilder startLineBuffer = new StringBuilder();
84 while (true)
85 {
86 int readChar = bufferedReader.read();
87
88 if (readChar == -1)
89 {
90 break;
91 }
92 if (!onlySpacesInLineSoFar)
93 {
94 outputStreamWriter.write(readChar);
95 if ('\r' == readChar || '\n' == readChar)
96 {
97 onlySpacesInLineSoFar = true;
98 }
99 }
100 else
101 {
102 if (' ' == readChar)
103 {
104 startLineBuffer.append((char) readChar);
105 }
106 else if ('\t' == readChar)
107 {
108 startLineBuffer.append(TAB_REPLACEMENT);
109 }
110 else if ('#' == readChar)
111 {
112 if (startLineBuffer.length() != 0)
113 {
114 startLineBuffer = new StringBuilder();
115 }
116 outputStreamWriter.write(readChar);
117 onlySpacesInLineSoFar = false;
118 }
119 else if ('\r' == readChar || '\n' == readChar)
120 {
121 if (startLineBuffer.length() != 0)
122 {
123 outputStreamWriter.write(startLineBuffer.toString());
124 startLineBuffer = new StringBuilder();
125 }
126 outputStreamWriter.write(readChar);
127 }
128 else
129 {
130 if (startLineBuffer.length() != 0)
131 {
132 outputStreamWriter.write(startLineBuffer.toString());
133 startLineBuffer = new StringBuilder();
134 }
135 outputStreamWriter.write(readChar);
136 onlySpacesInLineSoFar = false;
137
138 }
139 }
140 }
141 outputStreamWriter.write(startLineBuffer.toString());
142
143 outputStreamWriter.flush();
144 outputStreamWriter.close();
145
146 return new ByteArrayInputStream(outputStream.toByteArray());
147 }
148 }