1 /*
2 * Copyright (c) 2003 The Visigoth Software Society. All rights
3 * reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. The end-user documentation included with the redistribution, if
18 * any, must include the following acknowledgement:
19 * "This product includes software developed by the
20 * Visigoth Software Society (http://www.visigoths.org/)."
21 * Alternately, this acknowledgement may appear in the software itself,
22 * if and wherever such third-party acknowledgements normally appear.
23 *
24 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
25 * project contributors may be used to endorse or promote products derived
26 * from this software without prior written permission. For written
27 * permission, please contact visigoths@visigoths.org.
28 *
29 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
30 * nor may "FreeMarker" or "Visigoth" appear in their names
31 * without prior written permission of the Visigoth Software Society.
32 *
33 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
34 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
36 * DISCLAIMED. IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
37 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
38 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
39 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
40 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
41 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
42 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
43 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44 * SUCH DAMAGE.
45 * ====================================================================
46 *
47 * This software consists of voluntary contributions made by many
48 * individuals on behalf of the Visigoth Software Society. For more
49 * information on the Visigoth Software Society, please see
50 * http://www.visigoths.org/
51 */
52
53 package freemarker.template;
54
55 import java.io.IOException;
56 import java.io.Writer;
57 import java.util.Map;
58
59 /**
60 * Objects that implement this interface can be used as user-defined directives
61 * (much like macros); you should rather use the newer {@link TemplateDirectiveModel}
62 * instead. Altough implementing output filters is more handy with this interface,
63 * this interface will be certainly deprecated as superfluous, starting from
64 * FreeMarker 2.4. But as far as the template engine is concerned, you can use both
65 * equivalently as a user-defined directive.
66 *
67 * <P>Note that, as of FreeMarker 2.1, <tt>TemplateTransformModel</tt>
68 * has changed. This is a more powerful implementation.
69 * There is a quick-and-dirty way to patch any legacy
70 * TemplateTransformModel so that it implements the new API.
71 * You simply add the following as your implementation
72 * of the getWriter() call:
73 * <PRE>
74 *
75 * public Writer getWriter(final Writer out,
76 * Map args)
77 * {
78 * final StringBuffer buf = new StringBuffer();
79 * return new Writer() {
80 * public void write(char cbuf[], int off, int len) {
81 * buf.append(cbuf, off, len);
82 * }
83 *
84 * public void flush() throws IOException {
85 * out.flush();
86 * }
87 *
88 * public void close() throws IOException {
89 * StringReader sr = new StringReader(buf.toString());
90 * StringWriter sw = new StringWriter();
91 * transform(sr, sw);
92 * out.write(sw.toString());
93 * }
94 * };
95 * }
96 *
97 *
98 * </PRE>
99 *
100 * <P>Implementions of <tt>TemplateTransformModel</tt> should be thread-safe.
101 *
102 * @since FreeMarker 2.3.11
103 *
104 * @version $Id: TemplateTransformModel.java,v 1.36 2003/04/11 20:57:32 revusky Exp $
105 */
106 public interface TemplateTransformModel extends TemplateModel {
107
108 /**
109 * Returns a writer that will be used by the engine to feed the
110 * transformation input to the transform. Each call to this method
111 * must return a new instance of the writer so that the transformation
112 * is thread-safe.
113 * @param out the character stream to which to write the transformed output
114 * @param args the arguments (if any) passed to the transformation as a
115 * map of key/value pairs where the keys are strings and the arguments are
116 * TemplateModel instances. This is never null.
117 * @return a writer to which the engine will feed the transformation
118 * input, or null if the transform does not support nested content (body).
119 * The returned writer can implement the {@link TransformControl}
120 * interface if it needs advanced control over the evaluation of the
121 * transformation body.
122 */
123 Writer getWriter(Writer out, Map args)
124 throws TemplateModelException, IOException;
125 }