001: /*
002: * Copyright (c) 2003 The Visigoth Software Society. All rights
003: * reserved.
004: *
005: * Redistribution and use in source and binary forms, with or without
006: * modification, are permitted provided that the following conditions
007: * are met:
008: *
009: * 1. Redistributions of source code must retain the above copyright
010: * notice, this list of conditions and the following disclaimer.
011: *
012: * 2. Redistributions in binary form must reproduce the above copyright
013: * notice, this list of conditions and the following disclaimer in
014: * the documentation and/or other materials provided with the
015: * distribution.
016: *
017: * 3. The end-user documentation included with the redistribution, if
018: * any, must include the following acknowledgement:
019: * "This product includes software developed by the
020: * Visigoth Software Society (http://www.visigoths.org/)."
021: * Alternately, this acknowledgement may appear in the software itself,
022: * if and wherever such third-party acknowledgements normally appear.
023: *
024: * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
025: * project contributors may be used to endorse or promote products derived
026: * from this software without prior written permission. For written
027: * permission, please contact visigoths@visigoths.org.
028: *
029: * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
030: * nor may "FreeMarker" or "Visigoth" appear in their names
031: * without prior written permission of the Visigoth Software Society.
032: *
033: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
034: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
035: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
036: * DISCLAIMED. IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
037: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
038: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
039: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
040: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
041: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
042: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
043: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
044: * SUCH DAMAGE.
045: * ====================================================================
046: *
047: * This software consists of voluntary contributions made by many
048: * individuals on behalf of the Visigoth Software Society. For more
049: * information on the Visigoth Software Society, please see
050: * http://www.visigoths.org/
051: */
052:
053: package freemarker.template;
054:
055: import java.io.IOException;
056: import java.io.Writer;
057: import java.util.Map;
058:
059: /**
060: * Objects that implement this interface can be used in a <code><transform></code>
061: * block to perform arbitrary transformations on a part of the template
062: * processing output.
063: * <P>Note that, as of FreeMarker 2.1, TemplateTransform Model
064: * has changed. This is a more powerful implementation.
065: * There is a quick-and-dirty way to patch any legacy
066: * TemplateTransformModel so that it implements the new API.
067: * You simply add the following as your implementation
068: * of the getWriter() call:
069: * <PRE>
070: *
071: * public Writer getWriter(final Writer out,
072: * Map args)
073: * {
074: * final StringBuffer buf = new StringBuffer();
075: * return new Writer() {
076: * public void write(char cbuf[], int off, int len) {
077: * buf.append(cbuf, off, len);
078: * }
079: *
080: * public void flush() throws IOException {
081: * out.flush();
082: * }
083: *
084: * public void close() throws IOException {
085: * StringReader sr = new StringReader(buf.toString());
086: * StringWriter sw = new StringWriter();
087: * transform(sr, sw);
088: * out.write(sw.toString());
089: * }
090: * };
091: * }
092: *
093: *
094: * </PRE>
095: *
096: * <P>Implementions of <tt>TemplateTransformModel</tt> should be thread-safe.
097: *
098: * @version $Id: TemplateTransformModel.java,v 1.36 2003/04/11 20:57:32 revusky Exp $
099: */
100: public interface TemplateTransformModel extends TemplateModel {
101:
102: /**
103: * Returns a writer that will be used by the engine to feed the
104: * transformation input to the transform. Each call to this method
105: * must return a new instance of the writer so that the transformation
106: * is thread-safe.
107: * @param out the character stream to which to write the transformed output
108: * @param args the arguments (if any) passed to the transformation as a
109: * map of key/value pairs where the keys are strings and the arguments are
110: * TemplateModel instances. This is never null.
111: * @return a writer to which the engine will feed the transformation
112: * input, or null if the transform does not support nested content (body).
113: * The returned writer can implement the {@link TransformControl}
114: * interface if it needs advanced control over the evaluation of the
115: * transformation body.
116: */
117: Writer getWriter(Writer out, Map args)
118: throws TemplateModelException, IOException;
119: }
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