Source code

001/*
002 *                    BioJava development code
003 *
004 * This code may be freely distributed and modified under the
005 * terms of the GNU Lesser General Public Licence.  This should
006 * be distributed with the code.  If you do not have a copy,
007 * see:
008 *
009 *      http://www.gnu.org/copyleft/lesser.html
010 *
011 * Copyright for this code is held jointly by the individual
012 * authors.  These should be listed in @author doc comments.
013 *
014 * For more information on the BioJava project and its aims,
015 * or to join the biojava-l mailing list, visit the home page
016 * at:
017 *
018 *      http://www.biojava.org/
019 *
020 */
021
022package org.biojava.nbio.core.util;
023
024import java.io.IOException;
025import java.io.PrintWriter;
026import java.util.*;
027
028/**
029 * Implementation of XMLWriter which emits nicely formatted documents
030 * to a PrintWriter.
031 *
032 * @author Thomas Down
033 * @since 1.3
034 */
035
036public class PrettyXMLWriter implements XMLWriter {
037        private int indentUnit = 2;
038
039        private PrintWriter writer;
040        private boolean isOpeningTag = false;
041        private boolean afterNewline = true;
042        private int indent = 0;
043
044        private Map<String, String> namespacePrefixes = new HashMap<String, String>();
045        private int namespaceSeed = 0;
046        private LinkedList<List<String>> namespaceBindings = new LinkedList<List<String>>();
047        private List<String> namespacesDeclared = new ArrayList<String>();
048
049        public PrettyXMLWriter(PrintWriter writer) {
050                this.writer = writer;
051        }
052
053        /**
054         * Declare a namespace for current and following elements
055         * 'prefixHint' is ignored entirely in this implementation      
056         * 
057         */
058        @Override
059        public void declareNamespace(String nsURI, String prefixHint)
060                throws IOException
061        {
062                if (!namespacePrefixes.containsKey(nsURI)) {
063                        if (isOpeningTag) {
064                                String prefix = allocPrefix(nsURI);
065                                attribute("xmlns:" + prefix, nsURI);
066                        } else {
067                                namespacesDeclared.add(nsURI);
068                        }
069                }
070        }
071
072        private void handleDeclaredNamespaces()
073                throws IOException
074        {
075                if (namespacesDeclared.size() == 0) {
076                        for (Iterator<String> nsi = namespacesDeclared.iterator(); nsi.hasNext(); ) {
077                                String nsURI = nsi.next();
078                                if (!namespacePrefixes.containsKey(nsURI)) {
079                                        String prefix = allocPrefix(nsURI);
080                                        attribute("xmlns:" + prefix, nsURI);
081                                }
082                        }
083                        namespacesDeclared.clear();
084                }
085        }
086
087        protected void writeIndent()
088                throws IOException
089        {
090                for (int i = 0; i < indent * indentUnit; ++i) {
091                        writer.write(' ');
092                }
093        }
094
095        private void _openTag()
096                throws IOException
097        {
098                if (isOpeningTag) {
099                        writer.println('>');
100                        afterNewline = true;
101                }
102                if (afterNewline) {
103                        writeIndent();
104                }
105                indent++;
106                isOpeningTag = true;
107                afterNewline = false;
108                namespaceBindings.add(null);
109        }
110
111        private String allocPrefix(String nsURI) {
112                String prefix = "ns" + (++namespaceSeed);
113                namespacePrefixes.put(nsURI, prefix);
114                List<String> bindings = namespaceBindings.getLast();
115                if (bindings == null) {
116                        bindings = new ArrayList<String>();
117                        namespaceBindings.removeLast();
118                        namespaceBindings.add(bindings);
119                }
120                bindings.add(nsURI);
121                return prefix;
122        }
123
124        @Override
125        public void openTag(String nsURI, String localName)
126                throws IOException
127        {
128                if (nsURI == null || nsURI.length() == 0)
129                {
130                        throw new IOException("Invalid namespace URI: "+nsURI);
131                }
132                _openTag();
133                boolean alloced = false;
134                String prefix = namespacePrefixes.get(nsURI);
135                if (prefix == null) {
136                        prefix = allocPrefix(nsURI);
137                        alloced = true;
138                }
139                writer.print('<');
140                writer.print(prefix);
141                writer.print(':');
142                writer.print(localName);
143                if (alloced) {
144                        attribute("xmlns:" + prefix, nsURI);
145                }
146                handleDeclaredNamespaces();
147        }
148
149        @Override
150        public void openTag(String qName)
151                throws IOException
152        {
153                _openTag();
154                writer.print('<');
155                writer.print(qName);
156                handleDeclaredNamespaces();
157        }
158
159        @Override
160        public void attribute(String nsURI, String localName, String value)
161                throws IOException
162        {
163                if (! isOpeningTag) {
164                        throw new IOException("attributes must follow an openTag");
165                }
166
167                String prefix = namespacePrefixes.get(nsURI);
168                if (prefix == null) {
169                        prefix = allocPrefix(nsURI);
170                        attribute("xmlns:" + prefix, nsURI);
171                }
172
173                writer.print(' ');
174                writer.print(prefix);
175                writer.print(':');
176                writer.print(localName);
177                writer.print("=\"");
178                printAttributeValue(value);
179                writer.print('"');
180        }
181
182        @Override
183        public void attribute(String qName, String value)
184                throws IOException
185        {
186                if (! isOpeningTag) {
187                        throw new IOException("attributes must follow an openTag");
188                }
189
190                writer.print(' ');
191                writer.print(qName);
192                writer.print("=\"");
193                printAttributeValue(value);
194                writer.print('"');
195        }
196
197        private void _closeTag() {
198                isOpeningTag = false;
199                afterNewline = true;
200                List<String> hereBindings = namespaceBindings.removeLast();
201                if (hereBindings != null) {
202                        for (Iterator<String> bi = hereBindings.iterator(); bi.hasNext(); ) {
203                                namespacePrefixes.remove(bi.next());
204                        }
205                }
206        }
207
208        @Override
209        public void closeTag(String nsURI, String localName)
210                throws IOException
211        {
212                String prefix = namespacePrefixes.get(nsURI);
213                if (prefix == null) {
214                        throw new IOException("Assertion failed: unknown namespace when closing tag");
215                }
216                indent--;
217
218                if (isOpeningTag) {
219                        writer.println(" />");
220                } else {
221                        if (afterNewline) {
222                                writeIndent();
223                        }
224                        writer.print("</");
225                        writer.print(prefix);
226                        writer.print(':');
227                        writer.print(localName);
228                        writer.println('>');
229                }
230                _closeTag();
231        }
232
233        @Override
234        public void closeTag(String qName)
235                throws IOException
236        {
237                indent--;
238
239                if (isOpeningTag) {
240                        writer.println(" />");
241                } else {
242                        if (afterNewline) {
243                                writeIndent();
244                        }
245                        writer.print("</");
246                        writer.print(qName);
247                        writer.println('>');
248                }
249                _closeTag();
250        }
251
252        @Override
253        public void println(String data)
254                throws IOException
255        {
256        if (isOpeningTag) {
257                writer.println('>');
258                isOpeningTag = false;
259        }
260        printChars(data);
261        writer.println();
262        afterNewline = true;
263        }
264
265        @Override
266        public void print(String data)
267                throws IOException
268        {
269        if (isOpeningTag) {
270                writer.print('>');
271                isOpeningTag = false;
272        }
273        printChars(data);
274        afterNewline = false;
275        }
276
277        // does not work for adding literal XML elements.
278        @Override
279        public void printRaw(String data)
280                throws IOException
281        {
282        writer.println(data);
283        }
284
285        protected void printChars(String data)
286                throws IOException
287        {
288        if (data == null) {
289                printChars("null");
290                return;
291        }
292
293        for (int pos = 0; pos < data.length(); ++pos) {
294                char c = data.charAt(pos);
295                if (c == '<' || c == '>' || c == '&') {
296                numericalEntity(c);
297                } else {
298                writer.write(c);
299                }
300        }
301        }
302
303        protected void printAttributeValue(String data)
304                throws IOException
305        {
306        if (data == null) {
307                printAttributeValue("null");
308                return;
309        }
310
311        for (int pos = 0; pos < data.length(); ++pos) {
312                char c = data.charAt(pos);
313                if (c == '<' || c == '>' || c == '&' || c == '"') {
314                numericalEntity(c);
315                } else {
316                writer.write(c);
317                }
318        }
319        }
320
321        protected void numericalEntity(char c)
322                throws IOException
323        {
324        writer.print("&#");
325        writer.print((int) c);
326        writer.print(';');
327        }
328
329        @Override
330        public void close()
331                throws IOException
332        {
333                writer.close();
334        }
335}