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Diffstat (limited to 'libjava/gnu/xml/pipeline/WellFormednessFilter.java')
| -rw-r--r-- | libjava/gnu/xml/pipeline/WellFormednessFilter.java | 362 |
1 files changed, 362 insertions, 0 deletions
diff --git a/libjava/gnu/xml/pipeline/WellFormednessFilter.java b/libjava/gnu/xml/pipeline/WellFormednessFilter.java new file mode 100644 index 0000000..3047ae3 --- /dev/null +++ b/libjava/gnu/xml/pipeline/WellFormednessFilter.java @@ -0,0 +1,362 @@ +/* WellFormednessFilter.java -- + Copyright (C) 1999,2000,2001 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA +02111-1307 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + +package gnu.xml.pipeline; + +import java.util.EmptyStackException; +import java.util.Stack; + +import gnu.xml.aelfred2.SAXDriver; +import org.xml.sax.*; +import org.xml.sax.ext.*; + + +/** + * This filter reports fatal exceptions in the case of event streams that + * are not well formed. The rules currently tested include: <ul> + * + * <li>setDocumentLocator ... may be called only before startDocument + * + * <li>startDocument/endDocument ... must be paired, and all other + * calls (except setDocumentLocator) must be nested within these. + * + * <li>startElement/endElement ... must be correctly paired, and + * may never appear within CDATA sections. + * + * <li>comment ... can't contain "--" + * + * <li>character data ... can't contain "]]>" + * + * <li>whitespace ... can't contain CR + * + * <li>whitespace and character data must be within an element + * + * <li>processing instruction ... can't contain "?>" or CR + * + * <li>startCDATA/endCDATA ... must be correctly paired. + * + * </ul> + * + * <p> Other checks for event stream correctness may be provided in + * the future. For example, insisting that + * entity boundaries nest correctly, + * namespace scopes nest correctly, + * namespace values never contain relative URIs, + * attributes don't have "<" characters; + * and more. + * + * @author David Brownell + */ +public final class WellFormednessFilter extends EventFilter +{ + private boolean startedDoc; + private Stack elementStack = new Stack (); + private boolean startedCDATA; + private String dtdState = "before"; + + + /** + * Swallows all events after performing well formedness checks. + */ + // constructor used by PipelineFactory + public WellFormednessFilter () + { this (null); } + + + /** + * Passes events through to the specified consumer, after first + * processing them. + */ + // constructor used by PipelineFactory + public WellFormednessFilter (EventConsumer consumer) + { + super (consumer); + + setContentHandler (this); + setDTDHandler (this); + + try { + setProperty (LEXICAL_HANDLER, this); + } catch (SAXException e) { /* can't happen */ } + } + + /** + * Resets state as if any preceding event stream was well formed. + * Particularly useful if it ended through some sort of error, + * and the endDocument call wasn't made. + */ + public void reset () + { + startedDoc = false; + startedCDATA = false; + elementStack.removeAllElements (); + } + + + private SAXParseException getException (String message) + { + SAXParseException e; + Locator locator = getDocumentLocator (); + + if (locator == null) + return new SAXParseException (message, null, null, -1, -1); + else + return new SAXParseException (message, locator); + } + + private void fatalError (String message) + throws SAXException + { + SAXParseException e = getException (message); + ErrorHandler handler = getErrorHandler (); + + if (handler != null) + handler.fatalError (e); + throw e; + } + + /** + * Throws an exception when called after startDocument. + * + * @param locator the locator, to be used in error reporting or relative + * URI resolution. + * + * @exception IllegalStateException when called after the document + * has already been started + */ + public void setDocumentLocator (Locator locator) + { + if (startedDoc) + throw new IllegalStateException ( + "setDocumentLocator called after startDocument"); + super.setDocumentLocator (locator); + } + + public void startDocument () throws SAXException + { + if (startedDoc) + fatalError ("startDocument called more than once"); + startedDoc = true; + startedCDATA = false; + elementStack.removeAllElements (); + super.startDocument (); + } + + public void startElement ( + String uri, String localName, + String qName, Attributes atts + ) throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + if ("inside".equals (dtdState)) + fatalError ("element inside DTD?"); + else + dtdState = "after"; + if (startedCDATA) + fatalError ("element inside CDATA section"); + if (qName == null || "".equals (qName)) + fatalError ("startElement name missing"); + elementStack.push (qName); + super.startElement (uri, localName, qName, atts); + } + + public void endElement (String uri, String localName, String qName) + throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + if (startedCDATA) + fatalError ("element inside CDATA section"); + if (qName == null || "".equals (qName)) + fatalError ("endElement name missing"); + + try { + String top = (String) elementStack.pop (); + + if (!qName.equals (top)) + fatalError ("<" + top + " ...>...</" + qName + ">"); + // XXX could record/test namespace info + } catch (EmptyStackException e) { + fatalError ("endElement without startElement: </" + qName + ">"); + } + super.endElement (uri, localName, qName); + } + + public void endDocument () throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + dtdState = "before"; + startedDoc = false; + super.endDocument (); + } + + + public void startDTD (String root, String publicId, String systemId) + throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + if ("before" != dtdState) + fatalError ("two DTDs?"); + if (!elementStack.empty ()) + fatalError ("DTD must precede root element"); + dtdState = "inside"; + super.startDTD (root, publicId, systemId); + } + + public void notationDecl (String name, String publicId, String systemId) + throws SAXException + { +// FIXME: not all parsers will report startDTD() ... +// we'd rather insist we're "inside". + if ("after" == dtdState) + fatalError ("not inside DTD"); + super.notationDecl (name, publicId, systemId); + } + + public void unparsedEntityDecl (String name, + String publicId, String systemId, String notationName) + throws SAXException + { +// FIXME: not all parsers will report startDTD() ... +// we'd rather insist we're "inside". + if ("after" == dtdState) + fatalError ("not inside DTD"); + super.unparsedEntityDecl (name, publicId, systemId, notationName); + } + + // FIXME: add the four DeclHandler calls too + + public void endDTD () + throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + if ("inside" != dtdState) + fatalError ("DTD ends without start?"); + dtdState = "after"; + super.endDTD (); + } + + public void characters (char ch [], int start, int length) + throws SAXException + { + int here = start, end = start + length; + if (elementStack.empty ()) + fatalError ("characters must be in an element"); + while (here < end) { + if (ch [here++] != ']') + continue; + if (here == end) // potential problem ... + continue; + if (ch [here++] != ']') + continue; + if (here == end) // potential problem ... + continue; + if (ch [here++] == '>') + fatalError ("character data can't contain \"]]>\""); + } + super.characters (ch, start, length); + } + + public void ignorableWhitespace (char ch [], int start, int length) + throws SAXException + { + int here = start, end = start + length; + if (elementStack.empty ()) + fatalError ("characters must be in an element"); + while (here < end) { + if (ch [here++] == '\r') + fatalError ("whitespace can't contain CR"); + } + super.ignorableWhitespace (ch, start, length); + } + + public void processingInstruction (String target, String data) + throws SAXException + { + if (data.indexOf ('\r') > 0) + fatalError ("PIs can't contain CR"); + if (data.indexOf ("?>") > 0) + fatalError ("PIs can't contain \"?>\""); + } + + public void comment (char ch [], int start, int length) + throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + if (startedCDATA) + fatalError ("comments can't nest in CDATA"); + int here = start, end = start + length; + while (here < end) { + if (ch [here] == '\r') + fatalError ("comments can't contain CR"); + if (ch [here++] != '-') + continue; + if (here == end) + fatalError ("comments can't end with \"--->\""); + if (ch [here++] == '-') + fatalError ("comments can't contain \"--\""); + } + super.comment (ch, start, length); + } + + public void startCDATA () + throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + if (startedCDATA) + fatalError ("CDATA starts can't nest"); + startedCDATA = true; + super.startCDATA (); + } + + public void endCDATA () + throws SAXException + { + if (!startedDoc) + fatalError ("callback outside of document?"); + if (!startedCDATA) + fatalError ("CDATA end without start?"); + startedCDATA = false; + super.endCDATA (); + } +} |