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Diffstat (limited to 'libjava/gnu/xml/pipeline/DomConsumer.java')
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diff --git a/libjava/gnu/xml/pipeline/DomConsumer.java b/libjava/gnu/xml/pipeline/DomConsumer.java new file mode 100644 index 00000000000..17fdeeb3453 --- /dev/null +++ b/libjava/gnu/xml/pipeline/DomConsumer.java @@ -0,0 +1,969 @@ +/* DomConsumer.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.Hashtable; + +import org.w3c.dom.*; +import org.xml.sax.*; +import org.xml.sax.ext.DeclHandler; +import org.xml.sax.ext.LexicalHandler; +import org.xml.sax.helpers.AttributesImpl; + +import gnu.xml.aelfred2.ContentHandler2; +import gnu.xml.util.DomParser; + + +/** + * This consumer builds a DOM Document from its input, acting either as a + * pipeline terminus or as an intermediate buffer. When a document's worth + * of events has been delivered to this consumer, that document is read with + * a {@link DomParser} and sent to the next consumer. It is also available + * as a read-once property. + * + * <p>The DOM tree is constructed as faithfully as possible. There are some + * complications since a DOM should expose behaviors that can't be implemented + * without API backdoors into that DOM, and because some SAX parsers don't + * report all the information that DOM permits to be exposed. The general + * problem areas involve information from the Document Type Declaration (DTD). + * DOM only represents a limited subset, but has some behaviors that depend + * on much deeper knowledge of a document's DTD. You shouldn't have much to + * worry about unless you change handling of "noise" nodes from its default + * setting (which ignores them all); note if you use JAXP to populate your + * DOM trees, it wants to save "noise" nodes by default. (Such nodes include + * ignorable whitespace, comments, entity references and CDATA boundaries.) + * Otherwise, your + * main worry will be if you use a SAX parser that doesn't flag ignorable + * whitespace unless it's validating (few don't). + * + * <p> The SAX2 events used as input must contain XML Names for elements + * and attributes, with original prefixes. In SAX2, + * this is optional unless the "namespace-prefixes" parser feature is set. + * Moreover, many application components won't provide completely correct + * structures anyway. <em>Before you convert a DOM to an output document, + * you should plan to postprocess it to create or repair such namespace + * information.</em> The {@link NSFilter} pipeline stage does such work. + * + * <p> <em>Note: changes late in DOM L2 process made it impractical to + * attempt to create the DocumentType node in any implementation-neutral way, + * much less to populate it (L1 didn't support even creating such nodes). + * To create and populate such a node, subclass the inner + * {@link DomConsumer.Handler} class and teach it about the backdoors into + * whatever DOM implementation you want. It's possible that some revised + * DOM API (L3?) will make this problem solvable again. </em> + * + * @see DomParser + * + * @author David Brownell + */ +public class DomConsumer implements EventConsumer +{ + private Class domImpl; + + private boolean hidingCDATA = true; + private boolean hidingComments = true; + private boolean hidingWhitespace = true; + private boolean hidingReferences = true; + + private Handler handler; + private ErrorHandler errHandler; + + private EventConsumer next; + + // FIXME: this can't be a generic pipeline stage just now, + // since its input became a Class not a String (to be turned + // into a class, using the right class loader) + + + /** + * Configures this pipeline terminus to use the specified implementation + * of DOM when constructing its result value. + * + * @param impl class implementing {@link org.w3c.dom.Document Document} + * which publicly exposes a default constructor + * + * @exception SAXException when there is a problem creating an + * empty DOM document using the specified implementation + */ + public DomConsumer (Class impl) + throws SAXException + { + domImpl = impl; + handler = new Handler (this); + } + + /** + * This is the hook through which a subclass provides a handler + * which knows how to access DOM extensions, specific to some + * implementation, to record additional data in a DOM. + * Treat this as part of construction; don't call it except + * before (or between) parses. + */ + protected void setHandler (Handler h) + { + handler = h; + } + + + private Document emptyDocument () + throws SAXException + { + try { + return (Document) domImpl.newInstance (); + } catch (IllegalAccessException e) { + throw new SAXException ("can't access constructor: " + + e.getMessage ()); + } catch (InstantiationException e) { + throw new SAXException ("can't instantiate Document: " + + e.getMessage ()); + } + } + + + /** + * Configures this consumer as a buffer/filter, using the specified + * DOM implementation when constructing its result value. + * + * <p> This event consumer acts as a buffer and filter, in that it + * builds a DOM tree and then writes it out when <em>endDocument</em> + * is invoked. Because of the limitations of DOM, much information + * will as a rule not be seen in that replay. To get a full fidelity + * copy of the input event stream, use a {@link TeeConsumer}. + * + * @param impl class implementing {@link org.w3c.dom.Document Document} + * which publicly exposes a default constructor + * @param next receives a "replayed" sequence of parse events when + * the <em>endDocument</em> method is invoked. + * + * @exception SAXException when there is a problem creating an + * empty DOM document using the specified DOM implementation + */ + public DomConsumer (Class impl, EventConsumer n) + throws SAXException + { + this (impl); + next = n; + } + + + /** + * Returns the document constructed from the preceding + * sequence of events. This method should not be + * used again until another sequence of events has been + * given to this EventConsumer. + */ + final public Document getDocument () + { + return handler.clearDocument (); + } + + public void setErrorHandler (ErrorHandler handler) + { + errHandler = handler; + } + + + /** + * Returns true if the consumer is hiding entity references nodes + * (the default), and false if EntityReference nodes should + * instead be created. Such EntityReference nodes will normally be + * empty, unless an implementation arranges to populate them and then + * turn them back into readonly objects. + * + * @see #setHidingReferences + */ + final public boolean isHidingReferences () + { return hidingReferences; } + + /** + * Controls whether the consumer will hide entity expansions, + * or will instead mark them with entity reference nodes. + * + * @see #isHidingReferences + * @param flag False if entity reference nodes will appear + */ + final public void setHidingReferences (boolean flag) + { hidingReferences = flag; } + + + /** + * Returns true if the consumer is hiding comments (the default), + * and false if they should be placed into the output document. + * + * @see #setHidingComments + */ + public final boolean isHidingComments () + { return hidingComments; } + + /** + * Controls whether the consumer is hiding comments. + * + * @see #isHidingComments + */ + public final void setHidingComments (boolean flag) + { hidingComments = flag; } + + + /** + * Returns true if the consumer is hiding ignorable whitespace + * (the default), and false if such whitespace should be placed + * into the output document as children of element nodes. + * + * @see #setHidingWhitespace + */ + public final boolean isHidingWhitespace () + { return hidingWhitespace; } + + /** + * Controls whether the consumer hides ignorable whitespace + * + * @see #isHidingComments + */ + public final void setHidingWhitespace (boolean flag) + { hidingWhitespace = flag; } + + + /** + * Returns true if the consumer is saving CDATA boundaries, or + * false (the default) otherwise. + * + * @see #setHidingCDATA + */ + final public boolean isHidingCDATA () + { return hidingCDATA; } + + /** + * Controls whether the consumer will save CDATA boundaries. + * + * @see #isHidingCDATA + * @param flag True to treat CDATA text differently from other + * text nodes + */ + final public void setHidingCDATA (boolean flag) + { hidingCDATA = flag; } + + + + /** Returns the document handler being used. */ + final public ContentHandler getContentHandler () + { return handler; } + + /** Returns the DTD handler being used. */ + final public DTDHandler getDTDHandler () + { return handler; } + + /** + * Returns the lexical handler being used. + * (DOM construction can't really use declaration handlers.) + */ + final public Object getProperty (String id) + throws SAXNotRecognizedException + { + if ("http://xml.org/sax/properties/lexical-handler".equals (id)) + return handler; + if ("http://xml.org/sax/properties/declaration-handler".equals (id)) + return handler; + throw new SAXNotRecognizedException (id); + } + + EventConsumer getNext () { return next; } + + ErrorHandler getErrorHandler () { return errHandler; } + + /** + * Class used to intercept various parsing events and use them to + * populate a DOM document. Subclasses would typically know and use + * backdoors into specific DOM implementations, used to implement + * DTD-related functionality. + * + * <p> Note that if this ever throws a DOMException (runtime exception) + * that will indicate a bug in the DOM (e.g. doesn't support something + * per specification) or the parser (e.g. emitted an illegal name, or + * accepted illegal input data). </p> + */ + public static class Handler + implements ContentHandler2, LexicalHandler, + DTDHandler, DeclHandler + { + protected DomConsumer consumer; + + private DOMImplementation impl; + private Document document; + private boolean isL2; + + private Locator locator; + private Node top; + private boolean inCDATA; + private boolean mergeCDATA; + private boolean inDTD; + private String currentEntity; + + private boolean recreatedAttrs; + private AttributesImpl attributes = new AttributesImpl (); + + /** + * Subclasses may use SAX2 events to provide additional + * behaviors in the resulting DOM. + */ + protected Handler (DomConsumer consumer) + throws SAXException + { + this.consumer = consumer; + document = consumer.emptyDocument (); + impl = document.getImplementation (); + isL2 = impl.hasFeature ("XML", "2.0"); + } + + private void fatal (String message, Exception x) + throws SAXException + { + SAXParseException e; + ErrorHandler errHandler = consumer.getErrorHandler ();; + + if (locator == null) + e = new SAXParseException (message, null, null, -1, -1, x); + else + e = new SAXParseException (message, locator, x); + if (errHandler != null) + errHandler.fatalError (e); + throw e; + } + + /** + * Returns and forgets the document produced. If the handler is + * reused, a new document may be created. + */ + Document clearDocument () + { + Document retval = document; + document = null; + locator = null; + return retval; + } + + /** + * Returns the document under construction. + */ + protected Document getDocument () + { return document; } + + /** + * Returns the current node being populated. This is usually + * an Element or Document, but it might be an EntityReference + * node if some implementation-specific code knows how to put + * those into the result tree and later mark them as readonly. + */ + protected Node getTop () + { return top; } + + + // SAX1 + public void setDocumentLocator (Locator locator) + { + this.locator = locator; + } + + // SAX1 + public void startDocument () + throws SAXException + { + if (document == null) + try { + if (isL2) { + // couple to original implementation + document = impl.createDocument (null, "foo", null); + document.removeChild (document.getFirstChild ()); + } else { + document = consumer.emptyDocument (); + } + } catch (Exception e) { + fatal ("DOM create document", e); + } + top = document; + } + + // ContentHandler2 + public void xmlDecl(String version, + String encoding, + boolean standalone, + String inputEncoding) + throws SAXException + { + if (document != null) + { + document.setXmlVersion(version); + document.setXmlStandalone(standalone); + } + } + + // SAX1 + public void endDocument () + throws SAXException + { + try { + if (consumer.getNext () != null && document != null) { + DomParser parser = new DomParser (document); + + EventFilter.bind (parser, consumer.getNext ()); + parser.parse ("ignored"); + } + } finally { + top = null; + } + } + + // SAX1 + public void processingInstruction (String target, String data) + throws SAXException + { + // we can't create populated entity ref nodes using + // only public DOM APIs (they've got to be readonly) + if (currentEntity != null) + return; + + ProcessingInstruction pi; + + if (isL2 + // && consumer.isUsingNamespaces () + && target.indexOf (':') != -1) + namespaceError ( + "PI target name is namespace nonconformant: " + + target); + if (inDTD) + return; + pi = document.createProcessingInstruction (target, data); + top.appendChild (pi); + } + + /** + * Subclasses may overrride this method to provide a more efficient + * way to construct text nodes. + * Typically, copying the text into a single character array will + * be more efficient than doing that as well as allocating other + * needed for a String, including an internal StringBuffer. + * Those additional memory and CPU costs can be incurred later, + * if ever needed. + * Unfortunately the standard DOM factory APIs encourage those costs + * to be incurred early. + */ + protected Text createText ( + boolean isCDATA, + char ch [], + int start, + int length + ) { + String value = new String (ch, start, length); + + if (isCDATA) + return document.createCDATASection (value); + else + return document.createTextNode (value); + } + + // SAX1 + public void characters (char ch [], int start, int length) + throws SAXException + { + // we can't create populated entity ref nodes using + // only public DOM APIs (they've got to be readonly + // at creation time) + if (currentEntity != null) + return; + + Node lastChild = top.getLastChild (); + + // merge consecutive text or CDATA nodes if appropriate. + if (lastChild instanceof Text) { + if (consumer.isHidingCDATA () + // consecutive Text content ... always merge + || (!inCDATA + && !(lastChild instanceof CDATASection)) + // consecutive CDATASection content ... don't + // merge between sections, only within them + || (inCDATA && mergeCDATA + && lastChild instanceof CDATASection) + ) { + CharacterData last = (CharacterData) lastChild; + String value = new String (ch, start, length); + + last.appendData (value); + return; + } + } + if (inCDATA && !consumer.isHidingCDATA ()) { + top.appendChild (createText (true, ch, start, length)); + mergeCDATA = true; + } else + top.appendChild (createText (false, ch, start, length)); + } + + // SAX2 + public void skippedEntity (String name) + throws SAXException + { + // this callback is useless except to report errors, since + // we can't know if the ref was in content, within an + // attribute, within a declaration ... only one of those + // cases supports more intelligent action than a panic. + fatal ("skipped entity: " + name, null); + } + + // SAX2 + public void startPrefixMapping (String prefix, String uri) + throws SAXException + { + // reconstruct "xmlns" attributes deleted by all + // SAX2 parsers without "namespace-prefixes" = true + if ("".equals (prefix)) + attributes.addAttribute ("", "", "xmlns", + "CDATA", uri); + else + attributes.addAttribute ("", "", "xmlns:" + prefix, + "CDATA", uri); + recreatedAttrs = true; + } + + // SAX2 + public void endPrefixMapping (String prefix) + throws SAXException + { } + + // SAX2 + public void startElement ( + String uri, + String localName, + String qName, + Attributes atts + ) throws SAXException + { + // we can't create populated entity ref nodes using + // only public DOM APIs (they've got to be readonly) + if (currentEntity != null) + return; + + // parser discarded basic information; DOM tree isn't writable + // without massaging to assign prefixes to all nodes. + // the "NSFilter" class does that massaging. + if (qName.length () == 0) + qName = localName; + + + Element element; + int length = atts.getLength (); + + if (!isL2) { + element = document.createElement (qName); + + // first the explicit attributes ... + length = atts.getLength (); + for (int i = 0; i < length; i++) + element.setAttribute (atts.getQName (i), + atts.getValue (i)); + // ... then any recreated ones (DOM deletes duplicates) + if (recreatedAttrs) { + recreatedAttrs = false; + length = attributes.getLength (); + for (int i = 0; i < length; i++) + element.setAttribute (attributes.getQName (i), + attributes.getValue (i)); + attributes.clear (); + } + + top.appendChild (element); + top = element; + return; + } + + // For an L2 DOM when namespace use is enabled, use + // createElementNS/createAttributeNS except when + // (a) it's an element in the default namespace, or + // (b) it's an attribute with no prefix + String namespace; + + if (localName.length () != 0) + namespace = (uri.length () == 0) ? null : uri; + else + namespace = getNamespace (getPrefix (qName), atts); + + if (namespace == null) + element = document.createElement (qName); + else + element = document.createElementNS (namespace, qName); + + populateAttributes (element, atts); + if (recreatedAttrs) { + recreatedAttrs = false; + // ... DOM deletes any duplicates + populateAttributes (element, attributes); + attributes.clear (); + } + + top.appendChild (element); + top = element; + } + + final static String xmlnsURI = "http://www.w3.org/2000/xmlns/"; + + private void populateAttributes (Element element, Attributes attrs) + throws SAXParseException + { + int length = attrs.getLength (); + + for (int i = 0; i < length; i++) { + String type = attrs.getType (i); + String value = attrs.getValue (i); + String name = attrs.getQName (i); + String local = attrs.getLocalName (i); + String uri = attrs.getURI (i); + + // parser discarded basic information, DOM tree isn't writable + if (name.length () == 0) + name = local; + + // all attribute types other than these three may not + // contain scoped names... enumerated attributes get + // reported as NMTOKEN, except for NOTATION values + if (!("CDATA".equals (type) + || "NMTOKEN".equals (type) + || "NMTOKENS".equals (type))) { + if (value.indexOf (':') != -1) { + namespaceError ( + "namespace nonconformant attribute value: " + + "<" + element.getNodeName () + + " " + name + "='" + value + "' ...>"); + } + } + + // xmlns="" is legal (undoes default NS) + // xmlns:foo="" is illegal + String prefix = getPrefix (name); + String namespace; + + if ("xmlns".equals (prefix)) { + if ("".equals (value)) + namespaceError ("illegal null namespace decl, " + name); + namespace = xmlnsURI; + } else if ("xmlns".equals (name)) + namespace = xmlnsURI; + + else if (prefix == null) + namespace = null; + else if (!"".equals(uri) && uri.length () != 0) + namespace = uri; + else + namespace = getNamespace (prefix, attrs); + + if (namespace == null) + element.setAttribute (name, value); + else + element.setAttributeNS (namespace, name, value); + } + } + + private String getPrefix (String name) + { + int temp; + + if ((temp = name.indexOf (':')) > 0) + return name.substring (0, temp); + return null; + } + + // used with SAX1-level parser output + private String getNamespace (String prefix, Attributes attrs) + throws SAXParseException + { + String namespace; + String decl; + + // defaulting + if (prefix == null) { + decl = "xmlns"; + namespace = attrs.getValue (decl); + if ("".equals (namespace)) + return null; + else if (namespace != null) + return namespace; + + // "xmlns" is like a keyword + // ... according to the Namespace REC, but DOM L2 CR2+ + // and Infoset violate that by assigning a namespace. + // that conflict is resolved elsewhere. + } else if ("xmlns".equals (prefix)) + return null; + + // "xml" prefix is fixed + else if ("xml".equals (prefix)) + return "http://www.w3.org/XML/1998/namespace"; + + // otherwise, expect a declaration + else { + decl = "xmlns:" + prefix; + namespace = attrs.getValue (decl); + } + + // if we found a local declaration, great + if (namespace != null) + return namespace; + + + // ELSE ... search up the tree we've been building + for (Node n = top; + n != null && n.getNodeType () != Node.DOCUMENT_NODE; + n = (Node) n.getParentNode ()) { + if (n.getNodeType () == Node.ENTITY_REFERENCE_NODE) + continue; + Element e = (Element) n; + Attr attr = e.getAttributeNode (decl); + if (attr != null) + return attr.getNodeValue (); + } + // see above re "xmlns" as keyword + if ("xmlns".equals (decl)) + return null; + + namespaceError ("Undeclared namespace prefix: " + prefix); + return null; + } + + // SAX2 + public void endElement (String uri, String localName, String qName) + throws SAXException + { + // we can't create populated entity ref nodes using + // only public DOM APIs (they've got to be readonly) + if (currentEntity != null) + return; + + top = top.getParentNode (); + } + + // SAX1 (mandatory reporting if validating) + public void ignorableWhitespace (char ch [], int start, int length) + throws SAXException + { + if (consumer.isHidingWhitespace ()) + return; + characters (ch, start, length); + } + + // SAX2 lexical event + public void startCDATA () + throws SAXException + { + inCDATA = true; + // true except for the first fragment of a cdata section + mergeCDATA = false; + } + + // SAX2 lexical event + public void endCDATA () + throws SAXException + { + inCDATA = false; + } + + // SAX2 lexical event + // + // this SAX2 callback merges two unrelated things: + // - Declaration of the root element type ... belongs with + // the other DTD declaration methods, NOT HERE. + // - IDs for the optional external subset ... belongs here + // with other lexical information. + // + // ...and it doesn't include the internal DTD subset, desired + // both to support DOM L2 and to enable "pass through" processing + // + public void startDTD (String name, String publicId, String SystemId) + throws SAXException + { + // need to filter out comments and PIs within the DTD + inDTD = true; + } + + // SAX2 lexical event + public void endDTD () + throws SAXException + { + inDTD = false; + } + + // SAX2 lexical event + public void comment (char ch [], int start, int length) + throws SAXException + { + Node comment; + + // we can't create populated entity ref nodes using + // only public DOM APIs (they've got to be readonly) + if (consumer.isHidingComments () + || inDTD + || currentEntity != null) + return; + comment = document.createComment (new String (ch, start, length)); + top.appendChild (comment); + } + + /** + * May be overridden by subclasses to return true, indicating + * that entity reference nodes can be populated and then made + * read-only. + */ + public boolean canPopulateEntityRefs () + { return false; } + + // SAX2 lexical event + public void startEntity (String name) + throws SAXException + { + // are we ignoring what would be contents of an + // entity ref, since we can't populate it? + if (currentEntity != null) + return; + + // Are we hiding all entity boundaries? + if (consumer.isHidingReferences ()) + return; + + // SAX2 shows parameter entities; DOM hides them + if (name.charAt (0) == '%' || "[dtd]".equals (name)) + return; + + // Since we can't create a populated entity ref node in any + // standard way, we create an unpopulated one. + EntityReference ref = document.createEntityReference (name); + top.appendChild (ref); + top = ref; + + // ... allowing subclasses to populate them + if (!canPopulateEntityRefs ()) + currentEntity = name; + } + + // SAX2 lexical event + public void endEntity (String name) + throws SAXException + { + if (name.charAt (0) == '%' || "[dtd]".equals (name)) + return; + if (name.equals (currentEntity)) + currentEntity = null; + if (!consumer.isHidingReferences ()) + top = top.getParentNode (); + } + + + // SAX1 DTD event + public void notationDecl ( + String name, + String publicId, String SystemId + ) throws SAXException + { + /* IGNORE -- no public DOM API lets us store these + * into the doctype node + */ + } + + // SAX1 DTD event + public void unparsedEntityDecl ( + String name, + String publicId, String SystemId, + String notationName + ) throws SAXException + { + /* IGNORE -- no public DOM API lets us store these + * into the doctype node + */ + } + + // SAX2 declaration event + public void elementDecl (String name, String model) + throws SAXException + { + /* IGNORE -- no content model support in DOM L2 */ + } + + // SAX2 declaration event + public void attributeDecl ( + String eName, + String aName, + String type, + String mode, + String value + ) throws SAXException + { + /* IGNORE -- no attribute model support in DOM L2 */ + } + + // SAX2 declaration event + public void internalEntityDecl (String name, String value) + throws SAXException + { + /* IGNORE -- no public DOM API lets us store these + * into the doctype node + */ + } + + // SAX2 declaration event + public void externalEntityDecl ( + String name, + String publicId, + String SystemId + ) throws SAXException + { + /* IGNORE -- no public DOM API lets us store these + * into the doctype node + */ + } + + // + // These really should offer the option of nonfatal handling, + // like other validity errors, though that would cause major + // chaos in the DOM data structures. DOM is already spec'd + // to treat many of these as fatal, so this is consistent. + // + private void namespaceError (String description) + throws SAXParseException + { + SAXParseException err; + + err = new SAXParseException (description, locator); + throw err; + } + } +} |