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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2023 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.event;

import net.sf.saxon.expr.parser.Loc;
import net.sf.saxon.lib.StandardURIChecker;
import net.sf.saxon.om.*;
import net.sf.saxon.pull.NamespaceContextImpl;
import net.sf.saxon.serialize.charcode.UTF16CharacterSet;
import net.sf.saxon.str.StringView;
import net.sf.saxon.str.UnicodeString;
import net.sf.saxon.trans.Err;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.type.Untyped;
import net.sf.saxon.z.IntPredicateProxy;

import javax.xml.namespace.NamespaceContext;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamWriter;
import java.util.*;

/**
 * This class implements the XmlStreamWriter interface, translating the events into Saxon
 * Receiver events. The Receiver can be anything: a serializer, a schema validator, a tree builder.
 *
 * 

This class does not itself perform "namespace repairing" as defined in the interface Javadoc * (also referred to as "prefix defaulting" in the StaX JSR specification). In normal use, however, * the events emitted by this class are piped into a {@link NamespaceReducer} which performs a function * very similar to namespace repairing; specifically, it ensures that when elements and attribute are * generated with a given namespace URI and local name, then namespace declarations are generated * automatically without any explicit need to call the {@link #writeNamespace(String, String)} method.

* *

The class will check all names, URIs, and character content for conformance against XML well-formedness * rules unless the checkValues option is set to false.

* *

The implementation of this class is influenced not only by the Javadoc documentation of the * XMLStreamWriter interface (which is woefully inadequate), but also by the helpful * but unofficial interpretation of the spec to be found at * http://veithen.github.io/2009/11/01/understanding-stax.html

* *

Provided that the sequence of events sent to this class is legitimate, the events * sent to the supplied {@code Receiver} should constitute a regular sequence * as defined in the documentation of class {@link RegularSequenceChecker}.

* * @since 9.3. Rewritten May 2015 to fix bug 2357. Further modified in 9.7.0.2 in light of the discussion * of bug 2398, and the interpretation of the spec cited above. */ public class StreamWriterToReceiver implements XMLStreamWriter { private static final boolean DEBUG = false; private static class Triple { public String prefix; public NamespaceUri uri; public String local; public String value; } private static class StartTag { public Triple elementName; public List attributes; public List namespaces; public StartTag() { elementName = new Triple(); attributes = new ArrayList<>(); namespaces = new ArrayList<>(); } } private StartTag pendingTag = null; private final Stack namespaceStack = new Stack<>(); /** * The receiver to which events will be passed */ private final Receiver receiver; /** * The Checker used for testing valid characters */ private final IntPredicateProxy charChecker; /** * Flag to indicate whether names etc are to be checked for well-formedness */ private boolean isChecking = false; /** * The current depth of element nesting. -1 indicates outside startDocument/endDocument; non-negative * values indicate the number of open start element tags */ private int depth = -1; /** * Flag indicating that an empty element has been requested. */ private boolean isEmptyElement; /** * inScopeNamespaces represents namespaces that have been declared in the XML stream */ private final NamespaceReducer inScopeNamespaces; /** * setPrefixes represents the namespace bindings that have been set, at each level of the stack, * using {@link #setPrefix}. There is one entry for each level of element nesting, and the entry is a list * of NamespaceBinding objects, that is, prefix/uri pairs */ private final Stack> setPrefixes = new Stack<>(); /** * rootNamespaceContext is the namespace context supplied at the start, is the final fallback * for allocating a prefix to a URI */ private javax.xml.namespace.NamespaceContext rootNamespaceContext = null; /** * Constructor. Creates a StreamWriter as a front-end to a given Receiver. * * @param receiver the Receiver that is to receive the events generated * by this StreamWriter. */ public StreamWriterToReceiver(Receiver receiver) { // Events are passed through a NamespaceReducer which maintains the namespace context // It also eliminates duplicate namespace declarations, and creates extra namespace declarations // where needed to support prefix-uri mappings used on elements and attributes PipelineConfiguration pipe = receiver.getPipelineConfiguration(); this.inScopeNamespaces = new NamespaceReducer(receiver); this.namespaceStack.push(NamespaceMap.emptyMap()); this.receiver = inScopeNamespaces; this.charChecker = pipe.getConfiguration().getValidCharacterChecker(); this.setPrefixes.push(new ArrayList<>()); this.rootNamespaceContext = new NamespaceContextImpl(NamespaceMap.emptyMap()); // See bug 2902; initialise rootNamespaceContext to an empty set of namespaces } /** * Get the Receiver to which this StreamWriterToReceiver is writing events * * @return the destination Receiver */ public Receiver getReceiver() { return receiver; } /** * Say whether names and values are to be checked for conformance with XML rules * * @param check true if names and values are to be checked. Default is false; */ public void setCheckValues(boolean check) { this.isChecking = check; } /** * Ask whether names and values are to be checked for conformance with XML rules * * @return true if names and values are to be checked. Default is false; */ public boolean isCheckValues() { return this.isChecking; } private void flushStartTag() throws XMLStreamException { if (depth == -1) { writeStartDocument(); } if (pendingTag != null) { try { completeTriple(pendingTag.elementName, false); for (Triple t : pendingTag.attributes) { completeTriple(t, true); } NodeName elemName; if (pendingTag.elementName.uri.isEmpty()) { elemName = new NoNamespaceName(pendingTag.elementName.local); } else { elemName = new FingerprintedQName(pendingTag.elementName.prefix, pendingTag.elementName.uri, pendingTag.elementName.local); } NamespaceMap nsMap = namespaceStack.peek(); if (!pendingTag.elementName.uri.isEmpty()) { nsMap = nsMap.put(pendingTag.elementName.prefix, pendingTag.elementName.uri); } for (Triple t : pendingTag.namespaces) { if (t.prefix == null) { t.prefix = ""; } if (t.uri == null) { t.uri = NamespaceUri.NULL; } if (!t.uri.isEmpty()) { nsMap = nsMap.put(t.prefix, t.uri); } } AttributeMap attributes = EmptyAttributeMap.getInstance(); for (Triple t : pendingTag.attributes) { NodeName attName; if (t.uri.isEmpty()) { attName = new NoNamespaceName(t.local); } else { attName = new FingerprintedQName(t.prefix, t.uri, t.local); nsMap = nsMap.put(t.prefix, t.uri); } attributes = attributes.put(new AttributeInfo(attName, BuiltInAtomicType.UNTYPED_ATOMIC, t.value, Loc.NONE, ReceiverOption.NONE)); } receiver.startElement(elemName, Untyped.getInstance(), attributes, nsMap, Loc.NONE, ReceiverOption.NONE); pendingTag = null; if (isEmptyElement) { isEmptyElement = false; depth--; setPrefixes.pop(); receiver.endElement(); } else { namespaceStack.push(nsMap); } } catch (XPathException e) { throw new XMLStreamException(e); } } } /** * Fill in the unknown parts of a (prefix, uri, localname) triple by reference to the namespace * context. *

For details see the table in the XMLStreamWriter javadoc.

* @param t the (prefix, uri, localname) triple. Note that the prefix will be null if not supplied * in the call, and will be "" if an empty string or null was supplied in the call; these * cases are handled differently. * @param isAttribute true if this is an attribute name rather than an element name * @throws XMLStreamException if the name is invalid or incomplete */ private void completeTriple(Triple t, boolean isAttribute) throws XMLStreamException { if (t.local == null) { throw new XMLStreamException("Local name of " + (isAttribute ? "Attribute" : "Element") + " is missing"); } if (isChecking && !isValidNCName(t.local)) { throw new XMLStreamException("Local name of " + (isAttribute ? "Attribute" : "Element") + Err.wrap(t.local) + " is invalid"); } if (t.prefix == null) { t.prefix = ""; } if (t.uri == null) { t.uri = NamespaceUri.NULL; } if (isChecking && !t.uri.isEmpty() && isInvalidURI(t.uri.toString())) { throw new XMLStreamException("Namespace URI " + Err.wrap(t.local) + " is invalid"); } if (t.prefix.isEmpty() && !t.uri.isEmpty()) { t.prefix = getPrefixForUri(t.uri); } } private String getPrefixForUri(NamespaceUri uri) { for (Triple t : pendingTag.namespaces) { if (uri.equals(t.uri)) { return t.prefix == null ? "" : t.prefix; } } String setPrefix = getPrefix(uri); if (setPrefix != null) { return setPrefix; } Iterator prefixes = inScopeNamespaces.iteratePrefixes(); while (prefixes.hasNext()) { String p = prefixes.next(); if (inScopeNamespaces.getURIForPrefix(p, false).equals(uri)) { return p; } } return ""; } /** * Generate a start element event for an element in no namespace. Note: the element * will be in no namespace, even if {@link #setDefaultNamespace(String)} has been called; * this is Saxon's interpretation of the intended effect of the StAX specification. * * @param localName local name of the tag, may not be null * @throws XMLStreamException if names are being checked and the name is invalid, or if an error occurs downstream * @throws NullPointerException if the supplied local name is null */ @Override public void writeStartElement(String localName) throws XMLStreamException { if (DEBUG) { System.err.println("StartElement " + localName); } checkNonNull(localName); setPrefixes.push(new ArrayList<>()); flushStartTag(); depth++; pendingTag = new StartTag(); pendingTag.elementName.local = localName; } /** * Generate a start element event. The name of the element is determined by the supplied * namespace URI and local name. The prefix used for the element is determined by the in-scope * prefixes established using {@link #setPrefix(String, String)} and/or {@link #setDefaultNamespace(String)} * if these include the specified namespace URI; otherwise the namespace will become the default namespace * and there will therefore be no prefix. * * @param namespaceURI the namespace URI of the element name. Must not be null. A zero-length * string means the element is in no namespace. * @param localName local part of the element name. Must not be null * @throws XMLStreamException if names are being checked and are found to be invalid, or if an * error occurs downstream in the pipeline. * @throws NullPointerException if either argument is null */ @Override public void writeStartElement(String namespaceURI, String localName) throws XMLStreamException { if (DEBUG) { System.err.println("StartElement Q{" + namespaceURI + "}" + localName); } checkNonNull(namespaceURI); checkNonNull(localName); setPrefixes.push(new ArrayList<>()); flushStartTag(); depth++; pendingTag = new StartTag(); pendingTag.elementName.local = localName; pendingTag.elementName.uri = NamespaceUri.of(namespaceURI); } /** * Generate a start element event. The name of the element is determined by the supplied * namespace URI and local name, and the prefix will be as supplied in the call. * * @param prefix the prefix of the element, must not be null. If the prefix is supplied as a zero-length * string, the element will nave no prefix (that is, the namespace URI will become the default * namespace). * @param localName local name of the element, must not be null * @param namespaceURI the uri to bind the prefix to, must not be null. If the value is a zero-length string, * the element will be in no namespace; in this case any prefix is ignored. * @throws NullPointerException if any of the arguments is null. * @throws XMLStreamException if names are being checked and are found to be invalid, or if an * error occurs downstream in the pipeline. */ @Override public void writeStartElement(String prefix, String localName, String namespaceURI) throws XMLStreamException { if (DEBUG) { System.err.println("StartElement " + prefix + "=Q{" + namespaceURI + "}" + localName); } checkNonNull(prefix); checkNonNull(localName); checkNonNull(namespaceURI); setPrefixes.push(new ArrayList<>()); flushStartTag(); depth++; pendingTag = new StartTag(); pendingTag.elementName.local = localName; pendingTag.elementName.uri = NamespaceUri.of(namespaceURI); pendingTag.elementName.prefix = prefix; } @Override public void writeEmptyElement(String namespaceURI, String localName) throws XMLStreamException { checkNonNull(namespaceURI); checkNonNull(localName); flushStartTag(); writeStartElement(namespaceURI, localName); isEmptyElement = true; } @Override public void writeEmptyElement(String prefix, String localName, String namespaceURI) throws XMLStreamException { checkNonNull(prefix); checkNonNull(localName); checkNonNull(namespaceURI); flushStartTag(); writeStartElement(prefix, localName, namespaceURI); isEmptyElement = true; } @Override public void writeEmptyElement(String localName) throws XMLStreamException { checkNonNull(localName); flushStartTag(); writeStartElement(localName); isEmptyElement = true; } @Override public void writeEndElement() throws XMLStreamException { if (DEBUG) { System.err.println("EndElement" + depth); } if (depth <= 0) { throw new IllegalStateException("writeEndElement with no matching writeStartElement"); } // if (isEmptyElement) { // throw new IllegalStateException("writeEndElement called for an empty element"); // } try { flushStartTag(); setPrefixes.pop(); namespaceStack.pop(); receiver.endElement(); depth--; } catch (XPathException err) { throw new XMLStreamException(err); } } @Override public void writeEndDocument() throws XMLStreamException { if (depth == -1) { throw new IllegalStateException("writeEndDocument with no matching writeStartDocument"); } try { flushStartTag(); while (depth > 0) { writeEndElement(); } receiver.endDocument(); depth = -1; } catch (XPathException err) { throw new XMLStreamException(err); } } @Override public void close() throws XMLStreamException { if (depth >= 0) { writeEndDocument(); } try { receiver.close(); } catch (XPathException err) { throw new XMLStreamException(err); } } @Override public void flush() { // no action } @Override public void writeAttribute(String localName, String value) { checkNonNull(localName); checkNonNull(value); if (pendingTag == null) { throw new IllegalStateException("Cannot write attribute when not in a start tag"); } Triple t = new Triple(); t.local = localName; t.value = value; pendingTag.attributes.add(t); } @Override public void writeAttribute(String prefix, String namespaceURI, String localName, String value) { checkNonNull(prefix); checkNonNull(namespaceURI); checkNonNull(localName); checkNonNull(value); if (pendingTag == null) { throw new IllegalStateException("Cannot write attribute when not in a start tag"); } Triple t = new Triple(); t.prefix = prefix; t.uri = NamespaceUri.of(namespaceURI); t.local = localName; t.value = value; pendingTag.attributes.add(t); } @Override public void writeAttribute(String namespaceURI, String localName, String value) { checkNonNull(namespaceURI); checkNonNull(localName); checkNonNull(value); Triple t = new Triple(); t.uri = NamespaceUri.of(namespaceURI); t.local = localName; t.value = value; pendingTag.attributes.add(t); } /** * Emits a namespace declaration event. * *

If the prefix argument to this method is the empty string, * "xmlns", or null this method will delegate to writeDefaultNamespace.

* *

This method does not change the name of any element or attribute; its only use is to write * additional or redundant namespace declarations. With this implementation of XMLStreamWriter, * this method is needed only to generate namespace declarations for prefixes that do not appear * in element or attribute names. If an attempt is made to generate a namespace declaration that * conflicts with the prefix-uri bindings in scope for element and attribute names, an exception * occurs.

* * @param prefix the prefix to bind this namespace to * @param namespaceURI the uri to bind the prefix to * @throws IllegalStateException if the current state does not allow Namespace writing * @throws XMLStreamException if things go wrong */ @Override public void writeNamespace(String prefix, String namespaceURI) throws XMLStreamException { if (prefix == null || prefix.equals("") || prefix.equals("xmlns")) { writeDefaultNamespace(namespaceURI); } else { checkNonNull(namespaceURI); if (pendingTag == null) { throw new IllegalStateException("Cannot write namespace when not in a start tag"); } Triple t = new Triple(); t.uri = NamespaceUri.of(namespaceURI); t.prefix = prefix; pendingTag.namespaces.add(t); } } /** * Emits a default namespace declaration * *

This method does not change the name of any element or attribute; its only use is to write * additional or redundant namespace declarations. With this implementation of XMLStreamWriter, * this method is needed only to generate namespace declarations for prefixes that do not appear * in element or attribute names. If an attempt is made to generate a namespace declaration that * conflicts with the prefix-uri bindings in scope for element and attribute names, an exception * occurs.

* * @param namespaceURI the uri to bind the default namespace to * @throws IllegalStateException if the current state does not allow Namespace writing */ @Override public void writeDefaultNamespace(String namespaceURI) { checkNonNull(namespaceURI); if (pendingTag == null) { throw new IllegalStateException("Cannot write namespace when not in a start tag"); } Triple t = new Triple(); t.uri = NamespaceUri.of(namespaceURI); pendingTag.namespaces.add(t); } @Override public void writeComment(String data) throws XMLStreamException { flushStartTag(); if (data == null) { data = ""; } UnicodeString uData = StringView.of(data); try { if (!isValidChars(uData)) { throw new IllegalArgumentException("Invalid XML character in comment: " + data); } if (isChecking && data.contains("--")) { throw new IllegalArgumentException("Comment contains '--'"); } receiver.comment(uData, Loc.NONE, ReceiverOption.NONE); } catch (XPathException err) { throw new XMLStreamException(err); } } @Override public void writeProcessingInstruction(String target) throws XMLStreamException { writeProcessingInstruction(target, ""); } @Override public void writeProcessingInstruction(/*@NotNull*/ String target, /*@NotNull*/ String data) throws XMLStreamException { checkNonNull(target); checkNonNull(data); flushStartTag(); final UnicodeString uData = StringView.of(data); try { if (isChecking) { if (!isValidNCName(target) || "xml".equalsIgnoreCase(target)) { throw new IllegalArgumentException("Invalid PITarget: " + target); } if (!isValidChars(uData)) { throw new IllegalArgumentException("Invalid character in PI data: " + data); } } receiver.processingInstruction(target, uData, Loc.NONE, ReceiverOption.NONE); } catch (XPathException err) { throw new XMLStreamException(err); } } @Override public void writeCData(/*@NotNull*/ String data) throws XMLStreamException { checkNonNull(data); flushStartTag(); writeCharacters(data); } @Override public void writeDTD(String dtd) throws XMLStreamException { // no-op } @Override public void writeEntityRef(String name) { throw new UnsupportedOperationException("writeEntityRef"); } @Override public void writeStartDocument() throws XMLStreamException { writeStartDocument("utf-8", "1.0"); } @Override public void writeStartDocument(/*@Nullable*/ String version) throws XMLStreamException { writeStartDocument("utf-8", version); } @Override public void writeStartDocument(/*@Nullable*/ String encoding, /*@Nullable*/ String version) throws XMLStreamException { if (encoding == null) { encoding = "utf-8"; } if (version == null) { version = "1.0"; } if (depth != -1) { throw new IllegalStateException("writeStartDocument must be the first call"); } try { receiver.open(); receiver.startDocument(ReceiverOption.NONE); } catch (XPathException err) { throw new XMLStreamException(err); } depth = 0; } @Override public void writeCharacters(String text) throws XMLStreamException { checkNonNull(text); flushStartTag(); final UnicodeString uData = StringView.of(text); if (!isValidChars(uData)) { throw new IllegalArgumentException("illegal XML character: " + text); } try { receiver.characters(uData, Loc.NONE, ReceiverOption.NONE); } catch (XPathException err) { throw new XMLStreamException(err); } } @Override public void writeCharacters(char[] text, int start, int len) throws XMLStreamException { checkNonNull(text); writeCharacters(new String(text, start, len)); } @Override public String getPrefix(String uri) { return getPrefix(NamespaceUri.of(uri)); } private String getPrefix(NamespaceUri uri) { for (int i=setPrefixes.size()-1; i>=0; i--) { List bindings = setPrefixes.get(i); for (int j=bindings.size()-1; j>=0; j--) { NamespaceBinding binding = bindings.get(j); if (binding.getNamespaceUri().equals(uri)) { return binding.getPrefix(); } } } if (rootNamespaceContext != null) { return rootNamespaceContext.getPrefix(uri.toString()); } return null; } @Override public void setPrefix(String prefix, String uri) { // See Saxon bug 2398: this should have stack-like effect checkNonNull(prefix); if (uri == null) { uri = ""; } if (isInvalidURI(uri)) { throw new IllegalArgumentException("Invalid namespace URI: " + uri); } if (!"".equals(prefix) && !isValidNCName(prefix)) { throw new IllegalArgumentException("Invalid namespace prefix: " + prefix); } setPrefixes.peek().add(new NamespaceBinding(prefix, NamespaceUri.of(uri))); } @Override public void setDefaultNamespace(String uri) { setPrefix("", uri); } @Override public void setNamespaceContext(javax.xml.namespace.NamespaceContext context) { // Note, we do not enforce the rule that this can only be called once, because the spec is self-contradictory // on this point. if (depth > 0) { throw new IllegalStateException("setNamespaceContext may only be called at the start of the document"); } // Unfortunately the JAXP NamespaceContext class does not allow us to discover all the namespaces // that were declared, nor to declare new ones. So we have to retain it separately rootNamespaceContext = context; } /** * Return the current namespace context. * *

The specification of this method is hopelessly vague. This method returns a namespace context * that contains the namespaces declared using {@link #setPrefix(String, String)} calls that are * in-scope at the time, overlaid on the root namespace context that was defined using * {@link #setNamespaceContext(NamespaceContext)}. The namespaces bound using {@link #setPrefix(String, String)} * are copied, and are therefore unaffected by subsequent changes, but the root namespace context * is not copied, because the {@link NamespaceContext} interface provides no way of doing so.

* @return a copy of the current namespace context. */ @Override public javax.xml.namespace.NamespaceContext getNamespaceContext() { return new StreamWriterNamespaceContext(this); } private static class StreamWriterNamespaceContext implements javax.xml.namespace.NamespaceContext { final NamespaceContext rootNamespaceContext; final Map bindings = new HashMap<>(); public StreamWriterNamespaceContext(StreamWriterToReceiver streamWriter) { rootNamespaceContext = streamWriter.rootNamespaceContext; for (List list : streamWriter.setPrefixes) { for (NamespaceBinding binding : list) { bindings.put(binding.getPrefix(), binding.getNamespaceUri()); } } } @Override public String getNamespaceURI(String prefix) { NamespaceUri uri = bindings.get(prefix); if (uri != null) { return uri.toString(); } return rootNamespaceContext.getNamespaceURI(prefix); } @Override public String getPrefix(String namespaceURI) { for (Map.Entry entry : bindings.entrySet()) { if (entry.getValue().toString().equals(namespaceURI)) { return entry.getKey(); } } return rootNamespaceContext.getPrefix(namespaceURI); } @Override public Iterator getPrefixes(String namespaceURI) { List prefixes = new ArrayList<>(); for (Map.Entry entry : bindings.entrySet()) { if (entry.getValue().toString().equals(namespaceURI)) { prefixes.add(entry.getKey()); } } @SuppressWarnings("unchecked") Iterator root = (Iterator)rootNamespaceContext.getPrefixes(namespaceURI); while (root.hasNext()) { prefixes.add(root.next()); } return prefixes.iterator(); } } @Override public Object getProperty(String name) throws IllegalArgumentException { if (name.equals("javax.xml.stream.isRepairingNamespaces")) { return receiver instanceof NamespaceReducer; } else { throw new IllegalArgumentException(name); } } /** * Test whether a supplied name is a valid NCName * * @param name the name to be tested * @return true if the name is valid or if checking is disabled */ private boolean isValidNCName(String name) { return !isChecking || NameChecker.isValidNCName(name); } /** * Test whether a supplied character string is valid in XML * * @param text the string to be tested * @return true if the string is valid or if checking is disabled */ private boolean isValidChars(UnicodeString text) { return !isChecking || (UTF16CharacterSet.firstInvalidChar(text.codePoints(), charChecker) == -1); } /** * Test whether a supplied namespace URI is a valid URI * * @param uri the namespace URI to be tested * @return true if the name is invalid (unless checking is disabled) */ private boolean isInvalidURI(String uri) { return isChecking && !StandardURIChecker.getInstance().isValidURI(uri); } private void checkNonNull(Object value) { if (value == null) { throw new NullPointerException(); } } }




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