net.sf.saxon.pull.TreeWalker Maven / Gradle / Ivy
package net.sf.saxon.pull;
import net.sf.saxon.event.PipelineConfiguration;
import net.sf.saxon.om.*;
import net.sf.saxon.tinytree.TinyNodeImpl;
import net.sf.saxon.tinytree.TinyTreeWalker;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.Type;
import net.sf.saxon.value.AtomicValue;
import javax.xml.transform.SourceLocator;
import java.util.Stack;
import java.util.List;
/**
* This implementation of the Saxon pull interface starts from any NodeInfo,
* and returns the events corresponding to that node and its descendants (including
* their attributes and namespaces). This works with any tree model: alternative
* implementations may be available that take advantage of particular implementations
* of the tree model.
*/
public class TreeWalker implements PullProvider, SourceLocator {
private NodeInfo startNode;
private NodeInfo currentNode;
private int currentEvent;
private Stack iteratorStack = new Stack();
private PipelineConfiguration pipe;
/**
* Factory method to get a tree walker starting an a given node
* @param startNode the start node
* @return a PullProvider that delivers events associated with the subtree starting at the given node
*/
public static PullProvider makeTreeWalker(NodeInfo startNode) {
if (startNode instanceof UnconstructedParent) {
return ((UnconstructedParent)startNode).getPuller();
}
if (startNode instanceof TinyNodeImpl) {
switch (startNode.getNodeKind()) {
case Type.DOCUMENT:
case Type.ELEMENT:
return new TinyTreeWalker((TinyNodeImpl)startNode);
default:
return new PullFromIterator(SingletonIterator.makeIterator(startNode));
}
} else {
return new TreeWalker(startNode);
}
}
/**
* Private constructor: the class should be instantiated using the static factory method
* @param startNode the root node of the subtree to be walked
*/
private TreeWalker(NodeInfo startNode) {
this.startNode = startNode;
}
/**
* Set configuration information. This must only be called before any events
* have been read.
*/
public void setPipelineConfiguration(PipelineConfiguration pipe) {
this.pipe = pipe;
}
/**
* Get configuration information.
*/
public PipelineConfiguration getPipelineConfiguration() {
return pipe;
}
/**
* Get the next event
*
* @return an integer code indicating the type of event. The code
* {@link #END_OF_INPUT} is returned if there are no more events to return.
*/
public int next() throws XPathException {
switch(currentEvent) {
case START_OF_INPUT:
currentNode = startNode;
switch (currentNode.getNodeKind()) {
case Type.DOCUMENT:
currentEvent = START_DOCUMENT;
break;
case Type.ELEMENT:
currentEvent = START_ELEMENT;
break;
case Type.TEXT:
currentEvent = TEXT;
break;
case Type.COMMENT:
currentEvent = COMMENT;
break;
case Type.PROCESSING_INSTRUCTION:
currentEvent = PROCESSING_INSTRUCTION;
break;
case Type.ATTRIBUTE:
currentEvent = ATTRIBUTE;
break;
case Type.NAMESPACE:
currentEvent = NAMESPACE;
break;
}
return currentEvent;
case START_DOCUMENT:
case START_ELEMENT:
AxisIterator kids = currentNode.iterateAxis(Axis.CHILD);
iteratorStack.push(kids);
currentNode = (NodeInfo)kids.next();
if (currentNode != null) {
switch (currentNode.getNodeKind()) {
case Type.ELEMENT:
currentEvent = START_ELEMENT;
break;
case Type.TEXT:
currentEvent = TEXT;
break;
case Type.COMMENT:
currentEvent = COMMENT;
break;
case Type.PROCESSING_INSTRUCTION:
currentEvent = PROCESSING_INSTRUCTION;
break;
}
return currentEvent;
} else {
iteratorStack.pop();
if (iteratorStack.isEmpty()) {
currentNode = startNode;
}
if (currentEvent == START_DOCUMENT) {
currentEvent = END_DOCUMENT;
} else {
currentEvent = END_ELEMENT;
}
return currentEvent;
}
case TEXT:
case COMMENT:
case PROCESSING_INSTRUCTION:
case END_ELEMENT:
if (iteratorStack.isEmpty()) {
if (currentNode == startNode) {
currentNode = null;
currentEvent = END_OF_INPUT;
} else {
currentNode = startNode;
if (currentNode.getNodeKind() == Type.ELEMENT) {
currentEvent = END_ELEMENT;
} else {
currentEvent = END_DOCUMENT;
}
}
return currentEvent;
}
AxisIterator siblings = (AxisIterator)iteratorStack.peek();
currentNode = (NodeInfo)siblings.next();
if (currentNode == null) {
iteratorStack.pop();
if (iteratorStack.isEmpty()) {
currentNode = startNode;
if (currentNode.getNodeKind() == Type.ELEMENT) {
currentEvent = END_ELEMENT;
} else {
currentEvent = END_DOCUMENT;
}
return currentEvent;
}
AxisIterator uncles = (AxisIterator)iteratorStack.peek();
currentNode = (NodeInfo)uncles.current();
if (currentNode.getNodeKind() == Type.DOCUMENT) {
currentEvent = END_DOCUMENT;
} else {
currentEvent = END_ELEMENT;
}
return currentEvent;
} else {
switch (currentNode.getNodeKind()) {
case Type.ELEMENT:
currentEvent = START_ELEMENT;
break;
case Type.TEXT:
currentEvent = TEXT;
break;
case Type.COMMENT:
currentEvent = COMMENT;
break;
case Type.PROCESSING_INSTRUCTION:
currentEvent = PROCESSING_INSTRUCTION;
break;
}
return currentEvent;
}
case ATTRIBUTE:
case NAMESPACE:
case END_DOCUMENT:
currentEvent = END_OF_INPUT;
return currentEvent;
case END_OF_INPUT:
throw new IllegalStateException("Cannot call next() when input is exhausted");
default:
throw new IllegalStateException("Unrecognized event " + currentEvent);
}
}
/**
* Get the event most recently returned by next(), or by other calls that change
* the position, for example getStringValue() and skipToMatchingEnd(). This
* method does not change the position of the PullProvider.
*
* @return the current event
*/
public int current() {
return currentEvent;
}
/**
* Get the attributes associated with the current element. This method must
* be called only after a START_ELEMENT event has been notified. The contents
* of the returned AttributeCollection are guaranteed to remain unchanged
* until the next START_ELEMENT event, but may be modified thereafter. The object
* should not be modified by the client.
*
* Attributes may be read before or after reading the namespaces of an element,
* but must not be read after the first child node has been read, or after calling
* one of the methods skipToEnd(), getStringValue(), or getTypedValue().
*
* @return an AttributeCollection representing the attributes of the element
* that has just been notified.
*/
public AttributeCollection getAttributes() throws XPathException {
if (currentNode.getNodeKind() == Type.ELEMENT) {
AttributeCollectionImpl atts = new AttributeCollectionImpl(getNamePool());
SequenceIterator iter = currentNode.iterateAxis(Axis.ATTRIBUTE);
while (true) {
NodeInfo node = (NodeInfo)iter.next();
if (node == null) {
break;
}
atts.addAttribute(node.getNameCode(), node.getTypeAnnotation(), node.getStringValue(), 0, 0);
}
return atts;
} else {
throw new IllegalStateException("getAttributes() called when current event is not ELEMENT_START");
}
}
/**
* Get the namespace declarations associated with the current element. This method must
* be called only after a START_ELEMENT event has been notified. In the case of a top-level
* START_ELEMENT event (that is, an element that either has no parent node, or whose parent
* is not included in the sequence being read), the NamespaceDeclarations object returned
* will contain a namespace declaration for each namespace that is in-scope for this element
* node. In the case of a non-top-level element, the NamespaceDeclarations will contain
* a set of namespace declarations and undeclarations, representing the differences between
* this element and its parent.
*
* It is permissible for this method to return namespace declarations that are redundant.
*
* The NamespaceDeclarations object is guaranteed to remain unchanged until the next START_ELEMENT
* event, but may then be overwritten. The object should not be modified by the client.
*
* Namespaces may be read before or after reading the attributes of an element,
* but must not be read after the first child node has been read, or after calling
* one of the methods skipToEnd(), getStringValue(), or getTypedValue().
*
*/
public NamespaceDeclarations getNamespaceDeclarations() throws XPathException {
if (currentNode.getNodeKind() == Type.ELEMENT) {
if (iteratorStack.isEmpty()) {
// get all inscope namespaces for a top-level element in the sequence.
int[] codes = NamespaceIterator.getInScopeNamespaceCodes(currentNode);
return new NamespaceDeclarationsImpl(getNamePool(), codes);
} else {
// only namespace declarations (and undeclarations) on this element are required
return new NamespaceDeclarationsImpl(getNamePool(), currentNode.getDeclaredNamespaces(nsBuffer));
}
}
throw new IllegalStateException("getNamespaceDeclarations() called when current event is not ELEMENT_START");
}
private int[] nsBuffer = new int[10];
/**
* Skip the current subtree. This method may be called only immediately after
* a START_DOCUMENT or START_ELEMENT event. This call returns the matching
* END_DOCUMENT or END_ELEMENT event; the next call on next() will return
* the event following the END_DOCUMENT or END_ELEMENT.
*/
public int skipToMatchingEnd() throws XPathException {
// For this implementation, we simply leave the current node unchanged, and change
// the current event
switch (currentEvent) {
case START_DOCUMENT:
currentEvent = END_DOCUMENT;
return currentEvent;
case START_ELEMENT:
currentEvent = END_ELEMENT;
return currentEvent;
default:
throw new IllegalStateException(
"Cannot call skipToMatchingEnd() except when at start of element or document");
}
}
/**
* Close the event reader. This indicates that no further events are required.
* It is not necessary to close an event reader after {@link #END_OF_INPUT} has
* been reported, but it is recommended to close it if reading terminates
* prematurely. Once an event reader has been closed, the effect of further
* calls on next() is undefined.
*/
public void close() {
// no action
}
/**
* Get the namePool used to lookup all name codes and namespace codes
*
* @return the namePool
*/
public NamePool getNamePool() {
return pipe.getConfiguration().getNamePool();
}
/**
* Get the nameCode identifying the name of the current node. This method
* can be used after the {@link #START_ELEMENT}, {@link #PROCESSING_INSTRUCTION},
* {@link #ATTRIBUTE}, or {@link #NAMESPACE} events. With some PullProvider implementations,
* including this one, it can also be used after {@link #END_ELEMENT}.
* If called at other times, the result is undefined and may result in an IllegalStateException.
* If called when the current node is an unnamed namespace node (a node representing the default namespace)
* the returned value is -1.
* @return the nameCode. The nameCode can be used to obtain the prefix, local name,
* and namespace URI from the name pool.
*/
public int getNameCode() {
return currentNode.getNameCode();
}
/**
* Get the fingerprint of the name of the element. This is similar to the nameCode, except that
* it does not contain any information about the prefix: so two elements with the same fingerprint
* have the same name, excluding prefix. This method
* can be used after the {@link #START_ELEMENT}, {@link #END_ELEMENT}, {@link #PROCESSING_INSTRUCTION},
* {@link #ATTRIBUTE}, or {@link #NAMESPACE} events.
* If called at other times, the result is undefined and may result in an IllegalStateException.
* If called when the current node is an unnamed namespace node (a node representing the default namespace)
* the returned value is -1.
*
* @return the fingerprint. The fingerprint can be used to obtain the local name
* and namespace URI from the name pool.
*/
public int getFingerprint() {
return currentNode.getFingerprint();
}
/**
* Get the string value of the current attribute, text node, processing-instruction,
* or atomic value.
* This method cannot be used to obtain the string value of an element, or of a namespace
* node. If the most recent event was anything other than {@link #START_ELEMENT}, {@link #TEXT},
* {@link #PROCESSING_INSTRUCTION}, or {@link #ATOMIC_VALUE}, the result is undefined.
*/
public CharSequence getStringValue() throws XPathException {
if (currentNode.getNodeKind() == Type.ELEMENT) {
skipToMatchingEnd();
}
return currentNode.getStringValueCS();
}
/**
* Get the type annotation of the current attribute or element node, or atomic value.
* The result of this method is undefined unless the most recent event was START_ELEMENT,
* START_CONTENT, ATTRIBUTE, or ATOMIC_VALUE.
*
* @return the type code. This code is the fingerprint of a type name, which may be
* resolved to a {@link net.sf.saxon.type.SchemaType} by access to the Configuration.
*/
public int getTypeAnnotation() {
return currentNode.getTypeAnnotation();
}
/**
* Get an atomic value. This call may be used only when the last event reported was
* ATOMIC_VALUE. This indicates that the PullProvider is reading a sequence that contains
* a free-standing atomic value; it is never used when reading the content of a node.
*/
public AtomicValue getAtomicValue() {
throw new IllegalStateException();
}
/**
* Get the location of the current event.
* For an event stream representing a real document, the location information
* should identify the location in the lexical XML source. For a constructed document, it should
* identify the location in the query or stylesheet that caused the node to be created.
* A value of null can be returned if no location information is available.
*/
public SourceLocator getSourceLocator() {
return this;
}
/**
* Return the public identifier for the current document event.
*
* The return value is the public identifier of the document
* entity or of the external parsed entity in which the markup that
* triggered the event appears.
*
* @return A string containing the public identifier, or
* null if none is available.
* @see #getSystemId
*/
public String getPublicId() {
return null;
}
/**
* Return the system identifier for the current document event.
*
* The return value is the system identifier of the document
* entity or of the external parsed entity in which the markup that
* triggered the event appears.
*
* If the system identifier is a URL, the parser must resolve it
* fully before passing it to the application.
*
* @return A string containing the system identifier, or null
* if none is available.
* @see #getPublicId
*/
public String getSystemId() {
return currentNode.getSystemId();
}
/**
* Return the line number where the current document event ends.
*
* Warning: The return value from the method
* is intended only as an approximation for the sake of error
* reporting; it is not intended to provide sufficient information
* to edit the character content of the original XML document.
*
* The return value is an approximation of the line number
* in the document entity or external parsed entity where the
* markup that triggered the event appears.
*
* @return The line number, or -1 if none is available.
* @see #getColumnNumber
*/
public int getLineNumber() {
return currentNode.getLineNumber();
}
/**
* Return the character position where the current document event ends.
*
* Warning: The return value from the method
* is intended only as an approximation for the sake of error
* reporting; it is not intended to provide sufficient information
* to edit the character content of the original XML document.
*
* The return value is an approximation of the column number
* in the document entity or external parsed entity where the
* markup that triggered the event appears.
*
* @return The column number, or -1 if none is available.
* @see #getLineNumber
*/
public int getColumnNumber() {
return -1;
}
/**
* Get a list of unparsed entities.
*
* @return a list of unparsed entities, or null if the information is not available, or
* an empty list if there are no unparsed entities.
*/
public List getUnparsedEntities() {
return null;
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
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