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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 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.tree.wrapper;
import net.sf.saxon.Configuration;
import net.sf.saxon.event.Receiver;
import net.sf.saxon.om.*;
import net.sf.saxon.pattern.NodePredicate;
import net.sf.saxon.s9api.Location;
import net.sf.saxon.str.UnicodeString;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.NamespaceNode;
import net.sf.saxon.tree.iter.AxisIterator;
import net.sf.saxon.tree.iter.EmptyIterator;
import net.sf.saxon.tree.util.Navigator;
import net.sf.saxon.type.SchemaType;
import net.sf.saxon.type.Type;
import java.util.ArrayList;
import java.util.List;
import java.util.function.Supplier;
/**
* This class represents a node that is a virtual copy of another node: that is, it behaves as a node that's the
* same as another node, but has different identity. Moreover, this class can create a virtual copy of a subtree,
* so that the parent of the virtual copy is null rather than being a virtual copy of the parent of the original.
* This means that none of the axes when applied to the virtual copy is allowed to stray outside the subtree.
* The virtual copy is implemented by means of a reference to the node of which
* it is a copy, but methods that are sensitive to node identity return a different result.
*
*/
public class VirtualCopy implements NodeInfo {
protected Supplier systemIdSupplier;
protected NodeInfo original;
protected VirtualCopy parent;
protected NodeInfo root; // the node forming the root of the subtree that was copied
protected VirtualTreeInfo tree;
private boolean dropNamespaces = false;
/**
* Protected constructor: create a virtual copy of a node
*
* @param base the node to be copied
* @param root the node in the source tree corresponding to the root of the virtual tree. This must be an ancestor
* of the base node
*/
protected VirtualCopy(NodeInfo base, NodeInfo root) {
original = base;
//noinspection Convert2MethodRef
systemIdSupplier = () -> base.getBaseURI(); // computing the base URI can be expensive, so do it lazily
this.root = root;
}
/**
* Public factory method: create a parentless virtual tree as a copy of an existing node
*
* @param original the node to be copied
* @return the virtual copy. If the original was already a virtual copy, this will be a virtual copy
* of the real underlying node.
*/
public static VirtualCopy makeVirtualCopy(NodeInfo original) {
VirtualCopy vc;
// Don't allow copies of copies of copies: define the new copy in terms of the original
while (original instanceof VirtualCopy) {
original = ((VirtualCopy) original).original;
}
vc = new VirtualCopy(original, original);
Configuration config = original.getConfiguration();
VirtualTreeInfo doc = new VirtualTreeInfo(config, vc);
long docNr = config.getDocumentNumberAllocator().allocateDocumentNumber();
doc.setDocumentNumber(docNr);
vc.tree = doc;
return vc;
}
/**
* Wrap a node within an existing VirtualCopy.
*
* @param node the node to be wrapped
* @return a virtual copy of the node
*/
/*@NotNull*/
protected VirtualCopy wrap(NodeInfo node) {
VirtualCopy vc = new VirtualCopy(node, root);
vc.tree = tree;
vc.systemIdSupplier = systemIdSupplier;
vc.dropNamespaces = dropNamespaces;
return vc;
}
/**
* Get the original (wrapped) node
* @return the node of which this one is a virtual copy
*/
public NodeInfo getOriginalNode() {
return original;
}
/**
* Get information about the tree to which this NodeInfo belongs
*
* @return the TreeInfo
* @since 9.7
*/
@Override
public VirtualTreeInfo getTreeInfo() {
return tree;
}
/**
* Say that namespaces in the virtual tree should not be copied from the underlying
* tree. The semantics follow the rules for xsl:copy-of with copy-namespaces="no": that
* is, the only namespaces that are retained are those explicitly used in element or
* attribute nodes.
* @param drop true if namespaces are to be dropped
*/
public void setDropNamespaces(boolean drop) {
this.dropNamespaces = drop;
}
@Override
public NamespaceMap getAllNamespaces() {
if (getNodeKind() == Type.ELEMENT) {
if (dropNamespaces) {
NamespaceMap nsMap = NamespaceMap.emptyMap();
String ns = getURI();
if (!ns.isEmpty()) {
nsMap = nsMap.put(getPrefix(), ns);
}
AxisIterator iter = original.iterateAxis(AxisInfo.ATTRIBUTE);
NodeInfo att;
while ((att = iter.next()) != null) {
if (!att.getURI().equals("")) {
nsMap = nsMap.put(att.getPrefix(), att.getURI());
}
}
return nsMap;
} else {
return original.getAllNamespaces();
}
} else {
return null;
}
}
/**
* Get fingerprint. The fingerprint is a coded form of the expanded name
* of the node: two nodes
* with the same name code have the same namespace URI and the same local name.
* The fingerprint contains no information about the namespace prefix. For a name
* in the null namespace, the fingerprint is the same as the name code.
*
* @return an integer fingerprint; two nodes with the same fingerprint have
* the same expanded QName. For unnamed nodes (text nodes, comments, document nodes,
* and namespace nodes for the default namespace), returns -1.
* @throws UnsupportedOperationException if this kind of node does not hold
* namepool fingerprints (specifically, if {@link #hasFingerprint()} returns false).
* @since 8.4 (moved into FingerprintedNode at some stage; then back into NodeInfo at 9.8).
*/
@Override
public int getFingerprint() {
return original.getFingerprint();
}
/**
* Ask whether this NodeInfo implementation holds a fingerprint identifying the name of the
* node in the NamePool. If the answer is true, then the {@link #getFingerprint} method must
* return the fingerprint of the node. If the answer is false, then the {@link #getFingerprint}
* method should throw an {@code UnsupportedOperationException}. In the case of unnamed nodes
* such as text nodes, the result can be either true (in which case getFingerprint() should
* return -1) or false (in which case getFingerprint may throw an exception).
*
* @return true if the implementation of this node provides fingerprints.
* @since 9.8; previously Saxon relied on using FingerprintedNode as a marker interface.
*/
@Override
public boolean hasFingerprint() {
return original.hasFingerprint();
}
/**
* Get the kind of node. This will be a value such as Type.ELEMENT or Type.ATTRIBUTE
*
* @return an integer identifying the kind of node. These integer values are the
* same as those used in the DOM
* @see net.sf.saxon.type.Type
*/
@Override
public int getNodeKind() {
return original.getNodeKind();
}
/**
* Determine whether this is the same node as another node.
* Note: a.isSameNodeInfo(b) if and only if generateId(a)==generateId(b).
* This method has the same semantics as isSameNode() in DOM Level 3, but
* works on Saxon NodeInfo objects rather than DOM Node objects.
*
* @param other the node to be compared with this node
* @return true if this NodeInfo object and the supplied NodeInfo object represent
* the same node in the tree.
*/
public boolean equals(Object other) {
return other instanceof VirtualCopy &&
getTreeInfo() == ((VirtualCopy) other).getTreeInfo() &&
original.equals(((VirtualCopy) other).original);
}
/**
* The hashCode() method obeys the contract for hashCode(): that is, if two objects are equal
* (represent the same node) then they must have the same hashCode()
*/
public int hashCode() {
return original.hashCode() ^ ((int) (getTreeInfo().getDocumentNumber() & 0x7fffffff) << 19);
}
/**
* Get the System ID for the node.
*
* @return the System Identifier of the entity in the source document
* containing the node, or null if not known. Note this is not the
* same as the base URI: the base URI can be modified by xml:base, but
* the system ID cannot.
*/
@Override
public String getSystemId() {
return systemIdSupplier.get();
}
/**
* Get the Base URI for the node, that is, the URI used for resolving a relative URI contained
* in the node. This will be the same as the System ID unless xml:base has been used.
*
* @return the base URI of the node
*/
/*@Nullable*/
@Override
public String getBaseURI() {
return Navigator.getBaseURI(this);
}
/**
* Get line number
*
* @return the line number of the node in its original source document; or
* -1 if not available
*/
@Override
public int getLineNumber() {
return original.getLineNumber();
}
/**
* Get column number
*
* @return the column number of the node in its original source document; or -1 if not available
*/
@Override
public int getColumnNumber() {
return original.getColumnNumber();
}
/**
* Get an immutable copy of this Location object. By default Location objects may be mutable, so they
* should not be saved for later use. The result of this operation holds the same location information,
* but in an immutable form.
*/
@Override
public Location saveLocation() {
return this;
}
/**
* Determine the relative position of this node and another node, in document order.
* The other node will always be in the same document.
*
* @param other The other node, whose position is to be compared with this
* node
* @return -1 if this node precedes the other node, +1 if it follows the
* other node, or 0 if they are the same node. (In this case,
* isSameNode() will always return true, and the two nodes will
* produce the same result for generateId())
*/
@Override
public int compareOrder(/*@NotNull*/ NodeInfo other) {
if (other instanceof VirtualCopy) {
int c = root.compareOrder(((VirtualCopy) other).root);
if (c == 0) {
return original.compareOrder(((VirtualCopy) other).original);
} else {
return c;
}
} else {
return other.compareOrder(original);
}
}
/**
* Get the string value of the item
* @return the string value of this node
*/
@Override
public UnicodeString getUnicodeStringValue() {
return original.getUnicodeStringValue();
}
/**
* Get the local part of the name of this node. This is the name after the ":" if any.
*
* @return the local part of the name. For an unnamed node, returns "". Unlike the DOM
* interface, this returns the full name in the case of a non-namespaced name.
*/
@Override
public String getLocalPart() {
return original.getLocalPart();
}
/**
* Get the URI part of the name of this node. This is the URI corresponding to the
* prefix, or the URI of the default namespace if appropriate.
*
* @return The URI of the namespace of this node. For an unnamed node,
* or for a node with an empty prefix, return an empty
* string.
*/
@Override
public String getURI() {
return original.getURI();
}
/**
* Get the prefix of the name of the node. This is defined only for elements and attributes.
* If the node has no prefix, or for other kinds of node, return a zero-length string.
*
* @return The prefix of the name of the node.
*/
@Override
public String getPrefix() {
return original.getPrefix();
}
/**
* Get the display name of this node. For elements and attributes this is [prefix:]localname.
* For unnamed nodes, it is an empty string.
*
* @return The display name of this node. For a node with no name, return
* an empty string.
*/
@Override
public String getDisplayName() {
return original.getDisplayName();
}
/**
* Get the configuration
*/
@Override
public Configuration getConfiguration() {
return original.getConfiguration();
}
/**
* Get the type annotation of this node, if any. The type annotation is represented as
* SchemaType object.
* Types derived from a DTD are not reflected in the result of this method.
*
* @return For element and attribute nodes: the type annotation derived from schema
* validation (defaulting to xs:untyped and xs:untypedAtomic in the absence of schema
* validation). For comments, text nodes, processing instructions, and namespaces: null.
* For document nodes, either xs:untyped if the document has not been validated, or
* xs:anyType if it has.
* @since 9.4
*/
@Override
public SchemaType getSchemaType() {
return original.getSchemaType();
}
/**
* Get the NodeInfo object representing the parent of this node
*
* @return the parent of this node; null if this node has no parent
*/
/*@Nullable*/
@Override
public NodeInfo getParent() {
if (original.equals(root)) {
return null;
}
if (parent == null) {
NodeInfo basep = original.getParent();
if (basep == null) {
return null;
}
parent = wrap(basep);
}
return parent;
}
/**
* Return an iteration over all the nodes reached by the given axis from this node
* that match a given NodeTest
*
* @param axisNumber an integer identifying the axis; one of the constants
* defined in class net.sf.saxon.om.Axis
* @param nodeTest A pattern to be matched by the returned nodes; nodes
* that do not match this pattern are not included in the result
* @return an AxisIterator that scans the nodes reached by the axis in
* turn.
* @throws UnsupportedOperationException if the namespace axis is
* requested and this axis is not supported for this implementation.
* @see net.sf.saxon.om.AxisInfo
*/
@Override
public AxisIterator iterateAxis(int axisNumber, NodePredicate nodeTest) {
VirtualCopy newParent = null;
switch (axisNumber) {
case AxisInfo.CHILD:
case AxisInfo.ATTRIBUTE:
newParent = this;
break;
case AxisInfo.SELF:
case AxisInfo.PRECEDING_SIBLING:
case AxisInfo.FOLLOWING_SIBLING:
newParent = parent;
break;
// Ensure that the ancestor, ancestor-or-self, following, and preceding axes use an implementation
// that relies on getParent() to escape from the subtree
case AxisInfo.ANCESTOR:
return new Navigator.AxisFilter(
new Navigator.AncestorEnumeration(this, false), nodeTest);
case AxisInfo.ANCESTOR_OR_SELF:
return new Navigator.AxisFilter(
new Navigator.AncestorEnumeration(this, true), nodeTest);
case AxisInfo.NAMESPACE:
if (getNodeKind() != Type.ELEMENT) {
return EmptyIterator.ofNodes();
}
return NamespaceNode.makeIterator(this, nodeTest);
case AxisInfo.PARENT:
return Navigator.filteredSingleton(getParent(), nodeTest);
case AxisInfo.PRECEDING:
return new Navigator.AxisFilter(
new Navigator.PrecedingEnumeration(this, false), nodeTest);
case AxisInfo.FOLLOWING:
return new Navigator.AxisFilter(
new Navigator.FollowingEnumeration(this), nodeTest);
case AxisInfo.PRECEDING_OR_ANCESTOR:
return new Navigator.AxisFilter(
new Navigator.PrecedingEnumeration(this, true), nodeTest);
}
return makeCopier(original.iterateAxis(axisNumber, nodeTest), newParent, !AxisInfo.isSubtreeAxis[axisNumber]);
}
/**
* Get the string value of a given attribute of this node
*
* @param uri the namespace URI of the attribute name. Supply the empty string for an attribute
* that is in no namespace
* @param local the local part of the attribute name.
* @return the attribute value if it exists, or null if it does not exist. Always returns null
* if this node is not an element.
*/
@Override
public String getAttributeValue(/*@NotNull*/ String uri, /*@NotNull*/ String local) {
return original.getAttributeValue(uri, local);
}
/**
* Get the root node of the tree containing this node
*
* @return the NodeInfo representing the top-level ancestor of this node.
* This will not necessarily be a document node
*/
/*@Nullable*/
@Override
public NodeInfo getRoot() {
NodeInfo n = this;
while (true) {
NodeInfo p = n.getParent();
if (p == null) {
return n;
}
n = p;
}
}
/**
* Determine whether the node has any children.
* Note: the result is equivalent to
* getEnumeration(Axis.CHILD, AnyNodeTest.getInstance()).hasNext()
*
* @return True if the node has one or more children
*/
@Override
public boolean hasChildNodes() {
return original.hasChildNodes();
}
/**
* Get a character string that uniquely identifies this node.
* Note: a.isSameNode(b) if and only if generateId(a)==generateId(b)
*
* @param buffer a buffer, to which will be appended
* a string that uniquely identifies this node, across all
* documents.
*/
@Override
public void generateId(/*@NotNull*/ StringBuilder buffer) {
buffer.append("d");
buffer.append(getTreeInfo().getDocumentNumber());
original.generateId(buffer);
}
/**
* Copy this node to a given outputter
* @param out the Receiver to which the node should be copied
* @param copyOptions a selection of the options defined in {@link CopyOptions}
* @param locationId Identifies the location of the instruction
*/
@Override
public void copy(Receiver out, int copyOptions, Location locationId) throws XPathException {
if (dropNamespaces) {
copyOptions &= ~CopyOptions.ALL_NAMESPACES;
}
original.copy(out, copyOptions, locationId);
}
/**
* Get all namespace declarations and undeclarations defined on this element.
*
* @param buffer If this is non-null, and the result array fits in this buffer, then the result
* may overwrite the contents of this array, to avoid the cost of allocating a new array on the heap.
* @return An array representing the namespace declarations and undeclarations present on
* this element. For a node other than an element, return null. Otherwise, the returned array is a
* sequence of NamespaceBinding objects.
* The XML namespace is never included in the list. If the supplied array is larger than required,
* then the first unused entry will be set to null.
* For a VirtualCopy, the method needs to return all namespaces that are in scope for
* this element, because the virtual copy is assumed to contain copies of all the in-scope
* namespaces of the original.
*/
@Override
@SuppressWarnings("deprecation")
public NamespaceBinding[] getDeclaredNamespaces(NamespaceBinding[] buffer) {
if (getNodeKind() == Type.ELEMENT) {
if (dropNamespaces) {
List allNamespaces = new ArrayList<>(5);
String ns = getURI();
if (ns.isEmpty()) {
if (getParent() != null && !getParent().getURI().isEmpty()) {
allNamespaces.add(new NamespaceBinding("", ""));
}
} else {
allNamespaces.add(new NamespaceBinding(getPrefix(), getURI()));
}
for (AttributeInfo att : original.attributes()) {
NodeName name = att.getNodeName();
if (name.getURI() != null) {
NamespaceBinding b = new NamespaceBinding(name.getPrefix(), name.getURI());
if (!allNamespaces.contains(b)) {
allNamespaces.add(b);
}
}
}
return allNamespaces.toArray(NamespaceBinding.EMPTY_ARRAY);
} else {
if (original == root) {
List bindings = new ArrayList<>();
for (NamespaceBinding binding : original.getAllNamespaces()) {
bindings.add(binding);
}
return bindings.toArray(NamespaceBinding.EMPTY_ARRAY);
} else {
return original.getDeclaredNamespaces(buffer);
}
}
} else {
return null;
}
}
/**
* Set the system identifier for this Source.
* The system identifier is optional if the source does not
* get its data from a URL, but it may still be useful to provide one.
* The application can use a system identifier, for example, to resolve
* relative URIs and to include in error messages and warnings.
*
* @param systemId The system identifier as a URL string.
*/
@Override
public void setSystemId(String systemId) {
this.systemIdSupplier = () -> systemId;
}
/**
* Get the typed value.
*
* @return the typed value. If requireSingleton is set to true, the result will always be an
* AtomicValue. In other cases it may be a Value representing a sequence whose items are atomic
* values.
* @since 8.5
*/
@Override
public AtomicSequence atomize() throws XPathException {
return original.atomize();
}
/**
* Determine whether this node has the is-id property
*
* @return true if the node is an ID
*/
@Override
public boolean isId() {
return original.isId();
}
/**
* Determine whether this node has the is-idref property
*
* @return true if the node is an IDREF or IDREFS element or attribute
*/
@Override
public boolean isIdref() {
return original.isIdref();
}
/**
* Determine whether the node has the is-nilled property
*
* @return true if the node has the is-nilled property
*/
@Override
public boolean isNilled() {
return original.isNilled();
}
/**
* 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
*/
/*@Nullable*/
@Override
public String getPublicId() {
return original != null ? original.getPublicId() : null;
}
/**
* Ask whether a node in the source tree is within the scope of this virtual copy
* @param sourceNode the node being tested
* @return true if the node is within the scope of the subtree
*/
protected boolean isIncludedInCopy(NodeInfo sourceNode) {
return Navigator.isAncestorOrSelf(root, sourceNode);
}
/**
* Create an iterator that makes and returns virtual copies of nodes on the original tree
*
* @param axis the axis to be navigated
* @param newParent the parent of the nodes in the new virtual tree (may be null)
* @param testInclusion if true, it is necessary to test whether nodes found in the source tree are
* included in the copy. If false, this test is unnecessary.
* @return the iterator that does the copying
*/
protected VirtualCopier makeCopier(AxisIterator axis, VirtualCopy newParent, boolean testInclusion) {
return new VirtualCopier(this, axis, newParent, testInclusion);
}
/**
* VirtualCopier implements the XPath axes as applied to a VirtualCopy node. It works by
* applying the requested axis to the node of which this is a copy. There are two
* complications: firstly, all nodes encountered must themselves be (virtually) copied
* to give them a new identity. Secondly, axes that stray outside the subtree rooted at
* the original copied node must be truncated.
*/
protected static class VirtualCopier implements AxisIterator {
protected VirtualCopy node;
protected AxisIterator base;
private final VirtualCopy parent;
protected boolean testInclusion;
public VirtualCopier(VirtualCopy node, AxisIterator base, VirtualCopy parent, boolean testInclusion) {
this.node = node;
this.base = base;
this.parent = parent;
this.testInclusion = testInclusion;
}
/**
* Get the next item in the sequence.
*
* @return the next Item. If there are no more nodes, return null.
*/
/*@Nullable*/
@Override
public NodeInfo next() {
NodeInfo next = base.next();
if (next != null) {
if (testInclusion && !node.isIncludedInCopy(next)) {
// we're only interested in nodes within the subtree that was copied.
// Assert: once we find a node outside this subtree, all further nodes will also be outside
// the subtree.
return null;
}
VirtualCopy vc = node.wrap(next);
vc.parent = parent;
vc.systemIdSupplier = node.systemIdSupplier;
next = vc;
}
return next;
}
@Override
public void close() {
base.close();
}
@Override
public void discharge() {
base.discharge();
}
}
}