net.sf.saxon.tree.linked.TreeEnumeration Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of saxon-he Show documentation
Show all versions of saxon-he Show documentation
An OSGi bundle for Saxon-HE
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 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.linked;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.pattern.NodeTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.iter.AxisIterator;
import net.sf.saxon.tree.iter.LookaheadIterator;
abstract class TreeEnumeration implements AxisIterator, LookaheadIterator {
protected NodeImpl start;
/*@Nullable*/ protected NodeImpl next;
protected NodeTest nodeTest;
/*@Nullable*/ protected NodeImpl current = null;
protected int position = 0;
//protected int last = -1;
/**
* Create an axis enumeration for a given type and name of node, from a given
* origin node
* @param origin the node from which the axis originates
* @param nodeTest test to be satisfied by the returned nodes, or null if all nodes
* are to be returned.
*/
public TreeEnumeration(NodeImpl origin, NodeTest nodeTest) {
next = origin;
start = origin;
this.nodeTest = nodeTest;
}
/**
* Test whether a node conforms to the node type and name constraints.
* Note that this returns true if the supplied node is null, this is a way of
* terminating a loop.
* @param node the node to be tested
* @return true if the node matches the requested node type and name
*/
protected boolean conforms(/*@Nullable*/ NodeImpl node) {
return node == null || nodeTest == null || nodeTest.matches(node);
}
/**
* Advance along the axis until a node is found that matches the required criteria
*/
protected final void advance() {
do {
step();
} while (!conforms(next));
}
/**
* Advance one step along the axis: the resulting node might not meet the required
* criteria for inclusion
*/
protected abstract void step();
/**
* Determine whether there are more items to come. Note that this operation
* is stateless and it is not necessary (or usual) to call it before calling
* next(). It is used only when there is an explicit need to tell if we
* are at the last element.
*
* @return true if there are more items in the sequence
*/
public boolean hasNext() {
return next != null;
}
/**
* Move to the next node, without returning it. Returns true if there is
* a next node, false if the end of the sequence has been reached. After
* calling this method, the current node may be retrieved using the
* current() function.
*/
public boolean moveNext() {
return (next() != null);
}
/**
* Return the next node in the sequence
*/
/*@Nullable*/ public final NodeInfo next() {
if (next==null) {
current = null;
position = -1;
return null;
} else {
current = next;
position++;
advance();
return current;
}
}
/**
* Return the current Item
*/
/*@Nullable*/ public final NodeInfo current() {
return current;
}
/**
* Return the current position
*/
public final int position() {
return position;
}
/**
* Indicate that no more items are required from the iterator
*/
public void close() {
}
/**
* Return an iterator over an axis, starting at the current node.
*
* @param axis the axis to iterate over, using a constant such as
* {@link net.sf.saxon.om.AxisInfo#CHILD}
* @param test a predicate to apply to the nodes before returning them.
* @throws NullPointerException if there is no current node
*/
public AxisIterator iterateAxis(byte axis, /*@NotNull*/ NodeTest test) {
return current.iterateAxis(axis, test);
}
/**
* Return the atomized value of the current node.
*
* @return the atomized value.
* @throws NullPointerException if there is no current node
*/
public Sequence atomize() throws XPathException {
return current.atomize();
}
/**
* Return the string value of the current node.
*
* @return the string value, as an instance of CharSequence.
* @throws NullPointerException if there is no current node
*/
public CharSequence getStringValue() {
return current.getStringValueCS();
}
/**
* Get properties of this iterator, as a bit-significant integer.
*
* @return the properties of this iterator. This will be some combination of
* properties such as {@link #GROUNDED}, {@link #LAST_POSITION_FINDER},
* and {@link #LOOKAHEAD}. It is always
* acceptable to return the value zero, indicating that there are no known special properties.
* It is acceptable for the properties of the iterator to change depending on its state.
*/
public int getProperties() {
return LOOKAHEAD;
}
}