package client.net.sf.saxon.ce.expr.sort;
import client.net.sf.saxon.ce.expr.Expression;
import client.net.sf.saxon.ce.expr.XPathContext;
import client.net.sf.saxon.ce.lib.StringCollator;
import client.net.sf.saxon.ce.om.Item;
import client.net.sf.saxon.ce.tree.iter.ListIterator;
import client.net.sf.saxon.ce.om.SequenceIterator;
import client.net.sf.saxon.ce.trans.XPathException;
import client.net.sf.saxon.ce.type.Type;
import client.net.sf.saxon.ce.value.AtomicValue;
import java.util.ArrayList;
import java.util.List;
/**
* A GroupAdjacentIterator iterates over a sequence of groups defined by
* xsl:for-each-group group-adjacent="x". The groups are returned in
* order of first appearance.
* <p>
* Each step of this iterator advances to the first item of the next group,
* leaving the members of that group in a saved list.
*/
public class GroupAdjacentIterator implements GroupIterator {
private SequenceIterator population;
private Expression keyExpression;
private StringCollator collator;
private AtomicComparer comparer;
private ComparisonKey currentComparisonKey;
private XPathContext baseContext;
private XPathContext runningContext;
private AtomicValue currentKey = null;
private List currentMembers;
private AtomicValue nextKey = null;
private Item next;
private Item current = null;
private int position = 0;
public GroupAdjacentIterator(SequenceIterator population, Expression keyExpression,
XPathContext baseContext, StringCollator collator)
throws XPathException {
this.population = population;
this.keyExpression = keyExpression;
this.baseContext = baseContext;
this.runningContext = baseContext.newMinorContext();
runningContext.setCurrentIterator(population);
this.collator = collator;
int type = keyExpression.getItemType(baseContext.getConfiguration().getTypeHierarchy()).getPrimitiveType();
this.comparer = AtomicSortComparer.makeSortComparer(collator, type, baseContext);
next = population.next();
if (next != null) {
nextKey = (AtomicValue)keyExpression.evaluateItem(runningContext);
}
}
private void advance() throws XPathException {
currentMembers = new ArrayList(20);
currentMembers.add(current);
while (true) {
Item nextCandidate = population.next();
if (nextCandidate == null) {
break;
}
AtomicValue candidateKey =
(AtomicValue)keyExpression.evaluateItem(runningContext);
try {
if (currentComparisonKey.equals(comparer.getComparisonKey(candidateKey))) {
currentMembers.add(nextCandidate);
} else {
next = nextCandidate;
nextKey = candidateKey;
return;
}
} catch (ClassCastException e) {
XPathException err = new XPathException("Grouping key values are of non-comparable types (" +
Type.displayTypeName(currentKey) +
" and " +
Type.displayTypeName(candidateKey) + ')');
err.setIsTypeError(true);
err.setXPathContext(runningContext);
throw err;
}
}
next = null;
nextKey = null;
}
public AtomicValue getCurrentGroupingKey() {
return currentKey;
}
public SequenceIterator iterateCurrentGroup() {
return new ListIterator(currentMembers);
}
public Item next() throws XPathException {
if (next == null) {
current = null;
position = -1;
return null;
}
current = next;
currentKey = nextKey;
currentComparisonKey = comparer.getComparisonKey(currentKey);
position++;
advance();
return current;
}
public Item current() {
return current;
}
public int position() {
return position;
}
public SequenceIterator getAnother() throws XPathException {
return new GroupAdjacentIterator(population.getAnother(), keyExpression, baseContext, collator);
}
/**
* 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}. 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 0;
}
}
// 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.