package net.sf.saxon.expr;
import net.sf.saxon.om.*;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.Int64Value;
import net.sf.saxon.value.IntegerRange;
/**
* An Iterator that produces numeric values in a monotonic sequence,
* ascending or descending. Although a range expression (N to M) is always
* in ascending order, applying the reverse() function will produce
* a RangeIterator that works in descending order.
*/
public class RangeIterator implements SequenceIterator,
ReversibleIterator,
LastPositionFinder,
LookaheadIterator,
GroundedIterator {
long start;
long currentValue;
long limit;
/**
* Create an iterator over a range of monotonically increasing integers
* @param start the first integer in the sequence
* @param end the last integer in the sequence. Must be >= start.
*/
public RangeIterator(long start, long end) {
this.start = start;
currentValue = start - 1;
limit = end;
}
public boolean hasNext() {
return currentValue < limit;
}
public Item next() {
if (++currentValue > limit) {
return null;
}
return Int64Value.makeIntegerValue(currentValue);
}
public Item current() {
if (currentValue > limit) {
return null;
} else {
return Int64Value.makeIntegerValue(currentValue);
}
}
public int position() {
if (currentValue > limit) {
return -1;
} else {
return (int)(currentValue - start + 1);
}
}
public int getLastPosition() {
return (int)((limit - start) + 1);
}
public SequenceIterator getAnother() throws XPathException {
return new RangeIterator(start, limit);
}
/**
* 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 net.sf.saxon.om.SequenceIterator#GROUNDED}, {@link net.sf.saxon.om.SequenceIterator#LAST_POSITION_FINDER},
* and {@link net.sf.saxon.om.SequenceIterator#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 | LAST_POSITION_FINDER | GROUNDED;
}
public SequenceIterator getReverseIterator() {
return new ReverseRangeIterator(limit, start);
}
/**
* Return a Value containing all the items in the sequence returned by this
* SequenceIterator. This should be an "in-memory" value, not a Closure.
*
* @return the corresponding Value
*/
public GroundedValue materialize() throws XPathException {
return new IntegerRange(start, limit);
}
}
//
// 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.
//