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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.evpull;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.trans.XPathException;
/**
* MappingIterator merges a sequence of sequences into a single sequence.
* It takes as inputs an iteration, and a mapping function to be
* applied to each Item returned by that iteration. The mapping function itself
* returns another iteration. The result is an iteration of iterators. To convert this
* int a single flat iterator over a uniform sequence of events, the result must be wrapped
* in an {@link EventStackIterator}
*/
public final class EventMappingIterator implements EventIterator {
private SequenceIterator base;
private EventMappingFunction action;
/**
* Construct a MappingIterator that will apply a specified MappingFunction to
* each Item returned by the base iterator.
* @param base the base iterator
* @param action the mapping function to be applied
*/
public EventMappingIterator(SequenceIterator base, EventMappingFunction action) {
this.base = base;
this.action = action;
}
/*@Nullable*/ public PullEvent next() throws XPathException {
Item nextSource = base.next();
return (nextSource == null ? null : action.map(nextSource));
}
/**
* Determine whether the EventIterator returns a flat sequence of events, or whether it can return
* nested event iterators
*
* @return true if the next() method is guaranteed never to return an EventIterator
*/
public boolean isFlatSequence() {
return false;
}
}