net.sf.saxon.functions.InScopePrefixes Maven / Gradle / Ivy
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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 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.functions;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.NamespaceBinding;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.om.SequenceTool;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.iter.UnfailingIterator;
import net.sf.saxon.tree.util.NamespaceIterator;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.value.StringValue;
import java.util.Iterator;
/**
* This class implements the XPath 2.0 function fn:in-scope-prefixes()
*/
public class InScopePrefixes extends SystemFunction {
/**
* Given an element node, return an iterator over the namespace
* prefixes, taking into account special rules for the XML namespace and the default namespace
*
* @param element an element
* @return an iterator over the prefixes.
*/
private UnfailingIterator iteratePrefixes(final NodeInfo element) {
final Iterator iter = NamespaceIterator.iterateNamespaces(element);
return new UnfailingIterator() {
private int position = 0;
/*@NotNull*/
public UnfailingIterator getAnother() {
return iteratePrefixes(element);
}
public int getProperties() {
return 0;
}
public StringValue next() {
if (position == 0) {
position++;
return new StringValue("xml");
} else if (iter.hasNext()) {
String prefix = iter.next().getPrefix();
StringValue current;
if (prefix.isEmpty()) {
current = StringValue.EMPTY_STRING;
} else {
current = new StringValue(prefix, BuiltInAtomicType.NCNAME);
}
position++;
return current;
} else {
position = -1;
return null;
}
}
public void close() {
}
};
}
/**
* Dynamic function call of in-scope-prefixes
* @param context the dynamic evaluation context
* @param arguments the values of the arguments, supplied as Sequences.
* Generally it is advisable, if calling iterate() to process a supplied sequence, to
* call it only once; if the value is required more than once, it should first be converted
* to a {@link net.sf.saxon.om.GroundedValue} by calling the utility methd
* SequenceTool.toGroundedValue().
* If the expected value is a single item, the item should be obtained by calling
* Sequence.head(): it cannot be assumed that the item will be passed as an instance of
* {@link net.sf.saxon.om.Item} or {@link net.sf.saxon.value.AtomicValue}.
* It is the caller's responsibility to perform any type conversions required
* to convert arguments to the type expected by the callee. An exception is where
* this Callable is explicitly an argument-converting wrapper around the original
* Callable.
* @return the sequence of prefixes
* @throws XPathException
*/
public Sequence call(final XPathContext context, Sequence[] arguments) throws XPathException {
final NodeInfo element = (NodeInfo) arguments[0].head();
return SequenceTool.toLazySequence(iteratePrefixes(element));
}
}