AbstractExpression.java
/*
* Portions of this software was developed by employees of the National Institute
* of Standards and Technology (NIST), an agency of the Federal Government and is
* being made available as a public service. Pursuant to title 17 United States
* Code Section 105, works of NIST employees are not subject to copyright
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* extent that NIST may hold copyright, to use, copy, modify, create derivative
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* of warranty appears in all copies.
*
* THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
* EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
* THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
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package gov.nist.secauto.metaschema.core.metapath;
import gov.nist.secauto.metaschema.core.metapath.function.FunctionUtils;
import gov.nist.secauto.metaschema.core.metapath.function.library.FnData;
import gov.nist.secauto.metaschema.core.metapath.item.IItem;
import gov.nist.secauto.metaschema.core.metapath.item.atomic.IAnyAtomicItem;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
abstract class AbstractExpression implements IExpression {
/**
* Get the first data item of the provided {@code sequence} cast to an
* {@link IAnyAtomicItem}.
*
* @param sequence
* the sequence to get the data item from
* @param requireSingleton
* if {@code true} then a {@link TypeMetapathException} is thrown if
* the sequence contains more than one item
* @return {@code null} if the sequence is empty, or the item otherwise
* @throws TypeMetapathException
* if the sequence contains more than one item and requireSingleton is
* {@code true}, or if the data item cannot be cast
*/
@Nullable
public static IAnyAtomicItem getFirstDataItem(@NonNull ISequence<?> sequence,
boolean requireSingleton) {
IItem item = FunctionUtils.getFirstItem(sequence, requireSingleton);
return item == null ? null : FnData.fnDataItem(item);
}
@Override
public String toString() {
return ASTPrinter.instance().visit(this);
}
}