1 /*
2 * Portions of this software was developed by employees of the National Institute
3 * of Standards and Technology (NIST), an agency of the Federal Government and is
4 * being made available as a public service. Pursuant to title 17 United States
5 * Code Section 105, works of NIST employees are not subject to copyright
6 * protection in the United States. This software may be subject to foreign
7 * copyright. Permission in the United States and in foreign countries, to the
8 * extent that NIST may hold copyright, to use, copy, modify, create derivative
9 * works, and distribute this software and its documentation without fee is hereby
10 * granted on a non-exclusive basis, provided that this notice and disclaimer
11 * of warranty appears in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
14 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
15 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
17 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
18 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
19 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
20 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
21 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
22 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
23 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
24 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
25 */
26
27 package gov.nist.secauto.metaschema.core.metapath;
28
29 import gov.nist.secauto.metaschema.core.metapath.function.FunctionUtils;
30 import gov.nist.secauto.metaschema.core.metapath.function.library.FnData;
31 import gov.nist.secauto.metaschema.core.metapath.item.IItem;
32 import gov.nist.secauto.metaschema.core.metapath.item.atomic.IAnyAtomicItem;
33
34 import edu.umd.cs.findbugs.annotations.NonNull;
35 import edu.umd.cs.findbugs.annotations.Nullable;
36
37 abstract class AbstractExpression implements IExpression {
38 /**
39 * Get the first data item of the provided {@code sequence} cast to an
40 * {@link IAnyAtomicItem}.
41 *
42 * @param sequence
43 * the sequence to get the data item from
44 * @param requireSingleton
45 * if {@code true} then a {@link TypeMetapathException} is thrown if
46 * the sequence contains more than one item
47 * @return {@code null} if the sequence is empty, or the item otherwise
48 * @throws TypeMetapathException
49 * if the sequence contains more than one item and requireSingleton is
50 * {@code true}, or if the data item cannot be cast
51 */
52 @Nullable
53 public static IAnyAtomicItem getFirstDataItem(@NonNull ISequence<?> sequence,
54 boolean requireSingleton) {
55 IItem item = FunctionUtils.getFirstItem(sequence, requireSingleton);
56
57 return item == null ? null : FnData.fnDataItem(item);
58 }
59
60 @Override
61 public String toString() {
62 return ASTPrinter.instance().visit(this);
63 }
64 }