001/*
002 * Portions of this software was developed by employees of the National Institute
003 * of Standards and Technology (NIST), an agency of the Federal Government and is
004 * being made available as a public service. Pursuant to title 17 United States
005 * Code Section 105, works of NIST employees are not subject to copyright
006 * protection in the United States. This software may be subject to foreign
007 * copyright. Permission in the United States and in foreign countries, to the
008 * extent that NIST may hold copyright, to use, copy, modify, create derivative
009 * works, and distribute this software and its documentation without fee is hereby
010 * granted on a non-exclusive basis, provided that this notice and disclaimer
011 * of warranty appears in all copies.
012 *
013 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
014 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
015 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
016 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
017 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
018 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE.  IN NO EVENT
019 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
020 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
021 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
022 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
023 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
024 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
025 */
026
027package gov.nist.secauto.metaschema.core.metapath.function.library;
028
029import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
030import gov.nist.secauto.metaschema.core.metapath.ISequence;
031import gov.nist.secauto.metaschema.core.metapath.MetapathConstants;
032import gov.nist.secauto.metaschema.core.metapath.function.FunctionUtils;
033import gov.nist.secauto.metaschema.core.metapath.function.IArgument;
034import gov.nist.secauto.metaschema.core.metapath.function.IFunction;
035import gov.nist.secauto.metaschema.core.metapath.item.IItem;
036import gov.nist.secauto.metaschema.core.metapath.item.atomic.IBooleanItem;
037import gov.nist.secauto.metaschema.core.util.ObjectUtils;
038
039import java.util.List;
040
041import edu.umd.cs.findbugs.annotations.NonNull;
042
043public final class FnExists {
044  @NonNull
045  static final IFunction SIGNATURE = IFunction.builder()
046      .name("exists")
047      .namespace(MetapathConstants.NS_XPATH_FUNCTIONS)
048      .deterministic()
049      .contextIndependent()
050      .focusIndependent()
051      .argument(IArgument.newBuilder()
052          .name("arg")
053          .type(IItem.class)
054          .zeroOrMore()
055          .build())
056      .returnType(IBooleanItem.class)
057      .returnOne()
058      .functionHandler(FnExists::execute)
059      .build();
060
061  private FnExists() {
062    // disable construction
063  }
064
065  @SuppressWarnings("unused")
066  @NonNull
067  private static ISequence<IBooleanItem> execute(@NonNull IFunction function,
068      @NonNull List<ISequence<?>> arguments,
069      @NonNull DynamicContext dynamicContext,
070      IItem focus) {
071    ISequence<?> items = FunctionUtils.asType(ObjectUtils.requireNonNull(arguments.get(0)));
072    return ISequence.of(fnExists(items));
073  }
074
075  /**
076   * Identify if there is at least one item in the {@code sequence}.
077   *
078   * @param sequence
079   *          the sequence to check
080   * @return {@code true} if the sequence contains at least one item, or
081   *         {@code false} otherwise
082   */
083  public static IBooleanItem fnExists(ISequence<?> sequence) {
084    return IBooleanItem.valueOf(!sequence.isEmpty());
085  }
086}