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}