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.metapath.item.atomic.IStringItem;
038import gov.nist.secauto.metaschema.core.util.ObjectUtils;
039
040import java.util.List;
041
042import edu.umd.cs.findbugs.annotations.NonNull;
043import edu.umd.cs.findbugs.annotations.Nullable;
044
045public final class FnStartsWith {
046
047  @NonNull
048  static final IFunction SIGNATURE = IFunction.builder()
049      .name("starts-with")
050      .namespace(MetapathConstants.NS_XPATH_FUNCTIONS)
051      .argument(IArgument.newBuilder()
052          .name("arg1").type(IStringItem.class)
053          .zeroOrOne()
054          .build())
055      .argument(IArgument.newBuilder()
056          .name("arg2")
057          .type(IStringItem.class)
058          .zeroOrOne()
059          .build())
060      .returnType(IBooleanItem.class)
061      .returnOne()
062      .functionHandler(FnStartsWith::execute)
063      .build();
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    IStringItem arg1 = FunctionUtils.getFirstItem(
072        FunctionUtils.asType(ObjectUtils.requireNonNull(arguments.get(0))), true);
073    IStringItem arg2 = FunctionUtils.getFirstItem(
074        FunctionUtils.asType(ObjectUtils.requireNonNull(arguments.get(1))), true);
075
076    return ISequence.of(fnStartsWith(arg1, arg2));
077  }
078
079  private FnStartsWith() {
080    // disable construction
081  }
082
083  /**
084   * Determine if the string provided in the first argument contains the string in
085   * the second argument as a leading substring.
086   * <p>
087   * Based on the XPath 3.1 <a href=
088   * "https://www.w3.org/TR/xpath-functions-31/#func-starts-with">fn:starts-with</a>
089   * function.
090   *
091   * @param arg1
092   *          the string to examine
093   * @param arg2
094   *          the string to check as the leading substring
095   * @return {@link IBooleanItem#TRUE} if {@code arg1} starts with {@code arg2},
096   *         or {@link IBooleanItem#FALSE} otherwise
097   */
098  public static IBooleanItem fnStartsWith(@Nullable IStringItem arg1, @Nullable IStringItem arg2) {
099    String arg2String = arg2 == null ? "" : arg2.asString();
100
101    boolean retval;
102    if (arg2String.isEmpty()) {
103      retval = true;
104    } else {
105      String arg1String = arg1 == null ? "" : arg1.asString();
106      retval = arg1String.contains(arg2String);
107    }
108    return IBooleanItem.valueOf(retval);
109  }
110}