FnStartsWith.java
/*
* SPDX-FileCopyrightText: none
* SPDX-License-Identifier: CC0-1.0
*/
package gov.nist.secauto.metaschema.core.metapath.function.library;
import gov.nist.secauto.metaschema.core.metapath.DynamicContext;
import gov.nist.secauto.metaschema.core.metapath.ISequence;
import gov.nist.secauto.metaschema.core.metapath.MetapathConstants;
import gov.nist.secauto.metaschema.core.metapath.function.FunctionUtils;
import gov.nist.secauto.metaschema.core.metapath.function.IArgument;
import gov.nist.secauto.metaschema.core.metapath.function.IFunction;
import gov.nist.secauto.metaschema.core.metapath.item.IItem;
import gov.nist.secauto.metaschema.core.metapath.item.atomic.IBooleanItem;
import gov.nist.secauto.metaschema.core.metapath.item.atomic.IStringItem;
import java.util.List;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
public final class FnStartsWith {
@NonNull
static final IFunction SIGNATURE = IFunction.builder()
.name("starts-with")
.namespace(MetapathConstants.NS_METAPATH_FUNCTIONS)
.deterministic()
.contextDependent()
.focusIndependent()
.argument(IArgument.builder()
.name("arg1").type(IStringItem.class)
.zeroOrOne()
.build())
.argument(IArgument.builder()
.name("arg2")
.type(IStringItem.class)
.zeroOrOne()
.build())
.returnType(IBooleanItem.class)
.returnOne()
.functionHandler(FnStartsWith::execute)
.build();
@SuppressWarnings("unused")
@NonNull
private static ISequence<IBooleanItem> execute(@NonNull IFunction function,
@NonNull List<ISequence<?>> arguments,
@NonNull DynamicContext dynamicContext,
IItem focus) {
IStringItem arg1 = FunctionUtils.asTypeOrNull(arguments.get(0).getFirstItem(true));
IStringItem arg2 = FunctionUtils.asTypeOrNull(arguments.get(1).getFirstItem(true));
return ISequence.of(fnStartsWith(arg1, arg2));
}
private FnStartsWith() {
// disable construction
}
/**
* Determine if the string provided in the first argument contains the string in
* the second argument as a leading substring.
* <p>
* Based on the XPath 3.1 <a href=
* "https://www.w3.org/TR/xpath-functions-31/#func-starts-with">fn:starts-with</a>
* function.
*
* @param arg1
* the string to examine
* @param arg2
* the string to check as the leading substring
* @return {@link IBooleanItem#TRUE} if {@code arg1} starts with {@code arg2},
* or {@link IBooleanItem#FALSE} otherwise
*/
public static IBooleanItem fnStartsWith(@Nullable IStringItem arg1, @Nullable IStringItem arg2) {
String arg2String = arg2 == null ? "" : arg2.asString();
boolean retval;
if (arg2String.isEmpty()) {
retval = true;
} else {
String arg1String = arg1 == null ? "" : arg1.asString();
retval = arg1String.startsWith(arg2String);
}
return IBooleanItem.valueOf(retval);
}
}