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Added support for the Metapath fn:distinct-values function. (#278)
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david-waltermire authored Dec 9, 2024
1 parent bcfee31 commit 5410178
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Expand Up @@ -64,7 +64,8 @@ public DefaultFunctionLibrary() { // NOPMD - intentional
// https://www.w3.org/TR/xpath-functions-31/#func-days-from-duration
// https://www.w3.org/TR/xpath-functions-31/#func-deep-equal
registerFunction(FnDeepEqual.SIGNATURE_TWO_ARG);
// P1: https://www.w3.org/TR/xpath-functions-31/#func-distinct-values
// https://www.w3.org/TR/xpath-functions-31/#func-distinct-values
registerFunction(FnDistinctValues.SIGNATURE_ONE_ARG);
// https://www.w3.org/TR/xpath-functions-31/#func-doc
registerFunction(FnDoc.SIGNATURE);
// https://www.w3.org/TR/xpath-functions-31/#func-doc-available
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/*
* 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.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.function.InvalidTypeFunctionException;
import gov.nist.secauto.metaschema.core.metapath.function.InvalidValueForCastFunctionException;
import gov.nist.secauto.metaschema.core.metapath.item.IItem;
import gov.nist.secauto.metaschema.core.metapath.item.ISequence;
import gov.nist.secauto.metaschema.core.metapath.item.atomic.IAnyAtomicItem;
import gov.nist.secauto.metaschema.core.util.ObjectUtils;

import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import java.util.stream.Stream;

import edu.umd.cs.findbugs.annotations.NonNull;

/**
* /** Implements <a href=
* "https://www.w3.org/TR/xpath-functions-31/#func-distinct-values">fn:distinct-values</a>
* functions. This implementation does not implement the two-arg variant with
* collation at this time.
*/
public final class FnDistinctValues {
@NonNull
private static final String NAME = "distinct-values";
@NonNull
static final IFunction SIGNATURE_ONE_ARG = IFunction.builder()
.name(NAME)
.namespace(MetapathConstants.NS_METAPATH_FUNCTIONS)
.deterministic()
.contextDependent()
.focusIndependent()
.argument(IArgument.builder()
.name("arg")
.type(IAnyAtomicItem.type())
.zeroOrMore()
.build())
.returnType(IAnyAtomicItem.type())
.returnZeroOrMore()
.functionHandler(FnDistinctValues::executeOneArg)
.build();

@SuppressWarnings("unused")
@NonNull
private static ISequence<IAnyAtomicItem> executeOneArg(@NonNull IFunction function,
@NonNull List<ISequence<?>> arguments,
@NonNull DynamicContext dynamicContext,
IItem focus) {
ISequence<IAnyAtomicItem> seq = FunctionUtils.asType(ObjectUtils.requireNonNull(arguments.get(0)));

return ISequence.of(fnDistinctValues(seq));
}

/**
* Get the first occurrence of each distinct value in the provided list.
* <p>
* Based on the XPath 3.1 <a href=
* "https://www.w3.org/TR/xpath-functions-31/#func-distinct-values">fn:distinct-values</a>
* function.
*
* @param values
* the items to get destinct values for
* @return a the list of distinct values
*/
@NonNull
public static Stream<IAnyAtomicItem> fnDistinctValues(@NonNull List<IAnyAtomicItem> values) {
Set<IAnyAtomicItem> distinctValues = new TreeSet<>(FnDistinctValues::compare);
distinctValues.addAll(values);
return ObjectUtils.notNull(distinctValues.stream());
}

private static int compare(@NonNull IAnyAtomicItem item1, @NonNull IAnyAtomicItem item2) {
int retval;
try {
retval = item1.compareTo(item2);
} catch (InvalidTypeFunctionException | InvalidValueForCastFunctionException ex) {
retval = 1;
}
return retval;
}

private FnDistinctValues() {
// disable construction
}
}
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/*
* SPDX-FileCopyrightText: none
* SPDX-License-Identifier: CC0-1.0
*/

package gov.nist.secauto.metaschema.core.metapath.function.library;

import static gov.nist.secauto.metaschema.core.metapath.TestUtils.decimal;
import static gov.nist.secauto.metaschema.core.metapath.TestUtils.integer;
import static gov.nist.secauto.metaschema.core.metapath.TestUtils.sequence;
import static gov.nist.secauto.metaschema.core.metapath.TestUtils.string;
import static org.junit.jupiter.api.Assertions.assertEquals;

import gov.nist.secauto.metaschema.core.metapath.ExpressionTestBase;
import gov.nist.secauto.metaschema.core.metapath.IMetapathExpression;
import gov.nist.secauto.metaschema.core.metapath.item.ISequence;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;

import java.util.stream.Stream;

import edu.umd.cs.findbugs.annotations.NonNull;

class FnDistinctValuesTest
extends ExpressionTestBase {
private static Stream<Arguments> provideValues() {
return Stream.of(
Arguments.of(
sequence(integer(1), decimal(2.0), integer(3)),
"fn:distinct-values((1, 2.0, 3, 2))"),
Arguments.of(
sequence(string("cherry"), string("plum")),
"fn:distinct-values((meta:string('cherry'),meta:string('plum'),meta:string('plum')))"),
Arguments.of(
sequence(string("a"), integer(2)),
"fn:distinct-values(('a', 2, 'a', 2.0))"));
}

@ParameterizedTest
@MethodSource("provideValues")
void test(@NonNull ISequence<?> expected, @NonNull String metapath) {
assertEquals(expected, IMetapathExpression.compile(metapath)
.evaluate(null, newDynamicContext()));
}
}

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