Predicate.java
/*
* Portions of this software was developed by employees of the National Institute
* of Standards and Technology (NIST), an agency of the Federal Government and is
* being made available as a public service. Pursuant to title 17 United States
* Code Section 105, works of NIST employees are not subject to copyright
* protection in the United States. This software may be subject to foreign
* copyright. Permission in the United States and in foreign countries, to the
* extent that NIST may hold copyright, to use, copy, modify, create derivative
* works, and distribute this software and its documentation without fee is hereby
* granted on a non-exclusive basis, provided that this notice and disclaimer
* of warranty appears in all copies.
*
* THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
* EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
* THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
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* SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
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package gov.nist.secauto.metaschema.core.metapath;
import gov.nist.secauto.metaschema.core.metapath.function.library.FnBoolean;
import gov.nist.secauto.metaschema.core.metapath.item.IItem;
import gov.nist.secauto.metaschema.core.util.ObjectUtils;
import java.math.BigInteger;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import edu.umd.cs.findbugs.annotations.NonNull;
class Predicate implements IExpression {
@NonNull
private final IExpression base;
@NonNull
private final List<IExpression> predicates;
/**
* Construct a new predicate expression.
*
* @param base
* the base to evaluate against
* @param predicates
* the expression(s) to apply as a filter
*/
protected Predicate(@NonNull IExpression base, @NonNull List<IExpression> predicates) {
this.base = base;
this.predicates = predicates;
}
/**
* Get the base sub-expression.
*
* @return the sub-expression
*/
@NonNull
public IExpression getBase() {
return base;
}
/**
* Retrieve the list of predicates to filter with.
*
* @return the list of predicates
*/
@NonNull
public List<IExpression> getPredicates() {
return predicates;
}
@Override
public List<? extends IExpression> getChildren() {
return ObjectUtils.notNull(
Stream.concat(Stream.of(getBase()), getPredicates().stream()).collect(Collectors.toList()));
}
@Override
public @NonNull ISequence<? extends IItem> accept(@NonNull DynamicContext dynamicContext,
@NonNull ISequence<?> focus) {
ISequence<?> retval = getBase().accept(dynamicContext, focus);
if (dynamicContext.getConfiguration().isFeatureEnabled(MetapathEvaluationFeature.METAPATH_EVALUATE_PREDICATES)) {
// evaluate the predicates for this step
AtomicInteger index = new AtomicInteger();
Stream<? extends IItem> stream = ObjectUtils.notNull(
retval.asStream().map(item -> {
// build a positional index of the items
return Map.entry(BigInteger.valueOf(index.incrementAndGet()), item);
}).filter(entry -> {
@SuppressWarnings("null")
@NonNull IItem item = entry.getValue();
// return false if any predicate evaluates to false
return !predicates.stream()
.map(predicateExpr -> {
boolean bool;
if (predicateExpr instanceof IntegerLiteral) {
// reduce the result to the matching item
BigInteger predicateIndex = ((IntegerLiteral) predicateExpr).getValue();
// get the position of the item
final BigInteger position = entry.getKey();
// it is a match if the position matches
bool = position.equals(predicateIndex);
} else {
ISequence<?> innerFocus = ISequence.of(item);
ISequence<?> predicateResult = predicateExpr.accept(dynamicContext, innerFocus);
bool = FnBoolean.fnBoolean(predicateResult).toBoolean();
}
return bool;
}).anyMatch(x -> !x);
}).map(entry -> entry.getValue()));
retval = ISequence.of(stream);
}
return retval;
}
@Override
public <RESULT, CONTEXT> RESULT accept(@NonNull IExpressionVisitor<RESULT, CONTEXT> visitor, CONTEXT context) {
return visitor.visitPredicate(this, context);
}
}