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/*
* SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
*
* SPDX-License-Identifier: EPL-2.0
*/
package tools.refinery.logic.util;
import java.util.*;
import java.util.function.Function;
import java.util.stream.Collectors;
public class CycleDetectingMapper<T, R> {
private static final String SEPARATOR = " -> ";
private final Function<T, String> getName;
private final Function<T, R> doMap;
private final Set<T> inProgress = new LinkedHashSet<>();
private final Map<T, R> results = new HashMap<>();
public CycleDetectingMapper(Function<T, R> doMap) {
this(Objects::toString, doMap);
}
public CycleDetectingMapper(Function<T, String> getName, Function<T, R> doMap) {
this.getName = getName;
this.doMap = doMap;
}
public R map(T input) {
if (inProgress.contains(input)) {
var path = inProgress.stream().map(getName).collect(Collectors.joining(SEPARATOR));
throw new IllegalArgumentException("Circular reference %s%s%s detected".formatted(path, SEPARATOR,
getName.apply(input)));
}
// We can't use computeIfAbsent here, because translating referenced queries calls this method in a reentrant
// way, which would cause a ConcurrentModificationException with computeIfAbsent.
@SuppressWarnings("squid:S3824")
var result = results.get(input);
if (result == null) {
inProgress.add(input);
try {
result = doMap.apply(input);
results.put(input, result);
} finally {
inProgress.remove(input);
}
}
return result;
}
public List<T> getInProgress() {
return List.copyOf(inProgress);
}
public R getAlreadyMapped(T input) {
return results.get(input);
}
}
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