ModifyPhaseUtils.java
/*
* SPDX-FileCopyrightText: none
* SPDX-License-Identifier: CC0-1.0
*/
package gov.nist.secauto.oscal.lib.profile.resolver;
import gov.nist.secauto.metaschema.core.util.CollectionUtil;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
public final class ModifyPhaseUtils {
private ModifyPhaseUtils() {
// disable construction
}
public static <T> Function<? super T, String> identityKey() {
return item -> Integer.toString(Objects.hashCode(item));
}
public static <T, R> Function<? super T, String> identifierKey(@NonNull Function<T, R> identifierFunction) {
return item -> {
R identifier = identifierFunction.apply(item);
String retval;
if (identifier == null) {
retval = Integer.toString(Objects.hashCode(item));
} else {
retval = identifier.toString();
}
return retval;
};
}
@SuppressWarnings("PMD.OnlyOneReturn") // readability
public static <T> T mergeItem(@Nullable T original, @Nullable T additional) {
if (additional == null) {
return original;
}
return additional;
}
@SuppressWarnings("PMD.OnlyOneReturn") // readability
public static <T> List<T> merge(@Nullable List<T> original, @Nullable List<T> additional,
Function<? super T, String> keyFunction) {
if (additional == null || additional.isEmpty()) {
return original;
}
if (original == null || original.isEmpty()) {
return additional;
}
// reverse the stream
List<T> reversed = Stream.concat(
CollectionUtil.listOrEmpty(original).stream(),
CollectionUtil.listOrEmpty(additional).stream())
.collect(Collectors.collectingAndThen(
Collectors.toList(),
l -> {
Collections.reverse(l);
return l;
}));
// build a map of each unique identity
Map<String, List<T>> identityMap = reversed.stream()
.collect(Collectors.groupingBy(keyFunction, LinkedHashMap::new, Collectors.toList()));
// build a reversed list of items, using the first item
return identityMap.values().stream()
.map(list -> list.stream().findFirst().get())
.collect(Collectors.collectingAndThen(
Collectors.toList(),
l -> {
Collections.reverse(l);
return l;
}));
}
}