StreamSequenceImpl.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
* INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
* SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
* SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
* INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
* OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
* CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
* PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
* OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
*/
package gov.nist.secauto.metaschema.core.metapath;
import gov.nist.secauto.metaschema.core.metapath.item.IItem;
import gov.nist.secauto.metaschema.core.util.ObjectUtils;
import java.util.List;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import edu.umd.cs.findbugs.annotations.NonNull;
class StreamSequenceImpl<ITEM_TYPE extends IItem> implements ISequence<ITEM_TYPE> {
private Stream<ITEM_TYPE> stream;
private List<ITEM_TYPE> list;
public StreamSequenceImpl(@NonNull Stream<ITEM_TYPE> stream) {
Objects.requireNonNull(stream, "stream");
this.stream = stream;
}
@Override
public boolean isEmpty() {
return asList().isEmpty();
}
@Override
public List<ITEM_TYPE> asList() {
synchronized (this) {
if (list == null) {
list = asStream().collect(Collectors.toUnmodifiableList());
}
assert list != null;
return list;
}
}
@Override
public Stream<ITEM_TYPE> asStream() {
@NonNull Stream<ITEM_TYPE> retval;
synchronized (this) {
if (list == null) {
if (stream == null) {
throw new IllegalStateException("stream is already consumed");
}
assert stream != null;
retval = stream;
stream = null; // NOPMD - readability
} else {
retval = ObjectUtils.notNull(list.stream());
}
}
return retval;
}
@Override
public void forEach(Consumer<? super ITEM_TYPE> action) {
asStream().forEachOrdered(action);
}
@Override
public String toString() {
return asList().toString();
}
@Override
public int size() {
return asList().size();
}
@Override
public void collect() {
asList();
}
@Override
public boolean equals(Object other) {
// must either be the same instance or a sequence that has the same list
// contents
return other == this
|| other instanceof ISequence && asList().equals(((ISequence<?>) other).asList());
}
@Override
public int hashCode() {
return asList().hashCode();
}
}