com.google.gerrit.index.query.ListResultSet Maven / Gradle / Ivy
// Copyright 2008 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.index.query;
import static java.util.Objects.requireNonNull;
import com.google.common.collect.ImmutableList;
import java.util.Iterator;
import java.util.List;
/**
* Result set for queries that run synchronously or for cases where the result is already known and
* we just need to pipe it back through our interfaces.
*
* If your implementation benefits from asynchronous execution (i.e. dispatching a query and
* awaiting results only when {@link ResultSet#toList()} is called, consider using {@link
* LazyResultSet}.
*/
public class ListResultSet implements ResultSet {
private ImmutableList results;
public ListResultSet(List r) {
results = ImmutableList.copyOf(requireNonNull(r, "results can't be null"));
}
@Override
public Iterator iterator() {
return toList().iterator();
}
@Override
public ImmutableList toList() {
if (results == null) {
throw new IllegalStateException("Results already obtained");
}
ImmutableList r = results;
results = null;
return r;
}
@Override
public void close() {
results = null;
}
}