com.metamx.common.guava.FilteredSequence Maven / Gradle / Ivy
/*
* Copyright 2011,2012 Metamarkets Group 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.metamx.common.guava;
import com.google.common.base.Predicate;
import java.io.IOException;
/**
*/
public class FilteredSequence implements Sequence
{
private final Sequence baseSequence;
private final Predicate pred;
public FilteredSequence(
Sequence baseSequence,
Predicate pred
)
{
this.baseSequence = baseSequence;
this.pred = pred;
}
@Override
public OutType accumulate(OutType initValue, Accumulator accumulator)
{
return baseSequence.accumulate(initValue, new FilteringAccumulator<>(pred, accumulator));
}
@Override
public Yielder toYielder(OutType initValue, YieldingAccumulator accumulator)
{
final FilteringYieldingAccumulator filteringAccumulator = new FilteringYieldingAccumulator<>(
pred, accumulator
);
return wrapYielder(baseSequence.toYielder(initValue, filteringAccumulator), filteringAccumulator);
}
private Yielder wrapYielder(
final Yielder yielder, final FilteringYieldingAccumulator accumulator
)
{
return new Yielder()
{
@Override
public OutType get()
{
return yielder.get();
}
@Override
public Yielder next(OutType initValue)
{
return wrapYielder(yielder.next(initValue), accumulator);
}
@Override
public boolean isDone()
{
return !accumulator.didSomething() || yielder.isDone();
}
@Override
public void close() throws IOException
{
yielder.close();
}
};
}
}