ix.IxTakeLast Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of ixjava Show documentation

ixjava developed by David Karnok

There is a newer version: 1.0.0

/*
 * Copyright 2011-2016 David Karnok
 *
 * 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 ix;

import java.util.Iterator;

final class IxTakeLast extends IxSource {

    final int n;

    IxTakeLast(Iterable source, int n) {
        super(source);
        this.n = n;
    }

    @Override
    public Iterator iterator() {
        return new TakeLastIterator(source.iterator(), n);
    }

    static final class TakeLastIterator extends IxSourceQueuedIterator {

        int n;

        TakeLastIterator(Iterator it, int n) {
            super(it);
            this.n = n;
        }

        @Override
        protected boolean moveNext() {

            int n = this.n;
            if (n != 0) {
                Iterator it = this.it;
                while (it.hasNext()) {
                    if (n == 0) {
                        poll();
                    } else {
                        n--;
                    }
                    offer(toObject(it.next()));
                }
                this.n = n;
            }

            Object o = poll();
            if (o != null) {
                value = fromObject(o);
                hasValue = true;
                return true;
            }
            done = true;
            return false;
        }
    }

}