Copyright (c) 2016-present, RxJava Contributors.
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.
/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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 io.reactivex.internal.operators.observable;

import io.reactivex.*;
import io.reactivex.annotations.Nullable;
import io.reactivex.internal.observers.BasicIntQueueDisposable;

Emits a range of integer values from start to end.
/**
 * Emits a range of integer values from start to end.
 */
public final class ObservableRange extends Observable<Integer> {
    private final int start;
    private final long end;

    public ObservableRange(int start, int count) {
        this.start = start;
        this.end = (long)start + count;
    }

    @Override
    protected void subscribeActual(Observer<? super Integer> o) {
        RangeDisposable parent = new RangeDisposable(o, start, end);
        o.onSubscribe(parent);
        parent.run();
    }

    static final class RangeDisposable
    extends BasicIntQueueDisposable<Integer> {

        private static final long serialVersionUID = 396518478098735504L;

        final Observer<? super Integer> downstream;

        final long end;

        long index;

        boolean fused;

        RangeDisposable(Observer<? super Integer> actual, long start, long end) {
            this.downstream = actual;
            this.index = start;
            this.end = end;
        }

        void run() {
            if (fused) {
                return;
            }
            Observer<? super Integer> actual = this.downstream;
            long e = end;
            for (long i = index; i != e && get() == 0; i++) {
                actual.onNext((int)i);
            }
            if (get() == 0) {
                lazySet(1);
                actual.onComplete();
            }
        }

        @Nullable
        @Override
        public Integer poll() throws Exception {
            long i = index;
            if (i != end) {
                index = i + 1;
                return (int)i;
            }
            lazySet(1);
            return null;
        }

        @Override
        public boolean isEmpty() {
            return index == end;
        }

        @Override
        public void clear() {
            index = end;
            lazySet(1);
        }

        @Override
        public void dispose() {
            set(1);
        }

        @Override
        public boolean isDisposed() {
            return get() != 0;
        }

        @Override
        public int requestFusion(int mode) {
            if ((mode & SYNC) != 0) {
                fused = true;
                return SYNC;
            }
            return NONE;
        }
    }
}