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/**
 * Copyright 2014 Netflix, 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 rx.internal.operators;

import rx.*;
import rx.exceptions.*;
import rx.functions.Func1;
import rx.plugins.RxJavaHooks;

/**
 * Applies a function of your choosing to every item emitted by an {@code Single}, and emits the results of
 * this transformation as a new {@code Single}.
 * 
 * @param  the input value type
 * @param  the return value type
 */
public final class SingleOnSubscribeMap implements Single.OnSubscribe {

    final Single source;
    
    final Func1 transformer;

    public SingleOnSubscribeMap(Single source, Func1 transformer) {
        this.source = source;
        this.transformer = transformer;
    }
    
    @Override
    public void call(final SingleSubscriber o) {
        MapSubscriber parent = new MapSubscriber(o, transformer);
        o.add(parent);
        source.subscribe(parent);
    }
    
    static final class MapSubscriber extends SingleSubscriber {
        
        final SingleSubscriber actual;
        
        final Func1 mapper;

        boolean done;
        
        public MapSubscriber(SingleSubscriber actual, Func1 mapper) {
            this.actual = actual;
            this.mapper = mapper;
        }
        
        @Override
        public void onSuccess(T t) {
            R result;
            
            try {
                result = mapper.call(t);
            } catch (Throwable ex) {
                Exceptions.throwIfFatal(ex);
                unsubscribe();
                onError(OnErrorThrowable.addValueAsLastCause(ex, t));
                return;
            }
            
            actual.onSuccess(result);
        }
        
        @Override
        public void onError(Throwable e) {
            if (done) {
                RxJavaHooks.onError(e);
                return;
            }
            done = true;
            
            actual.onError(e);
        }
    }

}