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Operator: Generate #509

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110 changes: 109 additions & 1 deletion rxjava-core/src/main/java/rx/Observable.java
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Date;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Future;
Expand Down Expand Up @@ -49,6 +50,7 @@
import rx.operators.OperationFilter;
import rx.operators.OperationFinally;
import rx.operators.OperationFirstOrDefault;
import rx.operators.OperationGenerate;
import rx.operators.OperationGroupBy;
import rx.operators.OperationInterval;
import rx.operators.OperationLast;
Expand Down Expand Up @@ -105,6 +107,7 @@
import rx.util.Opening;
import rx.util.Range;
import rx.util.TimeInterval;
import rx.util.TimeSpan;
import rx.util.Timestamped;
import rx.util.functions.Action0;
import rx.util.functions.Action1;
Expand Down Expand Up @@ -5689,5 +5692,110 @@ private boolean isInternalImplementation(Object o) {
return isInternal;
}
}

/**
* Generates an observable sequence by iterating a state from an initial state until the condition fails.
* @param initialState The initial state.
* @param condition The condition to terminate generation.
* @param iterate The iteration step function.
* @param resultSelector The selector function for results produced in the sequence.
* @return The generated sequence.
* @see <a href='http://msdn.microsoft.com/en-us/library/hh229642.aspx'>MSDN: Observable.Generate</a>
*/
public static <TState, R> Observable<R> generate(TState initialState, Func1<TState, Boolean> condition,
Func1<TState, TState> iterate, Func1<TState, R> resultSelector) {
return generate(initialState, condition, iterate, resultSelector,
Schedulers.threadPoolForComputation());
}
/**
* Generates an observable sequence by iterating a state from an initial state until the condition fails.
* @param initialState The initial state.
* @param condition The condition to terminate generation.
* @param iterate The iteration step function.
* @param resultSelector The selector function for results produced in the sequence.
* @param scheduler he scheduler on which to run the generator loop.
* @return The generated sequence.
* @see <a href='http://msdn.microsoft.com/en-us/library/hh212014.aspx'>MSDN: Observable.Generate</a>
*/
public static <TState, R> Observable<R> generate(TState initialState, Func1<TState, Boolean> condition,
Func1<TState, TState> iterate, Func1<TState, R> resultSelector, Scheduler scheduler) {
return create(OperationGenerate.generate(initialState, condition, iterate,
resultSelector, scheduler));
}
/**
* Generates an observable sequence by iterating a state from an initial state until the condition fails.
* @param initialState The initial state.
* @param condition The condition to terminate generation.
* @param iterate The iteration step function.
* @param resultSelector The selector function for results produced in the sequence.
* @param timeSelector The time selector function to control the speed of values being produced each iteration.
* @return The generated sequence.
* @see <a href='http://msdn.microsoft.com/en-us/library/hh212066.aspx'>MSDN: Observable.Generate</a>
*/
public static <TState, R> Observable<R> generate(TState initialState,
Func1<TState, Boolean> condition,
Func1<TState, TState> iterate,
Func1<TState, R> resultSelector,
Func1<TState, TimeSpan> timeSelector) {
return generate(initialState, condition, iterate, resultSelector,
timeSelector, Schedulers.threadPoolForComputation());
}
/**
* Generates an observable sequence by iterating a state from an initial state until the condition fails.
* @param initialState The initial state.
* @param condition The condition to terminate generation.
* @param iterate The iteration step function.
* @param resultSelector The selector function for results produced in the sequence.
* @param timeSelector The time selector function to control the speed of values being produced each iteration.
* @param scheduler he scheduler on which to run the generator loop.
* @return The generated sequence.
* @see <a href='http://msdn.microsoft.com/en-us/library/hh211794.aspx'>MSDN: Observable.Generate</a>
*/
public static <TState, R> Observable<R> generate(TState initialState,
Func1<TState, Boolean> condition,
Func1<TState, TState> iterate,
Func1<TState, R> resultSelector,
Func1<TState, TimeSpan> timeSelector,
Scheduler scheduler) {
return create(OperationGenerate.generate(initialState, condition, iterate, resultSelector,
timeSelector, scheduler));
}
/**
* Generates an observable sequence by iterating a state from an initial state until the condition fails.
* @param initialState The initial state.
* @param condition The condition to terminate generation.
* @param iterate The iteration step function.
* @param resultSelector The selector function for results produced in the sequence.
* @param timeSelector The time selector function to control the speed of values being produced each iteration.
* @return The generated sequence.
* @see <a href='http://msdn.microsoft.com/en-us/library/hh229270.aspx'>MSDN: Observable.Generate</a>
*/
public static <TState, R> Observable<R> generateAbsoluteTime(TState initialState,
Func1<TState, Boolean> condition,
Func1<TState, TState> iterate,
Func1<TState, R> resultSelector,
Func1<TState, Date> timeSelector
) {
return generateAbsoluteTime(initialState, condition, iterate, resultSelector,
timeSelector, Schedulers.threadPoolForComputation());
}
/**
* Generates an observable sequence by iterating a state from an initial state until the condition fails.
* @param initialState The initial state.
* @param condition The condition to terminate generation.
* @param iterate The iteration step function.
* @param resultSelector The selector function for results produced in the sequence.
* @param timeSelector The time selector function to control the speed of values being produced each iteration.
* @param scheduler he scheduler on which to run the generator loop.
* @return The generated sequence.
* @see <a href='http://msdn.microsoft.com/en-us/library/hh244290.aspx'>MSDN: Observable.Generate</a>
*/
public static <TState, R> Observable<R> generateAbsoluteTime(TState initialState,
Func1<TState, Boolean> condition,
Func1<TState, TState> iterate,
Func1<TState, R> resultSelector,
Func1<TState, Date> timeSelector,
Scheduler scheduler) {
return create(OperationGenerate.generateAbsoluteTime(initialState, condition,
iterate, resultSelector, timeSelector, scheduler));
}
}
225 changes: 225 additions & 0 deletions rxjava-core/src/main/java/rx/operators/OperationGenerate.java
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@@ -0,0 +1,225 @@
/**
* Copyright 2013 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.operators;

import java.util.Date;
import java.util.concurrent.TimeUnit;
import rx.Observable.OnSubscribeFunc;
import rx.Observer;
import rx.Scheduler;
import rx.Subscription;
import rx.subscriptions.Subscriptions;
import rx.util.TimeSpan;
import rx.util.functions.Func1;
import rx.util.functions.Func2;

/**
* Generates an observable sequence by iterating a state from an initial state
* until the condition returns false.
* <p>
* Behaves like a generalized for loop.
*/
public final class OperationGenerate {
/**
* Generates an observable sequence by iterating a state from an initial
* state until the condition returns false.
*/
public static <TState, R> OnSubscribeFunc<R> generate(
final TState initialState,
final Func1<TState, Boolean> condition,
final Func1<TState, TState> iterate,
final Func1<TState, R> resultSelector,
final Scheduler scheduler) {
return new OnSubscribeFunc<R>() {
@Override
public Subscription onSubscribe(final Observer<? super R> observer) {
return scheduler.schedule(initialState, new Func2<Scheduler, TState, Subscription>() {
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Is it OK that creating a special timeSelector which always returns 0 to remove these duplicated codes?

@Override
public Subscription call(Scheduler s, TState state) {
boolean hasNext;
try {
hasNext = condition.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}
if (hasNext) {
R result;
try {
result = resultSelector.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}
observer.onNext(result);

TState nextState;
try {
nextState = iterate.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}

return s.schedule(nextState, this);
}
observer.onCompleted();
return Subscriptions.empty();
}
});
}
};
}
/**
* Generates an observable sequence by iterating a state, in relative timed fashion,
* from an initial state until the condition fails.
*/
public static <TState, R> OnSubscribeFunc<R> generate(
final TState initialState,
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Bad indent.

final Func1<TState, Boolean> condition,
final Func1<TState, TState> iterate,
final Func1<TState, R> resultSelector,
final Func1<TState, TimeSpan> timeSelector,
final Scheduler scheduler) {
return new OnSubscribeFunc<R>() {
@Override
public Subscription onSubscribe(final Observer<? super R> observer) {
TimeSpan first;
try {
first = timeSelector.call(initialState);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}

return scheduler.schedule(initialState,
new Func2<Scheduler, TState, Subscription>() {
@Override
public Subscription call(Scheduler s, TState state) {
boolean hasNext;
try {
hasNext = condition.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}
if (hasNext) {
R result;
try {
result = resultSelector.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}
observer.onNext(result);

TState nextState;
try {
nextState = iterate.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}

TimeSpan nextDate;
try {
nextDate = timeSelector.call(initialState);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}

return s.schedule(nextState, this, nextDate.value(), nextDate.unit());
}
observer.onCompleted();
return Subscriptions.empty();
}
}, first.value(), first.unit());
}
};
}
/**
* Generates an observable sequence by iterating a state, in absolute timed fashion,
* from an initial state until the condition fails.
*/
public static <TState, R> OnSubscribeFunc<R> generateAbsoluteTime(
final TState initialState,
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Bad indent.

final Func1<TState, Boolean> condition,
final Func1<TState, TState> iterate,
final Func1<TState, R> resultSelector,
final Func1<TState, Date> timeSelector,
final Scheduler scheduler) {
return new OnSubscribeFunc<R>() {
@Override
public Subscription onSubscribe(final Observer<? super R> observer) {
Date first;
try {
first = timeSelector.call(initialState);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}

long delta = Math.max(0, first.getTime() - scheduler.now());

return scheduler.schedule(initialState,
new Func2<Scheduler, TState, Subscription>() {
@Override
public Subscription call(Scheduler s, TState state) {
boolean hasNext;
try {
hasNext = condition.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}
if (hasNext) {
R result;
try {
result = resultSelector.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}
observer.onNext(result);

TState nextState;
try {
nextState = iterate.call(state);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}

Date nextDate;
try {
nextDate = timeSelector.call(initialState);
} catch (Throwable t) {
observer.onError(t);
return Subscriptions.empty();
}

long deltaNext = Math.max(0, nextDate.getTime() - s.now());
return s.schedule(nextState, this, deltaNext, TimeUnit.MILLISECONDS);
}
observer.onCompleted();
return Subscriptions.empty();
}
}, delta, TimeUnit.MILLISECONDS);
}
};
}
}
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