Merge pull request #563 from akarnokd/GroupByUntil5

Operation GroupByUntil

Author: benjchristensen

rxjava-core/src/main/java/rx/Observable.java

@@ -54,6 +54,7 @@
 import rx.operators.OperationFinally;
 import rx.operators.OperationFirstOrDefault;
 import rx.operators.OperationGroupBy;
+import rx.operators.OperationGroupByUntil;
 import rx.operators.OperationInterval;
 import rx.operators.OperationJoin;
 import rx.operators.OperationJoinPatterns;
@@ -129,6 +130,7 @@
 import rx.util.functions.Func9;
 import rx.util.functions.FuncN;
 import rx.util.functions.Function;
+import rx.util.functions.Functions;
 
 /**
  * The Observable interface that implements the Reactive Pattern.
@@ -6143,4 +6145,29 @@ public <K, V> Observable<Map<K, Collection<V>>> toMultimap(Func1<? super T, ? ex
     public <U> Observable<T> skipUntil(Observable<U> other) {
         return create(new OperationSkipUntil<T, U>(this, other));
     }
+        
+    /**
+     * Groups the elements of an observable sequence according to a specified key selector function until the duration observable expires for the key.
+     * @param keySelector A function to extract the key for each element.
+     * @param durationSelector A function to signal the expiration of a group.
+     * @return A sequence of observable groups, each of which corresponds to a unique key value, containing all elements that share that same key value.
+     * 
+     * @see <a href='http://msdn.microsoft.com/en-us/library/hh211932.aspx'>MSDN: Observable.GroupByUntil</a>
+     */
+    public <TKey, TDuration> Observable<GroupedObservable<TKey, T>> groupByUntil(Func1<? super T, ? extends TKey> keySelector, Func1<? super GroupedObservable<TKey, T>, ? extends Observable<TDuration>> durationSelector) {
+        return groupByUntil(keySelector, Functions.<T>identity(), durationSelector);
+    }
+    
+    /**
+     * Groups the elements of an observable sequence according to a specified key and value selector function  until the duration observable expires for the key.
+     * @param keySelector A function to extract the key for each element.
+     * @param valueSelector A function to map each source element to an element in an onbservable group.
+     * @param durationSelector A function to signal the expiration of a group.
+     * @return A sequence of observable groups, each of which corresponds to a unique key value, containing all elements that share that same key value.
+     * 
+     * @see <a href='http://msdn.microsoft.com/en-us/library/hh229433.aspx'>MSDN: Observable.GroupByUntil</a>
+     */
+    public <TKey, TValue, TDuration> Observable<GroupedObservable<TKey, TValue>> groupByUntil(Func1<? super T, ? extends TKey> keySelector, Func1<? super T, ? extends TValue> valueSelector, Func1<? super GroupedObservable<TKey, TValue>, ? extends Observable<TDuration>> durationSelector) {
+        return create(new OperationGroupByUntil<T, TKey, TValue, TDuration>(this, keySelector, valueSelector, durationSelector));
+    }
 }

rxjava-core/src/main/java/rx/operators/OperationGroupByUntil.java

@@ -0,0 +1,236 @@
+ /**
+  * 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.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import rx.Observable;
+import rx.Observable.OnSubscribeFunc;
+import rx.Observer;
+import rx.Subscription;
+import rx.observables.GroupedObservable;
+import rx.subjects.PublishSubject;
+import rx.subjects.Subject;
+import rx.subscriptions.CompositeSubscription;
+import rx.subscriptions.SerialSubscription;
+import rx.subscriptions.Subscriptions;
+import rx.util.functions.Func1;
+
+/**
+ * Groups the elements of an observable sequence according to a specified key selector, value selector and duration selector function.
+ *
+ * @see <a href='http://msdn.microsoft.com/en-us/library/hh211932.aspx'>MSDN: Observable.GroupByUntil</a>
+ * @see <a href='http://msdn.microsoft.com/en-us/library/hh229433.aspx'>MSDN: Observable.GroupByUntil</a>
+ */
+public class OperationGroupByUntil<TSource, TKey, TResult, TDuration> implements OnSubscribeFunc<GroupedObservable<TKey, TResult>> {
+    final Observable<TSource> source;
+    final Func1<? super TSource, ? extends TKey> keySelector;
+    final Func1<? super TSource, ? extends TResult> valueSelector;
+    final Func1<? super GroupedObservable<TKey, TResult>, ? extends Observable<TDuration>> durationSelector;
+    public OperationGroupByUntil(Observable<TSource> source,
+            Func1<? super TSource, ? extends TKey> keySelector,
+            Func1<? super TSource, ? extends TResult> valueSelector,
+            Func1<? super GroupedObservable<TKey, TResult>, ? extends Observable<TDuration>> durationSelector) {
+        this.source = source;
+        this.keySelector = keySelector;
+        this.valueSelector = valueSelector;
+        this.durationSelector = durationSelector;
+    }
+    
+    @Override
+    public Subscription onSubscribe(Observer<? super GroupedObservable<TKey, TResult>> t1) {
+        SerialSubscription cancel = new SerialSubscription();
+        ResultSink sink = new ResultSink(t1, cancel);
+        cancel.setSubscription(sink.run());
+        return cancel;
+    }
+    /** The source value sink and group manager. */
+    class ResultSink implements Observer<TSource> {
+        /** Guarded by gate. */
+        protected final Observer<? super GroupedObservable<TKey, TResult>> observer;
+        protected final Subscription cancel;
+        protected final CompositeSubscription group = new CompositeSubscription();
+        protected final Object gate = new Object();
+        /** Guarded by gate. */
+        protected final Map<TKey, GroupSubject<TKey, TResult>> map = new HashMap<TKey, GroupSubject<TKey, TResult>>();
+        public ResultSink(Observer<? super GroupedObservable<TKey, TResult>> observer, Subscription cancel) {
+            this.observer = observer;
+            this.cancel = cancel;
+        }
+        /** Prepare the subscription tree. */
+        public Subscription run() {
+            SerialSubscription toSource = new SerialSubscription();
+            group.add(toSource);
+            
+            toSource.setSubscription(source.subscribe(this));
+            
+            return group;
+        }
+        
+        @Override
+        public void onNext(TSource args) {
+            TKey key;
+            TResult value;
+            try {
+                key = keySelector.call(args);
+                value = valueSelector.call(args);
+            } catch (Throwable t) {
+                onError(t);
+                return;
+            }
+            
+            GroupSubject<TKey, TResult> g;
+            boolean newGroup = false;
+            synchronized (key) {
+                g = map.get(key);
+                if (g == null) {
+                    g = create(key);
+                    map.put(key, g);
+                    newGroup = true;
+                }
+            }
+            
+            if (newGroup) {
+                Observable<TDuration> duration;
+                try {
+                    duration = durationSelector.call(g);
+                } catch (Throwable t) {
+                    onError(t);
+                    return;
+                }
+                
+                synchronized (gate) {
+                    observer.onNext(g);
+                }
+                
+                SerialSubscription durationHandle = new SerialSubscription();
+                group.add(durationHandle);
+                
+                DurationObserver durationObserver = new DurationObserver(key, durationHandle);
+                durationHandle.setSubscription(duration.subscribe(durationObserver));
+                
+            }
+            
+            synchronized (gate) {
+                g.onNext(value);
+            }
+        }
+        
+        @Override
+        public void onError(Throwable e) {
+            synchronized (gate) {
+                List<GroupSubject<TKey, TResult>> gs = new ArrayList<GroupSubject<TKey, TResult>>(map.values());
+                map.clear();
+                for (GroupSubject<TKey, TResult> g : gs) {
+                    g.onError(e);
+                }
+                observer.onError(e);
+            }
+            cancel.unsubscribe();
+        }
+        
+        @Override
+        public void onCompleted() {
+            synchronized (gate) {
+                List<GroupSubject<TKey, TResult>> gs = new ArrayList<GroupSubject<TKey, TResult>>(map.values());
+                map.clear();
+                for (GroupSubject<TKey, TResult> g : gs) {
+                    g.onCompleted();
+                }
+                observer.onCompleted();
+            }
+            cancel.unsubscribe();
+        }
+        /** Create a new group. */
+        public GroupSubject<TKey, TResult> create(TKey key) {
+            PublishSubject<TResult> publish = PublishSubject.create();
+            return new GroupSubject<TKey, TResult>(key, publish);
+        }
+        /** Terminate a group. */
+        public void expire(TKey key, Subscription handle) {
+            synchronized (gate) {
+                GroupSubject<TKey, TResult> g = map.remove(key);
+                if (g != null) {
+                    g.onCompleted();
+                }
+            }
+            handle.unsubscribe();
+        }
+        /** Observe the completion of a group. */
+        class DurationObserver implements Observer<TDuration> {
+            final TKey key;
+            final Subscription handle;
+            public DurationObserver(TKey key, Subscription handle) {
+                this.key = key;
+                this.handle = handle;
+            }
+            @Override
+            public void onNext(TDuration args) {
+                expire(key, handle);
+            }
+            
+            @Override
+            public void onError(Throwable e) {
+                ResultSink.this.onError(e);
+            }
+            
+            @Override
+            public void onCompleted() {
+                expire(key, handle);
+            }
+            
+        }
+    }
+    protected static <T> OnSubscribeFunc<T> neverSubscribe() {
+        return new OnSubscribeFunc<T>() {
+            @Override
+            public Subscription onSubscribe(Observer<? super T> t1) {
+                return Subscriptions.empty();
+            }
+        };
+    }
+    /** A grouped observable with subject-like behavior. */
+    public static class GroupSubject<K, V> extends GroupedObservable<K, V> implements Observer<V> {
+        protected final Subject<V, V> publish;
+        public GroupSubject(K key, Subject<V, V> publish) {
+            super(key, OperationGroupByUntil.<V>neverSubscribe());
+            this.publish = publish;
+        }
+        
+        @Override
+        public Subscription subscribe(Observer<? super V> observer) {
+            return publish.subscribe(observer);
+        }
+        
+        @Override
+        public void onNext(V args) {
+            publish.onNext(args);
+        }
+        
+        @Override
+        public void onError(Throwable e) {
+            publish.onError(e);
+        }
+        
+        @Override
+        public void onCompleted() {
+            publish.onCompleted();
+        }
+        
+    }
+}