Added Utility

extractor/src/main/java/org/schabi/newpipe/extractor/streamdata/stream/util/NewPipeStreamCollectors.java

@@ -0,0 +1,100 @@
+package org.schabi.newpipe.extractor.streamdata.stream.util;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
+import java.util.stream.Stream;
+
+public final class NewPipeStreamCollectors {
+    private NewPipeStreamCollectors() {
+        // No impl
+    }
+
+    public static <T extends org.schabi.newpipe.extractor.streamdata.stream.Stream>
+        Collector<T, ?, List<T>> toDistinctList() {
+        return deduplicateEqualStreams(x -> x);
+    }
+
+    public static <T extends org.schabi.newpipe.extractor.streamdata.stream.Stream>
+        Collector<T, ?, Stream<T>> toDistinctStream() {
+        return deduplicateEqualStreams(List::stream);
+    }
+
+    public static <T extends org.schabi.newpipe.extractor.streamdata.stream.Stream, R>
+        Collector<T, ?, R> deduplicateEqualStreams(final Function<List<T>, R> finisher) {
+        return new CollectorImpl<>(
+                (Supplier<List<T>>) ArrayList::new,
+                List::add,
+                (left, right) -> {
+                    for(final T rightElement : right) {
+                        if (NewPipeStreamUtil.containSimilarStream(rightElement, left)) {
+                            left.add(rightElement);
+                        }
+                    }
+                    return left;
+                },
+                finisher,
+                CH_ID);
+    }
+
+    /**
+     * Copied from {@link java.util.stream.Collectors}
+     */
+    static final Set<Collector.Characteristics> CH_ID =
+            Collections.unmodifiableSet(EnumSet.of(Collector.Characteristics.IDENTITY_FINISH));
+
+    /**
+     * Copied from {@link java.util.stream.Collectors}
+     */
+    static class CollectorImpl<T, A, R> implements Collector<T, A, R> {
+        private final Supplier<A> supplier;
+        private final BiConsumer<A, T> accumulator;
+        private final BinaryOperator<A> combiner;
+        private final Function<A, R> finisher;
+        private final Set<Characteristics> characteristics;
+
+        CollectorImpl(final Supplier<A> supplier,
+                      final BiConsumer<A, T> accumulator,
+                      final BinaryOperator<A> combiner,
+                      final Function<A,R> finisher,
+                      final Set<Characteristics> characteristics) {
+            this.supplier = supplier;
+            this.accumulator = accumulator;
+            this.combiner = combiner;
+            this.finisher = finisher;
+            this.characteristics = characteristics;
+        }
+
+        @Override
+        public BiConsumer<A, T> accumulator() {
+            return accumulator;
+        }
+
+        @Override
+        public Supplier<A> supplier() {
+            return supplier;
+        }
+
+        @Override
+        public BinaryOperator<A> combiner() {
+            return combiner;
+        }
+
+        @Override
+        public Function<A, R> finisher() {
+            return finisher;
+        }
+
+        @Override
+        public Set<Characteristics> characteristics() {
+            return characteristics;
+        }
+    }
+}

extractor/src/main/java/org/schabi/newpipe/extractor/streamdata/stream/util/NewPipeStreamUtil.java

@@ -0,0 +1,38 @@
+package org.schabi.newpipe.extractor.streamdata.stream.util;
+
+import org.schabi.newpipe.extractor.streamdata.stream.Stream;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+public final class NewPipeStreamUtil {
+    private NewPipeStreamUtil() {
+        // No impl
+    }
+
+    /**
+     * Checks if the list already contains a stream with the same statistics.
+     *
+     * @param stream the stream to be compared against the streams in the stream list
+     * @param streams the list of {@link Stream}s which will be compared
+     * @return whether the list already contains one stream with equals stats
+     */
+    public static boolean containSimilarStream(final Stream stream,
+                                               final Collection<? extends Stream> streams) {
+        if (streams == null || streams.isEmpty()) {
+            return false;
+        }
+        return streams.stream().anyMatch(stream::equalsStream);
+    }
+
+    public <T extends Stream> List<T> removeEqualStreams(final Collection<T> streams) {
+        final List<T> returnList = new ArrayList<>();
+        for(final T stream : streams) {
+            if (!containSimilarStream(stream, returnList)) {
+                returnList.add(stream);
+            }
+        }
+        return returnList;
+    }
+}