From 4dbbe6c32ae8fc583d99f54045d8cbb9f8320d33 Mon Sep 17 00:00:00 2001
From: Keir Nellyer <keir@nellyer.co.uk>
Date: Wed, 27 Jul 2016 16:49:50 +0100
Subject: [PATCH] Allow Collector instance to be configured in parameters

---
 .../mineplex/core/common/util/UtilFuture.java | 30 +++++++++++++++----
 1 file changed, 25 insertions(+), 5 deletions(-)

diff --git a/Plugins/Mineplex.Core.Common/src/mineplex/core/common/util/UtilFuture.java b/Plugins/Mineplex.Core.Common/src/mineplex/core/common/util/UtilFuture.java
index 330ac1957..7e9aa87aa 100644
--- a/Plugins/Mineplex.Core.Common/src/mineplex/core/common/util/UtilFuture.java
+++ b/Plugins/Mineplex.Core.Common/src/mineplex/core/common/util/UtilFuture.java
@@ -7,6 +7,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Function;
+import java.util.stream.Collector;
 import java.util.stream.Collectors;
 
 public class UtilFuture
@@ -16,20 +17,39 @@ public class UtilFuture
 	 * This is a workaround for {@link CompletableFuture#anyOf(CompletableFuture[])} returning void.
 	 *
 	 * @param futures the futures to wait to complete
-	 * @param <T> the return type of the supplied futures
+	 * @param <T> the type of item(s)
 	 * @return a future which will complete when all supplied futures have completed
 	 */
-	public static <T> CompletableFuture<List<T>> sequence(List<CompletableFuture<T>> futures)
+	public static <T> CompletableFuture<List<T>> sequence(Collection<CompletableFuture<T>> futures)
+	{
+		return sequence(futures, Collectors.toList());
+	}
+
+	/**
+	 * Returns a {@link CompletableFuture} which will complete when supplied futures have completed.
+	 * This is a workaround for {@link CompletableFuture#anyOf(CompletableFuture[])} returning void.
+	 *
+	 * @param futures the futures to wait to complete
+	 * @param <R> the collection type
+	 * @param <T> the type of the collection's items
+	 * @return a future which will complete when all supplied futures have completed
+	 */
+	public static <R, T> CompletableFuture<R> sequence(Collection<CompletableFuture<T>> futures, Collector<T, ?, R> collector)
 	{
 		CompletableFuture<Void> futuresCompletedFuture =
 				CompletableFuture.allOf(futures.toArray(new CompletableFuture[futures.size()]));
 
 		return futuresCompletedFuture.thenApply(v ->
-				futures.stream().map(CompletableFuture::join).collect(Collectors.toList()));
+				futures.stream().map(CompletableFuture::join).collect(collector));
+	}
+
+	public static <T> CompletableFuture<List<T>> filter(List<T> list, Function<T, CompletableFuture<Boolean>> futureFunction)
+	{
+		return filter(list, futureFunction, Collectors.toList());
 	}
 
 	// TODO javadocs
-	public static <T> CompletableFuture<List<T>> filter(List<T> list, Function<T, CompletableFuture<Boolean>> futureFunction)
+	public static <R, T> CompletableFuture<R> filter(List<T> list, Function<T, CompletableFuture<Boolean>> futureFunction, Collector<T, ?, R> collector)
 	{
 		Map<T, CompletableFuture<Boolean>> elementFutureMap = list.stream()
 				.collect(Collectors.toMap(
@@ -43,6 +63,6 @@ public class UtilFuture
 				elementFutureMap.entrySet().stream()
 						.filter(entry -> entry.getValue().join()) // this doesn't block as all futures have completed
 						.map(Map.Entry::getKey)
-						.collect(Collectors.toList()));
+						.collect(collector));
 	}
 }