refactor into subprojects event-api, event-async, event-common, event-loop, event-net-http

build.gradle

@@ -6,7 +6,7 @@ plugins {
 
 wrapper {
     gradleVersion = libs.versions.gradle.get()
-    distributionType = Wrapper.DistributionType.ALL
+    distributionType = Wrapper.DistributionType.BIN
 }
 
 ext {
@@ -24,12 +24,15 @@ ext {
     licenseUrl = 'http://www.apache.org/licenses/LICENSE-2.0.txt'
 }
 
-apply plugin: 'java-library'
+subprojects {
-apply from: rootProject.file('gradle/compile/java.gradle')
+    apply from: rootProject.file('gradle/compile/java.gradle')
-apply from: rootProject.file('gradle/test/junit5.gradle')
+    apply from: rootProject.file('gradle/test/junit5.gradle')
-apply from: rootProject.file('gradle/repositories/maven.gradle')
+    apply from: rootProject.file('gradle/repositories/maven.gradle')
-apply from: rootProject.file('gradle/publish/maven.gradle')
+}
+apply from: rootProject.file('gradle/publish/sonatype.gradle')
+apply from: rootProject.file('gradle/publish/forgejo.gradle')
 
+/*
 dependencies {
     api libs.settings.api
     implementation libs.net
@@ -41,3 +44,4 @@ dependencies {
     testImplementation libs.rxjava3
     testImplementation libs.settings.datastructures.json
 }
+*/

event-api/src/main/java/module-info.java

@@ -0,0 +1,3 @@
+module org.xbib.event.api {
+    exports org.xbib.event;
+}

event-async/build.gradle

@@ -0,0 +1,5 @@
+dependencies {
+    api project(':event-loop')
+    implementation libs.reactivestreams
+    testImplementation libs.rxjava3
+}

event-async/src/main/java/module-info.java

@@ -0,0 +1,11 @@
+module org.xbib.event.async {
+    exports org.xbib.event.async;
+    exports org.xbib.event.async.impl;
+    exports org.xbib.event.async.impl.future;
+    exports org.xbib.event.async.spi;
+    exports org.xbib.event.async.streams;
+    exports org.xbib.event.async.streams.impl;
+    requires org.xbib.event.loop;
+    requires org.reactivestreams;
+    requires java.logging;
+}

event-async/src/main/java/org/xbib/event/async/impl/AsyncThread.java

@@ -0,0 +1,56 @@
+package org.xbib.event.async.impl;
+
+import org.xbib.event.loop.thread.FastThreadLocalThread;
+import org.xbib.event.loop.thread.ThreadInfo;
+
+import java.util.concurrent.TimeUnit;
+
+public class AsyncThread extends FastThreadLocalThread {
+
+    private final boolean worker;
+    final ThreadInfo info;
+    ContextInternal context;
+    ClassLoader topLevelTCCL;
+
+    public AsyncThread(Runnable target, String name, boolean worker, long maxExecTime, TimeUnit maxExecTimeUnit) {
+        super(target, name);
+        this.worker = worker;
+        this.info = new ThreadInfo(maxExecTimeUnit, maxExecTime);
+    }
+
+    /**
+     * @return the current context of this thread, this method must be called from the current thread
+     */
+    ContextInternal context() {
+        return context;
+    }
+
+    void executeStart() {
+        if (context == null) {
+            info.startTime = System.nanoTime();
+        }
+    }
+
+    void executeEnd() {
+        if (context == null) {
+            info.startTime = 0;
+        }
+    }
+
+    public long startTime() {
+        return info.startTime;
+    }
+
+    public boolean isWorker() {
+        return worker;
+    }
+
+    public long maxExecTime() {
+        return info.maxExecTime;
+    }
+
+    public TimeUnit maxExecTimeUnit() {
+        return info.maxExecTimeUnit;
+    }
+
+}

event-async/src/main/java/org/xbib/event/async/impl/future/PromiseImpl.java

@@ -1,6 +1,6 @@
 package org.xbib.event.async.impl.future;
 
-import org.xbib.event.Future;
+import org.xbib.event.loop.Future;
 import org.xbib.event.async.AsyncResult;
 import org.xbib.event.async.impl.ContextInternal;
 

event-async/src/main/java/org/xbib/event/async/impl/future/PromiseInternal.java

@@ -1,6 +1,6 @@
 package org.xbib.event.async.impl.future;
 
-import org.xbib.event.FutureListener;
+import org.xbib.event.loop.FutureListener;
 import org.xbib.event.async.Promise;
 import org.xbib.event.async.impl.ContextInternal;
 

event-async/src/main/java/org/xbib/event/async/io/AbstractAsyncFileReaderLines.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;

event-async/src/main/java/org/xbib/event/async/io/AddOnComplete.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Subscriber;
 

event-async/src/main/java/org/xbib/event/async/io/AddOnError.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Subscriber;
 

event-async/src/main/java/org/xbib/event/async/io/AddOnNext.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Subscriber;
 

event-async/src/main/java/org/xbib/event/async/io/AddOnSubscribe.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;

event-async/src/main/java/org/xbib/event/async/io/AsyncFileQuery.java

@@ -1,6 +1,6 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.io.IOException;
 import java.nio.file.Path;

event-async/src/main/java/org/xbib/event/async/io/AsyncFileReaderBytes.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;

event-async/src/main/java/org/xbib/event/async/io/AsyncFileReaderLines.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;

event-async/src/main/java/org/xbib/event/async/io/AsyncFileWriter.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;

event-async/src/main/java/org/xbib/event/async/io/AsyncFiles.java

@@ -1,7 +1,7 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Publisher;
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;

event-async/src/main/java/org/xbib/event/async/io/EmptySubscriber.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Subscription;
 

event-async/src/main/java/org/xbib/event/async/io/SubscriberBuilder.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;

event-async/src/main/java/org/xbib/event/async/io/Subscribers.java

@@ -1,4 +1,4 @@
-package org.xbib.event.io;
+package org.xbib.event.async.io;
 
 import java.util.function.Consumer;
 

event-async/src/main/java/org/xbib/event/async/yield/Advancer.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield;
+package org.xbib.event.async.yield;
 
 /**
  * Sequential traverser with internal and individually step approach.

event-async/src/main/java/org/xbib/event/async/yield/AsyncQuery.java

@@ -1,16 +1,16 @@
-package org.xbib.event.yield;
+package org.xbib.event.async.yield;
 
-import org.xbib.event.yield.async.AsyncQueryDistinct;
+import org.xbib.event.async.yield.async.AsyncQueryDistinct;
-import org.xbib.event.yield.async.AsyncQueryFilter;
+import org.xbib.event.async.yield.async.AsyncQueryFilter;
-import org.xbib.event.yield.async.AsyncQueryFlatMapConcat;
+import org.xbib.event.async.yield.async.AsyncQueryFlatMapConcat;
-import org.xbib.event.yield.async.AsyncQueryFlatMapMerge;
+import org.xbib.event.async.yield.async.AsyncQueryFlatMapMerge;
-import org.xbib.event.yield.async.AsyncQueryFork;
+import org.xbib.event.async.yield.async.AsyncQueryFork;
-import org.xbib.event.yield.async.AsyncQueryMap;
+import org.xbib.event.async.yield.async.AsyncQueryMap;
-import org.xbib.event.yield.async.AsyncQueryOf;
+import org.xbib.event.async.yield.async.AsyncQueryOf;
-import org.xbib.event.yield.async.AsyncQueryOfIterator;
+import org.xbib.event.async.yield.async.AsyncQueryOfIterator;
-import org.xbib.event.yield.async.AsyncQueryOnNext;
+import org.xbib.event.async.yield.async.AsyncQueryOnNext;
-import org.xbib.event.yield.async.AsyncQuerySkip;
+import org.xbib.event.async.yield.async.AsyncQuerySkip;
-import org.xbib.event.yield.async.AsyncQueryTakeWhile;
+import org.xbib.event.async.yield.async.AsyncQueryTakeWhile;
 
 import java.util.Iterator;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/AsyncTraverser.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield;
+package org.xbib.event.async.yield;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/Query.java

@@ -1,32 +1,32 @@
-package org.xbib.event.yield;
+package org.xbib.event.async.yield;
 
-import org.xbib.event.yield.boxes.BoolBox;
+import org.xbib.event.async.yield.boxes.BoolBox;
-import org.xbib.event.yield.boxes.Box;
+import org.xbib.event.async.yield.boxes.Box;
-import org.xbib.event.yield.ops.Concat;
+import org.xbib.event.async.yield.ops.Concat;
-import org.xbib.event.yield.ops.Distinct;
+import org.xbib.event.async.yield.ops.Distinct;
-import org.xbib.event.yield.ops.DropWhile;
+import org.xbib.event.async.yield.ops.DropWhile;
-import org.xbib.event.yield.ops.Filter;
+import org.xbib.event.async.yield.ops.Filter;
-import org.xbib.event.yield.ops.FlatMap;
+import org.xbib.event.async.yield.ops.FlatMap;
-import org.xbib.event.yield.ops.FromArray;
+import org.xbib.event.async.yield.ops.FromArray;
-import org.xbib.event.yield.ops.FromList;
+import org.xbib.event.async.yield.ops.FromList;
-import org.xbib.event.yield.ops.FromStream;
+import org.xbib.event.async.yield.ops.FromStream;
-import org.xbib.event.yield.ops.Generate;
+import org.xbib.event.async.yield.ops.Generate;
-import org.xbib.event.yield.ops.Iterate;
+import org.xbib.event.async.yield.ops.Iterate;
-import org.xbib.event.yield.ops.Limit;
+import org.xbib.event.async.yield.ops.Limit;
-import org.xbib.event.yield.ops.Mapping;
+import org.xbib.event.async.yield.ops.Mapping;
-import org.xbib.event.yield.ops.Peek;
+import org.xbib.event.async.yield.ops.Peek;
-import org.xbib.event.yield.ops.Skip;
+import org.xbib.event.async.yield.ops.Skip;
-import org.xbib.event.yield.ops.TakeWhile;
+import org.xbib.event.async.yield.ops.TakeWhile;
-import org.xbib.event.yield.ops.Zip;
+import org.xbib.event.async.yield.ops.Zip;
-import org.xbib.event.yield.primitives.dbl.DoubleAdvancer;
+import org.xbib.event.async.yield.primitives.dbl.DoubleAdvancer;
-import org.xbib.event.yield.primitives.dbl.DoubleQuery;
+import org.xbib.event.async.yield.primitives.dbl.DoubleQuery;
-import org.xbib.event.yield.primitives.dbl.DoubleTraverser;
+import org.xbib.event.async.yield.primitives.dbl.DoubleTraverser;
-import org.xbib.event.yield.primitives.intgr.IntAdvancer;
+import org.xbib.event.async.yield.primitives.intgr.IntAdvancer;
-import org.xbib.event.yield.primitives.intgr.IntQuery;
+import org.xbib.event.async.yield.primitives.intgr.IntQuery;
-import org.xbib.event.yield.primitives.intgr.IntTraverser;
+import org.xbib.event.async.yield.primitives.intgr.IntTraverser;
-import org.xbib.event.yield.primitives.lng.LongAdvancer;
+import org.xbib.event.async.yield.primitives.lng.LongAdvancer;
-import org.xbib.event.yield.primitives.lng.LongQuery;
+import org.xbib.event.async.yield.primitives.lng.LongQuery;
-import org.xbib.event.yield.primitives.lng.LongTraverser;
+import org.xbib.event.async.yield.primitives.lng.LongTraverser;
 
 import java.util.ArrayList;
 import java.util.Arrays;

event-async/src/main/java/org/xbib/event/async/yield/TraversableFinishError.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield;
+package org.xbib.event.async.yield;
 
 @SuppressWarnings("serial")
 public class TraversableFinishError extends Error {

event-async/src/main/java/org/xbib/event/async/yield/Traverser.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield;
+package org.xbib.event.async.yield;
 
 /**
  * Bulk traversal.

event-async/src/main/java/org/xbib/event/async/yield/Yield.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield;
+package org.xbib.event.async.yield;
 
 /**
  * Equivalent to {@code Consumer<T>} with a yield semantics.

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryDistinct.java

@@ -1,6 +1,6 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.HashSet;
 import java.util.concurrent.CompletableFuture;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryFilter.java

@@ -1,6 +1,6 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryFlatMapConcat.java

@@ -1,6 +1,6 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryFlatMapMerge.java

@@ -1,7 +1,7 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.ArrayList;
 import java.util.List;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryFork.java

@@ -1,7 +1,7 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
-import org.xbib.event.yield.Query;
+import org.xbib.event.async.yield.Query;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryMap.java

@@ -1,6 +1,6 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryOf.java

@@ -1,7 +1,7 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
-import org.xbib.event.yield.Query;
+import org.xbib.event.async.yield.Query;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryOfIterator.java

@@ -1,6 +1,6 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.Iterator;
 import java.util.concurrent.CompletableFuture;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryOnNext.java

@@ -1,6 +1,6 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQuerySkip.java

@@ -1,7 +1,7 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
-import org.xbib.event.yield.AsyncTraverser;
+import org.xbib.event.async.yield.AsyncTraverser;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/async/AsyncQueryTakeWhile.java

@@ -1,6 +1,6 @@
-package org.xbib.event.yield.async;
+package org.xbib.event.async.yield.async;
 
-import org.xbib.event.yield.AsyncQuery;
+import org.xbib.event.async.yield.AsyncQuery;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.function.BiConsumer;

event-async/src/main/java/org/xbib/event/async/yield/boxes/BoolBox.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield.boxes;
+package org.xbib.event.async.yield.boxes;
 
 public class BoolBox {
 

event-async/src/main/java/org/xbib/event/async/yield/boxes/Box.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield.boxes;
+package org.xbib.event.async.yield.boxes;
 
 public class Box<T> {
 

event-async/src/main/java/org/xbib/event/async/yield/boxes/DoubleBox.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield.boxes;
+package org.xbib.event.async.yield.boxes;
 
 public class DoubleBox {
 

event-async/src/main/java/org/xbib/event/async/yield/boxes/IntBox.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield.boxes;
+package org.xbib.event.async.yield.boxes;
 
 public class IntBox {
 

event-async/src/main/java/org/xbib/event/async/yield/boxes/LongBox.java

@@ -1,4 +1,4 @@
-package org.xbib.event.yield.boxes;
+package org.xbib.event.async.yield.boxes;
 
 public class LongBox {
 

event-async/src/main/java/org/xbib/event/async/yield/ops/Concat.java

@@ -1,9 +1,9 @@
-package org.xbib.event.yield.ops;
+package org.xbib.event.async.yield.ops;
 
-import org.xbib.event.yield.Advancer;
+import org.xbib.event.async.yield.Advancer;
-import org.xbib.event.yield.Query;
+import org.xbib.event.async.yield.Query;
-import org.xbib.event.yield.Traverser;
+import org.xbib.event.async.yield.Traverser;
-import org.xbib.event.yield.Yield;
+import org.xbib.event.async.yield.Yield;
 
 public class Concat<T> implements Advancer<T>, Traverser<T> {
 

event-async/src/main/java/org/xbib/event/async/yield/ops/Distinct.java

@@ -1,10 +1,10 @@
-package org.xbib.event.yield.ops;
+package org.xbib.event.async.yield.ops;
 
-import org.xbib.event.yield.Advancer;
+import org.xbib.event.async.yield.Advancer;
-import org.xbib.event.yield.Query;
+import org.xbib.event.async.yield.Query;
-import org.xbib.event.yield.Traverser;
+import org.xbib.event.async.yield.Traverser;
-import org.xbib.event.yield.Yield;
+import org.xbib.event.async.yield.Yield;
-import org.xbib.event.yield.boxes.BoolBox;
+import org.xbib.event.async.yield.boxes.BoolBox;
 
 import java.util.HashSet;
 

event-async/src/main/java/org/xbib/event/async/yield/ops/DropWhile.java

@@ -1,9 +1,9 @@
-package org.xbib.event.yield.ops;
+package org.xbib.event.async.yield.ops;
 
-import org.xbib.event.yield.Advancer;
+import org.xbib.event.async.yield.Advancer;
-import org.xbib.event.yield.Query;
+import org.xbib.event.async.yield.Query;
-import org.xbib.event.yield.Traverser;
+import org.xbib.event.async.yield.Traverser;
-import org.xbib.event.yield.Yield;
+import org.xbib.event.async.yield.Yield;
 
 import java.util.function.Predicate;
 

event-async/src/main/java/org/xbib/event/async/yield/ops/Filter.java

@@ -1,10 +1,10 @@
-package org.xbib.event.yield.ops;
+package org.xbib.event.async.yield.ops;
 
-import org.xbib.event.yield.Advancer;
+import org.xbib.event.async.yield.Advancer;
-import org.xbib.event.yield.Query;
+import org.xbib.event.async.yield.Query;
-import org.xbib.event.yield.Traverser;
+import org.xbib.event.async.yield.Traverser;
-import org.xbib.event.yield.Yield;
+import org.xbib.event.async.yield.Yield;
-import org.xbib.event.yield.boxes.BoolBox;
+import org.xbib.event.async.yield.boxes.BoolBox;
 
 import java.util.function.Predicate;
 

event-async/src/main/java/org/xbib/event/async/yield/ops/FlatMap.java

@@ -1,9 +1,9 @@
-package org.xbib.event.yield.ops;
+package org.xbib.event.async.yield.ops;
 
-import org.xbib.event.yield.Advancer;
+import org.xbib.event.async.yield.Advancer;
-import org.xbib.event.yield.Query;
+import org.xbib.event.async.yield.Query;
-import org.xbib.event.yield.Traverser;
+import org.xbib.event.async.yield.Traverser;
-import org.xbib.event.yield.Yield;
+import org.xbib.event.async.yield.Yield;
 
 import java.util.function.Function;
 

event-async/src/main/java/org/xbib/event/async/yield/ops/FromArray.java

@@ -1,8 +1,8 @@
-package org.xbib.event.yield.ops;
+package org.xbib.event.async.yield.ops;
 
-import org.xbib.event.yield.Advancer;
+import org.xbib.event.async.yield.Advancer;
-import org.xbib.event.yield.Traverser;
+import org.xbib.event.async.yield.Traverser;
-import org.xbib.event.yield.Yield;
+import org.xbib.event.async.yield.Yield;
 
 public class FromArray<U> implements Advancer<U>, Traverser<U> {