OAK-11408: Extract IteratorUtils from CollectionUtils

oak-commons/src/main/java/org/apache/jackrabbit/oak/commons/collections/CollectionUtils.java

@@ -19,7 +19,6 @@
 package org.apache.jackrabbit.oak.commons.collections;
 
 import java.util.ArrayDeque;
-import java.util.Iterator;
 import java.util.Objects;
 
 import org.jetbrains.annotations.NotNull;
@@ -52,39 +51,6 @@ public static <T> ArrayDeque<T> toArrayDeque(@NotNull Iterable<? extends T> iter
         return arrayDeque;
     }
 
-    /**
-     * Convert an {@code Iterator} to an {@code Iterable}.
-     * <p>
-     * This method is not thread-safe
-     *
-     * @param iterator
-     *            iterator to convert
-     * @return a single-use iterable for the iterator (representing the remaining
-     *         elements in the iterator)
-     * @throws IllegalStateException
-     *             when {@linkplain Iterable#iterator()} is called more than
-     *             once
-     */
-    @NotNull
-    public static <T> Iterable<T> toIterable(@NotNull final Iterator<T> iterator) {
-        Objects.requireNonNull(iterator);
-
-        return new Iterable<>() {
-
-            private boolean consumed = false;
-
-            @Override
-            public @NotNull Iterator<T> iterator() {
-                if (consumed) {
-                    throw new IllegalStateException("Iterator already returned once");
-                } else {
-                    consumed = true;
-                    return iterator;
-                }
-            }
-        };
-    }
-
     /**
      * Ensure the capacity of a map or set given the expected number of elements.
      *

oak-commons/src/main/java/org/apache/jackrabbit/oak/commons/collections/IteratorUtils.java

@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.jackrabbit.oak.commons.collections;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Iterator;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+/**
+ * Utility methods for {@link Iterator} conversions.
+ */
+public class IteratorUtils {
+
+    private IteratorUtils() {
+        // no instances for you
+    }
+    /**
+     * Convert an {@code Iterator} to an {@code Iterable}.
+     * <p>
+     * This method is not thread-safe
+     *
+     * @param iterator iterator to convert
+     * @return a single-use iterable for the iterator (representing the remaining
+     * elements in the iterator)
+     * @throws IllegalStateException when {@linkplain Iterable#iterator()} is called more than
+     *                               once
+     */
+    @NotNull
+    public static <T> Iterable<T> toIterable(@NotNull final Iterator<T> iterator) {
+        Objects.requireNonNull(iterator);
+
+        return new Iterable<>() {
+
+            private boolean consumed = false;
+
+            @Override
+            public @NotNull Iterator<T> iterator() {
+                if (consumed) {
+                    throw new IllegalStateException("Iterator already returned once");
+                } else {
+                    consumed = true;
+                    return iterator;
+                }
+            }
+        };
+    }
+}

oak-commons/src/main/java/org/apache/jackrabbit/oak/commons/collections/StreamUtils.java

@@ -57,6 +57,6 @@ public static <T> Stream<T> toStream(@NotNull Iterable<T> iterable) {
      */
     @NotNull
     public static <T> Stream<T> toStream(@NotNull Iterator<T> iterator) {
-        return StreamSupport.stream(CollectionUtils.toIterable(iterator).spliterator(), false);
+        return StreamSupport.stream(IteratorUtils.toIterable(iterator).spliterator(), false);
     }
 }

oak-commons/src/test/java/org/apache/jackrabbit/oak/commons/collections/CollectionUtilsTest.java

@@ -24,7 +24,6 @@
 import java.util.ArrayDeque;
 import java.util.Arrays;
 import java.util.Collections;
-import java.util.Iterator;
 import java.util.List;
 
 import static org.junit.Assert.fail;
@@ -50,24 +49,6 @@ public void toArrayDequeWithEmptyIterable() {
         Assert.assertNotNull(result);
         Assert.assertTrue(result.isEmpty());
     }
-
-    @Test
-    public void iteratorToIIteratable() {
-        Iterator<String> iterator = List.of("a", "b", "c").iterator();
-        iterator.next();
-        Iterable<String> iterable = CollectionUtils.toIterable(iterator);
-        Iterator<String> testit = iterable.iterator();
-        Assert.assertEquals("b", testit.next());
-        Assert.assertEquals("c", testit.next());
-        Assert.assertFalse(testit.hasNext());
-        try {
-            testit = iterable.iterator();
-            fail("should only work once");
-        } catch (IllegalStateException expected) {
-            // that's what we want
-        }
-    }
-
     @Test
     public void ensureCapacity() {
         int capacity = CollectionUtils.ensureCapacity(8);

oak-commons/src/test/java/org/apache/jackrabbit/oak/commons/collections/IteratorUtilsTest.java

@@ -0,0 +1,48 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.jackrabbit.oak.commons.collections;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Iterator;
+import java.util.List;
+
+import static org.junit.Assert.fail;
+
+public class IteratorUtilsTest {
+
+    @Test
+    public void iteratorToIIteratable() {
+        Iterator<String> iterator = List.of("a", "b", "c").iterator();
+        iterator.next();
+        Iterable<String> iterable = IteratorUtils.toIterable(iterator);
+        Iterator<String> testit = iterable.iterator();
+        Assert.assertEquals("b", testit.next());
+        Assert.assertEquals("c", testit.next());
+        Assert.assertFalse(testit.hasNext());
+        try {
+            testit = iterable.iterator();
+            fail("should only work once");
+        } catch (IllegalStateException expected) {
+            // that's what we want
+        }
+    }
+
+}