diff options
| author | Brian S. O'Neill <bronee@gmail.com> | 2006-09-19 06:22:33 +0000 |
|---|---|---|
| committer | Brian S. O'Neill <bronee@gmail.com> | 2006-09-19 06:22:33 +0000 |
| commit | 86b7bd05e5e839f7d70296065f4373098e44669a (patch) | |
| tree | 34b3fa3269b2917952d89e6de25119cee6270a45 /src/main/java/com/amazon/carbonado | |
| parent | 2278740878264362fd0f51e5f782715a89e4964f (diff) | |
Added SingletonCursor.
Diffstat (limited to 'src/main/java/com/amazon/carbonado')
| -rw-r--r-- | src/main/java/com/amazon/carbonado/cursor/EmptyCursor.java | 1 | ||||
| -rw-r--r-- | src/main/java/com/amazon/carbonado/cursor/SingletonCursor.java | 103 |
2 files changed, 104 insertions, 0 deletions
diff --git a/src/main/java/com/amazon/carbonado/cursor/EmptyCursor.java b/src/main/java/com/amazon/carbonado/cursor/EmptyCursor.java index e0649cd..d851f0e 100644 --- a/src/main/java/com/amazon/carbonado/cursor/EmptyCursor.java +++ b/src/main/java/com/amazon/carbonado/cursor/EmptyCursor.java @@ -29,6 +29,7 @@ import com.amazon.carbonado.Cursor; * Special cursor implementation that is empty.
*
* @author Brian S O'Neill
+ * @see SingletonCursor
*/
public class EmptyCursor<S> implements Cursor<S> {
private static final Cursor EMPTY_CURSOR = new EmptyCursor();
diff --git a/src/main/java/com/amazon/carbonado/cursor/SingletonCursor.java b/src/main/java/com/amazon/carbonado/cursor/SingletonCursor.java new file mode 100644 index 0000000..55b6cb6 --- /dev/null +++ b/src/main/java/com/amazon/carbonado/cursor/SingletonCursor.java @@ -0,0 +1,103 @@ +/*
+ * Copyright 2006 Amazon Technologies, Inc. or its affiliates.
+ * Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
+ * of Amazon Technologies, Inc. or its affiliates. All rights reserved.
+ *
+ * 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 com.amazon.carbonado.cursor;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+import com.amazon.carbonado.Cursor;
+
+/**
+ * Special cursor implementation that returns only one element.
+ *
+ * @author Brian S O'Neill
+ * @see EmptyCursor
+ */
+public class SingletonCursor<S> implements Cursor<S> {
+ private volatile S mObject;
+
+ /**
+ * @param object single object to return from cursor, must not be null
+ * @throws IllegalArgumentException if object is null
+ */
+ public SingletonCursor(S object) {
+ if (object == null) {
+ throw new IllegalArgumentException();
+ }
+ mObject = object;
+ }
+
+ public void close() {
+ mObject = null;
+ }
+
+ public boolean hasNext() {
+ return mObject != null;
+ }
+
+ public S next() {
+ S object = mObject;
+ mObject = null;
+ if (object == null) {
+ throw new NoSuchElementException();
+ }
+ return object;
+ }
+
+ public int skipNext(int amount) {
+ if (amount <= 0) {
+ if (amount < 0) {
+ throw new IllegalArgumentException("Cannot skip negative amount: " + amount);
+ }
+ return 0;
+ }
+ S object = mObject;
+ mObject = null;
+ return object == null ? 0 : 1;
+ }
+
+ public int copyInto(Collection<? super S> c) {
+ S object = mObject;
+ mObject = null;
+ if (object == null) {
+ return 0;
+ }
+ int originalSize = c.size();
+ c.add(object);
+ return originalSize + 1;
+ }
+
+ public int copyInto(Collection<? super S> c, int limit) {
+ return limit <= 0 ? 0 : copyInto(c);
+ }
+
+ public List<S> toList() {
+ List<S> list = new ArrayList<S>(1);
+ copyInto(list);
+ return list;
+ }
+
+ public List<S> toList(int limit) {
+ List<S> list = new ArrayList<S>(1);
+ copyInto(list, limit);
+ return list;
+ }
+}
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