From 86b7bd05e5e839f7d70296065f4373098e44669a Mon Sep 17 00:00:00 2001
From: "Brian S. O'Neill" <bronee@gmail.com>
Date: Tue, 19 Sep 2006 06:22:33 +0000
Subject: Added SingletonCursor.

---
 .../com/amazon/carbonado/cursor/EmptyCursor.java   |   1 +
 .../amazon/carbonado/cursor/SingletonCursor.java   | 103 +++++++++++++++++++++
 2 files changed, 104 insertions(+)
 create mode 100644 src/main/java/com/amazon/carbonado/cursor/SingletonCursor.java

(limited to 'src/main/java/com/amazon')

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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