Replace SliceCursor with simpler SkipCursor and LimitCursor classes.

3 files changed, 166 insertions, 153 deletions

diff --git a/src/main/java/com/amazon/carbonado/cursor/LimitCursor.java b/src/main/java/com/amazon/carbonado/cursor/LimitCursor.java
new file mode 100644
index 0000000..ce96f6a
--- /dev/null
+++ b/src/main/java/com/amazon/carbonado/cursor/LimitCursor.java
@@ -0,0 +1,89 @@
+/*

+ * Copyright 2008 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.NoSuchElementException;

+

+import com.amazon.carbonado.Cursor;

+import com.amazon.carbonado.FetchException;

+

+/**

+ * Wraps another cursor to limit the amount of elements.

+ *

+ * @author Brian S O'Neill

+ */

+public class LimitCursor<S> extends AbstractCursor<S> {

+    private final Cursor<S> mSource;

+    private volatile long mRemaining;

+

+    /**

+     * @param limit maximum amount of elements

+     * @throws IllegalArgumentException if source is null or limit is negative

+     */

+    public LimitCursor(Cursor<S> source, long limit) {

+        if (source == null) {

+            throw new IllegalArgumentException("Source is null");

+        }

+        if (limit < 0) {

+            throw new IllegalArgumentException("Limit is negative: " + limit);

+        }

+        mSource = source;

+        mRemaining = limit;

+    }

+

+    public boolean hasNext() throws FetchException {

+        if (mSource.hasNext()) {

+            if (mRemaining > 0) {

+                return true;

+            }

+            mSource.close();

+        }

+        return false;

+    }

+

+    public S next() throws FetchException {

+        if (mRemaining <= 0) {

+            throw new NoSuchElementException();

+        }

+        S next = mSource.next();

+        if (--mRemaining <= 0) {

+            mSource.close();

+        }

+        return next;

+    }

+

+    @Override

+    public int skipNext(int amount) throws FetchException {

+        if (mRemaining <= 0) {

+            return 0;

+        }

+        if (amount > mRemaining) {

+            amount = (int) mRemaining;

+        }

+        amount = mSource.skipNext(amount);

+        if ((mRemaining -= amount) <= 0) {

+            mSource.close();

+        }

+        return amount;

+    }

+

+    public void close() throws FetchException {

+        mSource.close();

+    }

+}

diff --git a/src/main/java/com/amazon/carbonado/cursor/SkipCursor.java b/src/main/java/com/amazon/carbonado/cursor/SkipCursor.java
new file mode 100644
index 0000000..7379373
--- /dev/null
+++ b/src/main/java/com/amazon/carbonado/cursor/SkipCursor.java
@@ -0,0 +1,77 @@
+/*

+ * Copyright 2008 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 com.amazon.carbonado.Cursor;

+import com.amazon.carbonado.FetchException;

+

+/**

+ * Wraps another cursor to skip an initial amount of elements.

+ *

+ * @author Brian S O'Neill

+ */

+public class SkipCursor<S> extends AbstractCursor<S> {

+    private final Cursor<S> mSource;

+    private volatile long mSkip;

+

+    /**

+     * @param skip initial amount of elements to skip

+     * @throws IllegalArgumentException if source is null or skip is negative

+     */

+    public SkipCursor(Cursor<S> source, long skip) {

+        if (source == null) {

+            throw new IllegalArgumentException("Source is null");

+        }

+        if (skip < 0) {

+            throw new IllegalArgumentException("Skip is negative: " + skip);

+        }

+        mSource = source;

+        mSkip = skip;

+    }

+

+    public boolean hasNext() throws FetchException {

+        doSkip();

+        return mSource.hasNext();

+    }

+

+    public S next() throws FetchException {

+        doSkip();

+        return mSource.next();

+    }

+

+    @Override

+    public int skipNext(int amount) throws FetchException {

+        doSkip();

+        return mSource.skipNext(amount);

+    }

+

+    public void close() throws FetchException {

+        mSource.close();

+    }

+

+    private void doSkip() throws FetchException {

+        if (mSkip > 0) {

+            while (mSkip > Integer.MAX_VALUE) {

+                mSkip -= mSource.skipNext(Integer.MAX_VALUE);

+            }

+            mSource.skipNext((int) mSkip);

+            mSkip = 0;

+        }

+    }

+}

diff --git a/src/main/java/com/amazon/carbonado/cursor/SliceCursor.java b/src/main/java/com/amazon/carbonado/cursor/SliceCursor.java
deleted file mode 100644
index bf14339..0000000
--- a/src/main/java/com/amazon/carbonado/cursor/SliceCursor.java
+++ /dev/null
@@ -1,153 +0,0 @@
-/*

- * Copyright 2007 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.NoSuchElementException;

-

-import com.amazon.carbonado.Cursor;

-import com.amazon.carbonado.FetchException;

-

-/**

- * Wraps another cursor and only produces a range of elements. The actual range

- * might be smaller if the source cursor doesn't have enough elements.

- *

- * @author Brian S O'Neill

- * @since 1.2

- */

-public abstract class SliceCursor<S> extends AbstractCursor<S> {

-    /**

-     * @param from zero-based element to start from, inclusive

-     * @throws IllegalArgumentException if source is null or from is negative

-     */

-    public static <S> Cursor<S> slice(Cursor<S> source, long from) {

-        if (source == null) {

-            throw new IllegalArgumentException("Source is null");

-        }

-        if (from >= 0) {

-            return from == 0 ? source : new Skip<S>(source, from);

-        } else {

-            throw new IllegalArgumentException("Slice from is negative: " + from);

-        }

-    }

-

-    /**

-     * @param from zero-based element to start from, inclusive

-     * @param to zero-based element to end at, exclusive

-     * @throws IllegalArgumentException if source is null, from is negative or

-     * if from is more than to

-     */

-    public static <S> Cursor<S> slice(Cursor<S> source, long from, long to) {

-        source = slice(source, from);

-        long remaining = to - from;

-        if (remaining < 0) {

-            throw new IllegalArgumentException("Slice from is more than to: " + from + " > " + to);

-        }

-        return new Limit<S>(source, remaining);

-    }

-

-    final Cursor<S> mSource;

-

-    SliceCursor(Cursor<S> source) {

-        mSource = source;

-    }

-

-    public void close() throws FetchException {

-        mSource.close();

-    }

-

-    private static class Skip<S> extends SliceCursor<S> {

-        private volatile long mSkip;

-

-        Skip(Cursor<S> source, long skip) {

-            super(source);

-            mSkip = skip;

-        }

-

-        public boolean hasNext() throws FetchException {

-            doSkip();

-            return mSource.hasNext();

-        }

-

-        public S next() throws FetchException {

-            doSkip();

-            return mSource.next();

-        }

-

-        @Override

-        public int skipNext(int amount) throws FetchException {

-            doSkip();

-            return mSource.skipNext(amount);

-        }

-

-        private void doSkip() throws FetchException {

-            if (mSkip > 0) {

-                while (mSkip > Integer.MAX_VALUE) {

-                    mSkip -= mSource.skipNext(Integer.MAX_VALUE);

-                }

-                mSource.skipNext((int) mSkip);

-                mSkip = 0;

-            }

-        }

-    }

-

-    private static class Limit<S> extends SliceCursor<S> {

-        private volatile long mRemaining;

-

-        Limit(Cursor<S> source, long remaining) {

-            super(source);

-            mRemaining = remaining;

-        }

-

-        public boolean hasNext() throws FetchException {

-            if (mSource.hasNext()) {

-                if (mRemaining > 0) {

-                    return true;

-                }

-                mSource.close();

-            }

-            return false;

-        }

-

-        public S next() throws FetchException {

-            if (mRemaining <= 0) {

-                throw new NoSuchElementException();

-            }

-            S next = mSource.next();

-            if (--mRemaining <= 0) {

-                mSource.close();

-            }

-            return next;

-        }

-

-        @Override

-        public int skipNext(int amount) throws FetchException {

-            if (mRemaining <= 0) {

-                return 0;

-            }

-            if (amount > mRemaining) {

-                amount = (int) mRemaining;

-            }

-            amount = mSource.skipNext(amount);

-            if ((mRemaining -= amount) <= 0) {

-                mSource.close();

-            }

-            return amount;

-        }

-    }

-}