diff options
| author | Brian S. O'Neill <bronee@gmail.com> | 2008-04-06 04:17:35 +0000 |
|---|---|---|
| committer | Brian S. O'Neill <bronee@gmail.com> | 2008-04-06 04:17:35 +0000 |
| commit | 83c9091b5b1ae0fca552e03eb55e85cfb316ccd2 (patch) | |
| tree | 891578a2e124ad446d372103e4d6c2747e584180 /src/main/java/com/amazon/carbonado/cursor | |
| parent | 1754d1a15b4c49d6c89308697fe7a316b4ab766e (diff) | |
Replace SliceCursor with simpler SkipCursor and LimitCursor classes.
Diffstat (limited to 'src/main/java/com/amazon/carbonado/cursor')
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;
- }
- }
-}
|