diff options
Diffstat (limited to 'src/main/java/com/amazon/carbonado/cursor')
| -rw-r--r-- | src/main/java/com/amazon/carbonado/cursor/SliceCursor.java | 200 |
1 files changed, 93 insertions, 107 deletions
diff --git a/src/main/java/com/amazon/carbonado/cursor/SliceCursor.java b/src/main/java/com/amazon/carbonado/cursor/SliceCursor.java index 882932f..bf14339 100644 --- a/src/main/java/com/amazon/carbonado/cursor/SliceCursor.java +++ b/src/main/java/com/amazon/carbonado/cursor/SliceCursor.java @@ -33,52 +33,38 @@ import com.amazon.carbonado.FetchException; public abstract class SliceCursor<S> extends AbstractCursor<S> {
/**
* @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
+ * @throws IllegalArgumentException if source is null or from is negative
*/
- public static <S> Cursor<S> slice(Cursor<S> source, long from, long to) {
- return slice(source, (Long) from, (Long) to);
+ 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 optional zero-based element to start from, inclusive
- * @param to optional zero-based element to end at, exclusive
+ * @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) {
- if (source == null) {
- throw new IllegalArgumentException("Source is null");
+ 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);
}
-
- long actualFrom;
-
- if (from == null) {
- actualFrom = 0;
- } else if (from >= 0) {
- if ((actualFrom = from) > 0) {
- source = new Skip<S>(source, actualFrom);
- }
- } else {
- throw new IllegalArgumentException("Slice from is negative: " + from);
- }
-
- long remaining;
-
- if (to == null) {
- return source;
- } else if ((remaining = to - actualFrom) < 0) {
- throw new IllegalArgumentException("Slice from is more than to: " + from + " > " + to);
- }
-
- return new Limit<S>(source, remaining);
+ return new Limit<S>(source, remaining);
}
final Cursor<S> mSource;
SliceCursor(Cursor<S> source) {
- mSource = source;
+ mSource = source;
}
public void close() throws FetchException {
@@ -86,82 +72,82 @@ public abstract class SliceCursor<S> extends AbstractCursor<S> { }
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 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;
- }
+ 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;
+ }
}
}
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