com.bigdata.relation.accesspath.ArrayAccessPath Maven / Gradle / Ivy
/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.bigdata.relation.accesspath;
import java.util.Collections;
import com.bigdata.bop.IPredicate;
import com.bigdata.btree.IIndex;
import com.bigdata.striterator.ChunkedArrayIterator;
import com.bigdata.striterator.ChunkedWrappedIterator;
import com.bigdata.striterator.IChunkedOrderedIterator;
import com.bigdata.striterator.IKeyOrder;
/**
* An access path over an array of elements.
*/
public class ArrayAccessPath implements IAccessPath {
private final IPredicate predicate;
private final IKeyOrder keyOrder;
/**
* Array of elements
*/
private final E[] e;
/**
* Ctor variant does not specify the {@link #getPredicate()} or the
* {@link #getKeyOrder()} and those methods will throw an
* {@link UnsupportedOperationException} if invoked.
*/
public ArrayAccessPath(final E[] e) {
this(e, null/* predicate */, null/* keyOrder */);
}
/**
* Note: the {@link #getPredicate()} and {@link #getKeyOrder()} and methods
* will throw an {@link UnsupportedOperationException} if the corresponding
* argument is null.
*/
public ArrayAccessPath(final E[] e,
final IPredicate predicate, final IKeyOrder keyOrder) {
this.predicate = predicate;
this.keyOrder = keyOrder;
this.e = e;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException
* unless the caller specified an {@link IPredicate} to the
* ctor.
*/
@Override
public IPredicate getPredicate() {
if (predicate == null)
throw new UnsupportedOperationException();
return predicate;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException
* unless the caller specified an {@link IKeyOrder} to the ctor.
*/
@Override
public IKeyOrder getKeyOrder() {
if (keyOrder == null)
throw new UnsupportedOperationException();
return keyOrder;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException
* since no index is associated with this array
*/
@Override
public IIndex getIndex() {
throw new UnsupportedOperationException();
}
/**
* {@inheritDoc}
*
* Returns true when the array of elements is empty.
*/
@Override
public boolean isEmpty() {
return e.length == 0;
}
/**
* {@inheritDoc}
*
* Returns the size of the array of elements.
*/
@Override
public long rangeCount(boolean exact) {
return e.length;
}
// /**
// * @throws UnsupportedOperationException
// * since no index is associated with this array
// */
// @Override
// public ITupleIterator rangeIterator() {
//
// throw new UnsupportedOperationException();
//
// }
/**
* {@inheritDoc}
*
* Visits the entire array of elements.
*/
@Override
public IChunkedOrderedIterator iterator() {
return iterator(0L/* offset */, 0L/* limit */, 0/* capacity */);
}
// /**
// * Visits the array of elements up to the specified limit.
// */
// public IChunkedOrderedIterator iterator(final int limit,
// final int capacity) {
//
// return iterator(0L/* offset */, limit, capacity);
//
// }
/**
* {@inheritDoc}
*
* Visits the array of elements from the specified offset up to the
* specified limit.
*/
@Override
@SuppressWarnings("unchecked")
public IChunkedOrderedIterator iterator(final long offset,
long limit, final int capacity) {
if (offset < 0)
throw new IllegalArgumentException();
if (offset > e.length || e.length == 0) {
// Nothing to visit.
return new ChunkedWrappedIterator(
Collections.EMPTY_LIST.iterator());
}
if (limit >= Long.MAX_VALUE) {
// Treat MAX_VALUE as meaning NO limit.
limit = 0L;
}
if (limit >= offset+e.length) {
/*
* The caller requested more data than is available. Treat as
* meaning NO limit since we will read everything after the
* [offset].
*/
limit = 0L;
}
final int n;
if (limit == 0L) {
// No limit. Deliver everything after the offset.
n = e.length - (int) offset;
} else {
// Limit. Deliver no more than [limit] elements.
n = Math.min((int) limit, e.length - (int) offset);
}
if (offset == 0 && n == e.length) {
/*
* Array is already dense. No allocation is required.
*/
// Wrap as iterator and return.
return new ChunkedArrayIterator(e);
}
// Allocate dense array.
final E[] a = (E[]) java.lang.reflect.Array.newInstance(e.getClass()
.getComponentType(), n);
// Copy into array.
System.arraycopy(e/* src */, (int) offset/* srcPos */, a/* dst */,
0/* dstPos */, n/* length */);
// Wrap as iterator and return.
return new ChunkedArrayIterator(a);
}
/**
* {@inheritDoc}
*
* Does nothing and always returns ZERO(0).
*/
@Override
public long removeAll() {
return 0L;
}
}