Optimize fn:subsequence

src/org/exist/dom/memtree/NodeImpl.java

@@ -611,7 +611,7 @@ public int getItemType() {
     }
 
     @Override
-    public SequenceIterator iterate() throws XPathException {
+    public SequenceIterator iterate() {
         return new SingleNodeIterator(this);
     }
 
@@ -621,7 +621,7 @@ public SequenceIterator unorderedIterator() {
     }
 
     @Override
-    public int getItemCount() {
+    public long getItemCountLong() {
         return 1;
     }
 
@@ -983,7 +983,7 @@ protected DOMException unsupported() {
     }
 
     private final static class SingleNodeIterator implements SequenceIterator {
-        NodeImpl node;
+        private NodeImpl node;
 
         public SingleNodeIterator(final NodeImpl node) {
             this.node = node;
@@ -1001,5 +1001,21 @@ public Item nextItem() {
             return next;
         }
 
+        @Override
+        public long skippable() {
+            if (node != null) {
+                return 1;
+            }
+            return 0;
+        }
+
+        @Override
+        public long skip(final long n) {
+            final long skip = Math.min(n, node != null ? 1 : 0);
+            if (skip == 1) {
+                node = null;
+            }
+            return skip;
+        }
     }
 }

src/org/exist/dom/persistent/AVLTreeNodeSet.java

@@ -22,10 +22,10 @@
 package org.exist.dom.persistent;
 
 import org.exist.numbering.NodeId;
-import org.exist.xquery.XPathException;
 import org.exist.xquery.value.Item;
 import org.exist.xquery.value.SequenceIterator;
 
+import javax.annotation.Nullable;
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.Iterator;
@@ -36,17 +36,14 @@ public class AVLTreeNodeSet extends AbstractNodeSet {
     private int size = 0;
     private int state = 0;
 
-    /* (non-Javadoc)
-      * @see org.exist.dom.persistent.NodeSet#iterate()
-      */
     @Override
-    public SequenceIterator iterate() throws XPathException {
-        return new InorderTraversal();
+    public SequenceIterator iterate() {
+        return new InorderTraversal(root);
     }
 
     @Override
-    public SequenceIterator unorderedIterator() throws XPathException {
-        return new InorderTraversal();
+    public SequenceIterator unorderedIterator() {
+        return new InorderTraversal(root);
     }
 
     @Override
@@ -61,9 +58,8 @@ public int getLength() {
         return size;
     }
 
-    //TODO : evaluate both semantics
     @Override
-    public int getItemCount() {
+    public long getItemCountLong() {
         return size;
     }
 
@@ -82,7 +78,7 @@ public NodeProxy get(final int pos) {
 
     @Override
     public final NodeProxy get(final NodeProxy p) {
-        final Node n = searchData(p);
+        final Node n = searchData(root, p);
         return n == null ? null : n.getData();
     }
 
@@ -304,7 +300,7 @@ private void balance(final Node node) {
         }
     }
 
-    public final Node searchData(final NodeProxy proxy) {
+    private static @Nullable Node searchData(@Nullable final Node root, final NodeProxy proxy) {
         if(root == null) {
             return null;
         }
@@ -353,7 +349,7 @@ public final NodeProxy get(final DocumentImpl doc, final NodeId nodeId) {
 
     @Override
     public final boolean contains(final NodeProxy proxy) {
-        return searchData(proxy) != null;
+        return searchData(root, proxy) != null;
     }
 
     public void removeNode(final Node node) {
@@ -398,7 +394,7 @@ public void removeNode(final Node node) {
 
     @Override
     public NodeSetIterator iterator() {
-        return new InorderTraversal();
+        return new InorderTraversal(root);
     }
 
     @Override
@@ -420,11 +416,12 @@ private void setHasChanged() {
         state = (state == Integer.MAX_VALUE ? 0 : state + 1);
     }
 
-    class InorderTraversal implements NodeSetIterator, SequenceIterator {
-
+    private static class InorderTraversal implements NodeSetIterator, SequenceIterator {
+        @Nullable private final Node root;
         private final Deque<Node> nodes = new ArrayDeque<>();
 
-        public InorderTraversal() {
+        public InorderTraversal(@Nullable final Node root) {
+            this.root = root;
             if(root != null) {
                 Node tempNode = root;
                 do {
@@ -441,10 +438,10 @@ public boolean hasNext() {
 
         @Override
         public NodeProxy next() {
-            final Node currentNode = nodes.poll();
-            if (currentNode == null) {
+            if(nodes.isEmpty()) {
                 return null;
             }
+            final Node currentNode = nodes.pop();
             if(currentNode.hasRightChild()) {
                 Node tempNode = currentNode.rightChild;
                 do {
@@ -466,7 +463,7 @@ public NodeProxy peekNode() {
 
         @Override
         public void setPosition(final NodeProxy proxy) {
-            final Node n = searchData(proxy);
+            final Node n = searchData(root, proxy);
             nodes.clear();
             if(n != null) {
                 Node tempNode = n;
@@ -484,11 +481,11 @@ public void remove() {
 
         @Override
         public Item nextItem() {
-            final Node currentNode = nodes.poll();
-            if (currentNode == null) {
+            if(nodes.isEmpty()) {
                 return null;
             }
-            if(currentNode.hasRightChild()) {
+            final Node currentNode = nodes.pop();
+            if (currentNode.hasRightChild()) {
                 Node tempNode = currentNode.rightChild;
                 do {
                     nodes.push(tempNode);
@@ -505,7 +502,6 @@ public String toString() {
     }
 
     private static final class Node {
-
         private NodeProxy data;
         private Node parent;
         private Node leftChild;

src/org/exist/dom/persistent/AbstractArrayNodeSet.java

@@ -154,7 +154,7 @@ public int getLength() {
     }
 
     @Override
-    public int getItemCount() {
+    public long getItemCountLong() {
         return getLength();
     }
 

src/org/exist/dom/persistent/EmptyNodeSet.java

@@ -24,7 +24,6 @@
 
 import org.exist.collections.Collection;
 import org.exist.numbering.NodeId;
-import org.exist.xquery.XPathException;
 import org.exist.xquery.value.Item;
 import org.exist.xquery.value.SequenceIterator;
 import org.w3c.dom.Node;
@@ -40,12 +39,12 @@ public NodeSetIterator iterator() {
     }
 
     @Override
-    public SequenceIterator iterate() throws XPathException {
+    public SequenceIterator iterate() {
         return SequenceIterator.EMPTY_ITERATOR;
     }
 
     @Override
-    public SequenceIterator unorderedIterator() throws XPathException {
+    public SequenceIterator unorderedIterator() {
         return SequenceIterator.EMPTY_ITERATOR;
     }
 
@@ -78,7 +77,7 @@ public int getLength() {
     }
 
     @Override
-    public int getItemCount() {
+    public long getItemCountLong() {
         return 0;
     }
 

src/org/exist/dom/persistent/ExtArrayNodeSet.java

@@ -197,13 +197,13 @@ public NodeSetIterator iterator() {
     }
 
     @Override
-    public SequenceIterator iterate() throws XPathException {
+    public SequenceIterator iterate() {
         sortInDocumentOrder();
         return new ExtArrayIterator();
     }
 
     @Override
-    public SequenceIterator unorderedIterator() throws XPathException {
+    public SequenceIterator unorderedIterator() {
         if(!isSorted()) {
             sort();
         }

src/org/exist/dom/persistent/NewArrayNodeSet.java

@@ -161,13 +161,13 @@ public NodeSetIterator iterator() {
     }
 
     @Override
-    public SequenceIterator iterate() throws XPathException {
+    public SequenceIterator iterate() {
         sortInDocumentOrder();
         return new NewArrayIterator();
     }
 
     @Override
-    public SequenceIterator unorderedIterator() throws XPathException {
+    public SequenceIterator unorderedIterator() {
         if(!isSorted()) {
             sort();
         }
@@ -1109,9 +1109,8 @@ public void clearContext(final int contextId) throws XPathException {
         }
     }
 
-    private class NewArrayIterator implements NodeSetIterator, SequenceIterator {
-
-        int pos = 0;
+    protected class NewArrayIterator implements NodeSetIterator, SequenceIterator {
+        private int pos = 0;
 
         @Override
         public final boolean hasNext() {
@@ -1127,6 +1126,21 @@ public final NodeProxy next() {
             return nodes[pos++];
         }
 
+        @Override
+        public long skippable() {
+            if (pos == -1) {
+                return 0;
+            }
+            return size - pos;
+        }
+
+        @Override
+        public long skip(final long n) {
+            final long skip = Math.min(n, pos == -1 ? 0 : size - pos);
+            pos += skip;
+            return skip;
+        }
+
         @Override
         public final void remove() {
             throw new UnsupportedOperationException();

src/org/exist/dom/persistent/NodeProxy.java

@@ -829,7 +829,7 @@ public NodeSetIterator iterator() {
     }
 
     @Override
-    public SequenceIterator iterate() throws XPathException {
+    public SequenceIterator iterate() {
         return new SingleNodeIterator(this);
     }
 
@@ -893,9 +893,8 @@ public int getLength() {
         return 1;
     }
 
-    //TODO : evaluate both semantics
     @Override
-    public int getItemCount() {
+    public long getItemCountLong() {
         return 1;
     }
 
@@ -1304,6 +1303,23 @@ public final NodeProxy next() {
             }
         }
 
+        @Override
+        public long skippable() {
+            if (hasNext) {
+                return 1;
+            }
+            return 0;
+        }
+
+        @Override
+        public long skip(final long n) {
+            final long skip = Math.min(n, hasNext ? 1 : 0);
+            if(skip == 1) {
+                hasNext = false;
+            }
+            return skip;
+        }
+
         @Override
         public final NodeProxy peekNode() {
             return node;

src/org/exist/dom/persistent/SortedNodeSet.java

@@ -175,9 +175,8 @@ public int getLength() {
         return list.size();
     }
 
-    //TODO : evaluate both semantics (length/item count)
     @Override
-    public int getItemCount() {
+    public long getItemCountLong() {
         return list.size();
     }
 
@@ -200,12 +199,12 @@ public NodeSetIterator iterator() {
     }
 
     @Override
-    public SequenceIterator iterate() throws XPathException {
+    public SequenceIterator iterate() {
         return new SortedNodeSetIterator(list.iterator());
     }
 
     @Override
-    public SequenceIterator unorderedIterator() throws XPathException {
+    public SequenceIterator unorderedIterator() {
         return new SortedNodeSetIterator(list.iterator());
     }
 

src/org/exist/dom/persistent/VirtualNodeSet.java

@@ -621,10 +621,10 @@ public int getItemType() {
     }
 
     @Override
-    public int getItemCount() {
+    public long getItemCountLong() {
         //TODO : evaluate both semantics
         realize();
-        return realSet.getItemCount();
+        return realSet.getItemCountLong();
     }
 
     @Override