}
+inline
+bool operator<(DocIterator const & p, DocIterator const & q)
+{
+ size_t depth = std::min(p.depth(), q.depth());
+ for (size_t i = 0 ; i < depth ; ++i) {
+ if (p[i] != q[i])
+ return p[i] < q[i];
+ }
+ return p.depth() < q.depth();
+}
+
+
+inline
+bool operator>(DocIterator const & p, DocIterator const & q)
+{
+ return q < p;
+}
+
+
+inline
+bool operator<=(DocIterator const & p, DocIterator const & q)
+{
+ return !(q < p);
+}
+
+
// The difference to a ('non stable') DocIterator is the removed
// (overwritten by 0...) part of the CursorSlice data items. So this thing
// is suitable for external storage, but not for iteration as such.