}
-
-
+module QTree = struct
+ type t = query_tree
+ let rec equal q1 q2 =
+ q1 == q2 ||
+ (q1.id == q2.id && q1.id != -1) ||
+ match q1.desc, q2.desc with
+ | Binop(op1,qt1,qt2),Binop(op2,qt3,qt4)-> op1==op2&& (equal qt1 qt3 && equal qt2 qt4)
+
+ | Axis(a1,qt1),Axis(a2,qt2) -> compare_axis a1 a2 && equal qt1 qt2
+ | Tag(t1,k1),Tag(t2,k2) -> t1==t2&& k1==k2
+ | Dom,Dom | Start,Start -> true
+ | _,_ ->false
+ and compare_axis a1 a2 =
+ match a1,a2 with
+ Self ,Self | Attribute, Attribute | Child , Child | Parent , Parent
+ | FollowingSibling , FollowingSibling
+ | PrecedingSibling , PrecedingSibling
+ | Preceding , Preceding | Following , Following -> true
+ | Descendant b1, Descendant b2 -> b1==b2
+ | Ancestor b1, Ancestor b2 -> b1==b2
+ | _,_ -> false
+
+ let rec hash q =
+ if q.hash != -1 then q.hash
+ else match q.desc with
+ Dom -> 1
+ | Start -> 3
+ | Tag(s,_) -> 5 + 17*QNameSet.hash s
+ | Axis(a,q) -> 7 + 17 * Hashtbl.hash a + 23* hash q
+ | Binop(op,q1,q2) -> 11 + 17* Hashtbl.hash op + 23* hash q1 + 27* hash q2
+
+end
+
+
+module QTreeHash = Hashtbl.Make(QTree)