+
+(**
+ Compile the top-level XPath query in reverse (doing downward
+ to the last top-level state):
+ /a0::t0[p0]/.../an-1::tn-1[pn-1]/an::tn[pn] becomes:
+ self::node()[ pn and
+ self::tn[pn]/inv(an)::(tn-1)[pn-1]/.../inv(a1)::t0[p0]/inv(a0)::document()]
+
+ /child::a/attribute::b
+ self::@b/parent::a/parent::doc()
+*)
+
+let compile_top_level_step_list l trans states =
+ let rec loop l trans states phi_above =
+ match l with
+ | [] -> assert false
+ | (axis, (test,kind), elist) :: ll ->
+ let phi0, trans0, states0 =
+ compile_axis_test (invert_axis axis)
+ (QNameSet.any, Tree.Common.NodeKind.Node)
+ phi_above trans states
+ in
+ (* Only select attribute nodes if the previous axis
+ is attribute *)
+ let phi0 =
+ if axis != Attribute then
+ phi0 %% (Ata.SFormula.not_ Ata.SFormula.is_attribute)
+ else phi0
+ in
+ match ll with
+ [] ->
+ let phi1, trans1, states1 =
+ List.fold_left (fun (aphi, atrans, astates) e ->
+ let ephi, etrans, estates = compile_expr e atrans astates in
+ aphi %% ephi, etrans, estates) (phi0, trans0, states0) elist
+ in
+ let _, trans2, states2 =
+ compile_axis_test Self (test,kind) phi1 trans1 states1
+ in
+ let marking_state =
+ StateSet.choose (StateSet.diff states2 states1)
+ in
+ marking_state, trans2, states2
+ | _ ->
+ let phi1, trans1, states1 =
+ compile_axis_test Self (test,kind) phi0 trans0 states0
+ in
+ let phi2, trans2, states2 =
+ List.fold_left (fun (aphi, atrans, astates) e ->
+ let ephi, etrans, estates = compile_expr e atrans astates in
+ aphi %% ephi, etrans, estates) (phi1, trans1, states1) elist
+ in
+ loop ll trans2 states2 phi2
+ in
+ let phi0, trans0, states0 =
+ compile_axis_test
+ Self
+ (QNameSet.singleton QName.document, Tree.Common.NodeKind.Node)
+ Ata.SFormula.true_
+ trans
+ states
+ in
+ loop l trans0 states0 phi0
+;;
+
+let path p =
+ let mstates, trans, states = List.fold_left (fun (ams, atrs, asts) p ->
+ let ms, natrs, nasts =
+ match p with
+ | Absolute l | Relative l -> compile_top_level_step_list l atrs asts
+ in
+ (StateSet.add ms ams), natrs, nasts) (StateSet.empty, [], StateSet.empty) p
+ in
+ let a = Ata.create () in
+ a.Ata.states <- states;
+ a.Ata.selection_states <- mstates;
+ List.iter (fun (q, l) ->
+ List.iter (fun (lab, phi) ->
+ Ata.add_trans a q lab phi
+ ) l) trans;
+ Ata.complete_transitions a;
+ Ata.normalize_negations a;
+ a