* Seal the representation of states

[tatoo.git] / src / xpath / compile.ml

diff --git a/src/xpath/compile.ml b/src/xpath/compile.ml
index c53057e..20f06be 100644 (file)
--- a/src/xpath/compile.ml
+++ b/src/xpath/compile.ml
@@ -40,7 +40,7 @@ let root_set = QNameSet.singleton QName.document
 *)
 
 let compile_axis_test axis (test,kind) phi trans states =
-  let q = State.make () in
+  let q = State.next () in
   let phi = match kind with
     Tree.NodeKind.Node -> phi
   | _ -> phi %% F.is kind
@@ -65,16 +65,15 @@ let compile_axis_test axis (test,kind) phi trans states =
              ]) :: trans,
          states)
     | Descendant true ->
-        let q' = State.make () in
-        (F.or_ (F.stay q) (F.first_child q'),
-         (q', [ test => phi;
-               QNameSet.any => F.first_child q' ++ F.next_sibling q';
-             ])::
-         (q, [ test => phi]):: trans,
+        let q' = State.next () in
+        (F.stay q ++ F.first_child q',
+         (q', [ QNameSet.any => F.stay q ++ F.first_child q' ++ F.next_sibling q';
+              ])::
+           (q, [ test => phi]):: trans,
          states)
 
     | Parent ->
-        let q' = State.make () in
+        let q' = State.next () in
         let move = F.parent q ++ F.previous_sibling q' in
         (move,
          (q, [ test => phi ])
@@ -82,13 +81,12 @@ let compile_axis_test axis (test,kind) phi trans states =
          (q' @: states))
 
     | Ancestor self ->
-        let q' = State.make () in
-        let move = F.parent q ++ F.previous_sibling q' in
-        (if self then F.stay q else move),
-        (q, [ test => phi;
-              QNameSet.any => move ])
-        :: (q', [ QNameSet.any => move ]) :: trans,
-        (q' @: states)
+      let q' = State.next () in
+      let move = F.parent q' ++ F.previous_sibling q' in
+      (if self then F.stay q ++ F.stay q' else F.stay q'),
+      (q', [ QNameSet.any => move ++ F.parent q])
+      :: (q, [ test => phi ]) :: trans,
+      (q' @: states)
 
     | FollowingSibling | PrecedingSibling ->
         let move =
@@ -210,26 +208,40 @@ let compile_top_level_step_list l trans states =
             in
             loop ll trans2 states2  phi2
   in
+  let starting = State.next () in
   let phi0, trans0, states0 =
     compile_axis_test
       Self
-      (QNameSet.singleton QName.document, Tree.NodeKind.Node)
-      F.true_
+      (QNameSet.any, Tree.NodeKind.Node)
+      (F.stay starting)
       trans
       states
   in
-  loop l trans0 states0 phi0
+  let mstates, trans, states = loop l trans0 states0 phi0 in
+  starting, mstates, trans, states
 ;;
 
 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
+  let sstates, mstates, trans, states =
+    List.fold_left (fun (ass, ams, atrs, asts) p ->
+      let ss, ms, natrs, nasts =
+        match p with
+        | Absolute l | Relative l -> compile_top_level_step_list l atrs asts
+      in
+      (StateSet.add ss ass),
+      (StateSet.add ms ams),
+      natrs,
+      nasts) (StateSet.empty, StateSet.empty, [], StateSet.empty) p
   in
   let builder = Ata.Builder.make () in
+  (** ensure that we have a single selecting state at the end *)
+  let phi_sel = StateSet.fold (fun q acc -> F.or_ (F.stay q) acc) mstates F.false_ in
+  let q_sel = State.next () in
+  let states = StateSet.add q_sel states in
+  let mstates = StateSet.singleton q_sel in
+  let trans = (q_sel, [QNameSet.any, phi_sel]) :: trans in
+  StateSet.iter
+    (Ata.Builder.add_state builder ~starting:true) sstates;
   StateSet.iter
     (Ata.Builder.add_state builder ~selecting:true) mstates;
   StateSet.iter