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(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(************************************************************************)
(* $Id$ *)
(* This file implements the basic structure of what Chet called
``discrimination nets''. If my understanding is right, it serves
to associate actions (for example, tactics) with a priority to term
patterns, so that if a hypothesis matches a pattern in the net,
then the associated tactic is applied. Discrimination nets are used
(only) to implement the tactics Auto, DHyp and Point.
A discrimination net is a tries structure, that is, a tree structure
specially conceived for searching patterns, like for example strings
--see the file Tlm.ml in the directory lib/util--. Here the tries
structure are used for looking for term patterns.
This module is then used in :
- termdn.ml (discrimination nets of terms);
- btermdn.ml (discrimination nets of terms with bounded depth,
used in the tactic auto);
- nbtermdn.ml (named discrimination nets with bounded depth, used
in the tactics Dhyp and Point).
Eduardo (4/8/97) *)
(* Definition of the basic structure *)
type ('lbl,'pat) decompose_fun = 'pat -> ('lbl * 'pat list) option
type ('lbl,'pat,'inf) t = (('lbl * int) option,'pat * 'inf) Tlm.t
let create () = Tlm.empty
(* [path_of dna pat] returns the list of nodes of the pattern [pat] read in
prefix ordering, [dna] is the function returning the main node of a pattern *)
let path_of dna =
let rec path_of_deferred = function
| [] -> []
| h::tl -> pathrec tl h
and pathrec deferred t =
match dna t with
| None ->
None :: (path_of_deferred deferred)
| Some (lbl,[]) ->
(Some (lbl,0))::(path_of_deferred deferred)
| Some (lbl,(h::def_subl as v)) ->
(Some (lbl,List.length v))::(pathrec (def_subl@deferred) h)
in
pathrec []
let tm_of tm lbl =
try [Tlm.map tm lbl] with Not_found -> []
let lookup tm dna t =
let rec lookrec t tm =
(tm_of tm None)@
(match dna t with
| None -> []
| Some(lbl,v) ->
List.fold_left
(fun l c -> List.flatten(List.map (lookrec c) l))
(tm_of tm (Some(lbl,List.length v))) v)
in
List.flatten(List.map Tlm.xtract (lookrec t tm))
let add tm dna (pat,inf) =
let p = path_of dna pat in Tlm.add tm (p,(pat,inf))
let rmv tm dna (pat,inf) =
let p = path_of dna pat in Tlm.rmv tm (p,(pat,inf))
let app f tm = Tlm.app (fun (_,p) -> f p) tm
|