--- /dev/null
+(* Copyright (C) 2005, HELM Team.
+ *
+ * This file is part of HELM, an Hypertextual, Electronic
+ * Library of Mathematics, developed at the Computer Science
+ * Department, University of Bologna, Italy.
+ *
+ * HELM is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * HELM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with HELM; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ *
+ * For details, see the HELM World-Wide-Web page,
+ * http://helm.cs.unibo.it/
+ *)
+
+(* $Id$ *)
+
+open Printf
+
+type pattern_kind = Variable | Constructor
+type tag_t = int
+
+type pattern_id = int
+
+module OrderedInt =
+struct
+ type t = int
+ let compare (x1:t) (x2:t) = Pervasives.compare x2 x1 (* reverse order *)
+end
+
+module IntSet = Set.Make (OrderedInt)
+
+let int_set_of_int_list l =
+ List.fold_left (fun acc i -> IntSet.add i acc) IntSet.empty l
+
+module type PATTERN =
+sig
+ type pattern_t
+ type term_t
+ val classify : pattern_t -> pattern_kind
+ val tag_of_pattern : pattern_t -> tag_t * pattern_t list
+ val tag_of_term : term_t -> tag_t * term_t list
+ val string_of_term: term_t -> string
+ val string_of_pattern: pattern_t -> string
+end
+
+module Matcher (P: PATTERN) =
+struct
+ type row_t = P.pattern_t list * P.pattern_t list * pattern_id
+ type t = row_t list
+
+ let compatible p1 p2 = P.classify p1 = P.classify p2
+
+ let matched = List.map (fun (matched, _, pid) -> matched, pid)
+
+ let partition t pidl =
+ let partitions = Hashtbl.create 11 in
+ let add pid row = Hashtbl.add partitions pid row in
+ (try
+ List.iter2 add pidl t
+ with Invalid_argument _ -> assert false);
+ let pidset = int_set_of_int_list pidl in
+ IntSet.fold
+ (fun pid acc ->
+ match Hashtbl.find_all partitions pid with
+ | [] -> acc
+ | patterns -> (pid, List.rev patterns) :: acc)
+ pidset []
+
+ let are_empty t =
+ match t with
+ | (_, [], _) :: _ -> true
+ (* if first row has an empty list of patterns, then others have as well *)
+ | _ -> false
+
+ (* return 2 lists of rows, first one containing homogeneous rows according
+ * to "compatible" below *)
+ let horizontal_split t =
+ let ap, first_row, t', first_row_class =
+ match t with
+ | [] -> assert false
+ | (_, [], _) :: _ ->
+ assert false (* are_empty should have been invoked in advance *)
+ | ((_, hd :: _ , _) as row) :: tl -> hd, row, tl, P.classify hd
+ in
+ let rec aux prev_t = function
+ | [] -> List.rev prev_t, []
+ | (_, [], _) :: _ -> assert false
+ | ((_, hd :: _, _) as row) :: tl when compatible ap hd ->
+ aux (row :: prev_t) tl
+ | t -> List.rev prev_t, t
+ in
+ let rows1, rows2 = aux [first_row] t' in
+ first_row_class, rows1, rows2
+
+ (* return 2 lists, first one representing first column, second one
+ * representing a new pattern matrix where matched patterns have been moved
+ * to decl *)
+ let vertical_split t =
+ List.map
+ (function
+ | decls, hd :: tl, pid -> hd :: decls, tl, pid
+ | _ -> assert false)
+ t
+
+ let variable_closure ksucc =
+ (fun matched_terms constructors terms ->
+(* prerr_endline "variable_closure"; *)
+ match terms with
+ | hd :: tl -> ksucc (hd :: matched_terms) constructors tl
+ | _ -> assert false)
+
+ let success_closure ksucc =
+ (fun matched_terms constructors terms ->
+(* prerr_endline "success_closure"; *)
+ ksucc matched_terms constructors)
+
+ let constructor_closure ksuccs =
+ (fun matched_terms constructors terms ->
+(* prerr_endline "constructor_closure"; *)
+ match terms with
+ | t :: tl ->
+ (try
+ let tag, subterms = P.tag_of_term t in
+ let constructors' =
+ if subterms = [] then t :: constructors else constructors
+ in
+ let k' = List.assoc tag ksuccs in
+ k' matched_terms constructors' (subterms @ tl)
+ with Not_found -> None)
+ | [] -> assert false)
+
+ let backtrack_closure ksucc kfail =
+ (fun matched_terms constructors terms ->
+(* prerr_endline "backtrack_closure"; *)
+ match ksucc matched_terms constructors terms with
+ | Some x -> Some x
+ | None -> kfail matched_terms constructors terms)
+
+ let compiler rows match_cb fail_k =
+ let rec aux t =
+ if t = [] then
+ (fun _ _ _ -> fail_k ())
+ else if are_empty t then
+ success_closure (match_cb (matched t))
+ else
+ match horizontal_split t with
+ | _, [], _ -> assert false
+ | Variable, t', [] -> variable_closure (aux (vertical_split t'))
+ | Constructor, t', [] ->
+ let tagl =
+ List.map
+ (function
+ | _, p :: _, _ -> fst (P.tag_of_pattern p)
+ | _ -> assert false)
+ t'
+ in
+ let clusters = partition t' tagl in
+ let ksuccs =
+ List.map
+ (fun (tag, cluster) ->
+ let cluster' =
+ List.map (* add args as patterns heads *)
+ (function
+ | matched_p, p :: tl, pid ->
+ let _, subpatterns = P.tag_of_pattern p in
+ matched_p, subpatterns @ tl, pid
+ | _ -> assert false)
+ cluster
+ in
+ tag, aux cluster')
+ clusters
+ in
+ constructor_closure ksuccs
+ | _, t', t'' -> backtrack_closure (aux t') (aux t'')
+ in
+ let t = List.map (fun (p, pid) -> [], [p], pid) rows in
+ let matcher = aux t in
+ (fun term -> matcher [] [] [term])
+end
+
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