1 (* Copyright (C) 2000, HELM Team.
3 * This file is part of HELM, an Hypertextual, Electronic
4 * Library of Mathematics, developed at the Computer Science
5 * Department, University of Bologna, Italy.
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27 * implementazione del comando UNION
33 let xres_fill_context hr h1 l1 =
37 let hh = List.combine h1 l1
41 if (List.mem_assoc x hh) then
50 * implementazione del comando UNION
52 let union_ex alist1 alist2 =
53 let head1 = List.hd alist1
54 and tail1 = List.tl alist1
55 and head2 = List.hd alist2
56 and tail2 = List.tl alist2 (* e fin qui ... *)
58 match (head1, head2) with
59 ([], _) -> assert false (* gli header non devono mai essere vuoti *)
60 | (_, []) -> assert false (* devono contenere almeno [retVal] *)
61 | (_, _) -> let headr = (head2 @
63 (function t -> not (List.mem t head2))
65 ) in (* header del risultato finale *)
66 List.append (* il risultato finale e' la concatenazione ...*)
67 [headr] (* ... dell'header costruito prima ...*)
69 (fun l m -> List.hd l < List.hd m)
70 (match (tail1, tail2) with (* e di una coda "unione" *)
71 ([], _) -> tail2 (* va bene perche' l'altra lista e' vuota *)
72 | (_, []) -> tail1 (* va bene perche' l'altra lista e' vuota *)
74 let first = (* parte dell'unione che riguarda solo il primo set *)
79 xres_fill_context (List.tl headr) (List.tl head1) (List.tl l)
85 let y = (* elemento candidato ad entrare *)
89 (List.tl headr) (List.tl head2) (List.tl x)
91 par @ if (List.find_all (fun t -> t = y) par) = [] then
96 first (* List.fold_left *)
97 tail2 (* List.fold_left *)
99 List.map (fun l -> [List.hd l] @
101 (List.tl headr) (List.tl head2) (List.tl l)