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|
(* camlp5r *)
(* extfun.ml,v *)
(* Copyright (c) INRIA 2007-2017 *)
(* Extensible Functions *)
type t 'a 'b = list (matching 'a 'b)
and matching 'a 'b = { patt : patt; has_when : bool; expr : expr 'a 'b }
and patt =
[ Eapp of list patt
| Eacc of list patt
| Econ of string
| Estr of string
| Eint of string
| Etup of list patt
| Erec of list (patt * patt)
| Evar of unit ]
and expr 'a 'b = 'a -> option 'b;
exception Failure;
value empty = [];
(*** Apply ***)
value rec apply_matchings a =
fun
[ [m :: ml] ->
match m.expr a with
[ None -> apply_matchings a ml
| x -> x ]
| [] -> None ]
;
value apply ef a =
match apply_matchings a ef with
[ Some x -> x
| None -> raise Failure ]
;
(*** Trace ***)
value rec list_iter_sep f s =
fun
[ [] -> ()
| [x] -> f x
| [x :: l] -> do { f x; s (); list_iter_sep f s l } ]
;
value rec print_patt =
fun
[ Eapp pl -> list_iter_sep print_patt2 (fun () -> print_string " ") pl
| p -> print_patt2 p ]
and print_labeled_patt_pair (p1, p2) = do {
print_patt p1 ; print_string " = " ; print_patt p2
}
and print_patt2 =
fun
[ Eacc pl -> list_iter_sep print_patt1 (fun () -> print_string ".") pl
| p -> print_patt1 p ]
and print_patt1 =
fun
[ Econ s -> print_string s
| Estr s -> do { print_string "\""; print_string s; print_string "\"" }
| Eint s -> print_string s
| Evar () -> print_string "_"
| Etup pl -> do {
print_string "(";
list_iter_sep print_patt (fun () -> print_string ", ") pl;
print_string ")"
}
| Erec l -> do {
print_string "{";
list_iter_sep print_labeled_patt_pair (fun () -> print_string "; ") l;
print_string "}"
}
| Eapp _ | Eacc _ as p -> do {
print_string "(";
print_patt p;
print_string ")"
} ]
;
value print ef =
List.iter
(fun m -> do {
print_patt m.patt;
if m.has_when then print_string " when ..." else ();
print_newline ()
})
ef
;
(*** Extension ***)
value compare_patt p1 p2 =
match (p1, p2) with
[ (Evar _, _) -> 1
| (_, Evar _) -> -1
| _ -> compare p1 p2 ]
;
value insert_matching matchings (patt, has_when, expr) =
let m1 = {patt = patt; has_when = has_when; expr = expr} in
loop matchings where rec loop =
fun
[ [m :: ml] as gml ->
if m1.has_when && not m.has_when then [m1 :: gml]
else if not m1.has_when && m.has_when then [m :: loop ml]
else
let c = compare_patt m1.patt m.patt in
if c < 0 then [m1 :: gml]
else if c > 0 then [m :: loop ml]
else if m.has_when then [m1 :: gml]
else [m1 :: ml]
| [] -> [m1] ]
;
(* available extension function *)
value extend ef matchings_def =
List.fold_left insert_matching ef matchings_def
;
|
