* http://cs.unibo.it/helm/.
*)
-let default_connection_string =
- "dbname=mowgli user=helm"
-
-let connection_string =
- try Sys.getenv "POSTGRESQL_CONNECTION_STRING"
- with Not_found -> default_connection_string
+(* AUTOR: Ferruccio Guidi <fguidi@cs.unibo.it>
+ *)
let init () =
- try Some (new Postgres.connection connection_string)
- with _ -> raise (Failure ("MQIPostgres.init: " ^ connection_string))
+ let connection_string =
+ Helm_registry.get "mathql_interpreter.postgresql_connection_string"
+ in
+ try new Postgres.connection connection_string
+ with _ -> raise (Failure "mqi_connecion")
-let close = function
- | None -> ()
- | Some c -> c#close
+let close c = c#close
-let exec c q = match c with
- | None -> []
- | Some c -> (c#exec q)#get_list
-
let quote s =
let rec quote_aux s =
try
with Not_found -> s
in
"'" ^ quote_aux s ^ "'"
+
+let exec (c, out) q = out q; (c#exec q)#get_list
+
+let exec c table cols ct cfl =
+ let rec iter f last sep = function
+ | [] -> last
+ | [head] -> f head
+ | head :: tail -> f head ^ sep ^ iter f last sep tail
+ in
+ let pg_cols = iter (fun x -> x) "" ", " cols in
+ let pg_msval v = iter quote "" ", " v in
+ let pg_con (pat, col, v) =
+ if col <> "" then
+ let f s = col ^ " ~ " ^ quote ("^" ^ s ^ "$") in
+ if pat then "(" ^ iter f "false" " or " v ^ ")"
+ else match v with
+ | [s] -> col ^ " = " ^ (quote s)
+ | v -> col ^ " in (" ^ pg_msval v ^ ")"
+ else "true"
+ in
+ let pg_cons l = iter pg_con "true" " and " l in
+ let pg_cons_not l = "not (" ^ pg_cons l ^ ")" in
+ let pg_cons_not_l ll = iter pg_cons_not "true" " and " ll in
+ let pg_where = match ct, cfl with
+ | [], [] -> ""
+ | lt, [] -> " where " ^ pg_cons lt
+ | [], llf -> " where " ^ pg_cons_not_l llf
+ | lt, llf -> " where " ^ pg_cons lt ^ " and " ^ pg_cons_not_l llf
+ in
+ if cols = [] then
+ let r = exec c ("select count(source) from " ^ table ^ pg_where) in
+ match r with
+ | [[s]] when int_of_string s > 0 -> [[]]
+ | _ -> []
+ else
+ exec c ("select " ^ pg_cols ^ " from " ^ table ^ pg_where ^
+ " order by " ^ List.hd cols ^ " asc")
+
+(* funzioni vecchie ********************************************************)
+(*
+let pg_name h s =
+ let q = "select id from registry where uri = " ^ quote s in
+ match exec h q with
+ | [[id]] -> "t" ^ id
+ | _ -> ""
+
+let get_id b = if b then ["B"] else ["F"]
+*)