ocaml 3.09 transition

[helm.git] / helm / ocaml / mathql_interpreter / mQIPostgres.ml

diff --git a/helm/ocaml/mathql_interpreter/mQIPostgres.ml b/helm/ocaml/mathql_interpreter/mQIPostgres.ml
index b19a51c83bbb0ccfde390b50ae485df1e8a3a0ed..916f787321daf86eada1f1224d1cd0be2efcc383 100644 (file)
--- a/helm/ocaml/mathql_interpreter/mQIPostgres.ml
+++ b/helm/ocaml/mathql_interpreter/mQIPostgres.ml
@@ -23,25 +23,18 @@
  * 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
@@ -51,3 +44,51 @@ let quote s =
       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"] 
+*)