test branch

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

diff --git a/helm/ocaml/mathql_interpreter/mQIPostgres.ml b/helm/ocaml/mathql_interpreter/mQIPostgres.ml
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+(* Copyright (C) 2000, 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://cs.unibo.it/helm/.
+ *)
+
+(*  AUTOR: Ferruccio Guidi <fguidi@cs.unibo.it>
+ *)
+
+(* $Id$ *)
+
+let init () =
+   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 c = c#close
+
+let quote s =
+   let rec quote_aux s =
+      try
+         let l = String.length s in
+         let i = String.index s '\'' in
+         String.sub s 0 i ^ "\\'" ^ quote_aux (String.sub s (succ i) (l - (succ i)))
+      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"] 
+*)