src/lib/web.sml

   1 (*
   2  * Dynamic web page generation with Standard ML
   3  * Copyright (C) 2003  Adam Chlipala
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  *)
  19
  20 (* CGI interaction *)
  21
  22 structure Web :> WEB =
  23 struct
  24     val params : string StringMap.map ref = ref StringMap.empty
  25
  26     val paramStack : string StringMap.map list ref = ref []
  27
  28     fun setParam (n, v) = params := StringMap.insert (!params, n, v)
  29
  30     fun getParam v =
  31         (case StringMap.find (!params, v) of
  32              NONE => ""
  33            | SOME s => s)
  34
  35     fun pushParams nvs =
  36         (paramStack := (!params) :: (!paramStack);
  37          app setParam nvs)
  38
  39     fun popParams () =
  40         (case !paramStack of
  41              [] => raise Fail "Empty params stack in popParams"
  42            | h::t => (params := h;
  43                       paramStack := t))
  44
  45     fun withParams f nvs =
  46         (pushParams nvs;
  47          ((f ()) handle ex => (popParams (); raise ex))
  48          before popParams ())
  49
  50     val text = ref ([] : string list)
  51
  52     fun print x = text := x :: (!text)
  53
  54     fun output () =
  55         (TextIO.print "Status: 200\nContent-type: text/html\n\n";
  56          TextIO.print (String.concat (List.rev (!text))))
  57 end