(* HCoop Domtool (http://hcoop.sourceforge.net/)
 * Copyright (c) 2006, Adam Chlipala
 *
 * This program 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.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *)

(* Domtool type-checking and reduction environments *)

structure Env :> ENV = struct

open Ast

structure SS = StringSet
structure SM = StringMap

type typeRule = exp -> bool
val typeRules : typeRule SM.map ref = ref SM.empty
fun registerType (name, rule) = typeRules := SM.insert (!typeRules, name, rule)
fun typeRule name = SM.find (!typeRules, name)

type env_vars = exp SM.map
type action = env_vars * Ast.exp list -> env_vars
val actions : action SM.map ref = ref SM.empty
fun registerAction (name, action) = actions := SM.insert (!actions, name, action)
fun action name = SM.find (!actions, name)

val containers : (action * (unit -> unit)) SM.map ref = ref SM.empty
fun registerContainer (name, befor, after) =
    containers := SM.insert (!containers, name, (befor, after))
fun container name = SM.find (!containers, name)

fun badArgs (name, args) =
    (print ("Invalid arguments to " ^ name ^ "\n");
     app (fn arg => Print.preface ("Argument: ", Print.p_exp arg)) args;
     raise Domain)
fun badArg (func, arg, v) =
    (print ("Invalid " ^ arg ^ " argument to " ^ func ^ "\n");
     Print.preface ("Argument: ", Print.p_exp v);
     raise Domain)

type 'a arg = exp -> 'a option

fun int (EInt n, _) = SOME n
  | int _ = NONE

fun string (EString s, _) = SOME s
  | string _ = NONE

fun mapFail f [] = SOME []
  | mapFail f (h :: t) =
    case f h of
	NONE => NONE
      | SOME h' =>
	case mapFail f t of
	    NONE => NONE
	  | SOME t' => SOME (h' :: t')

fun list f (EList ls, _) = mapFail f ls
  | list _ _ = NONE

fun one func (name, arg) f (_, [e]) =
    (case arg e of
	 NONE => badArg (func, name, e)
       | SOME v => (f v;
		    SM.empty))
  | one func _ _ (_, es) = badArgs (func, es)

fun two func (name1, arg1, name2, arg2) f (_, [e1, e2]) =
    (case (arg1 e1, arg2 e2) of
	 (NONE, _) => badArg (func, name1, e1)
       | (_, NONE) => badArg (func, name2, e2)
       | (SOME v1, SOME v2) => (f (v1, v2);
				SM.empty))
  | two func _ _ (_, es) = badArgs (func, es)

fun type_one func arg f =
    registerType (func, fn e =>
			   case arg e of
			       NONE => false
			     | SOME v => f v)

fun action_one name args f = registerAction (name, one name args f)
fun action_two name args f = registerAction (name, two name args f)

fun container_one name args (f, g) = registerContainer (name, one name args f, g)

type env = SS.set * (typ * exp option) SM.map * SS.set
val empty : env = (SS.empty, SM.empty, SS.empty)

fun lookupType (ts, _, _) name = SS.member (ts, name)
fun lookupVal (_, vs, _) name =
    case SM.find (vs, name) of
	NONE => NONE
      | SOME (t, _) => SOME t
fun lookupEquation (_, vs, _) name =
    case SM.find (vs, name) of
	NONE => NONE
      | SOME (_, eqo) => eqo
fun lookupContext (_, _, cs) name = SS.member (cs, name)

fun bindType (ts, vs, cs) name = (SS.add (ts, name), vs, cs)
fun bindVal (ts, vs, cs) (name, t, eqo) = (ts, SM.insert (vs, name, (t, eqo)), cs)
fun bindContext (ts, vs, cs) name = (ts, vs, SS.add (cs, name))

fun types (ts, _, _) = ts
fun vals (_, vs, _) = SM.foldli (fn (name, _, vs) => SS.add (vs, name)) SS.empty vs
fun contexts (_, _, cs) = cs

end