module EnvCont(Env, empty_env, lookup_variable, maybe_lookup_variable, bind_variable,
  variable_table, merge_declarations, get_return_cont, get_break_cont, get_continue_cont,
  set_return_cont, set_break_cont, set_continue_cont) where

import qualified Table

type Symbol = String

data Env val c = Env (Table.T Symbol val) (c -> (String, String)) (c -> (String, String)) (c -> (String, String))

instance Eq val => Eq(Env val c) where
  (Env t1 _ _ _) == (Env t2 _ _ _) = t1 == t2

empty_env :: Env val c
empty_env = Env Table.empty
              (\ _ -> error "return out-side of function")
              (\ _ -> error "break out-side of loop")
              (\ _ -> error "continue out-side of loop")

lookup_variable :: Env val c -> Symbol -> val
lookup_variable (Env t _ _ _) name = Table.lookup t name

maybe_lookup_variable :: Env val c -> Symbol -> Maybe val
maybe_lookup_variable (Env t _ _ _) name = Table.maybe_lookup t name

bind_variable :: Env val c -> Symbol -> val -> Env val c
bind_variable (Env t rc bc cc) name loc = Env (Table.bind t name loc) rc bc cc

variable_table :: Env val c -> Table.T Symbol val
variable_table (Env t _ _ _) = t

merge_declarations :: Env val c -> Table.T Symbol val -> Env val c
merge_declarations (Env t rc bc cc) decls = Env (Table.merge t decls) rc bc cc

get_return_cont   (Env _ rc _ _) = rc
get_break_cont    (Env _ _ bc _) = bc
get_continue_cont (Env _ _ _ cc) = cc

set_return_cont   (Env t _  bc cc) rc = Env t rc bc cc
set_break_cont    (Env t rc _  cc) bc = Env t rc bc cc
set_continue_cont (Env t rc bc _ ) cc = Env t rc bc cc