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(* Copyright (c) 2008, Adam Chlipala
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - The names of contributors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*)
(* Simplify a Core program algebraically *)
structure Reduce :> REDUCE = struct
open Core
structure IM = IntBinaryMap
datatype env_item =
UnknownC
| KnownC of con
| UnknownE
| KnownE of exp
| Lift of int * int
type env = env_item list
fun conAndExp (namedC, namedE) =
let
fun con env (all as (c, loc)) =
case c of
TFun (c1, c2) => (TFun (con env c1, con env c2), loc)
| TCFun (x, k, c2) => (TCFun (x, k, con (UnknownC :: env) c2), loc)
| TRecord c => (TRecord (con env c), loc)
| CRel n =>
let
fun find (n', env, lift) =
if n' = 0 then
case env of
UnknownC :: _ => (CRel (n + lift), loc)
| KnownC c :: _ => con (Lift (lift, 0) :: env) c
| _ => raise Fail "Reduce.con: CRel [1]"
else
case env of
UnknownC :: rest => find (n' - 1, rest, lift + 1)
| KnownC _ :: rest => find (n' - 1, rest, lift)
| UnknownE :: rest => find (n' - 1, rest, lift)
| KnownE _ :: rest => find (n' - 1, rest, lift)
| Lift (lift', _) :: rest => find (n' - 1, rest, lift + lift')
| [] => raise Fail "Reduce.con: CRel [2]"
in
find (n, env, 0)
end
| CNamed n =>
(case IM.find (namedC, n) of
NONE => all
| SOME c => c)
| CFfi _ => all
| CApp (c1, c2) =>
let
val c1 = con env c1
val c2 = con env c2
in
case #1 c1 of
CAbs (_, _, b) =>
con (KnownC c2 :: env) b
| CApp ((CApp (fold as (CFold _, _), f), _), i) =>
(case #1 c2 of
CRecord (_, []) => i
| CRecord (k, (x, c) :: rest) =>
con env (CApp ((CApp ((CApp (f, x), loc), c), loc),
(CApp ((CApp ((CApp (fold, f), loc), i), loc),
(CRecord (k, rest), loc)), loc)), loc)
| _ => (CApp (c1, c2), loc))
| _ => (CApp (c1, c2), loc)
end
| CAbs (x, k, b) => (CAbs (x, k, con (UnknownC :: env) b), loc)
| CName _ => all
| CRecord (k, xcs) => (CRecord (k, map (fn (x, c) => (con env x, con env c)) xcs), loc)
| CConcat (c1, c2) =>
let
val c1 = con env c1
val c2 = con env c2
in
case (#1 c1, #1 c2) of
(CRecord (k, xcs1), CRecord (_, xcs2)) =>
(CRecord (k, xcs1 @ xcs2), loc)
| _ => (CConcat (c1, c2), loc)
end
| CFold _ => all
| CUnit => all
| CTuple cs => (CTuple (map (con env) cs), loc)
| CProj (c, n) =>
let
val c = con env c
in
case #1 c of
CTuple cs => List.nth (cs, n - 1)
| _ => (CProj (c, n), loc)
end
fun exp env e = e
in
{con = con, exp = exp}
end
fun con namedC c = #con (conAndExp (namedC, IM.empty)) [] c
fun exp (namedC, namedE) e = #exp (conAndExp (namedC, namedE)) [] e
fun reduce file =
let
fun doDecl (d as (_, loc), st as (namedC, namedE)) =
case #1 d of
DCon (x, n, k, c) =>
let
val c = con namedC c
in
((DCon (x, n, k, c), loc),
(IM.insert (namedC, n, c), namedE))
end
| DDatatype (x, n, ps, cs) =>
((DDatatype (x, n, ps, map (fn (x, n, co) => (x, n, Option.map (con namedC) co)) cs), loc),
st)
| DVal (x, n, t, e, s) =>
let
val t = con namedC t
val e = exp (namedC, namedE) e
in
((DVal (x, n, t, e, s), loc),
(namedC, IM.insert (namedE, n, e)))
end
| DValRec vis =>
((DValRec (map (fn (x, n, t, e, s) => (x, n, con namedC t, exp (namedC, namedE) e, s)) vis), loc),
st)
| DExport _ => (d, st)
| DTable (s, n, c, s') => ((DTable (s, n, con namedC c, s'), loc), st)
| DSequence _ => (d, st)
| DDatabase _ => (d, st)
| DCookie (s, n, c, s') => ((DCookie (s, n, con namedC c, s'), loc), st)
val (file, _) = ListUtil.foldlMap doDecl (IM.empty, IM.empty) file
in
file
end
end
|
