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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 E = CoreEnv
structure U = CoreUtil
val liftConInCon = E.liftConInCon
val subConInCon = E.subConInCon
val liftExpInExp =
U.Exp.mapB {kind = fn k => k,
con = fn _ => fn c => c,
exp = fn bound => fn e =>
case e of
ERel xn =>
if xn < bound then
e
else
ERel (xn + 1)
| _ => e,
bind = fn (bound, U.Exp.RelE _) => bound + 1
| (bound, _) => bound}
val subExpInExp =
U.Exp.mapB {kind = fn k => k,
con = fn _ => fn c => c,
exp = fn (xn, rep) => fn e =>
case e of
ERel xn' =>
(case Int.compare (xn', xn) of
EQUAL => #1 rep
| GREATER=> ERel (xn' - 1)
| LESS => e)
| _ => e,
bind = fn ((xn, rep), U.Exp.RelE _) => (xn+1, liftExpInExp 0 rep)
| (ctx, _) => ctx}
val liftConInExp = E.liftConInExp
val subConInExp = E.subConInExp
fun bindC (env, b) =
case b of
U.Con.Rel (x, k) => E.pushCRel env x k
| U.Con.Named (x, n, k, co) => E.pushCNamed env x n k co
fun bind (env, b) =
case b of
U.Decl.RelC (x, k) => E.pushCRel env x k
| U.Decl.NamedC (x, n, k, co) => E.pushCNamed env x n k co
| U.Decl.RelE (x, t) => E.pushERel env x t
| U.Decl.NamedE (x, n, t, eo, s) => E.pushENamed env x n t eo s
fun kind k = k
fun con env c =
case c of
CApp ((CApp ((CApp ((CFold ks, _), f), _), i), loc), (CRecord (k, xcs), _)) =>
(case xcs of
[] => #1 i
| (n, v) :: rest =>
#1 (reduceCon env (CApp ((CApp ((CApp (f, n), loc), v), loc),
(CApp ((CApp ((CApp ((CFold ks, loc), f), loc), i), loc),
(CRecord (k, rest), loc)), loc)), loc)))
| CApp ((CAbs (_, _, c1), loc), c2) =>
#1 (reduceCon env (subConInCon (0, c2) c1))
| CNamed n =>
(case E.lookupCNamed env n of
(_, _, SOME c') => #1 c'
| _ => c)
| CConcat ((CRecord (k, xcs1), loc), (CRecord (_, xcs2), _)) => CRecord (k, xcs1 @ xcs2)
| CProj ((CTuple cs, _), n) => #1 (List.nth (cs, n - 1))
| _ => c
and reduceCon env = U.Con.mapB {kind = kind, con = con, bind = bindC} env
fun exp env e =
case e of
ENamed n =>
(case E.lookupENamed env n of
(_, _, SOME e', _) => #1 e'
| _ => e)
| ECApp ((EApp ((EApp ((ECApp ((EFold ks, _), ran), _), f), _), i), _), (CRecord (k, xcs), loc)) =>
(case xcs of
[] => #1 i
| (n, v) :: rest =>
#1 (reduceExp env (EApp ((ECApp ((ECApp ((ECApp (f, n), loc), v), loc), (CRecord (k, rest), loc)), loc),
(ECApp ((EApp ((EApp ((ECApp ((EFold ks, loc), ran), loc), f), loc), i), loc),
(CRecord (k, rest), loc)), loc)), loc)))
| EApp ((EAbs (_, _, _, e1), loc), e2) =>
#1 (reduceExp env (subExpInExp (0, e2) e1))
| ECApp ((ECAbs (_, _, e1), loc), c) =>
#1 (reduceExp env (subConInExp (0, c) e1))
| EField ((ERecord xes, _), (CName x, _), _) =>
(case List.find (fn ((CName x', _), _, _) => x' = x
| _ => false) xes of
SOME (_, e, _) => #1 e
| NONE => e)
| ECut (r as (_, loc), _, {rest = (CRecord (k, xts), _), ...}) =>
let
fun fields (remaining, passed) =
case remaining of
[] => []
| (x, t) :: rest =>
(x,
(EField (r, x, {field = t,
rest = (CRecord (k, List.revAppend (passed, rest)), loc)}), loc),
t) :: fields (rest, (x, t) :: passed)
in
#1 (reduceExp env (ERecord (fields (xts, [])), loc))
end
| _ => e
and reduceExp env = U.Exp.mapB {kind = kind, con = con, exp = exp, bind = bind} env
fun decl env d =
case d of
DValRec [vi as (_, n, _, e, _)] =>
let
fun kind _ = false
fun con _ = false
fun exp e =
case e of
ENamed n' => n' = n
| _ => false
in
if U.Exp.exists {kind = kind, con = con, exp = exp} e then
d
else
DVal vi
end
| _ => d
val reduce = U.File.mapB {kind = kind, con = con, exp = exp, decl = decl, bind = bind} E.empty
end
|
