val with_local
  (#t: Type)
  (init: t)
  (#pre: vprop)
  (#ret_t: Type)
  (#post: ret_t -> vprop)
  (body: (r: ref t) ->
    STT ret_t
    (pts_to r full_perm init `star` pre)
    (fun v -> exists_ (pts_to r full_perm) `star` post v)
  )
: STF ret_t pre post True (fun _ -> True)
let with_local
  (#t: Type)
  (init: t)
  (#pre: vprop)
  (#ret_t: Type)
  (#post: ret_t -> vprop)
  (body: (r: ref t) ->
    STT ret_t
    (pts_to r full_perm init `star` pre)
    (fun v -> exists_ (pts_to r full_perm) `star` post v)
  )
: STF ret_t pre post True (fun _ -> True)
= _push_frame ();
  let r = _alloca init in
  let v = body r in
  let _ = elim_exists () in
  _free_and_pop_frame r;
  return v
val with_local
  (#t: Type)
  (init: t)
  (#pre: vprop)
  (#ret_t: Type)
  (#post: ret_t -> vprop)
  (body: (r: ref t) ->
    STT ret_t
    (pts_to r full_perm init `star` pre)
    (fun v -> exists_ (pts_to r full_perm) `star` post v)
  )
: STF ret_t pre post True (fun _ -> True)
let with_local
      (#t: Type)
      (init: t)
      (#pre: vprop)
      (#ret_t: Type)
      (#post: (ret_t -> vprop))
      (body:
          (r: ref t
              -> STT ret_t
                  ((pts_to r full_perm init) `star` pre)
                  (fun v -> (exists_ (pts_to r full_perm)) `star` (post v))))
    : STF ret_t pre post True (fun _ -> True) =
_push_frame ();
let r = _alloca init in
let v = body r in
let _ = elim_exists () in
_free_and_pop_frame r;
return v
Steel.ST.HigherReference.fst.checked
Steel.ST.Util.fsti.checked Steel.ST.Coercions.fsti.checked Steel.HigherReference.fsti.checked prims.fst.checked FStar.Pervasives.fsti.checked FStar.Ghost.fsti.checked
Steel.ST.HigherReference.fst
Steel.Effect.Common.vprop Steel.ST.HigherReference.ref Steel.Effect.Common.star Steel.ST.HigherReference.pts_to Steel.FractionalPermission.full_perm Steel.ST.Util.exists_ Steel.ST.Util.return FStar.Ghost.hide FStar.Set.set Steel.Memory.iname FStar.Set.empty Prims.unit Steel.ST.HigherReference._free_and_pop_frame FStar.Ghost.erased Steel.ST.Util.elim_exists Steel.ST.HigherReference._alloca Steel.ST.HigherReference._push_frame Prims.l_True
(*
   Copyright 2020 Microsoft Research

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*)

module Steel.ST.HigherReference
open FStar.Ghost
open Steel.ST.Util
open Steel.ST.Coercions
module R = Steel.HigherReference

let ref (a:Type u#1)
  : Type0
  = R.ref a

let null (#a:Type)
  : ref a
  = R.null #a

let is_null (#a:Type) (r:ref a)
  : b:bool{b <==> r == null}
  = R.is_null r

let pts_to (#a:Type)
           (r:ref a)
           ([@@@smt_fallback] p:perm)
           ([@@@smt_fallback] v:a)
  : vprop
  = R.pts_to r p v

let pts_to_injective_eq
      (#a: Type)
      (#opened:inames)
      (#p0 #p1:perm)
      (#v0 #v1:a)
      (r: ref a)
  : STGhost unit opened
      (pts_to r p0 v0 `star` pts_to r p1 v1)
      (fun _ -> pts_to r p0 v0 `star` pts_to r p1 v0)
      (requires True)
      (ensures fun _ -> v0 == v1)
  = coerce_ghost
    (fun _ -> R.higher_ref_pts_to_injective_eq #a #opened #p0 #p1 #(hide v0) #(hide v1) r)

let pts_to_not_null #a #opened #p #v r
  = extract_fact #opened (pts_to r p v) (r =!= null) (R.pts_to_not_null r p v);
    ()

let alloc (#a:Type) (x:a)
  : ST (ref a)
      emp
      (fun r -> pts_to r full_perm x)
      (requires True)
      (ensures fun r -> not (is_null r))
  = let r = coerce_steel (fun _ -> R.alloc x) in
    r

let read (#a:Type)
         (#p:perm)
         (#v:erased a)
         (r:ref a)
  : ST a
      (pts_to r p v)
      (fun _ -> pts_to r p v)
      (requires True)
      (ensures fun x -> x == Ghost.reveal v)
  = let u = coerce_steel (fun _ -> R.read r) in
    return u

let write (#a:Type)
          (#v:erased a)
          (r:ref a)
          (x:a)
  : STT unit
      (pts_to r full_perm v)
      (fun _ -> pts_to r full_perm x)
  = coerce_steel (fun _ -> R.write r x);
    return ()

let free (#a:Type)
         (#v:erased a)
         (r:ref a)
  : STT unit
        (pts_to r full_perm v)
        (fun _ -> emp)
  = coerce_steel(fun _ -> R.free r);
    return ()

/// Local primitive, to be extracted to Low* EPushFrame.  To remember
/// that we need to call some pop_frame later, we insert some dummy
/// vprop into the context.
let _stack_frame : vprop = pure True
let _push_frame () : STT unit emp (fun _ -> _stack_frame) =
  rewrite (pure True) _stack_frame

/// Local primitive, to be extracted to Low* EBufCreate
let _alloca (#a:Type) (x:a)
  : ST (ref a)
      emp
      (fun r -> pts_to r full_perm x)
      (requires True)
      (ensures fun r -> not (is_null r))
= alloc x

/// Local primitive, to be extracted to Low* EPopFrame
let _free_and_pop_frame
  (#a:Type)
  (#v:erased a)
  (r:ref a)
: STT unit
    (pts_to r full_perm v `star` _stack_frame)
    (fun _ -> emp)
= free r;
  rewrite _stack_frame (pure True);
  elim_pure _

let with_local
  (#t: Type)
  (init: t)
  (#pre: vprop)
  (#ret_t: Type)
  (#post: ret_t -> vprop)
  (body: (r: ref t) ->
    STT ret_t
    (pts_to r full_perm init `star` pre)
    (fun v -> exists_ (pts_to r full_perm) `star` post v)
  )
val with_local
  (#t: Type)
  (init: t)
  (#pre: vprop)
  (#ret_t: Type)
  (#post: ret_t -> vprop)
  (body: (r: ref t) ->
    STT ret_t
    (pts_to r full_perm init `star` pre)
    (fun v -> exists_ (pts_to r full_perm) `star` post v)
  )
: STF ret_t pre post True (fun _ -> True)
init: t -> body: (r: Steel.ST.HigherReference.ref t -> Steel.ST.Effect.STT ret_t)
  -> Steel.ST.Effect.STF ret_t