From heap_lang Require Export tactics substitution.
Import uPred.
(* TODO: The next few tactics are not wp-specific at all. They should move elsewhere. *)
Ltac revert_intros tac :=
lazymatch goal with
| |- ∀ _, _ => let H := fresh in intro H; revert_intros tac; revert H
| |- _ => tac
end.
(** Assumes a goal of the shape P ⊑ ▷ Q. Alterantively, if Q
is built of ★, ∧, ∨ with ▷ in all branches; that will work, too.
Will turn this goal into P ⊑ Q and strip ▷ in P below ★, ∧, ∨. *)
Ltac u_strip_later :=
let rec strip :=
lazymatch goal with
| |- (_ ★ _) ⊑ ▷ _ =>
etrans; last (eapply equiv_spec, later_sep);
apply sep_mono; strip
| |- (_ ∧ _) ⊑ ▷ _ =>
etrans; last (eapply equiv_spec, later_and);
apply sep_mono; strip
| |- (_ ∨ _) ⊑ ▷ _ =>
etrans; last (eapply equiv_spec, later_or);
apply sep_mono; strip
| |- ▷ _ ⊑ ▷ _ => apply later_mono; reflexivity
| |- _ ⊑ ▷ _ => apply later_intro; reflexivity
end
in let rec shape_Q :=
lazymatch goal with
| |- _ ⊑ (_ ★ _) =>
(* Force the later on the LHS to be top-level, matching laters
below ★ on the RHS *)
etrans; first (apply equiv_spec; symmetry; apply later_sep; reflexivity);
(* Match the arm recursively *)
apply sep_mono; shape_Q
| |- _ ⊑ (_ ∧ _) =>
etrans; first (apply equiv_spec; symmetry; apply later_and; reflexivity);
apply sep_mono; shape_Q
| |- _ ⊑ (_ ∨ _) =>
etrans; first (apply equiv_spec; symmetry; apply later_or; reflexivity);
apply sep_mono; shape_Q
| |- _ ⊑ ▷ _ => apply later_mono; reflexivity
(* We fail if we don't find laters in all branches. *)
end
in revert_intros ltac:(etrans; [|shape_Q];
etrans; last eapply later_mono; first solve [ strip ]).
(** Transforms a goal of the form ∀ ..., ?0... → ?1 ⊑ ?2
into True ⊑ ∀..., ■?0... → ?1 -★ ?2, applies tac, and
the moves all the assumptions back. *)
Ltac u_revert_all :=
lazymatch goal with
| |- ∀ _, _ => let H := fresh in intro H; u_revert_all;
(* TODO: Really, we should distinguish based on whether this is a
dependent function type or not. Right now, we distinguish based
on the sort of the argument, which is suboptimal. *)
first [ apply (const_intro_impl _ _ _ H); clear H
| revert H; apply forall_elim']
| |- ?C ⊑ _ => trans (True ★ C)%I;
first (rewrite [(True ★ C)%I]left_id; reflexivity);
apply wand_elim_l'
end.
(** This starts on a goal of the form ∀ ..., ?0... → ?1 ⊑ ?2.
It applies löb where all the Coq assumptions have been turned into logical
assumptions, then moves all the Coq assumptions back out to the context,
applies [tac] on the goal (now of the form _ ⊑ _), and then reverts the
Coq assumption so that we end up with the same shape as where we started. *)
Ltac u_löb tac :=
u_revert_all;
(* We now have a goal for the form True ⊑ P, with the "original" conclusion
being locked. *)
apply löb_strong; etransitivity;
first (apply equiv_spec; symmetry; apply (left_id _ _ _); reflexivity);
(* Now introduce again all the things that we reverted, and at the bottom,
do the work *)
let rec go :=
lazymatch goal with
| |- _ ⊑ (∀ _, _) => apply forall_intro;
let H := fresh in intro H; go; revert H
| |- _ ⊑ (■ _ → _) => apply impl_intro_l, const_elim_l;
let H := fresh in intro H; go; revert H
(* This is the "bottom" of the goal, where we see the wand introduced
by u_revert_all as well as the ▷ from löb_strong. *)
| |- ▷ _ ⊑ (_ -★ _) => apply wand_intro_l; tac
end
in go.
(** wp-specific helper tactics *)
(* First try to productively strip off laters; if that fails, at least
cosmetically get rid of laters in the conclusion. *)
Ltac wp_strip_later :=
let rec go :=
lazymatch goal with
| |- _ ⊑ (_ ★ _) => apply sep_mono; go
| |- _ ⊑ ▷ _ => apply later_intro
| |- _ ⊑ _ => reflexivity
end
in revert_intros ltac:(first [ u_strip_later | etrans; [|go] ] ).
Ltac wp_bind K :=
lazymatch eval hnf in K with
| [] => idtac
| _ => etrans; [|solve [ apply (wp_bind K) ]]; simpl
end.
Ltac wp_finish :=
let rec go :=
match goal with
| |- _ ⊑ ▷ _ => etrans; [|apply later_mono; go; reflexivity]
| |- _ ⊑ wp _ _ _ =>
etrans; [|eapply wp_value_pvs; reflexivity];
(* sometimes, we will have to do a final view shift, so only apply
wp_value if we obtain a consecutive wp *)
try (eapply pvs_intro;
match goal with |- _ ⊑ wp _ _ _ => simpl | _ => fail end)
| _ => idtac
end in simpl; revert_intros go.
Tactic Notation "wp_rec" ">" :=
u_löb ltac:((* Find the redex and apply wp_rec *)
idtac; (* FIXME WTF without this, it matches the goal before executing u_löb ?!? *)
lazymatch goal with
| |- _ ⊑ wp ?E ?e ?Q => reshape_expr e ltac:(fun K e' =>
match eval cbv in e' with
| App (Rec _ _ _) _ =>
wp_bind K; etrans; [|eapply wp_rec; reflexivity]; wp_finish
end)
end).
Tactic Notation "wp_rec" := wp_rec>; wp_strip_later.
Tactic Notation "wp_lam" ">" :=
match goal with
| |- _ ⊑ wp ?E ?e ?Q => reshape_expr e ltac:(fun K e' =>
match eval cbv in e' with
| App (Rec "" _ _) _ =>
wp_bind K; etrans; [|eapply wp_lam; reflexivity]; wp_finish
end)
end.
Tactic Notation "wp_lam" := wp_lam>; wp_strip_later.
Tactic Notation "wp_let" ">" := wp_lam>.
Tactic Notation "wp_let" := wp_lam.
Tactic Notation "wp_seq" ">" := wp_let>.
Tactic Notation "wp_seq" := wp_let.
Tactic Notation "wp_op" ">" :=
match goal with
| |- _ ⊑ wp ?E ?e ?Q => reshape_expr e ltac:(fun K e' =>
match eval cbv in e' with
| BinOp LtOp _ _ => wp_bind K; apply wp_lt; wp_finish
| BinOp LeOp _ _ => wp_bind K; apply wp_le; wp_finish
| BinOp EqOp _ _ => wp_bind K; apply wp_eq; wp_finish
| BinOp _ _ _ =>
wp_bind K; etrans; [|eapply wp_bin_op; reflexivity]; wp_finish
| UnOp _ _ =>
wp_bind K; etrans; [|eapply wp_un_op; reflexivity]; wp_finish
end)
end.
Tactic Notation "wp_op" := wp_op>; wp_strip_later.
Tactic Notation "wp_if" ">" :=
match goal with
| |- _ ⊑ wp ?E ?e ?Q => reshape_expr e ltac:(fun K e' =>
match eval cbv in e' with
| If _ _ _ =>
wp_bind K;
etrans; [|apply wp_if_true || apply wp_if_false]; wp_finish
end)
end.
Tactic Notation "wp_if" := wp_if>; wp_strip_later.
Tactic Notation "wp_focus" open_constr(efoc) :=
match goal with
| |- _ ⊑ wp ?E ?e ?Q => reshape_expr e ltac:(fun K e' =>
match e' with efoc => unify e' efoc; wp_bind K end)
end.
Tactic Notation "wp" ">" tactic(tac) :=
match goal with
| |- _ ⊑ wp ?E ?e ?Q => reshape_expr e ltac:(fun K e' => wp_bind K; tac)
end.
Tactic Notation "wp" tactic(tac) := (wp> tac); [wp_strip_later|..].
(* In case the precondition does not match *)
Tactic Notation "ewp" tactic(tac) := wp (etrans; [|tac]).
Tactic Notation "ewp" ">" tactic(tac) := wp> (etrans; [|tac]).