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From iris.algebra Require Export cmra.
From iris.prelude Require Export list.
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From iris.algebra Require Import upred.
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Section cofe.
Context {A : cofeT}.

Instance list_dist : Dist (list A) := λ n, Forall2 (dist n).

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Lemma list_dist_lookup n l1 l2 : l1 {n} l2   i, l1 !! i {n} l2 !! i.
Proof. setoid_rewrite dist_option_Forall2. apply Forall2_lookup. Qed.

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Global Instance cons_ne n : Proper (dist n ==> dist n ==> dist n) (@cons A) := _.
Global Instance app_ne n : Proper (dist n ==> dist n ==> dist n) (@app A) := _.
Global Instance length_ne n : Proper (dist n ==> (=)) (@length A) := _.
Global Instance tail_ne n : Proper (dist n ==> dist n) (@tail A) := _.
Global Instance take_ne n : Proper (dist n ==> dist n) (@take A n) := _.
Global Instance drop_ne n : Proper (dist n ==> dist n) (@drop A n) := _.
Global Instance list_lookup_ne n i :
  Proper (dist n ==> dist n) (lookup (M:=list A) i).
Proof. intros ???. by apply dist_option_Forall2, Forall2_lookup. Qed.
Global Instance list_alter_ne n f i :
  Proper (dist n ==> dist n) f 
  Proper (dist n ==> dist n) (alter (M:=list A) f i) := _.
Global Instance list_insert_ne n i :
  Proper (dist n ==> dist n ==> dist n) (insert (M:=list A) i) := _.
Global Instance list_inserts_ne n i :
  Proper (dist n ==> dist n ==> dist n) (@list_inserts A i) := _.
Global Instance list_delete_ne n i :
  Proper (dist n ==> dist n) (delete (M:=list A) i) := _.
Global Instance option_list_ne n : Proper (dist n ==> dist n) (@option_list A).
Proof. intros ???; by apply Forall2_option_list, dist_option_Forall2. Qed.
Global Instance list_filter_ne n P `{ x, Decision (P x)} :
  Proper (dist n ==> iff) P 
  Proper (dist n ==> dist n) (filter (B:=list A) P) := _.
Global Instance replicate_ne n :
  Proper (dist n ==> dist n) (@replicate A n) := _.
Global Instance reverse_ne n : Proper (dist n ==> dist n) (@reverse A) := _.
Global Instance last_ne n : Proper (dist n ==> dist n) (@last A).
Proof. intros ???; by apply dist_option_Forall2, Forall2_last. Qed.
Global Instance resize_ne n :
  Proper (dist n ==> dist n ==> dist n) (@resize A n) := _.

Program Definition list_chain
    (c : chain (list A)) (x : A) (k : nat) : chain A :=
  {| chain_car n := from_option x (c n !! k) |}.
Next Obligation. intros c x k n i ?. by rewrite /= (chain_cauchy c n i). Qed.
Instance list_compl : Compl (list A) := λ c,
  match c 0 with
  | [] => []
  | x :: _ => compl  list_chain c x <$> seq 0 (length (c 0))
  end.

Definition list_cofe_mixin : CofeMixin (list A).
Proof.
  split.
  - intros l k. rewrite equiv_Forall2 -Forall2_forall.
    split; induction 1; constructor; intros; try apply equiv_dist; auto.
  - apply _.
  - rewrite /dist /list_dist. eauto using Forall2_impl, dist_S.
  - intros n c; rewrite /compl /list_compl.
    destruct (c 0) as [|x l] eqn:Hc0 at 1.
    { by destruct (chain_cauchy c 0 n); auto with omega. }
    rewrite -(λ H, length_ne _ _ _ (chain_cauchy c 0 n H)); last omega.
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    apply Forall2_lookup=> i. rewrite -dist_option_Forall2 list_lookup_fmap.
    destruct (decide (i < length (c n))); last first.
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    { rewrite lookup_seq_ge ?lookup_ge_None_2; auto with omega. }
    rewrite lookup_seq //= (conv_compl n (list_chain c _ _)) /=.
    by destruct (lookup_lt_is_Some_2 (c n) i) as [? ->].
Qed.
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Canonical Structure listC := CofeT (list A) list_cofe_mixin.
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Global Instance list_discrete : Discrete A  Discrete listC.
Proof. induction 2; constructor; try apply (timeless _); auto. Qed.

Global Instance nil_timeless : Timeless (@nil A).
Proof. inversion_clear 1; constructor. Qed.
Global Instance cons_timeless x l : Timeless x  Timeless l  Timeless (x :: l).
Proof. intros ??; inversion_clear 1; constructor; by apply timeless. Qed.
End cofe.

Arguments listC : clear implicits.

(** Functor *)
Instance list_fmap_ne {A B : cofeT} (f : A  B) n:
  Proper (dist n ==> dist n) f  Proper (dist n ==> dist n) (fmap (M:=list) f).
Proof. intros Hf l k ?; by eapply Forall2_fmap, Forall2_impl; eauto. Qed. 
Definition listC_map {A B} (f : A -n> B) : listC A -n> listC B :=
  CofeMor (fmap f : listC A  listC B).
Instance listC_map_ne A B n : Proper (dist n ==> dist n) (@listC_map A B).
Proof. intros f f' ? l; by apply Forall2_fmap, Forall_Forall2, Forall_true. Qed.

Program Definition listCF (F : cFunctor) : cFunctor := {|
  cFunctor_car A B := listC (cFunctor_car F A B);
  cFunctor_map A1 A2 B1 B2 fg := listC_map (cFunctor_map F fg)
|}.
Next Obligation.
  by intros F A1 A2 B1 B2 n f g Hfg; apply listC_map_ne, cFunctor_ne.
Qed.
Next Obligation.
  intros F A B x. rewrite /= -{2}(list_fmap_id x).
  apply list_fmap_setoid_ext=>y. apply cFunctor_id.
Qed.
Next Obligation.
  intros F A1 A2 A3 B1 B2 B3 f g f' g' x. rewrite /= -list_fmap_compose.
  apply list_fmap_setoid_ext=>y; apply cFunctor_compose.
Qed.

Instance listCF_contractive F :
  cFunctorContractive F  cFunctorContractive (listCF F).
Proof.
  by intros ? A1 A2 B1 B2 n f g Hfg; apply listC_map_ne, cFunctor_contractive.
Qed.
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(* CMRA *)
Section cmra.
  Context {A : cmraT}.
  Implicit Types l : list A.
  Local Arguments op _ _ !_ !_ / : simpl nomatch.

  Instance list_op : Op (list A) :=
    fix go l1 l2 := let _ : Op _ := @go in
    match l1, l2 with
    | [], _ => l2
    | _, [] => l1
    | x :: l1, y :: l2 => x  y :: l1  l2
    end.
  Instance list_core : Core (list A) := fmap core.

  Instance list_valid : Valid (list A) := Forall (λ x,  x).
  Instance list_validN : ValidN (list A) := λ n, Forall (λ x, {n} x).

  Lemma list_lookup_valid l :  l   i,  (l !! i).
  Proof.
    rewrite {1}/valid /list_valid Forall_lookup; split.
    - intros Hl i. by destruct (l !! i) as [x|] eqn:?; [apply (Hl i)|].
    - intros Hl i x Hi. move: (Hl i); by rewrite Hi.
  Qed.
  Lemma list_lookup_validN n l : {n} l   i, {n} (l !! i).
  Proof.
    rewrite {1}/validN /list_validN Forall_lookup; split.
    - intros Hl i. by destruct (l !! i) as [x|] eqn:?; [apply (Hl i)|].
    - intros Hl i x Hi. move: (Hl i); by rewrite Hi.
  Qed.
  Lemma list_lookup_op l1 l2 i : (l1  l2) !! i = l1 !! i  l2 !! i.
  Proof.
    revert i l2. induction l1 as [|x l1]; intros [|i] [|y l2];
      by rewrite /= ?left_id_L ?right_id_L.
  Qed.
  Lemma list_lookup_core l i : core l !! i = core (l !! i).
  Proof. revert i; induction l; intros [|i]; simpl; auto. Qed.

  Lemma list_lookup_included l1 l2 : l1  l2   i, l1 !! i  l2 !! i.
  Proof.
    split.
    { intros [l Hl] i. exists (l !! i). by rewrite Hl list_lookup_op. }
    revert l1. induction l2 as [|y l2 IH]=>-[|x l1] Hl.
    - by exists [].
    - destruct (Hl 0) as [[z|] Hz]; inversion Hz.
    - by exists (y :: l2).
    - destruct (IH l1) as [l3 ?]; first (intros i; apply (Hl (S i))).
      destruct (Hl 0) as [[z|] Hz]; inversion_clear Hz; simplify_eq/=.
      + exists (z :: l3); by constructor.
      + exists (core x :: l3); constructor; by rewrite ?cmra_core_r.
  Qed.

  Definition list_cmra_mixin : CMRAMixin (list A).
  Proof.
    split.
    - intros n l l1 l2; rewrite !list_dist_lookup=> Hl i.
      by rewrite !list_lookup_op Hl.
    - apply _.
    - intros n l1 l2; rewrite !list_dist_lookup !list_lookup_validN=> Hl ? i.
      by rewrite -Hl.
    - intros l. rewrite list_lookup_valid. setoid_rewrite list_lookup_validN.
      setoid_rewrite cmra_valid_validN. naive_solver.
    - intros n x. rewrite !list_lookup_validN. auto using cmra_validN_S.
    - intros l1 l2 l3; rewrite list_equiv_lookup=> i.
      by rewrite !list_lookup_op assoc.
    - intros l1 l2; rewrite list_equiv_lookup=> i.
      by rewrite !list_lookup_op comm.
    - intros l; rewrite list_equiv_lookup=> i.
      by rewrite list_lookup_op list_lookup_core cmra_core_l.
    - intros l; rewrite list_equiv_lookup=> i.
      by rewrite !list_lookup_core cmra_core_idemp.
    - intros l1 l2; rewrite !list_lookup_included=> Hl i.
      rewrite !list_lookup_core. by apply cmra_core_preserving.
    - intros n l1 l2. rewrite !list_lookup_validN.
      setoid_rewrite list_lookup_op. eauto using cmra_validN_op_l.
    - intros n l. induction l as [|x l IH]=> -[|y1 l1] [|y2 l2] Hl Hl';
        try (by exfalso; inversion_clear Hl').
      + by exists ([], []).
      + by exists ([], x :: l).
      + by exists (x :: l, []).
      + destruct (IH l1 l2) as ([l1' l2']&?&?&?),
          (cmra_extend n x y1 y2) as ([y1' y2']&?&?&?);
          [inversion_clear Hl; inversion_clear Hl'; auto ..|]; simplify_eq/=.
        exists (y1' :: l1', y2' :: l2'); repeat constructor; auto.
  Qed.
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  Canonical Structure listR : cmraT :=
    CMRAT (list A) list_cofe_mixin list_cmra_mixin.
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  Global Instance empty_list : Empty (list A) := [].
  Global Instance list_cmra_unit : CMRAUnit listR.
  Proof.
    split.
    - constructor.
    - by intros l.
    - by inversion_clear 1.
  Qed.

  Global Instance list_cmra_discrete : CMRADiscrete A  CMRADiscrete listR.
  Proof.
    split; [apply _|]=> l; rewrite list_lookup_valid list_lookup_validN=> Hl i.
    by apply cmra_discrete_valid.
  Qed.

  Global Instance list_persistent l : ( x : A, Persistent x)  Persistent l.
  Proof.
    intros ?; apply list_equiv_lookup=> i.
    by rewrite list_lookup_core (persistent (l !! i)).
  Qed.

  (** Internalized properties *)
  Lemma list_equivI {M} l1 l2 : (l1  l2)  ( i, l1 !! i  l2 !! i : uPred M).
  Proof. uPred.unseal; constructor=> n x ?. apply list_dist_lookup. Qed.
  Lemma list_validI {M} l : ( l)  ( i,  (l !! i) : uPred M).
  Proof. uPred.unseal; constructor=> n x ?. apply list_lookup_validN. Qed.
End cmra.

Arguments listR : clear implicits.

Global Instance list_singletonM `{Empty A} : SingletonM nat A (list A) := λ n x,
  replicate n  ++ [x].

Section properties.
  Context {A : cmraT}.
  Implicit Types l : list A.
  Local Arguments op _ _ !_ !_ / : simpl nomatch.
  Local Arguments cmra_op _ !_ !_ / : simpl nomatch.

  Lemma list_op_app l1 l2 l3 :
    length l2  length l1  (l1 ++ l3)  l2 = (l1  l2) ++ l3.
  Proof.
    revert l2 l3.
    induction l1 as [|x1 l1]=> -[|x2 l2] [|x3 l3] ?; f_equal/=; auto with lia.
  Qed.

  Lemma list_lookup_validN_Some n l i x : {n} l  l !! i {n} Some x  {n} x.
  Proof. move=> /list_lookup_validN /(_ i)=> Hl Hi; move: Hl. by rewrite Hi. Qed.
  Lemma list_lookup_valid_Some l i x :  l  l !! i  Some x   x.
  Proof. move=> /list_lookup_valid /(_ i)=> Hl Hi; move: Hl. by rewrite Hi. Qed.

  Lemma list_op_length l1 l2 : length (l1  l2) = max (length l1) (length l2).
  Proof. revert l2. induction l1; intros [|??]; f_equal/=; auto. Qed.

  Lemma replicate_valid n (x : A) :  x   replicate n x.
  Proof. apply Forall_replicate. Qed.

  (* Singleton lists *)
  Section singleton.
    Context `{CMRAUnit A}.

    Global Instance list_singletonM_ne n i :
      Proper (dist n ==> dist n) (list_singletonM i).
    Proof. intros l1 l2 ?. apply Forall2_app; by repeat constructor. Qed.
    Global Instance list_singletonM_proper i :
      Proper (() ==> ()) (list_singletonM i) := ne_proper _.

    Lemma elem_of_list_singletonM i z x : z  {[i := x]}  z =   z = x.
    Proof.
      rewrite elem_of_app elem_of_list_singleton elem_of_replicate. naive_solver.
    Qed.
    Lemma list_lookup_singletonM i x : {[ i := x ]} !! i = Some x.
    Proof. induction i; by f_equal/=. Qed.
    Lemma list_lookup_singletonM_ne i j x :
      i  j  {[ i := x ]} !! j = None  {[ i := x ]} !! j = Some .
    Proof. revert j; induction i; intros [|j]; naive_solver auto with omega. Qed.
    Lemma list_singletonM_validN n i x : {n} {[ i := x ]}  {n} x.
    Proof.
      rewrite list_lookup_validN. split.
      { move=> /(_ i). by rewrite list_lookup_singletonM. }
      intros Hx j; destruct (decide (i = j)); subst.
      - by rewrite list_lookup_singletonM.
      - destruct (list_lookup_singletonM_ne i j x) as [Hi|Hi]; first done;
          rewrite Hi; by try apply (cmra_unit_validN (A:=A)).
    Qed.
    Lemma list_singleton_valid  i x :  {[ i := x ]}   x.
    Proof.
      rewrite !cmra_valid_validN. by setoid_rewrite list_singletonM_validN.
    Qed.
    Lemma list_singletonM_length i x : length {[ i := x ]} = S i.
    Proof.
      rewrite /singletonM /list_singletonM app_length replicate_length /=; lia.
    Qed.

    Lemma list_core_singletonM i (x : A) : core {[ i := x ]}  {[ i := core x ]}.
    Proof.
      rewrite /singletonM /list_singletonM /=.
      induction i; constructor; auto using cmra_core_unit.
    Qed.
    Lemma list_op_singletonM i (x y : A) :
      {[ i := x ]}  {[ i := y ]}  {[ i := x  y ]}.
    Proof.
      rewrite /singletonM /list_singletonM /=.
      induction i; constructor; rewrite ?left_id; auto.
    Qed.
    Lemma list_alter_singletonM f i x : alter f i {[i := x]} = {[i := f x]}.
    Proof.
      rewrite /singletonM /list_singletonM /=.
      induction i; f_equal/=; auto.
    Qed.
    Global Instance list_singleton_persistent i (x : A) :
      Persistent x  Persistent {[ i := x ]}.
    Proof. intros. by rewrite /Persistent list_core_singletonM persistent. Qed.
  End singleton.

  (* Update *)
  Lemma list_update_updateP (P : A  Prop) (Q : list A  Prop) l1 x l2 :
    x ~~>: P  ( y, P y  Q (l1 ++ y :: l2))  l1 ++ x :: l2 ~~>: Q.
  Proof.
    intros Hx%option_updateP' HP n mf; rewrite list_lookup_validN=> Hm.
    destruct (Hx n (mf !! length l1)) as ([y|]&H1&H2); simpl in *; try done.
    { move: (Hm (length l1)). by rewrite list_lookup_op list_lookup_middle. }
    exists (l1 ++ y :: l2); split; auto.
    apply list_lookup_validN=> i.
    destruct (lt_eq_lt_dec i (length l1)) as [[?|?]|?]; subst.
    - move: (Hm i); by rewrite !list_lookup_op !lookup_app_l.
    - by rewrite list_lookup_op list_lookup_middle.
    - move: (Hm i). rewrite !(cons_middle _ l1 l2) !assoc.
      rewrite !list_lookup_op !lookup_app_r !app_length //=; lia.
  Qed.

  Lemma list_update_update l1 l2 x y : x ~~> y  l1 ++ x :: l2 ~~> l1 ++ y :: l2.
  Proof.
    rewrite !cmra_update_updateP => H; eauto using list_update_updateP with subst.
  Qed.

  (* Applying a local update at a position we own is a local update. *)
  Global Instance list_alter_update `{LocalUpdate A Lv L} i :
    LocalUpdate (λ L,  x, L !! i = Some x  Lv x) (alter L i).
  Proof.
    split; [apply _|]; intros n l1 l2 (x&Hi1&?) Hm; apply list_dist_lookup=> j.
    destruct (decide (j = i)); subst; last first.
    { by rewrite list_lookup_op !list_lookup_alter_ne // list_lookup_op. }
    rewrite list_lookup_op !list_lookup_alter list_lookup_op Hi1.
    destruct (l2 !! i) as [y|] eqn:Hi2; rewrite Hi2; constructor; auto.
    eapply (local_updateN L), (list_lookup_validN_Some _ _ i); eauto.
    by rewrite list_lookup_op Hi1 Hi2.
  Qed.
End properties.

(** Functor *)
Instance list_fmap_cmra_monotone {A B : cmraT} (f : A  B)
  `{!CMRAMonotone f} : CMRAMonotone (fmap f : list A  list B).
Proof.
  split; try apply _.
  - intros n l. rewrite !list_lookup_validN=> Hl i. rewrite list_lookup_fmap.
    by apply (validN_preserving (fmap f : option A  option B)).
  - intros l1 l2. rewrite !list_lookup_included=> Hl i. rewrite !list_lookup_fmap.
    by apply (included_preserving (fmap f : option A  option B)).
Qed.

Program Definition listRF (F : rFunctor) : rFunctor := {|
  rFunctor_car A B := listR (rFunctor_car F A B);
  rFunctor_map A1 A2 B1 B2 fg := listC_map (rFunctor_map F fg)
|}.
Next Obligation.
  by intros F ???? n f g Hfg; apply listC_map_ne, rFunctor_ne.
Qed.
Next Obligation.
  intros F A B x. rewrite /= -{2}(list_fmap_id x).
  apply list_fmap_setoid_ext=>y. apply rFunctor_id.
Qed.
Next Obligation.
  intros F A1 A2 A3 B1 B2 B3 f g f' g' x. rewrite /= -list_fmap_compose.
  apply list_fmap_setoid_ext=>y; apply rFunctor_compose.
Qed.

Instance listRF_contractive F :
  rFunctorContractive F  rFunctorContractive (listRF F).
Proof.
  by intros ? A1 A2 B1 B2 n f g Hfg; apply listC_map_ne, rFunctor_contractive.
Qed.