theory FSet3
imports "../../../Nominal/FSet"
begin

notation
  list_eq (infix "\<approx>" 50)

lemma fset_exhaust[case_names fempty finsert, cases type: fset]:
  shows "\<lbrakk>S = {||} \<Longrightarrow> P; \<And>x S'. S = finsert x S' \<Longrightarrow> P\<rbrakk> \<Longrightarrow> P"
  by (lifting list.exhaust)

lemma list_rel_find_element:
  assumes a: "x \<in> set a"
  and b: "list_rel R a b"
  shows "\<exists>y. (y \<in> set b \<and> R x y)"
proof -
  have "length a = length b" using b by (rule list_rel_len)
  then show ?thesis using a b proof (induct a b rule: list_induct2)
    case Nil
    show ?case using Nil.prems by simp
  next
    case (Cons x xs y ys)
    show ?case using Cons by auto
  qed
qed

lemma concat_rsp_pre:
  assumes a: "list_rel op \<approx> x x'"
  and     b: "x' \<approx> y'"
  and     c: "list_rel op \<approx> y' y"
  and     d: "\<exists>x\<in>set x. xa \<in> set x"
  shows "\<exists>x\<in>set y. xa \<in> set x"
proof -
  obtain xb where e: "xb \<in> set x" and f: "xa \<in> set xb" using d by auto
  have "\<exists>y. y \<in> set x' \<and> xb \<approx> y" by (rule list_rel_find_element[OF e a])
  then obtain ya where h: "ya \<in> set x'" and i: "xb \<approx> ya" by auto
  have j: "ya \<in> set y'" using b h by simp
  have "\<exists>yb. yb \<in> set y \<and> ya \<approx> yb" by (rule list_rel_find_element[OF j c])
  then show ?thesis using f i by auto
qed

lemma fun_relI [intro]:
  assumes "\<And>a b. P a b \<Longrightarrow> Q (x a) (y b)"
  shows "(P ===> Q) x y"
  using assms by (simp add: fun_rel_def)

lemma [quot_respect]:
  shows "(list_rel op \<approx> OOO op \<approx> ===> op \<approx>) concat concat"
proof (rule fun_relI, elim pred_compE)
  fix a b ba bb
  assume a: "list_rel op \<approx> a ba"
  assume b: "ba \<approx> bb"
  assume c: "list_rel op \<approx> bb b"
  have "\<forall>x. (\<exists>xa\<in>set a. x \<in> set xa) = (\<exists>xa\<in>set b. x \<in> set xa)" proof
    fix x
    show "(\<exists>xa\<in>set a. x \<in> set xa) = (\<exists>xa\<in>set b. x \<in> set xa)" proof
      assume d: "\<exists>xa\<in>set a. x \<in> set xa"
      show "\<exists>xa\<in>set b. x \<in> set xa" by (rule concat_rsp_pre[OF a b c d])
    next
      assume e: "\<exists>xa\<in>set b. x \<in> set xa"
      have a': "list_rel op \<approx> ba a" by (rule list_rel_symp[OF list_eq_equivp, OF a])
      have b': "bb \<approx> ba" by (rule equivp_symp[OF list_eq_equivp, OF b])
      have c': "list_rel op \<approx> b bb" by (rule list_rel_symp[OF list_eq_equivp, OF c])
      show "\<exists>xa\<in>set a. x \<in> set xa" by (rule concat_rsp_pre[OF c' b' a' e])
    qed
  qed
  then show "concat a \<approx> concat b" by simp
qed

lemma nil_rsp2[quot_respect]: "(list_rel op \<approx> OOO op \<approx>) [] []"
  by (metis nil_rsp list_rel.simps(1) pred_compI)

lemma set_in_eq: "(\<forall>e. ((e \<in> A) \<longleftrightarrow> (e \<in> B))) \<equiv> A = B"
  by (rule eq_reflection) auto

lemma map_rel_cong: "b \<approx> ba \<Longrightarrow> map f b \<approx> map f ba"
  unfolding list_eq.simps
  by (simp only: set_map set_in_eq)

lemma compose_list_refl:
  shows "(list_rel op \<approx> OOO op \<approx>) r r"
proof
  show c: "list_rel op \<approx> r r" by (rule list_rel_refl) (metis equivp_def fset_equivp)
  have d: "r \<approx> r" by (rule equivp_reflp[OF fset_equivp])
  show b: "(op \<approx> OO list_rel op \<approx>) r r" by (rule pred_compI) (rule d, rule c)
qed

lemma list_rel_refl:
  shows "(list_rel op \<approx>) r r"
  by (rule list_rel_refl)(metis equivp_def fset_equivp)

lemma Quotient_fset_list:
  shows "Quotient (list_rel op \<approx>) (map abs_fset) (map rep_fset)"
  by (fact list_quotient[OF Quotient_fset])

lemma quotient_compose_list[quot_thm]:
  shows  "Quotient ((list_rel op \<approx>) OOO (op \<approx>))
    (abs_fset \<circ> (map abs_fset)) ((map rep_fset) \<circ> rep_fset)"
  unfolding Quotient_def comp_def
proof (intro conjI allI)
  fix a r s
  show "abs_fset (map abs_fset (map rep_fset (rep_fset a))) = a"
    by (simp add: abs_o_rep[OF Quotient_fset] Quotient_abs_rep[OF Quotient_fset] map_id)
  have b: "list_rel op \<approx> (map rep_fset (rep_fset a)) (map rep_fset (rep_fset a))"
    by (rule list_rel_refl)
  have c: "(op \<approx> OO list_rel op \<approx>) (map rep_fset (rep_fset a)) (map rep_fset (rep_fset a))"
    by (rule, rule equivp_reflp[OF fset_equivp]) (rule b)
  show "(list_rel op \<approx> OOO op \<approx>) (map rep_fset (rep_fset a)) (map rep_fset (rep_fset a))"
    by (rule, rule list_rel_refl) (rule c)
  show "(list_rel op \<approx> OOO op \<approx>) r s = ((list_rel op \<approx> OOO op \<approx>) r r \<and>
        (list_rel op \<approx> OOO op \<approx>) s s \<and> abs_fset (map abs_fset r) = abs_fset (map abs_fset s))"
  proof (intro iffI conjI)
    show "(list_rel op \<approx> OOO op \<approx>) r r" by (rule compose_list_refl)
    show "(list_rel op \<approx> OOO op \<approx>) s s" by (rule compose_list_refl)
  next
    assume a: "(list_rel op \<approx> OOO op \<approx>) r s"
    then have b: "map abs_fset r \<approx> map abs_fset s" proof (elim pred_compE)
      fix b ba
      assume c: "list_rel op \<approx> r b"
      assume d: "b \<approx> ba"
      assume e: "list_rel op \<approx> ba s"
      have f: "map abs_fset r = map abs_fset b"
        by (metis Quotient_rel[OF Quotient_fset_list] c)
      have g: "map abs_fset s = map abs_fset ba"
        by (metis Quotient_rel[OF Quotient_fset_list] e)
      show "map abs_fset r \<approx> map abs_fset s" using d f g map_rel_cong by simp
    qed
    then show "abs_fset (map abs_fset r) = abs_fset (map abs_fset s)"
      by (metis Quotient_rel[OF Quotient_fset])
  next
    assume a: "(list_rel op \<approx> OOO op \<approx>) r r \<and> (list_rel op \<approx> OOO op \<approx>) s s
      \<and> abs_fset (map abs_fset r) = abs_fset (map abs_fset s)"
    then have s: "(list_rel op \<approx> OOO op \<approx>) s s" by simp
    have d: "map abs_fset r \<approx> map abs_fset s"
      by (subst Quotient_rel[OF Quotient_fset]) (simp add: a)
    have b: "map rep_fset (map abs_fset r) \<approx> map rep_fset (map abs_fset s)"
      by (rule map_rel_cong[OF d])
    have y: "list_rel op \<approx> (map rep_fset (map abs_fset s)) s"
      by (fact rep_abs_rsp_left[OF Quotient_fset_list, OF list_rel_refl[of s]])
    have c: "(op \<approx> OO list_rel op \<approx>) (map rep_fset (map abs_fset r)) s"
      by (rule pred_compI) (rule b, rule y)
    have z: "list_rel op \<approx> r (map rep_fset (map abs_fset r))"
      by (fact rep_abs_rsp[OF Quotient_fset_list, OF list_rel_refl[of r]])
    then show "(list_rel op \<approx> OOO op \<approx>) r s"
      using a c pred_compI by simp
  qed
qed

lemma nil_prs2[quot_preserve]: "(abs_fset \<circ> map f) [] = abs_fset []"
  by simp

lemma fconcat_empty:
  shows "fconcat {||} = {||}"
  by (lifting concat.simps(1))

lemma insert_rsp2[quot_respect]:
  "(op \<approx> ===> list_rel op \<approx> OOO op \<approx> ===> list_rel op \<approx> OOO op \<approx>) op # op #"
  apply auto
  apply (simp add: set_in_eq)
  apply (rule_tac b="x # b" in pred_compI)
  apply auto
  apply (rule_tac b="x # ba" in pred_compI)
  apply auto
  done

lemma append_rsp[quot_respect]:
  "(op \<approx> ===> op \<approx> ===> op \<approx>) op @ op @"
  by (auto)

lemma insert_prs2[quot_preserve]:
  "(rep_fset ---> (map rep_fset \<circ> rep_fset) ---> (abs_fset \<circ> map abs_fset)) op # = finsert"
  by (simp add: expand_fun_eq Quotient_abs_rep[OF Quotient_fset]
      abs_o_rep[OF Quotient_fset] map_id finsert_def)

lemma fconcat_insert:
  shows "fconcat (finsert x S) = x |\<union>| fconcat S"
  by (lifting concat.simps(2))

lemma append_prs2[quot_preserve]:
  "((map rep_fset \<circ> rep_fset) ---> (map rep_fset \<circ> rep_fset) ---> abs_fset \<circ> map abs_fset) op @ = funion"
  by (simp add: expand_fun_eq Quotient_abs_rep[OF Quotient_fset]
      abs_o_rep[OF Quotient_fset] map_id sup_fset_def)

lemma list_rel_app_l:
  assumes a: "reflp R"
  and b: "list_rel R l r"
  shows "list_rel R (z @ l) (z @ r)"
  by (induct z) (simp_all add: b, metis a reflp_def)

lemma append_rsp2_pre0:
  assumes a:"list_rel op \<approx> x x'"
  shows "list_rel op \<approx> (x @ z) (x' @ z)"
  using a apply (induct x x' rule: list_induct2')
  apply simp_all
  apply (rule list_rel_refl)
  done

lemma append_rsp2_pre1:
  assumes a:"list_rel op \<approx> x x'"
  shows "list_rel op \<approx> (z @ x) (z @ x')"
  using a apply (induct x x' arbitrary: z rule: list_induct2')
  apply (rule list_rel_refl)
  apply (simp_all del: list_eq.simps)
  apply (rule list_rel_app_l)
  apply (simp_all add: reflp_def)
  done

lemma append_rsp2_pre:
  assumes a:"list_rel op \<approx> x x'"
  and     b: "list_rel op \<approx> z z'"
  shows "list_rel op \<approx> (x @ z) (x' @ z')"
  apply (rule list_rel_transp[OF fset_equivp])
  apply (rule append_rsp2_pre0)
  apply (rule a)
  using b apply (induct z z' rule: list_induct2')
  apply (simp_all only: append_Nil2)
  apply (rule list_rel_refl)
  apply simp_all
  apply (rule append_rsp2_pre1)
  apply simp
  done

lemma append_rsp2[quot_respect]:
  "(list_rel op \<approx> OOO op \<approx> ===> list_rel op \<approx> OOO op \<approx> ===> list_rel op \<approx> OOO op \<approx>) op @ op @"
proof (intro fun_relI, elim pred_compE)
  fix x y z w x' z' y' w' :: "'a list list"
  assume a:"list_rel op \<approx> x x'"
  and b:    "x' \<approx> y'"
  and c:    "list_rel op \<approx> y' y"
  assume aa: "list_rel op \<approx> z z'"
  and bb:   "z' \<approx> w'"
  and cc:   "list_rel op \<approx> w' w"
  have a': "list_rel op \<approx> (x @ z) (x' @ z')" using a aa append_rsp2_pre by auto
  have b': "x' @ z' \<approx> y' @ w'" using b bb by simp
  have c': "list_rel op \<approx> (y' @ w') (y @ w)" using c cc append_rsp2_pre by auto
  have d': "(op \<approx> OO list_rel op \<approx>) (x' @ z') (y @ w)"
    by (rule pred_compI) (rule b', rule c')
  show "(list_rel op \<approx> OOO op \<approx>) (x @ z) (y @ w)"
    by (rule pred_compI) (rule a', rule d')
qed

lemma "fconcat (xs |\<union>| ys) = fconcat xs |\<union>| fconcat ys"
  by (lifting concat_append)

(* TBD *)

text {* syntax for fset comprehensions (adapted from lists) *}

nonterminals fsc_qual fsc_quals

syntax
"_fsetcompr" :: "'a \<Rightarrow> fsc_qual \<Rightarrow> fsc_quals \<Rightarrow> 'a fset"  ("{|_ . __")
"_fsc_gen" :: "'a \<Rightarrow> 'a fset \<Rightarrow> fsc_qual" ("_ <- _")
"_fsc_test" :: "bool \<Rightarrow> fsc_qual" ("_")
"_fsc_end" :: "fsc_quals" ("|}")
"_fsc_quals" :: "fsc_qual \<Rightarrow> fsc_quals \<Rightarrow> fsc_quals" (", __")
"_fsc_abs" :: "'a => 'b fset => 'b fset"

syntax (xsymbols)
"_fsc_gen" :: "'a \<Rightarrow> 'a fset \<Rightarrow> fsc_qual" ("_ \<leftarrow> _")
syntax (HTML output)
"_fsc_gen" :: "'a \<Rightarrow> 'a fset \<Rightarrow> fsc_qual" ("_ \<leftarrow> _")

ML {* Syntax.check_term @{context} (Const ("List.append", dummyT) $ @{term "[3::nat,4]"}) *}

parse_translation (advanced) {*
let
  val femptyC = Syntax.const @{const_name fempty};
  val finsertC = Syntax.const @{const_name finsert};
  val fmapC = Syntax.const @{const_name fmap};
  val fconcatC = Syntax.const @{const_name fconcat};
  val IfC = Syntax.const @{const_name If};
  fun fsingl x = finsertC $ x $ femptyC;

  fun pat_tr ctxt p e opti = (* %x. case x of p => e | _ => [] *)
    let
      val x = Free (Name.variant (fold Term.add_free_names [p, e] []) "x", dummyT);
      val e = if opti then fsingl e else e;
      val case1 = Syntax.const "_case1" $ p $ e;
      val case2 = Syntax.const "_case1" $ Syntax.const Term.dummy_patternN
                                        $ femptyC;
      val cs = Syntax.const "_case2" $ case1 $ case2
      val ft = Datatype_Case.case_tr false Datatype.info_of_constr
                 ctxt [x, cs]
    in lambda x ft end;

  fun abs_tr ctxt (p as Free(s,T)) e opti =
        let val thy = ProofContext.theory_of ctxt;
            val s' = Sign.intern_const thy s
        in if Sign.declared_const thy s'
           then (pat_tr ctxt p e opti, false)
           else (lambda p e, true)
        end
    | abs_tr ctxt p e opti = (pat_tr ctxt p e opti, false);

  fun fsc_tr ctxt [e, Const("_fsc_test",_) $ b, qs] =
        let 
          val res = case qs of 
                      Const("_fsc_end",_) => fsingl e
                    | Const("_fsc_quals",_)$ q $ qs => fsc_tr ctxt [e, q, qs];
        in 
          IfC $ b $ res $ femptyC 
        end

    | fsc_tr ctxt [e, Const("_fsc_gen",_) $ p $ es, Const("_fsc_end",_)] =
         (case abs_tr ctxt p e true of
            (f,true) => fmapC $ f $ es
          | (f, false) => fconcatC $ (fmapC $ f $ es))
       
    | fsc_tr ctxt [e, Const("_fsc_gen",_) $ p $ es, Const("_fsc_quals",_) $ q $ qs] =
        let
          val e' = fsc_tr ctxt [e, q, qs];
        in 
          fconcatC $ (fmapC $ (fst (abs_tr ctxt p e' false)) $ es) 
        end

in [("_fsetcompr", fsc_tr)] end
*}


(* NEEDS FIXING *)
(* examles *)
(*
term "{|(x,y,z). b|}"
term "{|x. x \<leftarrow> xs|}"
term "{|(x,y,z). x\<leftarrow>xs|}"
term "{|e x y. x\<leftarrow>xs, y\<leftarrow>ys|}"
term "{|(x,y,z). x<a, x>b|}"
term "{|(x,y,z). x\<leftarrow>xs, x>b|}"
term "{|(x,y,z). x<a, x\<leftarrow>xs|}"
term "{|(x,y). Cons True x \<leftarrow> xs|}"
term "{|(x,y,z). Cons x [] \<leftarrow> xs|}"
term "{|(x,y,z). x<a, x>b, x=d|}"
term "{|(x,y,z). x<a, x>b, y\<leftarrow>ys|}"
term "{|(x,y,z). x<a, x\<leftarrow>xs,y>b|}"
term "{|(x,y,z). x<a, x\<leftarrow>xs, y\<leftarrow>ys|}"
term "{|(x,y,z). x\<leftarrow>xs, x>b, y<a|}"
term "{|(x,y,z). x\<leftarrow>xs, x>b, y\<leftarrow>ys|}"
term "{|(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,y>x|}"
term "{|(x,y,z). x\<leftarrow>xs, y\<leftarrow>ys,z\<leftarrow>zs|}"
*)

(* BELOW CONSTRUCTION SITE *)


end