theory BlexerSimp

  imports Blexer 

begin

fun flts :: "arexp list \<Rightarrow> arexp list"

  where 

  "flts [] = []"

| "flts (AZERO # rs) = flts rs"

| "flts ((AALTs bs  rs1) # rs) = (map (fuse bs) rs1) @ flts rs"

| "flts (r1 # rs) = r1 # flts rs"

fun bsimp_ASEQ :: "bit list \<Rightarrow> arexp \<Rightarrow> arexp \<Rightarrow> arexp"

  where

  "bsimp_ASEQ _ AZERO _ = AZERO"

| "bsimp_ASEQ _ _ AZERO = AZERO"

| "bsimp_ASEQ bs1 (AONE bs2) r2 = fuse (bs1 @ bs2) r2"

| "bsimp_ASEQ bs1 r1 r2 = ASEQ  bs1 r1 r2"

lemma bsimp_ASEQ0[simp]:

  shows "bsimp_ASEQ bs r1 AZERO = AZERO"

  by (case_tac r1)(simp_all)

lemma bsimp_ASEQ1:

  assumes "r1 \<noteq> AZERO" "r2 \<noteq> AZERO" "\<nexists>bs. r1 = AONE bs"

  shows "bsimp_ASEQ bs r1 r2 = ASEQ bs r1 r2"

  using assms

  apply(induct bs r1 r2 rule: bsimp_ASEQ.induct)

  apply(auto)

  done

lemma bsimp_ASEQ2[simp]:

  shows "bsimp_ASEQ bs1 (AONE bs2) r2 = fuse (bs1 @ bs2) r2"

  by (case_tac r2) (simp_all)

fun bsimp_AALTs :: "bit list \<Rightarrow> arexp list \<Rightarrow> arexp"

  where

  "bsimp_AALTs _ [] = AZERO"

| "bsimp_AALTs bs1 [r] = fuse bs1 r"

| "bsimp_AALTs bs1 rs = AALTs bs1 rs"

lemma bmkeps_fuse:

  assumes "bnullable r"

  shows "bmkeps (fuse bs r) = bs @ bmkeps r"

  using assms

  by (induct r rule: bnullable.induct) (auto)

lemma bmkepss_fuse: 

  assumes "bnullables rs"

  shows "bmkepss (map (fuse bs) rs) = bs @ bmkepss rs"

  using assms

  apply(induct rs arbitrary: bs)

  apply(auto simp add: bmkeps_fuse bnullable_fuse)

  done

lemma bder_fuse:

  shows "bder c (fuse bs a) = fuse bs  (bder c a)"

  apply(induct a arbitrary: bs c)

  apply(simp_all)

  done

fun ABIncludedByC :: "'a \<Rightarrow> 'b \<Rightarrow> 'c \<Rightarrow> ('a \<Rightarrow> 'b \<Rightarrow> 'c) \<Rightarrow> ('c \<Rightarrow> 'c \<Rightarrow> bool) \<Rightarrow> bool" where

  "ABIncludedByC a b c f subseteqPred = subseteqPred (f a b) c"

fun furtherSEQ :: "rexp \<Rightarrow> rexp \<Rightarrow> rexp list" and 

   turnIntoTerms :: "rexp \<Rightarrow> rexp list "

   where

  "furtherSEQ ONE r2 =  turnIntoTerms r2 "

| "furtherSEQ r11 r2 = [SEQ r11 r2]"

| "turnIntoTerms (SEQ ONE r2) =  turnIntoTerms r2"

| "turnIntoTerms (SEQ r1 r2) = concat (map (\<lambda>r11. furtherSEQ r11 r2) (turnIntoTerms r1))"

| "turnIntoTerms r = [r]"

abbreviation "tint \<equiv> turnIntoTerms"

fun seqFold :: "rexp \<Rightarrow> rexp list \<Rightarrow> rexp" where

  "seqFold acc [] = acc"

| "seqFold ONE (r # rs1) = seqFold r rs1"

| "seqFold acc (r # rs1) = seqFold (SEQ acc r) rs1"

fun attachCtx :: "arexp \<Rightarrow> rexp list \<Rightarrow> rexp set" where

  "attachCtx r ctx = set (turnIntoTerms (seqFold (erase r) ctx))"

fun rs1_subseteq_rs2 :: "rexp set \<Rightarrow> rexp set \<Rightarrow> bool" where

  "rs1_subseteq_rs2 rs1 rs2 = (rs1 \<subseteq> rs2)"

fun notZero :: "arexp \<Rightarrow> bool" where

  "notZero AZERO = True"

| "notZero _ = False"

fun tset :: "arexp list \<Rightarrow> rexp set" where

  "tset rs = set (concat (map turnIntoTerms (map erase rs)))"

fun prune6 :: "rexp set \<Rightarrow> arexp \<Rightarrow> rexp list \<Rightarrow> arexp" where

  "prune6 acc a ctx = (if (ABIncludedByC a ctx acc attachCtx rs1_subseteq_rs2) then AZERO else 

                        (case a of (ASEQ bs r1 r2) \<Rightarrow> bsimp_ASEQ bs (prune6 acc r1 (erase r2 # ctx)) r2

                                 | AALTs bs rs0 \<Rightarrow> bsimp_AALTs bs (filter notZero (map (\<lambda>r.(prune6 acc r ctx)) rs0))

                                 | r \<Rightarrow> r

                        )

                      )

            "

abbreviation

  "p6 acc r \<equiv> prune6 (tset acc) r Nil"

fun dB6 :: "arexp list \<Rightarrow> rexp set \<Rightarrow> arexp list" where

  "dB6 [] acc = []"

| "dB6 (a # as) acc = (if (erase a \<in> acc) then (dB6 as acc) 

                       else (let pruned = prune6 acc a [] in 

                              (case pruned of

                                 AZERO \<Rightarrow> dB6 as acc

                               |xPrime \<Rightarrow> xPrime # (dB6 as ( (set (turnIntoTerms (erase pruned))) \<union> acc)  ) ) ))   "

fun bsimpStrong6 :: "arexp \<Rightarrow> arexp" 

  where

  "bsimpStrong6 (ASEQ bs1 r1 r2) = bsimp_ASEQ bs1 (bsimpStrong6 r1) (bsimpStrong6 r2)"

| "bsimpStrong6 (AALTs bs1 rs) = bsimp_AALTs bs1 (dB6 (flts (map bsimpStrong6 rs)) {}) "

| "bsimpStrong6 r = r"

fun 

  bdersStrong6 :: "arexp \<Rightarrow> string \<Rightarrow> arexp"

where

  "bdersStrong6 r [] = r"

| "bdersStrong6 r (c # s) = bdersStrong6 (bsimpStrong6 (bder c r)) s"

definition blexerStrong where

 "blexerStrong r s \<equiv> if bnullable (bdersStrong6 (intern r) s) then 

                    decode (bmkeps (bdersStrong6 (intern r) s)) r else None"

inductive 

  rrewrite:: "arexp \<Rightarrow> arexp \<Rightarrow> bool" ("_ \<leadsto> _" [99, 99] 99)

and 

  srewrite:: "arexp list \<Rightarrow> arexp list \<Rightarrow> bool" (" _ s\<leadsto> _" [100, 100] 100)

where

  bs1: "ASEQ bs AZERO r2 \<leadsto> AZERO"

| bs2: "ASEQ bs r1 AZERO \<leadsto> AZERO"

| bs3: "ASEQ bs1 (AONE bs2) r \<leadsto> fuse (bs1@bs2) r"

| bs4: "r1 \<leadsto> r2 \<Longrightarrow> ASEQ bs r1 r3 \<leadsto> ASEQ bs r2 r3"

| bs5: "r3 \<leadsto> r4 \<Longrightarrow> ASEQ bs r1 r3 \<leadsto> ASEQ bs r1 r4"

| bs6: "AALTs bs [] \<leadsto> AZERO"

| bs7: "AALTs bs [r] \<leadsto> fuse bs r"

| bs10: "rs1 s\<leadsto> rs2 \<Longrightarrow> AALTs bs rs1 \<leadsto> AALTs bs rs2"

| ss1:  "[] s\<leadsto> []"

| ss2:  "rs1 s\<leadsto> rs2 \<Longrightarrow> (r # rs1) s\<leadsto> (r # rs2)"

| ss3:  "r1 \<leadsto> r2 \<Longrightarrow> (r1 # rs) s\<leadsto> (r2 # rs)"

| ss4:  "(AZERO # rs) s\<leadsto> rs"

| ss5:  "(AALTs bs1 rs1 # rsb) s\<leadsto> ((map (fuse bs1) rs1) @ rsb)"

| ss6:  "L (erase a2) \<subseteq> L (erase a1) \<Longrightarrow> (rsa@[a1]@rsb@[a2]@rsc) s\<leadsto> (rsa@[a1]@rsb@rsc)"

| ss7:  " (as @ [a] @ as1) s\<leadsto> (as @ [p6 as a] @ as1)"

thm tset.simps

inductive 

  rrewrites:: "arexp \<Rightarrow> arexp \<Rightarrow> bool" ("_ \<leadsto>* _" [100, 100] 100)

where 

  rs1[intro, simp]:"r \<leadsto>* r"

| rs2[intro]: "\<lbrakk>r1 \<leadsto>* r2; r2 \<leadsto> r3\<rbrakk> \<Longrightarrow> r1 \<leadsto>* r3"

inductive 

  srewrites:: "arexp list \<Rightarrow> arexp list \<Rightarrow> bool" ("_ s\<leadsto>* _" [100, 100] 100)

where 

  sss1[intro, simp]:"rs s\<leadsto>* rs"

| sss2[intro]: "\<lbrakk>rs1 s\<leadsto> rs2; rs2 s\<leadsto>* rs3\<rbrakk> \<Longrightarrow> rs1 s\<leadsto>* rs3"

lemma r_in_rstar : "r1 \<leadsto> r2 \<Longrightarrow> r1 \<leadsto>* r2"

  using rrewrites.intros(1) rrewrites.intros(2) by blast

lemma rs_in_rstar: 

  shows "r1 s\<leadsto> r2 \<Longrightarrow> r1 s\<leadsto>* r2"

  using rrewrites.intros(1) rrewrites.intros(2) by blast

lemma rrewrites_trans[trans]: 

  assumes a1: "r1 \<leadsto>* r2"  and a2: "r2 \<leadsto>* r3"

  shows "r1 \<leadsto>* r3"

  using a2 a1

  apply(induct r2 r3 arbitrary: r1 rule: rrewrites.induct) 

  apply(auto)

  done

lemma srewrites_trans[trans]: 

  assumes a1: "r1 s\<leadsto>* r2"  and a2: "r2 s\<leadsto>* r3"

  shows "r1 s\<leadsto>* r3"

  using a1 a2

  apply(induct r1 r2 arbitrary: r3 rule: srewrites.induct) 

   apply(auto)

  done

lemma contextrewrites0: 

  "rs1 s\<leadsto>* rs2 \<Longrightarrow> AALTs bs rs1 \<leadsto>* AALTs bs rs2"

  apply(induct rs1 rs2 rule: srewrites.inducts)

   apply simp

  using bs10 r_in_rstar rrewrites_trans by blast

lemma contextrewrites1: 

  "r \<leadsto>* r' \<Longrightarrow> AALTs bs (r # rs) \<leadsto>* AALTs bs (r' # rs)"

  apply(induct r r' rule: rrewrites.induct)

   apply simp

  using bs10 ss3 by blast

lemma srewrite1: 

  shows "rs1 s\<leadsto> rs2 \<Longrightarrow> (rs @ rs1) s\<leadsto> (rs @ rs2)"

  apply(induct rs)

   apply(auto)

  using ss2 by auto

lemma srewrites1: 

  shows "rs1 s\<leadsto>* rs2 \<Longrightarrow> (rs @ rs1) s\<leadsto>* (rs @ rs2)"

  apply(induct rs1 rs2 rule: srewrites.induct)

   apply(auto)

  using srewrite1 by blast

lemma srewrites_prepend:

  shows "rs1 s\<leadsto>* rs2 \<Longrightarrow> (r # rs1) s\<leadsto>* (r # rs2)"

  by (metis append_Cons append_Nil srewrites1)  

lemma srewrite2: 

  shows  "r1 \<leadsto> r2 \<Longrightarrow> True"

  and "rs1 s\<leadsto> rs2 \<Longrightarrow> (rs1 @ rs) s\<leadsto>* (rs2 @ rs)"

  apply(induct arbitrary: rs rule: rrewrite_srewrite.inducts)

                apply simp+

  using srewrites_prepend apply force

      apply (simp add: rs_in_rstar ss3)

  using ss4 apply force 

  using rs_in_rstar ss5 apply auto[1]

  using rs_in_rstar ss6 apply auto[1]

  using rs_in_rstar ss7 by force

lemma srewrites3: 

  shows "rs1 s\<leadsto>* rs2 \<Longrightarrow> (rs1 @ rs) s\<leadsto>* (rs2 @ rs)"

  apply(induct rs1 rs2 arbitrary: rs rule: srewrites.induct)

   apply(auto)

  by (meson srewrite2(2) srewrites_trans)

lemma srewrites6:

  assumes "r1 \<leadsto>* r2" 

  shows "[r1] s\<leadsto>* [r2]"

  using assms

  apply(induct r1 r2 rule: rrewrites.induct)

   apply(auto)

  by (meson srewrites.simps srewrites_trans ss3)

lemma srewrites7:

  assumes "rs3 s\<leadsto>* rs4" "r1 \<leadsto>* r2" 

  shows "(r1 # rs3) s\<leadsto>* (r2 # rs4)"

  using assms

  by (smt (verit, best) append_Cons append_Nil srewrites1 srewrites3 srewrites6 srewrites_trans)

(*harmless sorry*)

lemma existing_preimage :

  shows "f a \<in> f ` set rs1 \<Longrightarrow> \<exists>rs1a rs1b x. rs1 = rs1a @ [x] @ rs1b \<and> f x = f a "

  apply(induct rs1)

   apply simp

  apply(case_tac "f a = f aa")

  sorry

lemma deletes_dB:

  shows " \<lbrakk>erase a \<in> erase ` set rs1\<rbrakk> \<Longrightarrow> (rs1 @ a # rs2) s\<leadsto>* (rs1 @ rs2)"

  apply(subgoal_tac "\<exists>rs1a rs1b x. rs1 = rs1a @ [x] @ rs1b \<and> erase x = erase a")

  prefer 2

   apply (meson existing_preimage)

  apply(erule exE)+

  apply simp

  apply(subgoal_tac "(rs1a @ [x] @ rs1b @ [a] @ rs2) s\<leadsto> (rs1a @ [x] @ rs1b @ rs2)")  

  apply (simp add: rs_in_rstar)

  apply(subgoal_tac "L (erase a) \<subseteq> L (erase x)")

  using ss6 apply presburger

  by simp

lemma ss6_realistic:

  shows "(rs1 @ rs2) s\<leadsto>* (rs1 @ dB6 rs2 (tset rs1))"

  apply(induct rs2 arbitrary: rs1)

   apply simp

  apply(rename_tac cc' cc)

  apply(subgoal_tac "(cc @ a # cc') s\<leadsto>* (cc @ a # dB6 cc' (tset (cc @ [a])))")

   prefer 2

  apply (metis append.assoc append.left_neutral append_Cons)

  apply(subgoal_tac "(cc @ a # dB6 cc' (tset (cc @ [a]))) s\<leadsto>* (cc @ (p6 cc a) # dB6 cc' (tset (cc @ [a])))") 

  sorry

lemma ss6_stronger:

  shows "rs1 s\<leadsto>* dB6 rs1 {}"

  using ss6

  by (metis append_Nil concat.simps(1) list.set(1) list.simps(8) ss6_realistic tset.simps)

lemma tint_fuse:

  shows "tint (erase a) = tint (erase (fuse bs a))"

  by (simp add: erase_fuse)

lemma tint_fuse2:

  shows " set (tint (erase a)) =

     set (tint (erase (fuse bs a)))"

  using tint_fuse by auto

lemma fused_bits_at_head:

  shows "fuse bs a = ASEQ bs1 a1 a2 \<Longrightarrow> \<exists>bs2. bs1 = bs @ bs2"

(* by (smt (verit) arexp.distinct(13) arexp.distinct(19) arexp.distinct(25) arexp.distinct(27) arexp.distinct(5) arexp.inject(3) fuse.elims)

harmless sorry

*)

  sorry

thm seqFold.simps

lemma seqFold_concats:

  shows "r \<noteq> ONE \<Longrightarrow> seqFold r [r1] = SEQ r r1"

  apply(case_tac r)

       apply simp+

done

lemma tint_seqFold_eq: shows

"set (tint (seqFold (erase x42) [erase x43])) = 

           set (tint (SEQ (erase x42) (erase x43)))"

  apply(case_tac "erase x42 = ONE")

   apply simp

  using seqFold_concats

  apply simp

  done

fun top :: "arexp \<Rightarrow> bit list" where

  "top AZERO = []"

| "top (AONE bs) = bs"

| "top (ASEQ bs r1 r2) = bs"

| "top (ACHAR v va) = v"

| "top (AALTs v va) = v"

| "top (ASTAR v va) = v "

lemma p6fa_aux:

  shows " fuse bs

            (bsimp_AALTs bs\<^sub>0 as) = 

            (bsimp_AALTs (bs @ bs\<^sub>0) as)"

  by (metis bsimp_AALTs.simps(1) bsimp_AALTs.simps(2) bsimp_AALTs.simps(3) fuse.simps(1) fuse.simps(4) fuse_append neq_Nil_conv)

lemma p6pfuse_alts:

  shows 

" \<And>bs\<^sub>0 as\<^sub>0.     

       \<lbrakk>\<And>a bs. set (tint (erase a)) = set (tint (erase (fuse bs a))); a = AALTs bs\<^sub>0 as\<^sub>0\<rbrakk>

       \<Longrightarrow> \<not> set (tint (erase a)) \<subseteq> (\<Union>x\<in>set as. set (tint (erase x))) \<longrightarrow>

           fuse bs

            (case a of AZERO \<Rightarrow> AZERO | AONE x \<Rightarrow> AONE x | ACHAR x xa \<Rightarrow> ACHAR x xa

             | ASEQ bs r1 r2 \<Rightarrow> bsimp_ASEQ bs (prune6 (\<Union>x\<in>set as. set (tint (erase x))) r1 [erase r2]) r2

             | AALTs bs rs0 \<Rightarrow> bsimp_AALTs bs (filter notZero (map (\<lambda>r. prune6 (\<Union>x\<in>set as. set (tint (erase x))) r []) rs0)) | ASTAR x xa \<Rightarrow> ASTAR x xa) 

              =

           (case fuse bs a of AZERO \<Rightarrow> AZERO | AONE x \<Rightarrow> AONE x | ACHAR x xa \<Rightarrow> ACHAR x xa

            | ASEQ bs r1 r2 \<Rightarrow> bsimp_ASEQ bs (prune6 (\<Union>x\<in>set as. set (tint (erase x))) r1 [erase r2]) r2

            | AALTs bs rs0 \<Rightarrow> bsimp_AALTs bs (filter notZero (map (\<lambda>r. prune6 (\<Union>x\<in>set as. set (tint (erase x))) r []) rs0)) | ASTAR x xa \<Rightarrow> ASTAR x xa)"

  apply simp

  using p6fa_aux by presburger

lemma prune6_preserves_fuse:

  shows "fuse bs (p6 as a) = p6 as (fuse bs a)"

  using tint_fuse2

  apply simp

  apply(case_tac a)

       apply simp

  apply simp

     apply simp

  using fused_bits_at_head

    apply simp

  using tint_seqFold_eq

  apply simp

    apply (smt (z3) bsimp_ASEQ.simps(1) bsimp_ASEQ0 bsimp_ASEQ1 bsimp_ASEQ2 fuse.simps(1) fuse.simps(5) fuse_append)

  using p6pfuse_alts apply presburger

  by simp

(*

The top-level bitlist stays the same:

\<^sub>b\<^sub>sa ------pruning----->  \<^sub>b\<^sub>s\<^sub>' b  \<Longrightarrow>        \<exists>bs3. bs' = bs @ bs3 

*)

lemma top_bitcodes_preserved_p6:

  shows "top r = bs \<Longrightarrow> p6 as r = AZERO \<or> (\<exists>bs3. top (p6 as r) = bs @ bs3)"

  apply(induct r arbitrary: as)

(*this sorry requires more care *)

  sorry

corollary prune6_preserves_fuse_srewrite:

  shows "(as @ map (fuse bs) [a] @ as2) s\<leadsto>* (as @ map (fuse bs) [p6 as a] @ as2)"

  apply(subgoal_tac "map (fuse bs) [a] = [fuse bs a]")

  apply(subgoal_tac "(as @ [fuse bs a] @ as2) s\<leadsto>* (as @ [ (p6 as (fuse bs a))] @ as2)")

  using prune6_preserves_fuse apply auto[1]

  using rs_in_rstar ss7 apply presburger

  by simp

lemma prune6_invariant_fuse:

  shows "p6 as a = p6 (map (fuse bs) as) a"

  apply simp

  using erase_fuse by presburger

lemma p6pfs_cor:

  shows "(map (fuse bs) as @ map (fuse bs) [a] @ map (fuse bs) as1) s\<leadsto>* (map (fuse bs) as @ map (fuse bs) [p6 as a] @ map (fuse bs) as1)"

  by (metis prune6_invariant_fuse prune6_preserves_fuse_srewrite)

lemma rewrite_preserves_fuse: 

  shows "r2 \<leadsto> r3 \<Longrightarrow> fuse bs r2 \<leadsto> fuse bs r3"

  and   "rs2 s\<leadsto> rs3 \<Longrightarrow> map (fuse bs) rs2 s\<leadsto>* map (fuse bs) rs3"

proof(induct rule: rrewrite_srewrite.inducts)

  case (bs3 bs1 bs2 r)

  then show ?case

    by (metis fuse.simps(5) fuse_append rrewrite_srewrite.bs3) 

next

  case (bs7 bs r)

  then show ?case

    by (metis fuse.simps(4) fuse_append rrewrite_srewrite.bs7) 

next

  case (ss2 rs1 rs2 r)

  then show ?case

    using srewrites7 by force 

next

  case (ss3 r1 r2 rs)

  then show ?case by (simp add: r_in_rstar srewrites7)

next

  case (ss5 bs1 rs1 rsb)

  then show ?case 

    apply(simp)

    by (metis (mono_tags, lifting) comp_def fuse_append map_eq_conv rrewrite_srewrite.ss5 srewrites.simps)

next

  case (ss6 a1 a2 rsa rsb rsc)

  then show ?case 

    apply(simp only: map_append)

    by (smt (verit, best) erase_fuse list.simps(8) list.simps(9) rrewrite_srewrite.ss6 srewrites.simps)

next

  case (ss7 as a as1)

  then show ?case

    apply(simp only: map_append)

    using p6pfs_cor by presburger

qed (auto intro: rrewrite_srewrite.intros)

lemma rewrites_fuse:  

  assumes "r1 \<leadsto>* r2"

  shows "fuse bs r1 \<leadsto>* fuse bs r2"

using assms

apply(induction r1 r2 arbitrary: bs rule: rrewrites.induct)

apply(auto intro: rewrite_preserves_fuse rrewrites_trans)

done

lemma star_seq:  

  assumes "r1 \<leadsto>* r2"

  shows "ASEQ bs r1 r3 \<leadsto>* ASEQ bs r2 r3"

using assms

apply(induct r1 r2 arbitrary: r3 rule: rrewrites.induct)

apply(auto intro: rrewrite_srewrite.intros)

done

lemma star_seq2:  

  assumes "r3 \<leadsto>* r4"

  shows "ASEQ bs r1 r3 \<leadsto>* ASEQ bs r1 r4"

  using assms

apply(induct r3 r4 arbitrary: r1 rule: rrewrites.induct)

apply(auto intro: rrewrite_srewrite.intros)

done

lemma continuous_rewrite: 

  assumes "r1 \<leadsto>* AZERO"