(*  Title:      HOL/MicroJava/BV/Effect.thy
    Author:     Gerwin Klein
    Copyright   2000 Technische Universitaet Muenchen
*)

section ‹Effect of Instructions on the State Type›

theory Effect
imports JVM_SemiType "../JVM/JVMExceptions"
begin

― ‹FIXME›
locale prog =
  fixes P :: "'a prog"

locale jvm_method = prog +
  fixes mxs :: nat  
  fixes mxl₀ :: nat   
  fixes Ts :: "ty list" 
  fixes T_r :: ty
  fixes "is" :: "instr list" 
  fixes xt :: ex_table

  fixes mxl :: nat
  defines mxl_def: "mxl ≡ 1+size Ts+mxl₀"

text ‹Program counter of successor instructions:›
primrec succs :: "instr → ty_i → pc → pc list" where
  "succs (Load idx) τ pc = [pc+1]"
| "succs (Store idx) τ pc = [pc+1]"
| "succs (Push v) τ pc = [pc+1]"
| "succs (Getfield F C) τ pc = [pc+1]"
| "succs (Putfield F C) τ pc = [pc+1]"
| "succs (New C) τ pc = [pc+1]"
| "succs (Checkcast C) τ pc = [pc+1]"
| "succs Pop τ pc = [pc+1]"
| "succs IAdd τ pc = [pc+1]"
| "succs CmpEq τ pc = [pc+1]"
| succs_IfFalse:
    "succs (IfFalse b) τ pc = [pc+1, nat (int pc + b)]"
| succs_Goto:
    "succs (Goto b) τ pc = [nat (int pc + b)]"
| succs_Return:
    "succs Return τ pc = []"  
| succs_Invoke:
    "succs (Invoke M n) τ pc = (if (fst τ)!n = NT then [] else [pc+1])"
| succs_Throw:
    "succs Throw τ pc = []"

text "Effect of instruction on the state type:"

fun the_class:: "ty → cname" where
  "the_class (Class C) = C"

fun eff_i :: "instr × 'm prog × ty_i → ty_i" where
  eff_{i_Load}:
    "eff_i (Load n, P, (ST, LT)) = (ok_val (LT ! n) # ST, LT)"
| eff_{i_Store}:
    "eff_i (Store n, P, (T#ST, LT)) = (ST, LT[n:= OK T])"
| eff_{i_Push}:
    "eff_i (Push v, P, (ST, LT)) = (the (typeof v) # ST, LT)"
| eff_{i_Getfield}:
    "eff_i (Getfield F C, P, (T#ST, LT)) = (snd (field P C F) # ST, LT)"
| eff_{i_Putfield}:
   "eff_i (Putfield F C, P, (T₁#T₂#ST, LT)) = (ST,LT)"
| eff_{i_New}:
   "eff_i (New C, P, (ST,LT)) = (Class C # ST, LT)"
| eff_{i_Checkcast}:
   "eff_i (Checkcast C, P, (T#ST,LT)) = (Class C # ST,LT)"
| eff_{i_Pop}:
   "eff_i (Pop, P, (T#ST,LT)) = (ST,LT)"
| eff_{i_IAdd}:
   "eff_i (IAdd, P,(T₁#T₂#ST,LT)) = (Integer#ST,LT)"
| eff_{i_CmpEq}:
   "eff_i (CmpEq, P, (T₁#T₂#ST,LT)) = (Boolean#ST,LT)"
| eff_{i_IfFalse}:
   "eff_i (IfFalse b, P, (T₁#ST,LT)) = (ST,LT)"
| eff_{i_Invoke}:
   "eff_i (Invoke M n, P, (ST,LT)) =
    (let C = the_class (ST!n); (D,Ts,T_r,b) = method P C M
     in (T_r # drop (n+1) ST, LT))"
| eff_{i_Goto}:
   "eff_i (Goto n, P, s) = s"

fun is_relevant_class :: "instr → 'm prog → cname → bool" where
  rel_Getfield:
    "is_relevant_class (Getfield F D) = (λP C. P ⊨ NullPointer ⪯^* C)" 
| rel_Putfield:
    "is_relevant_class (Putfield F D) = (λP C. P ⊨ NullPointer ⪯^* C)" 
| rel_Checcast:
    "is_relevant_class (Checkcast D) = (λP C. P ⊨ ClassCast ⪯^* C)" 
| rel_New:
    "is_relevant_class (New D) = (λP C. P ⊨ OutOfMemory ⪯^* C)" 
| rel_Throw:
    "is_relevant_class Throw = (λP C. True)"
| rel_Invoke:
    "is_relevant_class (Invoke M n) = (λP C. True)"
| rel_default:
    "is_relevant_class i = (λP C. False)"

definition is_relevant_entry :: "'m prog → instr → pc → ex_entry → bool" where
  "is_relevant_entry P i pc e ⟷ (let (f,t,C,h,d) = e in is_relevant_class i P C ∧ pc ∈ {f..<t})"

definition relevant_entries :: "'m prog → instr → pc → ex_table → ex_table" where
  "relevant_entries P i pc = filter (is_relevant_entry P i pc)"

definition xcpt_eff :: "instr → 'm prog → pc → ty_i
               → ex_table → (pc × ty_i') list" where    
  "xcpt_eff i P pc τ et = (let (ST,LT) = τ in
  map (λ(f,t,C,h,d). (h, Some (Class C#drop (size ST - d) ST, LT))) (relevant_entries P i pc et))"

definition norm_eff :: "instr → 'm prog → nat → ty_i → (pc × ty_i') list" where
  "norm_eff i P pc τ = map (λpc'. (pc',Some (eff_i (i,P,τ)))) (succs i τ pc)"

definition eff :: "instr → 'm prog → pc → ex_table → ty_i' → (pc × ty_i') list" where
  "eff i P pc et t = (case t of
    None → []
  | Some τ → (norm_eff i P pc τ) @ (xcpt_eff i P pc τ et))"


lemma eff_None:
  "eff i P pc xt None = []"
by (simp add: eff_def)

lemma eff_Some:
  "eff i P pc xt (Some τ) = norm_eff i P pc τ @ xcpt_eff i P pc τ xt"
by (simp add: eff_def)

(* FIXME: getfield, \<exists>T D. P \<turnstile> C sees F:T in D \<and> .. *)

text "Conditions under which eff is applicable:"

fun app_i :: "instr × 'm prog × pc × nat × ty × ty_i → bool" where
  app_{i_Load}:
    "app_i (Load n, P, pc, mxs, T_r, (ST,LT)) =
    (n < length LT ∧ LT ! n ≠ Err ∧ length ST < mxs)"
| app_{i_Store}:
    "app_i (Store n, P, pc, mxs, T_r, (T#ST, LT)) =
    (n < length LT)"
| app_{i_Push}:
    "app_i (Push v, P, pc, mxs, T_r, (ST,LT)) =
     (length ST < mxs ∧ typeof v ≠ None)"
| app_{i_Getfield}:
    "app_i (Getfield F C, P, pc, mxs, T_r, (T#ST, LT)) =
    (∃T_f. P ⊨ C sees F:T_f in C ∧ P ⊨ T ≤ Class C)"
| app_{i_Putfield}:
    "app_i (Putfield F C, P, pc, mxs, T_r, (T₁#T₂#ST, LT)) =
    (∃T_f. P ⊨ C sees F:T_f in C ∧ P ⊨ T₂ ≤ (Class C) ∧ P ⊨ T₁ ≤ T_f)" 
| app_{i_New}:
    "app_i (New C, P, pc, mxs, T_r, (ST,LT)) =
    (is_class P C ∧ length ST < mxs)"
| app_{i_Checkcast}:
    "app_i (Checkcast C, P, pc, mxs, T_r, (T#ST,LT)) =
    (is_class P C ∧ is_refT T)"
| app_{i_Pop}:
    "app_i (Pop, P, pc, mxs, T_r, (T#ST,LT)) =
    True"
| app_{i_IAdd}:
    "app_i (IAdd, P, pc, mxs, T_r, (T₁#T₂#ST,LT)) = (T₁ = T₂ ∧ T₁ = Integer)"
| app_{i_CmpEq}:
    "app_i (CmpEq, P, pc, mxs, T_r, (T₁#T₂#ST,LT)) =
    (T₁ = T₂ ∨ is_refT T₁ ∧ is_refT T₂)"
| app_{i_IfFalse}:
    "app_i (IfFalse b, P, pc, mxs, T_r, (Boolean#ST,LT)) =
    (0 ≤ int pc + b)"
| app_{i_Goto}:
    "app_i (Goto b, P, pc, mxs, T_r, s) =
    (0 ≤ int pc + b)"
| app_{i_Return}:
    "app_i (Return, P, pc, mxs, T_r, (T#ST,LT)) =
    (P ⊨ T ≤ T_r)"
| app_{i_Throw}:
    "app_i (Throw, P, pc, mxs, T_r, (T#ST,LT)) =
    is_refT T"
| app_{i_Invoke}:
    "app_i (Invoke M n, P, pc, mxs, T_r, (ST,LT)) =
    (n < length ST ∧
    (ST!n ≠ NT ⟶
      (∃C D Ts T m. ST!n = Class C ∧ P ⊨ C sees M:Ts → T = m in D ∧
                    P ⊨ rev (take n ST) [≤] Ts)))"
  
| app_{i_default}:
    "app_i (i,P, pc,mxs,T_r,s) = False"


definition xcpt_app :: "instr → 'm prog → pc → nat → ex_table → ty_i → bool" where
  "xcpt_app i P pc mxs xt τ ⟷ (∀(f,t,C,h,d) ∈ set (relevant_entries P i pc xt). is_class P C ∧ d ≤ size (fst τ) ∧ d < mxs)"

definition app :: "instr → 'm prog → nat → ty → nat → nat → ex_table → ty_i' → bool" where
  "app i P mxs T_r pc mpc xt t = (case t of None → True | Some τ →
  app_i (i,P,pc,mxs,T_r,τ) ∧ xcpt_app i P pc mxs xt τ ∧
  (∀(pc',τ') ∈ set (eff i P pc xt t). pc' < mpc))"


lemma app_Some:
  "app i P mxs T_r pc mpc xt (Some τ) =
  (app_i (i,P,pc,mxs,T_r,τ) ∧ xcpt_app i P pc mxs xt τ ∧
  (∀(pc',s') ∈ set (eff i P pc xt (Some τ)). pc' < mpc))"
by (simp add: app_def)

locale eff = jvm_method +
  fixes eff_i and app_i and eff and app 
  fixes norm_eff and xcpt_app and xcpt_eff

  fixes mpc
  defines "mpc ≡ size is"

  defines "eff_i i τ ≡ Effect.eff_i (i,P,τ)"
  notes eff_{i_simps} [simp] = Effect.eff_i.simps [where P = P, folded eff_{i_def}]

  defines "app_i i pc τ ≡ Effect.app_i (i, P, pc, mxs, T_r, τ)"
  notes app_{i_simps} [simp] = Effect.app_i.simps [where P=P and mxs=mxs and T_r=T_r, folded app_{i_def}]

  defines "xcpt_eff i pc τ ≡ Effect.xcpt_eff i P pc τ xt"
  notes xcpt_eff = Effect.xcpt_eff_def [of _ P _ _ xt, folded xcpt_eff_def]

  defines "norm_eff i pc τ ≡ Effect.norm_eff i P pc τ"
  notes norm_eff = Effect.norm_eff_def [of _ P, folded norm_eff_def eff_{i_def}]

  defines "eff i pc ≡ Effect.eff i P pc xt"
  notes eff = Effect.eff_def [of _ P  _ xt, folded eff_def norm_eff_def xcpt_eff_def]

  defines "xcpt_app i pc τ ≡ Effect.xcpt_app i P pc mxs xt τ"
  notes xcpt_app = Effect.xcpt_app_def [of _ P _ mxs xt, folded xcpt_app_def]

  defines "app i pc ≡ Effect.app i P mxs T_r pc mpc xt"
  notes app = Effect.app_def [of _ P mxs T_r _ mpc xt, folded app_def xcpt_app_def app_{i_def} eff_def]


lemma length_cases2:
  assumes "∧LT. P ([],LT)"
  assumes "∧l ST LT. P (l#ST,LT)"
  shows "P s"
  by (cases s, cases "fst s") (auto intro!: assms)


lemma length_cases3:
  assumes "∧LT. P ([],LT)"
  assumes "∧l LT. P ([l],LT)"
  assumes "∧l ST LT. P (l#ST,LT)"
  shows "P s"
(*<*)
proof -
  obtain xs LT where s: "s = (xs,LT)" by (cases s)
  show ?thesis
  proof (cases xs)
    case Nil with assms s show ?thesis by simp
  next
    fix l xs' assume "xs = l#xs'"
    with assms s show ?thesis by simp
  qed
qed
(*>*)

lemma length_cases4:
  assumes "∧LT. P ([],LT)"
  assumes "∧l LT. P ([l],LT)"
  assumes "∧l l' LT. P ([l,l'],LT)"
  assumes "∧l l' ST LT. P (l#l'#ST,LT)"
  shows "P s"
(*<*)
proof -
  obtain xs LT where s: "s = (xs,LT)" by (cases s)
  show ?thesis
  proof (cases xs)
    case Nil with assms s show ?thesis by simp
  next
    fix l xs' assume xs: "xs = l#xs'"
    thus ?thesis
    proof (cases xs')
      case Nil with assms s xs show ?thesis by simp
    next
      fix l' ST assume "xs' = l'#ST"
     with assms s xs show ?thesis by simp
    qed
  qed
qed
(*>*)

text ‹
 medskip
  rules for @{term app}
 ›
lemma appNone[simp]: "app i P mxs T_r pc mpc et None = True" 
  by (simp add: app_def)


lemma appLoad[simp]:
"app_i (Load idx, P, T_r, mxs, pc, s) = (∃ST LT. s = (ST,LT) ∧ idx < length LT ∧ LT!idx ≠ Err ∧ length ST < mxs)"
  by (cases s, simp)

lemma appStore[simp]:
"app_i (Store idx,P,pc,mxs,T_r,s) = (∃ts ST LT. s = (ts#ST,LT) ∧ idx < length LT)"
  by (rule length_cases2, auto)

lemma appPush[simp]:
"app_i (Push v,P,pc,mxs,T_r,s) =
 (∃ST LT. s = (ST,LT) ∧ length ST < mxs ∧ typeof v ≠ None)"
  by (cases s, simp)

lemma appGetField[simp]:
"app_i (Getfield F C,P,pc,mxs,T_r,s) =
 (∃ oT vT ST LT. s = (oT#ST, LT) ∧
  P ⊨ C sees F:vT in C ∧ P ⊨ oT ≤ (Class C))"
  by (rule length_cases2 [of _ s]) auto

lemma appPutField[simp]:
"app_i (Putfield F C,P,pc,mxs,T_r,s) =
 (∃ vT vT' oT ST LT. s = (vT#oT#ST, LT) ∧
  P ⊨ C sees F:vT' in C ∧ P ⊨ oT ≤ (Class C) ∧ P ⊨ vT ≤ vT')"
  by (rule length_cases4 [of _ s], auto)

lemma appNew[simp]:
  "app_i (New C,P,pc,mxs,T_r,s) =
  (∃ST LT. s=(ST,LT) ∧ is_class P C ∧ length ST < mxs)"
  by (cases s, simp)

lemma appCheckcast[simp]: 
  "app_i (Checkcast C,P,pc,mxs,T_r,s) =
  (∃T ST LT. s = (T#ST,LT) ∧ is_class P C ∧ is_refT T)"
  by (cases s, cases "fst s", simp add: app_def) (cases "hd (fst s)", auto)

lemma app_iPop[simp]: 
"app_i (Pop,P,pc,mxs,T_r,s) = (∃ts ST LT. s = (ts#ST,LT))"
  by (rule length_cases2, auto)

lemma appIAdd[simp]:
"app_i (IAdd,P,pc,mxs,T_r,s) = (∃ST LT. s = (Integer#Integer#ST,LT))"
(*<*)
proof -
  obtain ST LT where [simp]: "s = (ST,LT)" by (cases s)
  have "ST = [] ∨ (∃T. ST = [T]) ∨ (∃T₁ T₂ ST'. ST = T₁#T₂#ST')"
    by (cases ST, auto, case_tac list, auto)
  moreover
  { assume "ST = []" hence ?thesis by simp }
  moreover
  { fix T assume "ST = [T]" hence ?thesis by (cases T, auto) }
  moreover
  { fix T₁ T₂ ST' assume "ST = T₁#T₂#ST'"
    hence ?thesis by (cases T₁, auto)
  }
  ultimately show ?thesis by blast
qed
(*>*)


lemma appIfFalse [simp]:
"app_i (IfFalse b,P,pc,mxs,T_r,s) =
  (∃ST LT. s = (Boolean#ST,LT) ∧ 0 ≤ int pc + b)"
(*<*)
 (is "?P s")
proof(rule length_cases2)
  fix LT show "?P ([],LT)" by simp
next
  fix l ST LT show "?P (l#ST,LT)"
    by (case_tac l) auto
qed
(*>*)

lemma appCmpEq[simp]:
"app_i (CmpEq,P,pc,mxs,T_r,s) =
  (∃T₁ T₂ ST LT. s = (T₁#T₂#ST,LT) ∧ (¬is_refT T₁ ∧ T₂ = T₁ ∨ is_refT T₁ ∧ is_refT T₂))"
  by (rule length_cases4, auto)

lemma appReturn[simp]:
"app_i (Return,P,pc,mxs,T_r,s) = (∃T ST LT. s = (T#ST,LT) ∧ P ⊨ T ≤ T_r)" 
  by (rule length_cases2, auto)

lemma appThrow[simp]:
  "app_i (Throw,P,pc,mxs,T_r,s) = (∃T ST LT. s=(T#ST,LT) ∧ is_refT T)"
  by (rule length_cases2, auto)  

lemma effNone: 
  "(pc', s') ∈ set (eff i P pc et None) ==> s' = None"
  by (auto simp add: eff_def xcpt_eff_def norm_eff_def)


text ‹some helpers to make the specification directly executable:›
lemma relevant_entries_append [simp]:
  "relevant_entries P i pc (xt @ xt') = relevant_entries P i pc xt @ relevant_entries P i pc xt'"
  by (unfold relevant_entries_def) simp

lemma xcpt_app_append [iff]:
  "xcpt_app i P pc mxs (xt@xt') τ = (xcpt_app i P pc mxs xt τ ∧ xcpt_app i P pc mxs xt' τ)"
  by (unfold xcpt_app_def) fastforce

lemma xcpt_eff_append [simp]:
  "xcpt_eff i P pc τ (xt@xt') = xcpt_eff i P pc τ xt @ xcpt_eff i P pc τ xt'"
 by (unfold xcpt_eff_def, cases τ) simp

lemma app_append [simp]:
  "app i P pc T mxs mpc (xt@xt') τ = (app i P pc T mxs mpc xt τ ∧ app i P pc T mxs mpc xt' τ)"
  by (unfold app_def eff_def) auto

end