Theory TypeInf

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theory TypeInf
imports WellType

(*  Title:      HOL/MicroJava/Comp/TypeInf.thy
Author: Martin Strecker
*)


(* Exact position in theory hierarchy still to be determined *)
theory TypeInf
imports "../J/WellType"
begin



(**********************************************************************)
;


(*** Inversion of typing rules -- to be moved into WellType.thy
Also modify the wtpd_expr_… proofs in CorrComp.thy ***)


lemma NewC_invers: "E\<turnstile>NewC C::T
==> T = Class C ∧ is_class (prg E) C"

by (erule ty_expr.cases, auto)

lemma Cast_invers: "E\<turnstile>Cast D e::T
==> ∃ C. T = Class D ∧ E\<turnstile>e::C ∧ is_class (prg E) D ∧ prg E\<turnstile>C\<preceq>? Class D"

by (erule ty_expr.cases, auto)

lemma Lit_invers: "E\<turnstile>Lit x::T
==> typeof (λv. None) x = Some T"

by (erule ty_expr.cases, auto)

lemma LAcc_invers: "E\<turnstile>LAcc v::T
==> localT E v = Some T ∧ is_type (prg E) T"

by (erule ty_expr.cases, auto)

lemma BinOp_invers: "E\<turnstile>BinOp bop e1 e2::T'
==> ∃ T. E\<turnstile>e1::T ∧ E\<turnstile>e2::T ∧
(if bop = Eq then T' = PrimT Boolean
else T' = T ∧ T = PrimT Integer)"

by (erule ty_expr.cases, auto)

lemma LAss_invers: "E\<turnstile>v::=e::T'
==> ∃ T. v ~= This ∧ E\<turnstile>LAcc v::T ∧ E\<turnstile>e::T' ∧ prg E\<turnstile>T'\<preceq>T"

by (erule ty_expr.cases, auto)

lemma FAcc_invers: "E\<turnstile>{fd}a..fn::fT
==> ∃ C. E\<turnstile>a::Class C ∧ field (prg E,C) fn = Some (fd,fT)"

by (erule ty_expr.cases, auto)

lemma FAss_invers: "E\<turnstile>{fd}a..fn:=v::T'
==> ∃ T. E\<turnstile>{fd}a..fn::T ∧ E\<turnstile>v ::T' ∧ prg E\<turnstile>T'\<preceq>T"

by (erule ty_expr.cases, auto)

lemma Call_invers: "E\<turnstile>{C}a..mn({pTs'}ps)::rT
==> ∃ pTs md.
E\<turnstile>a::Class C ∧ E\<turnstile>ps[::]pTs ∧ max_spec (prg E) C (mn, pTs) = {((md,rT),pTs')}"

by (erule ty_expr.cases, auto)


lemma Nil_invers: "E\<turnstile>[] [::] Ts ==> Ts = []"
by (erule ty_exprs.cases, auto)

lemma Cons_invers: "E\<turnstile>e#es[::]Ts ==>
∃ T Ts'. Ts = T#Ts' ∧ E \<turnstile>e::T ∧ E \<turnstile>es[::]Ts'"

by (erule ty_exprs.cases, auto)


lemma Expr_invers: "E\<turnstile>Expr e\<surd> ==> ∃ T. E\<turnstile>e::T"
by (erule wt_stmt.cases, auto)

lemma Comp_invers: "E\<turnstile>s1;; s2\<surd> ==> E\<turnstile>s1\<surd> ∧ E\<turnstile>s2\<surd>"
by (erule wt_stmt.cases, auto)

lemma Cond_invers: "E\<turnstile>If(e) s1 Else s2\<surd>
==> E\<turnstile>e::PrimT Boolean ∧ E\<turnstile>s1\<surd> ∧ E\<turnstile>s2\<surd>"

by (erule wt_stmt.cases, auto)

lemma Loop_invers: "E\<turnstile>While(e) s\<surd>
==> E\<turnstile>e::PrimT Boolean ∧ E\<turnstile>s\<surd>"

by (erule wt_stmt.cases, auto)


(**********************************************************************)


declare split_paired_All [simp del]
declare split_paired_Ex [simp del]

(* Uniqueness of types property *)

lemma uniqueness_of_types: "
(∀ (E::'a prog × (vname => ty option)) T1 T2.
E\<turnstile>e :: T1 --> E\<turnstile>e :: T2 --> T1 = T2) ∧
(∀ (E::'a prog × (vname => ty option)) Ts1 Ts2.
E\<turnstile>es [::] Ts1 --> E\<turnstile>es [::] Ts2 --> Ts1 = Ts2)"

apply (rule expr.induct)

(* NewC *)
apply (intro strip)
apply (erule ty_expr.cases) apply simp+
apply (erule ty_expr.cases) apply simp+

(* Cast *)
apply (intro strip)
apply (erule ty_expr.cases) apply simp+
apply (erule ty_expr.cases) apply simp+

(* Lit *)
apply (intro strip)
apply (erule ty_expr.cases) apply simp+
apply (erule ty_expr.cases) apply simp+

(* BinOp *)
apply (intro strip)
apply (case_tac binop)
(* Eq *)
apply (erule ty_expr.cases) apply simp+
apply (erule ty_expr.cases) apply simp+
(* Add *)
apply (erule ty_expr.cases) apply simp+
apply (erule ty_expr.cases) apply simp+

(* LAcc *)
apply (intro strip)
apply (erule ty_expr.cases) apply simp+
apply (erule ty_expr.cases) apply simp+

(* LAss *)
apply (intro strip)
apply (erule ty_expr.cases) apply simp+
apply (erule ty_expr.cases) apply simp+


(* FAcc *)
apply (intro strip)
apply (drule FAcc_invers)+ apply (erule exE)+
apply (subgoal_tac "C = Ca", simp) apply blast


(* FAss *)
apply (intro strip)
apply (drule FAss_invers)+ apply (erule exE)+ apply (erule conjE)+
apply (drule FAcc_invers)+ apply (erule exE)+ apply blast


(* Call *)
apply (intro strip)
apply (drule Call_invers)+ apply (erule exE)+ apply (erule conjE)+
apply (subgoal_tac "pTs = pTsa", simp) apply blast

(* expression lists *)
apply (intro strip)
apply (erule ty_exprs.cases)+ apply simp+

apply (intro strip)
apply (erule ty_exprs.cases, simp)
apply (erule ty_exprs.cases, simp)
apply (subgoal_tac "e = ea", simp) apply simp
done


lemma uniqueness_of_types_expr [rule_format (no_asm)]: "
(∀ E T1 T2. E\<turnstile>e :: T1 --> E\<turnstile>e :: T2 --> T1 = T2)"

by (rule uniqueness_of_types [THEN conjunct1])

lemma uniqueness_of_types_exprs [rule_format (no_asm)]: "
(∀ E Ts1 Ts2. E\<turnstile>es [::] Ts1 --> E\<turnstile>es [::] Ts2 --> Ts1 = Ts2)"

by (rule uniqueness_of_types [THEN conjunct2])




definition inferred_tp :: "[java_mb env, expr] => ty" where
"inferred_tp E e == (SOME T. E\<turnstile>e :: T)"


definition inferred_tps :: "[java_mb env, expr list] => ty list" where
"inferred_tps E es == (SOME Ts. E\<turnstile>es [::] Ts)"


(* get inferred type(s) for well-typed term *)
lemma inferred_tp_wt: "E\<turnstile>e :: T ==> (inferred_tp E e) = T"
by (auto simp: inferred_tp_def intro: uniqueness_of_types_expr)

lemma inferred_tps_wt: "E\<turnstile>es [::] Ts ==> (inferred_tps E es) = Ts"
by (auto simp: inferred_tps_def intro: uniqueness_of_types_exprs)


end