header "Operational Evaluation Semantics"
theory OpSem imports State begin
inductive
exec :: "[state,stmt, nat,state] => bool" ("_ -_-_-> _" [98,90, 65,98] 89)
and eval :: "[state,expr,val,nat,state] => bool" ("_ -_\<succ>_-_-> _"[98,95,99,65,98] 89)
where
Skip: " s -Skip-n-> s"
| Comp: "[| s0 -c1-n-> s1; s1 -c2-n-> s2 |] ==>
s0 -c1;; c2-n-> s2"
| Cond: "[| s0 -e\<succ>v-n-> s1; s1 -(if v≠Null then c1 else c2)-n-> s2 |] ==>
s0 -If(e) c1 Else c2-n-> s2"
| LoopF:" s0<x> = Null ==>
s0 -While(x) c-n-> s0"
| LoopT:"[| s0<x> ≠ Null; s0 -c-n-> s1; s1 -While(x) c-n-> s2 |] ==>
s0 -While(x) c-n-> s2"
| LAcc: " s -LAcc x\<succ>s<x>-n-> s"
| LAss: " s -e\<succ>v-n-> s' ==>
s -x:==e-n-> lupd(x\<mapsto>v) s'"
| FAcc: " s -e\<succ>Addr a-n-> s' ==>
s -e..f\<succ>get_field s' a f-n-> s'"
| FAss: "[| s0 -e1\<succ>Addr a-n-> s1; s1 -e2\<succ>v-n-> s2 |] ==>
s0 -e1..f:==e2-n-> upd_obj a f v s2"
| NewC: " new_Addr s = Addr a ==>
s -new C\<succ>Addr a-n-> new_obj a C s"
| Cast: "[| s -e\<succ>v-n-> s';
case v of Null => True | Addr a => obj_class s' a \<preceq>C C |] ==>
s -Cast C e\<succ>v-n-> s'"
| Call: "[| s0 -e1\<succ>a-n-> s1; s1 -e2\<succ>p-n-> s2;
lupd(This\<mapsto>a)(lupd(Par\<mapsto>p)(del_locs s2)) -Meth (C,m)-n-> s3
|] ==> s0 -{C}e1..m(e2)\<succ>s3<Res>-n-> set_locs s2 s3"
| Meth: "[| s<This> = Addr a; D = obj_class s a; D\<preceq>C C;
init_locs D m s -Impl (D,m)-n-> s' |] ==>
s -Meth (C,m)-n-> s'"
| Impl: " s -body Cm- n-> s' ==>
s -Impl Cm-Suc n-> s'"
inductive_cases exec_elim_cases':
"s -Skip -n-> t"
"s -c1;; c2 -n-> t"
"s -If(e) c1 Else c2-n-> t"
"s -While(x) c -n-> t"
"s -x:==e -n-> t"
"s -e1..f:==e2 -n-> t"
inductive_cases Meth_elim_cases: "s -Meth Cm -n-> t"
inductive_cases Impl_elim_cases: "s -Impl Cm -n-> t"
lemmas exec_elim_cases = exec_elim_cases' Meth_elim_cases Impl_elim_cases
inductive_cases eval_elim_cases:
"s -new C \<succ>v-n-> t"
"s -Cast C e \<succ>v-n-> t"
"s -LAcc x \<succ>v-n-> t"
"s -e..f \<succ>v-n-> t"
"s -{C}e1..m(e2) \<succ>v-n-> t"
lemma exec_eval_mono [rule_format]:
"(s -c -n-> t --> (∀m. n ≤ m --> s -c -m-> t)) ∧
(s -e\<succ>v-n-> t --> (∀m. n ≤ m --> s -e\<succ>v-m-> t))"
apply (rule exec_eval.induct)
prefer 14
apply clarify
apply (rename_tac n)
apply (case_tac n)
apply (blast intro:exec_eval.intros)+
done
lemmas exec_mono = exec_eval_mono [THEN conjunct1, rule_format]
lemmas eval_mono = exec_eval_mono [THEN conjunct2, rule_format]
lemma exec_exec_max: "[|s1 -c1- n1 -> t1 ; s2 -c2- n2-> t2|] ==>
s1 -c1-max n1 n2-> t1 ∧ s2 -c2-max n1 n2-> t2"
by (fast intro: exec_mono le_maxI1 le_maxI2)
lemma eval_exec_max: "[|s1 -c- n1 -> t1 ; s2 -e\<succ>v- n2-> t2|] ==>
s1 -c-max n1 n2-> t1 ∧ s2 -e\<succ>v-max n1 n2-> t2"
by (fast intro: eval_mono exec_mono le_maxI1 le_maxI2)
lemma eval_eval_max: "[|s1 -e1\<succ>v1- n1 -> t1 ; s2 -e2\<succ>v2- n2-> t2|] ==>
s1 -e1\<succ>v1-max n1 n2-> t1 ∧ s2 -e2\<succ>v2-max n1 n2-> t2"
by (fast intro: eval_mono le_maxI1 le_maxI2)
lemma eval_eval_exec_max:
"[|s1 -e1\<succ>v1-n1-> t1; s2 -e2\<succ>v2-n2-> t2; s3 -c-n3-> t3|] ==>
s1 -e1\<succ>v1-max (max n1 n2) n3-> t1 ∧
s2 -e2\<succ>v2-max (max n1 n2) n3-> t2 ∧
s3 -c -max (max n1 n2) n3-> t3"
apply (drule (1) eval_eval_max, erule thin_rl)
by (fast intro: exec_mono eval_mono le_maxI1 le_maxI2)
lemma Impl_body_eq: "(λt. ∃n. Z -Impl M-n-> t) = (λt. ∃n. Z -body M-n-> t)"
apply (rule ext)
apply (fast elim: exec_elim_cases intro: exec_eval.Impl)
done
end