(* Title: HOL/Bali/Value.thy
Author: David von Oheimb
*)
header {* Java values *}
theory Value imports Type begin
typedecl loc --{* locations, i.e. abstract references on objects *}
datatype val
= Unit --{* dummy result value of void methods *}
| Bool bool --{* Boolean value *}
| Intg int --{* integer value *}
| Null --{* null reference *}
| Addr loc --{* addresses, i.e. locations of objects *}
consts the_Bool :: "val \<Rightarrow> bool"
primrec "the_Bool (Bool b) = b"
consts the_Intg :: "val \<Rightarrow> int"
primrec "the_Intg (Intg i) = i"
consts the_Addr :: "val \<Rightarrow> loc"
primrec "the_Addr (Addr a) = a"
types dyn_ty = "loc \<Rightarrow> ty option"
consts
typeof :: "dyn_ty \<Rightarrow> val \<Rightarrow> ty option"
defpval :: "prim_ty \<Rightarrow> val" --{* default value for primitive types *}
default_val :: " ty \<Rightarrow> val" --{* default value for all types *}
primrec "typeof dt Unit = Some (PrimT Void)"
"typeof dt (Bool b) = Some (PrimT Boolean)"
"typeof dt (Intg i) = Some (PrimT Integer)"
"typeof dt Null = Some NT"
"typeof dt (Addr a) = dt a"
primrec "defpval Void = Unit"
"defpval Boolean = Bool False"
"defpval Integer = Intg 0"
primrec "default_val (PrimT pt) = defpval pt"
"default_val (RefT r ) = Null"
end