Theory Value

theory Value
imports Type
(*  Title:      HOL/MicroJava/J/Value.thy
Author: David von Oheimb, Technische Universitaet Muenchen
*)


header {* \isaheader{Java Values} *}

theory Value imports Type begin

typedecl loc' -- "locations, i.e. abstract references on objects"

datatype loc
= XcptRef xcpt -- "special locations for pre-allocated system exceptions"
| Loc loc' -- "usual locations (references on objects)"

datatype val
= Unit -- "dummy result value of void methods"
| Null -- "null reference"
| Bool bool -- "Boolean value"
| Intg int -- "integer value, name Intg instead of Int because
of clash with HOL/Set.thy"

| Addr loc -- "addresses, i.e. locations of objects "

primrec the_Bool :: "val => bool" where
"the_Bool (Bool b) = b"

primrec the_Intg :: "val => int" where
"the_Intg (Intg i) = i"

primrec the_Addr :: "val => loc" where
"the_Addr (Addr a) = a"

primrec defpval :: "prim_ty => val" -- "default value for primitive types" where
"defpval Void = Unit"
| "defpval Boolean = Bool False"
| "defpval Integer = Intg 0"

primrec default_val :: "ty => val" -- "default value for all types" where
"default_val (PrimT pt) = defpval pt"
| "default_val (RefT r ) = Null"

end