(* Title: HOL/Spec_Check/property.ML
Author: Lukas Bulwahn and Nicolai Schaffroth, TU Muenchen
Author: Christopher League
Conditional properties that can track argument distribution.
*)
signature PROPERTY =
sig
type 'a pred = 'a -> bool
type 'a prop
val pred : 'a pred -> 'a prop
val pred2 : ('a * 'b) pred -> 'b -> 'a prop
val implies : 'a pred * 'a prop -> 'a prop
val ==> : 'a pred * 'a pred -> 'a prop
val trivial : 'a pred -> 'a prop -> 'a prop
val classify : 'a pred -> string -> 'a prop -> 'a prop
val classify' : ('a -> string option) -> 'a prop -> 'a prop
(*Results*)
type result = bool option
type stats = { tags : (string * int) list, count : int }
val test : 'a prop -> 'a * stats -> result * stats
val stats : stats
val success : result pred
val failure : result pred
end
structure Property : PROPERTY =
struct
type result = bool option
type stats = { tags : (string * int) list, count : int }
type 'a pred = 'a -> bool
type 'a prop = 'a * stats -> result * stats
fun success (SOME true) = true
| success _ = false
fun failure (SOME false) = true
| failure _ = false
fun apply f x = SOME (f x) handle _ => SOME false (* TODO: do not catch all exceptions! *)
fun pred f (x,s) = (apply f x, s)
fun pred2 f z = pred (fn x => f (x, z))
fun implies (cond, p) (x,s) = if cond x then p (x, s) else (NONE, s)
fun ==> (p1, p2) = implies (p1, pred p2)
fun wrap trans p (x,s) =
let val (result,s) = p (x,s)
in (result, trans (x, result, s)) end
fun classify' f =
wrap (fn (x, result, {tags, count}) =>
{ tags = if is_some result then
case f x of NONE => tags | SOME tag => AList.map_default (op =) (tag, 0) (fn c => c + 1) tags
else tags, count = count })
fun classify p tag = classify' (fn x => if p x then SOME tag else NONE)
fun trivial cond = classify cond "trivial"
fun test p =
wrap (fn (_, result, {tags, count}) =>
{ tags = tags, count = if is_some result then count + 1 else count }) p
val stats = { tags = [], count = 0 }
end