Theory Statistics

section ‹Collecting Statistics about Algorithms›
theory Statistics
imports Main
begin

text ‹
  This theory contains an infrastructure to collect statistics about
  algorithms by instrumenting the formalization with dummy constants that
  get translated to functions that update the statistics as a side-effect.
›

code_printing
  (* HACK: code_modules seem to be sorted alphabetically when written to SML. 
    However, other code_modules will depend on this, so we put an A in front 
    of the name to get this first. *)
  code_module AStatistics ⇀ (SML) ‹
  structure Statistics : sig
    type stat_entry = string * (unit -> bool) * (unit -> string)
  
    val register_stat : stat_entry -> unit
    val get_active_stats : unit -> (string * string) list
    val pretty_stats : (string * string) list -> string

  end = struct
    type stat_entry = string * (unit -> bool) * (unit -> string)
    val stats : stat_entry list Unsynchronized.ref = Unsynchronized.ref []
  
    fun register_stat e = stats := e :: !stats

    fun get_active_stats () = let
      fun flt [] = []
        | flt ((n,a,s)::l) = if a () then (n,s ()) :: flt l else flt l

    in flt (!stats)
    end

    fun pretty_stats [] = ""
      | pretty_stats ((n,s)::l) = "=== " ^ n ^ " ===\n" ^ s ^ "\n" ^ pretty_stats l
  end

(* Argh! Functors not compatible with ML_val command!
  functor Timer () : sig 
    val reset : unit -> unit
    val start : unit -> unit
    val stop : unit -> unit
    val set : Time.time -> unit
    val get : unit -> Time.time
    val pretty : unit -> string
  end = struct

    open Time;

    val time : Time.time Unsynchronized.ref = Unsynchronized.ref Time.zeroTime
    val running : bool Unsynchronized.ref = Unsynchronized.ref false
    val start_time : Time.time Unsynchronized.ref = Unsynchronized.ref Time.zeroTime
        
    fun reset () = (
      time := Time.zeroTime;
      running := false;
      start_time := Time.zeroTime
    )

    fun start () = 
      if !running then 
        () 
      else (
        running := true;
        start_time := Time.now ()
      )

    fun this_runs_time () = 
      if !running then 
        Time.now () - !start_time 
      else 
        Time.zeroTime

    fun stop () = (
      time := !time + this_runs_time ();
      running := false
    )

    fun get () = !time + this_runs_time ()
    fun set t = time := t - this_runs_time ()
  
    fun pretty () = Time.toString (!time) ^ "s"
  end
  *)

›
code_reserved SML Statistics Timer


end