(*  Title:      HOL/Tools/Sledgehammer/sledgehammer_util.ML

    Author:     Jasmin Blanchette, TU Muenchen

General-purpose functions used by the Sledgehammer modules.

*)

signature SLEDGEHAMMER_UTIL =

sig

  val serial_commas : string -> string list -> string list

  val parse_bool_option : bool -> string -> string -> bool option

  val parse_time_option : string -> string -> Time.time option

  val hashw : word * word -> word

  val hashw_char : Char.char * word -> word

  val hashw_string : string * word -> word

end;

structure Sledgehammer_Util : SLEDGEHAMMER_UTIL =

struct

(* This hash function is recommended in Compilers: Principles, Techniques, and

   Tools, by Aho, Sethi and Ullman. The hashpjw function, which they

   particularly recommend, triggers a bug in versions of Poly/ML up to 4.2.0. *)

fun hashw (u, w) = Word.+ (u, Word.* (0w65599, w))

fun hashw_char (c, w) = hashw (Word.fromInt (Char.ord c), w)

fun hashw_string (s:string, w) = CharVector.foldl hashw_char w s

fun serial_commas _ [] = ["??"]

  | serial_commas _ [s] = [s]

  | serial_commas conj [s1, s2] = [s1, conj, s2]

  | serial_commas conj [s1, s2, s3] = [s1 ^ ",", s2 ^ ",", conj, s3]

  | serial_commas conj (s :: ss) = s ^ "," :: serial_commas conj ss

fun parse_bool_option option name s =

  (case s of

     "smart" => if option then NONE else raise Option

   | "false" => SOME false

   | "true" => SOME true

   | "" => SOME true

   | _ => raise Option)

  handle Option.Option =>

         let val ss = map quote ((option ? cons "smart") ["true", "false"]) in

           error ("Parameter " ^ quote name ^ " must be assigned " ^

                  space_implode " " (serial_commas "or" ss) ^ ".")

         end

fun parse_time_option _ "none" = NONE

  | parse_time_option name s =

    let

      val msecs =

        case space_explode " " s of

          [s1, "min"] => 60000 * the (Int.fromString s1)

        | [s1, "s"] => 1000 * the (Int.fromString s1)

        | [s1, "ms"] => the (Int.fromString s1)

        | _ => 0

    in

      if msecs <= 0 then

        error ("Parameter " ^ quote name ^ " must be assigned a positive time \

               \value (e.g., \"60 s\", \"200 ms\") or \"none\".")

      else

        SOME (Time.fromMilliseconds msecs)

    end

end;