(*  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 plural_s : int -> string

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

   val replace_all : string -> string -> string -> string

   val remove_all : string -> string -> string

   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

 fun plural_s n = if n = 1 then "" else "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 replace_all bef aft =

   let

     fun aux seen "" = String.implode (rev seen)

       | aux seen s =

       if String.isPrefix bef s then

           aux seen "" ^ aft ^ aux [] (unprefix bef s)

         else

           aux (String.sub (s, 0) :: seen) (String.extract (s, 1, NONE))

   in aux [] end

 fun remove_all bef = replace_all bef ""

 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

 (* 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

 end;