(*  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 pairf : ('a -> 'b) -> ('a -> 'c) -> 'a -> 'b * 'c

   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 timestamp : unit -> string

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

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

   val nat_subscript : int -> string

   val unyxml : string -> string

   val maybe_quote : string -> string

 end;

 structure Sledgehammer_Util : SLEDGEHAMMER_UTIL =

 struct

 fun pairf f g x = (f x, g x)

 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 ""

 val timestamp = Date.fmt "%Y-%m-%d %H:%M:%S" o Date.fromTimeLocal o Time.now

 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

 val subscript = implode o map (prefix "\<^isub>") o explode

 val nat_subscript = subscript o string_of_int

 fun plain_string_from_xml_tree t =

   Buffer.empty |> XML.add_content t |> Buffer.content

 val unyxml = plain_string_from_xml_tree o YXML.parse

 val is_long_identifier = forall Syntax.is_identifier o space_explode "."

 fun maybe_quote y =

   let val s = unyxml y in

     y |> ((not (is_long_identifier (perhaps (try (unprefix "'")) s)) andalso

            not (is_long_identifier (perhaps (try (unprefix "?")) s))) orelse

            OuterKeyword.is_keyword s) ? quote

   end

 end;