mlton/atoms/symbol.fun

   1 (* Copyright (C) 2004-2006 Henry Cejtin, Matthew Fluet, Suresh
   2  *    Jagannathan, and Stephen Weeks.
   3  *
   4  * MLton is released under a BSD-style license.
   5  * See the file MLton-LICENSE for details.
   6  *)
   7
   8 functor Symbol (S: SYMBOL_STRUCTS): SYMBOL =
   9 struct
  10
  11 open S
  12
  13 datatype t = T of {hash: word,
  14                    name: string,
  15                    plist: PropertyList.t}
  16
  17 local
  18    fun make f (T r) = f r
  19 in
  20    val hash = make #hash
  21    val plist = make #plist
  22    val name = make #name
  23 end
  24
  25 val table: t HashSet.t = HashSet.new {hash = hash}
  26
  27 fun fromString s =
  28    let
  29       val hash = String.hash s
  30    in
  31       HashSet.lookupOrInsert
  32       (table, hash, fn T {name, ...} => s = name,
  33        fn () => T {hash = hash,
  34                    name = s,
  35                    plist = PropertyList.new ()})
  36    end
  37
  38 fun foreach f = HashSet.foreach (table, f)
  39
  40 val toString = name
  41
  42 val layout = Layout.str o toString
  43
  44 fun equals (s, s') = PropertyList.equals (plist s, plist s')
  45
  46 local
  47    fun make f (s, s') = f (name s, name s')
  48 in
  49    val op <= = make String.<=
  50    val compare = make String.compare
  51 end
  52
  53 val asterisk = fromString "*"
  54 val bogus = fromString "<bogus>"
  55 val equal = fromString "="
  56 val itt = fromString "it"
  57 val unit = fromString "unit"
  58
  59 end