src/errormsg.sml

   1 (* This file comes mostly from "Modern Compiler Implementation in ML," by Andrew Appel
   2  * http://www.cs.princeton.edu/~appel/modern/ml/
   3  *)
   4
   5 structure ErrorMsg :> ERRORMSG =
   6   struct
   7     (* Initial values of compiler state variables *)
   8     val anyErrors = ref false
   9     val errorText = ref ""
  10     val fileName = ref ""
  11     val lineNum = ref 1
  12     val linePos = ref [1]
  13     val sourceStream = ref TextIO.stdIn
  14
  15     fun print msg = (errorText := !errorText ^ msg;
  16                      TextIO.print msg)
  17
  18     (* Reset compiler to initial state *)
  19     fun reset() = (anyErrors:=false;
  20                    errorText:="";
  21                    fileName:="";
  22                    lineNum:=1;
  23                    linePos:=[1];
  24                    sourceStream:=TextIO.stdIn)
  25
  26     (* Print the given error message *)
  27     fun error posopt (msg:string) =
  28       let
  29         val (startpos, endpos) = Option.getOpt (posopt, (0, 0))
  30         fun look(pos,a::rest,n) =
  31           if a<pos then app print [Int.toString n,
  32                                    ".",
  33                                    Int.toString (pos-a)]
  34           else look(pos,rest,n-1)
  35           | look _ = print "0.0"
  36       in
  37         anyErrors := true;
  38         print (!fileName); print ":";
  39         look(startpos, !linePos, !lineNum);
  40         if startpos=endpos then () else (print "-"; look(endpos, !linePos, !lineNum));
  41         app print [":error: ", msg, "\n"]
  42       end
  43
  44       val dummyLoc = (0, 0)
  45
  46       exception Error
  47   end
  48