(* Copyright (c) 2008, Adam Chlipala
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - The names of contributors may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *)

structure ErrorMsg :> ERROR_MSG = struct

type pos = {line : int,
            char : int}

type span = {file : string,
             first : pos,
             last : pos}

type 'a located = 'a * span


fun posToString {line, char} =
    String.concat [Int.toString line, ":", Int.toString char]

fun spanToString {file, first, last} =
    String.concat [file, ":", posToString first, "-", posToString last]

val dummyPos = {line = 0,
                char = 0}
val dummySpan = {file = "",
                 first = dummyPos,
                 last = dummyPos}


val file = ref ""
val numLines = ref 1
val lines : int list ref = ref []

fun resetPositioning fname = (file := fname;
                              numLines := 1;
                              lines := [])

fun newline pos = (numLines := !numLines + 1;
                   lines := pos :: !lines)

fun lastLineStart () =
    case !lines of
        [] => 0
      | n :: _ => n+1

fun posOf n =
    let
        fun search lineNum lines =
            case lines of
                [] => {line = 1,
                       char = n}
              | bound :: rest =>
                if n > bound then
                    {line = lineNum,
                     char = n - bound - 1}
                else
                    search (lineNum - 1) rest
    in
        search (!numLines) (!lines)
    end

fun spanOf (pos1, pos2) = {file = !file,
                           first = posOf pos1,
                           last = posOf pos2}


val errors = ref false

fun resetErrors () = errors := false
fun anyErrors () = !errors
fun error s = (TextIO.output (TextIO.stdErr, s);
               TextIO.output1 (TextIO.stdErr, #"\n");
               errors := true)
fun errorAt span s = (TextIO.output (TextIO.stdErr, spanToString span);
                      TextIO.output1 (TextIO.stdErr, #" ");
                      error s)
fun errorAt' span s = errorAt (spanOf span) s

end