location.star

location is package{
  type srcLoc is someWhere{
    lineCount has type integer
    lineOffset has type integer
    charCount has type integer
    length has type integer
  } or missing

  implementation pPrint over srcLoc is {
    ppDisp=showLoc
  } using {
    fun showLoc(someWhere{
      lineCount=Line
      lineOffset=Off
      length=Ln}) is 
        ppSequence(0,cons of [
          ppStr(Line as string), ppStr("["), ppStr(Off as string), ppStr(":"), ppStr(Ln as string), ppStr("]")])
     |  showLoc(missing) is ppStr("no where")
  }

  fun mergeLocation(someWhere{lineCount=Lc1;lineOffset=LO1;charCount=CC1;length=LN1},
    	someWhere{charCount=CC2;length=LN2}) is
          someWhere{lineCount=Lc1;lineOffset=LO1;charCount=CC1;length=CC2+LN2-CC1}

  fun sameLine(someWhere{lineCount=Lc1},someWhere{lineCount=Lc2}) is Lc1=Lc2
   |  sameLine(_,_) default is false

  contract hasLocation over t is {
    locOf has type (t)=>srcLoc;
  }

  implementation coercion over (astLocation,srcLoc) is {
    fun coerce(L) is someWhere{ lineCount = L.lineCount; lineOffset = L.lineOffset; charCount = L.charCount; length = L.length}
  }
}