SimpleLex.lex

%using SimpleParser;
%using QUT.Gppg;
%using System.Linq;

%namespace SimpleScanner

Alpha 	[a-zA-Z_]
Digit   [0-9]
AlphaDigit {Alpha}|{Digit}
INTNUM  {Digit}+
BOOL	false|true
ID {Alpha}{AlphaDigit}*

%%

{INTNUM} {
  yylval.iVal = int.Parse(yytext);
  return (int)Tokens.INUM;
}

{BOOL} {
    yylval.bVal = bool.Parse(yytext);
    return (int)Tokens.BOOL;
}

{ID}  {
  int res = ScannerHelper.GetIDToken(yytext);
  if (res == (int)Tokens.ID)
    yylval.sVal = yytext;
  return res;
}

"=" { return (int)Tokens.ASSIGN; }
";"  { return (int)Tokens.SEMICOLON; }
"{" { return (int)Tokens.BEGIN; }
"}" { return (int)Tokens.END; }
"," {return (int)Tokens.COMMA; }
"(" {return (int)Tokens.LPAR; }
")" {return (int)Tokens.RPAR; }
"+" {return (int)Tokens.PLUS; }
"-" {return (int)Tokens.MINUS; }
"*" {return (int)Tokens.MULT; }
"/" {return (int)Tokens.DIV; }
"==" {return (int)Tokens.EQUAL; }
"!=" {return (int)Tokens.NOTEQUAL; }
">" {return (int)Tokens.GREATER; }
"<" {return (int)Tokens.LESS; }
"<=" {return (int)Tokens.EQLESS; }
">=" {return (int)Tokens.EQGREATER; }
":" {return (int)Tokens.COLON; }
"!" {return (int)Tokens.NOT; }

[^ \r\n\t] {
    LexError();
}

%{
  yylloc = new LexLocation(tokLin, tokCol, tokELin, tokECol);
%}

%%

public override void yyerror(string format, params object[] args)
{
  var ww = args.Skip(1).Cast<string>().ToArray();
  string errorMsg = string.Format("({0},{1}): Encountered {2}, expected {3}", yyline, yycol, args[0], string.Join(" or ", ww));
  throw new SyntaxException(errorMsg);
}

public void LexError()
{
  string errorMsg = string.Format("({0},{1}): Unknown symbol {2}", yyline, yycol, yytext);
  throw new LexException(errorMsg);
}

class ScannerHelper
{
  private static Dictionary<string,int> keywords;

  static ScannerHelper()
  {
    keywords = new Dictionary<string,int>();
    keywords.Add("for",(int)Tokens.FOR);
    keywords.Add("while",(int)Tokens.WHILE);
    keywords.Add("if",(int)Tokens.IF);
    keywords.Add("else",(int)Tokens.ELSE);
    keywords.Add("print",(int)Tokens.PRINT);
    keywords.Add("var",(int)Tokens.VAR);
    keywords.Add("and",(int)Tokens.AND);
    keywords.Add("or",(int)Tokens.OR);
    keywords.Add("goto",(int)Tokens.GOTO);
    keywords.Add("input",(int)Tokens.INPUT);
  }
  public static int GetIDToken(string s)
  {
    if (keywords.ContainsKey(s.ToLower()))
      return keywords[s];
    else
      return (int)Tokens.ID;
  }

}