/*

 * pascal.lex: An example PASCAL scanner

 *

 */

%{

#include <stdio.h>

#include "y.tab.h"

int line_number = 0;

void yyerror(char *message);

%}

%x COMMENT1 COMMENT2

white_space       [ \t]*

digit             [0-9]

alpha             [A-Za-z_]

alpha_num         ({alpha}|{digit})

hex_digit         [0-9A-F]

identifier        {alpha}{alpha_num}*

unsigned_integer  {digit}+

hex_integer       ${hex_digit}{hex_digit}*

exponent          e[+-]?{digit}+

i                 {unsigned_integer}

real              ({i}\.{i}?|{i}?\.{i}){exponent}?

string            \'([^'\n]|\'\')+\'

bad_string        \'([^'\n]|\'\')+

%%

"{"                  BEGIN(COMMENT1);

<COMMENT1>[^}\n]+

<COMMENT1>\n            ++line_number;

<COMMENT1><<EOF>>    yyerror("EOF in comment");

<COMMENT1>"}"        BEGIN(INITIAL);

"(*"                 BEGIN(COMMENT2);

<COMMENT2>[^)*\n]+

<COMMENT2>\n            ++line_number;

<COMMENT2><<EOF>>    yyerror("EOF in comment");

<COMMENT2>"*)"       BEGIN(INITIAL);

<COMMENT2>[*)]

 /* note that FILE and BEGIN are already 

  * defined in FLEX or C so they can't  

  * be used. This can be overcome in                               

  * a cleaner way by defining all the

  * tokens to start with TOK_ or some

  * other prefix.

  */

and                  return(AND);

array                return(ARRAY);

begin                return(_BEGIN);

case                 return(CASE);

const                return(CONST);

div                  return(DIV);

do                   return(DO);

downto               return(DOWNTO);

else                 return(ELSE);

end                  return(END);

file                 return(_FILE);

for                  return(FOR);

function             return(FUNCTION);

goto                 return(GOTO);

if                   return(IF);

in                   return(IN);

label                return(LABEL);

mod                  return(MOD);

nil                  return(NIL);

not                  return(NOT);

of                   return(OF);

packed               return(PACKED);

procedure            return(PROCEDURE);

program              return(PROGRAM);

record               return(RECORD);

repeat               return(REPEAT);

set                  return(SET);

then                 return(THEN);

to                   return(TO);

type                 return(TYPE);

until                return(UNTIL);

var                  return(VAR);

while                return(WHILE);

with                 return(WITH);

"<="|"=<"            return(LEQ);

"=>"|">="            return(GEQ);

"<>"                 return(NEQ);

"="                  return(EQ);

".."                 return(DOUBLEDOT);

{unsigned_integer}   return(UNSIGNED_INTEGER);

{real}               return(REAL);

{hex_integer}        return(HEX_INTEGER);

{string}             return{STRING};

{bad_string}         yyerror("Unterminated string");

{identifier}         return(IDENTIFIER);

[*/+\-,^.;:()\[\]]   return(yytext[0]);

{white_space}        /* do nothing */

\n                   line_number += 1;

.                    yyerror("Illegal input");

%%

void yyerror(char *message)

{

   fprintf(stderr,"Error: \"%s\" in line %d. Token = %s\n",

           message,line_number,yytext);

   exit(1);

}