flex-2.5.33/examples/manual/pascal.lex

   1 /*
   2  * pascal.lex: An example PASCAL scanner
   3  *
   4  */
   5
   6 %{
   7 #include <stdio.h>
   8 #include "y.tab.h"
   9
  10 int line_number = 0;
  11
  12 void yyerror(char *message);
  13
  14 %}
  15
  16 %x COMMENT1 COMMENT2
  17
  18 white_space       [ \t]*
  19 digit             [0-9]
  20 alpha             [A-Za-z_]
  21 alpha_num         ({alpha}|{digit})
  22 hex_digit         [0-9A-F]
  23 identifier        {alpha}{alpha_num}*
  24 unsigned_integer  {digit}+
  25 hex_integer       ${hex_digit}{hex_digit}*
  26 exponent          e[+-]?{digit}+
  27 i                 {unsigned_integer}
  28 real              ({i}\.{i}?|{i}?\.{i}){exponent}?
  29 string            \'([^'\n]|\'\')+\'
  30 bad_string        \'([^'\n]|\'\')+
  31
  32 %%
  33
  34 "{"                  BEGIN(COMMENT1);
  35 <COMMENT1>[^}\n]+
  36 <COMMENT1>\n            ++line_number;
  37 <COMMENT1><<EOF>>    yyerror("EOF in comment");
  38 <COMMENT1>"}"        BEGIN(INITIAL);
  39
  40 "(*"                 BEGIN(COMMENT2);
  41 <COMMENT2>[^)*\n]+
  42 <COMMENT2>\n            ++line_number;
  43 <COMMENT2><<EOF>>    yyerror("EOF in comment");
  44 <COMMENT2>"*)"       BEGIN(INITIAL);
  45 <COMMENT2>[*)]
  46
  47  /* note that FILE and BEGIN are already
  48   * defined in FLEX or C so they can't
  49   * be used. This can be overcome in
  50   * a cleaner way by defining all the
  51   * tokens to start with TOK_ or some
  52   * other prefix.
  53   */
  54
  55 and                  return(AND);
  56 array                return(ARRAY);
  57 begin                return(_BEGIN);
  58 case                 return(CASE);
  59 const                return(CONST);
  60 div                  return(DIV);
  61 do                   return(DO);
  62 downto               return(DOWNTO);
  63 else                 return(ELSE);
  64 end                  return(END);
  65 file                 return(_FILE);
  66 for                  return(FOR);
  67 function             return(FUNCTION);
  68 goto                 return(GOTO);
  69 if                   return(IF);
  70 in                   return(IN);
  71 label                return(LABEL);
  72 mod                  return(MOD);
  73 nil                  return(NIL);
  74 not                  return(NOT);
  75 of                   return(OF);
  76 packed               return(PACKED);
  77 procedure            return(PROCEDURE);
  78 program              return(PROGRAM);
  79 record               return(RECORD);
  80 repeat               return(REPEAT);
  81 set                  return(SET);
  82 then                 return(THEN);
  83 to                   return(TO);
  84 type                 return(TYPE);
  85 until                return(UNTIL);
  86 var                  return(VAR);
  87 while                return(WHILE);
  88 with                 return(WITH);
  89
  90 "<="|"=<"            return(LEQ);
  91 "=>"|">="            return(GEQ);
  92 "<>"                 return(NEQ);
  93 "="                  return(EQ);
  94
  95 ".."                 return(DOUBLEDOT);
  96
  97 {unsigned_integer}   return(UNSIGNED_INTEGER);
  98 {real}               return(REAL);
  99 {hex_integer}        return(HEX_INTEGER);
 100 {string}             return{STRING};
 101 {bad_string}         yyerror("Unterminated string");
 102
 103 {identifier}         return(IDENTIFIER);
 104
 105 [*/+\-,^.;:()\[\]]   return(yytext[0]);
 106
 107 {white_space}        /* do nothing */
 108 \n                   line_number += 1;
 109 .                    yyerror("Illegal input");
 110
 111 %%
 112
 113 void yyerror(char *message)
 114 {
 115    fprintf(stderr,"Error: \"%s\" in line %d. Token = %s\n",
 116            message,line_number,yytext);
 117    exit(1);
 118 }
 119
 120