external/bsd/flex/dist/examples/manual/expr.lex

   1 /*
   2  * expr.lex : Scanner for a simple
   3  *            expression parser.
   4  */
   5
   6 %{
   7 #include "y.tab.h"
   8
   9 %}
  10
  11 %%
  12
  13 [0-9]+     { yylval.val = atol(yytext);
  14              return(NUMBER);
  15            }
  16 [0-9]+\.[0-9]+ {
  17              sscanf(yytext,"%f",&yylval.val);
  18              return(NUMBER);
  19            }
  20 "+"        return(PLUS);
  21 "-"        return(MINUS);
  22 "*"        return(MULT);
  23 "/"        return(DIV);
  24 "^"        return(EXPON);
  25 "("        return(LB);
  26 ")"        return(RB);
  27 \n         return(EOL);
  28 [\t ]*     /* throw away whitespace */
  29 .          { yyerror("Illegal character");
  30              return(EOL);
  31            }
  32 %%
  33
  34
  35