diff options
Diffstat (limited to 'examples/manual/numbers.lex')
-rw-r--r-- | examples/manual/numbers.lex | 145 |
1 files changed, 145 insertions, 0 deletions
diff --git a/examples/manual/numbers.lex b/examples/manual/numbers.lex new file mode 100644 index 0000000..6484d6e --- /dev/null +++ b/examples/manual/numbers.lex @@ -0,0 +1,145 @@ +/* + * numbers.lex : An example of the definitions and techniques + * for scanning numbers + */ + +%{ +#include <stdio.h> + +#define UNSIGNED_LONG_SYM 1 +#define SIGNED_LONG_SYM 2 +#define UNSIGNED_SYM 3 +#define SIGNED_SYM 4 +#define LONG_DOUBLE_SYM 5 +#define FLOAT_SYM 6 + +union _yylval { + long double ylong_double; + float yfloat; + unsigned long yunsigned_long; + unsigned yunsigned; + long ysigned_long; + int ysigned; +} yylval; + +%} + +digit [0-9] +hex_digit [0-9a-fA-F] +oct_digit [0-7] + +exponent [eE][+-]?{digit}+ +i {digit}+ +float_constant ({i}\.{i}?|{i}?\.{i}){exponent}? +hex_constant 0[xX]{hex_digit}+ +oct_constant 0{oct_digit}* +int_constant {digit}+ +long_ext [lL] +unsigned_ext [uU] +float_ext [fF] +ulong_ext {long_ext}{unsigned_ext}|{unsigned_ext}{long_ext} + +%% + +{hex_constant}{ulong_ext} { /* we need to skip the "0x" part */ + sscanf(&yytext[2],"%lx",&yylval.yunsigned_long); + return(UNSIGNED_LONG_SYM); + } +{hex_constant}{long_ext} { + sscanf(&yytext[2],"%lx",&yylval.ysigned_long); + return(SIGNED_LONG_SYM); + } +{hex_constant}{unsigned_ext} { + sscanf(&yytext[2],"%x",&yylval.yunsigned); + return(UNSIGNED_SYM); + } +{hex_constant} { /* use %lx to protect against overflow */ + sscanf(&yytext[2],"%lx",&yylval.ysigned_long); + return(SIGNED_LONG_SYM); + } +{oct_constant}{ulong_ext} { + sscanf(yytext,"%lo",&yylval.yunsigned_long); + return(UNSIGNED_LONG_SYM); + } +{oct_constant}{long_ext} { + sscanf(yytext,"%lo",&yylval.ysigned_long); + return(SIGNED_LONG_SYM); + } +{oct_constant}{unsigned_ext} { + sscanf(yytext,"%o",&yylval.yunsigned); + return(UNSIGNED_SYM); + } +{oct_constant} { /* use %lo to protect against overflow */ + sscanf(yytext,"%lo",&yylval.ysigned_long); + return(SIGNED_LONG_SYM); + } +{int_constant}{ulong_ext} { + sscanf(yytext,"%ld",&yylval.yunsigned_long); + return(UNSIGNED_LONG_SYM); + } +{int_constant}{long_ext} { + sscanf(yytext,"%ld",&yylval.ysigned_long); + return(SIGNED_LONG_SYM); + } +{int_constant}{unsigned_ext} { + sscanf(yytext,"%d",&yylval.yunsigned); + return(UNSIGNED_SYM); + } +{int_constant} { /* use %ld to protect against overflow */ + sscanf(yytext,"%ld",&yylval.ysigned_long); + return(SIGNED_LONG_SYM); + } +{float_constant}{long_ext} { + sscanf(yytext,"%lf",&yylval.ylong_double); + return(LONG_DOUBLE_SYM); + } +{float_constant}{float_ext} { + sscanf(yytext,"%f",&yylval.yfloat); + return(FLOAT_SYM); + } +{float_constant} { /* use %lf to protect against overflow */ + sscanf(yytext,"%lf",&yylval.ylong_double); + return(LONG_DOUBLE_SYM); + } +%% + +int main(void) +{ + int code; + + while((code = yylex())){ + printf("yytext : %s\n",yytext); + switch(code){ + case UNSIGNED_LONG_SYM: + printf("Type of number : UNSIGNED LONG\n"); + printf("Value of number : %lu\n",yylval.yunsigned_long); + break; + case SIGNED_LONG_SYM: + printf("Type of number : SIGNED LONG\n"); + printf("Value of number : %ld\n",yylval.ysigned_long); + break; + case UNSIGNED_SYM: + printf("Type of number : UNSIGNED\n"); + printf("Value of number : %u\n",yylval.yunsigned); + break; + case SIGNED_SYM: + printf("Type of number : SIGNED\n"); + printf("Value of number : %d\n",yylval.ysigned); + break; + case LONG_DOUBLE_SYM: + printf("Type of number : LONG DOUBLE\n"); + printf("Value of number : %lf\n",yylval.ylong_double); + break; + case FLOAT_SYM: + printf("Type of number : FLOAT\n"); + printf("Value of number : %f\n",yylval.yfloat); + break; + default: + printf("Type of number : UNDEFINED\n"); + printf("Value of number : UNDEFINED\n"); + break; + } + } + return(0); +} + |