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