/*
* string2.lex: An example of using scanning strings
* by using start states.
*/
%{
#include <ctype.h>
#include <malloc.h>
#define isodigit(x) ((x) >= '0' && (x) <= '7')
#define hextoint(x) (isdigit((x)) ? (x) - '0' : ((x) - 'A') + 10)
char *buffer = NULL;
int buffer_size = 0;
void yyerror(char *message)
{
printf("\nError: %s\n",message);
}
%}
%x STRING
hex (x|X)[0-9a-fA-F]{1,2}
oct [0-7]{1,3}
%%
\" {
buffer = malloc(1);
buffer_size = 1; strcpy(buffer,"");
BEGIN(STRING);
}
<STRING>\n {
yyerror("Unterminated string");
free(buffer);
BEGIN(INITIAL);
}
<STRING><<EOF>> {
yyerror("EOF in string");
free(buffer);
BEGIN(INITIAL);
}
<STRING>[^\\\n"] {
buffer = realloc(buffer,buffer_size+yyleng+1);
buffer_size += yyleng;
strcat(buffer,yytext);
}
<STRING>\\\n /* ignore this */
<STRING>\\{hex} {
int temp =0,loop = 0;
for(loop=yyleng-2; loop>0; loop--){
temp <<= 4;
temp += hextoint(toupper(yytext[yyleng-loop]));
}
buffer = realloc(buffer,buffer_size+1);
buffer[buffer_size-1] = temp;
buffer[buffer_size] = '\0';
buffer_size += 1;
}
<STRING>\\{oct} {
int temp =0,loop = 0;
for(loop=yyleng-1; loop>0; loop--){
temp <<= 3;
temp += (yytext[yyleng-loop] - '0');
}
buffer = realloc(buffer,buffer_size+1);
buffer[buffer_size-1] = temp;
buffer[buffer_size] = '\0';
buffer_size += 1;
}
<STRING>\\[^\n] {
buffer = realloc(buffer,buffer_size+1);
switch(yytext[yyleng-1]){
case 'b' : buffer[buffer_size-1] = '\b'; break;
case 't' : buffer[buffer_size-1] = '\t'; break;
case 'n' : buffer[buffer_size-1] = '\n'; break;
case 'v' : buffer[buffer_size-1] = '\v'; break;
case 'f' : buffer[buffer_size-1] = '\f'; break;
case 'r' : buffer[buffer_size-1] = '\r'; break;
default : buffer[buffer_size-1] = yytext[yyleng-1];
}
buffer[buffer_size] = '\0';
buffer_size += 1;
}
<STRING>\" {
printf("string = \"%s\"",buffer);
free(buffer);
BEGIN(INITIAL);
}
%%
