ref: 2af6b0896040ab24c2d411a36781d7588935c6cf
dir: /sys/src/ape/lib/l/yyless.c/
#include <libl.h>
#include <stdio.h>
extern char yytext[];
extern int yyleng;
extern int yyprevious;
void yyunput(int c);
void
yyless(int x)
{
char *lastch, *ptr;
lastch = yytext+yyleng;
if(x>=0 && x <= yyleng)
ptr = x + yytext;
else
ptr = (char*)x;
while(lastch > ptr)
yyunput(*--lastch);
*lastch = 0;
if (ptr >yytext)
yyprevious = *--lastch;
yyleng = ptr-yytext;
}