git: 9front

ref: 5efe85a961d95f1b7935fe830933c84b5bf7c7b3
dir: /sys/src/ape/lib/l/yyless.c/

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#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;
}