This is xnu-8019. See this file in:
%{
/* 
 * Mach Operating System
 * Copyright (c) 1990 Carnegie-Mellon University
 * Copyright (c) 1989 Carnegie-Mellon University
 * Copyright (c) 1988 Carnegie-Mellon University
 * Copyright (c) 1987 Carnegie-Mellon University
 * All rights reserved.  The CMU software License Agreement specifies
 * the terms and conditions for use and redistribution.
 */

/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *	@(#)config.l	5.5 (Berkeley) 6/18/88
 */

#include <ctype.h>
#include "parser.h"
#include "config.h"

int	kw_lookup(char *word);
int	octal(char *str);
int	hex(char *str);
int	yylex(void);

#define tprintf if (do_trace) printf

/*
 * Key word table
 */

struct kt {
	const char *kt_name;
	int kt_val;
} key_words[] = {
	{ "builddir",	BUILDDIR },
	{ "init",	INIT },
	{ "machine",	MACHINE },
	{ "makeoptions", MAKEOPTIONS },
	{ "makevariables", MAKEOPTIONS },
	{ "objectdir",	OBJECTDIR },
	{ "options",	OPTIONS },
	{ "pseudo-device",PSEUDO_DEVICE },
	{ "sourcedir",	SOURCEDIR },
	{ "trace",	TRACE },
	{ 0, 0 },
};
%}

%option nounput

WORD	([A-Za-z_][-A-Za-z_]*|[A-Z][-A-Za-z_0-9]*)
WORD1	([A-Za-z_][-A-Za-z_0-9]*)
%%
{WORD} |
{WORD1}		{
			int i;

			if ((i = kw_lookup(yytext)) == -1)
			{
				yylval.str = yytext;
				tprintf("id(%s) ", yytext);
				return ID;
			}
			tprintf("(%s) ", yytext);
			return i;
		}
\"[^"]+\"	{
			yytext[strlen(yytext)-1] = '\0';
			yylval.str = yytext + 1;
			return ID;
		}
0[0-7]*		{
			yylval.val = octal(yytext);
			tprintf("#O:%o ", yylval.val);
			return NUMBER;
		}
0x[0-9a-fA-F]+	{
			yylval.val = hex(yytext);
			tprintf("#X:%x ", yylval.val);
			return NUMBER;
		}
[1-9][0-9]*	{
			yylval.val = atoi(yytext);
			tprintf("#D:%d ", yylval.val);
			return NUMBER;
		}
"?"		{
			yylval.val = -1;
			tprintf("? ");
			return NUMBER;
		}
\n/[ \t]	{
			yyline++;
			tprintf("\n... ");
		}
\n		{
			yyline++;
			tprintf("\n");
			return SEMICOLON;
		}
#.*		{	/* Ignored (comment) */;	}
[ \t]*		{	/* Ignored (white space) */;	}
";"		{	return SEMICOLON;		}
","		{	return COMMA;			}
"="		{	return EQUALS;			}
.		{	return yytext[0];		}


%%
/*
 * kw_lookup
 *	Look up a string in the keyword table.  Returns a -1 if the
 *	string is not a keyword otherwise it returns the keyword number
 */

int
kw_lookup(char *word)
{
	register struct kt *kp;

	for (kp = key_words; kp->kt_name != 0; kp++)
		if (eq(word, kp->kt_name))
			return kp->kt_val;
	return -1;
}

/*
 * Number conversion routines
 */

int
octal(char *str)
{
	int num;

	(void) sscanf(str, "%o", &num);
	return num;
}

int
hex(char *str)
{
	int num;

	(void) sscanf(str+2, "%x", &num);
	return num;
}

int
yywrap()
{
	return 1;
}