php/main/php_regex.h

#ifndef _PHP_REGEX_H
#define _PHP_REGEX_H

/*
 * REGEX means:
 * 0.. system regex
 * 1.. bundled regex
 */

#if REGEX
/* get aliases */
#include "regex/regex_extra.h"
#include "regex/regex.h"

/* get rid of aliases */
#define PHP_NO_ALIASES
#include "regex/regex_extra.h"
#undef PHP_NO_ALIASES

#ifndef _REGEX_H
#define _REGEX_H 1				/* this should stop Apache from loading the system version of regex.h */
#endif
#ifndef _REGEX_H_
#define _REGEX_H_ 1
#endif
#ifndef _RX_H
#define _RX_H 1				  	/* Try defining these for Linux to	*/
#endif
#ifndef __REGEXP_LIBRARY_H__
#define __REGEXP_LIBRARY_H__ 1 	/* avoid Apache including regex.h	*/
#endif
#ifndef _H_REGEX
#define _H_REGEX 1              /* This one is for AIX */
#endif
#elif REGEX == 0
#include <regex.h>
#ifndef _REGEX_H_
#define _REGEX_H_ 1
#endif
#endif

#endif /* _PHP_REGEX_H */