Open System Services Library Calls Reference Manual (G06.27+, H06.04+)

OSS Library Calls (a - d) compile(3)
INIT The INIT( ) macro is used for dependent declarations and initializations. In the |
regexp.h header file this macro is located right after the compile() macro |
declarations and opening { (left brace). Your INIT() declarations must end with
a ; (semicolon).
The INIT() macro is frequently used to set a register variable to point to the
beginning of the regular expression, so that this pointer can be used in declara-
tions for GETC(),PEEKC( ), and UNGETC( ). Alternatively, you can use
INIT() to declare external variables that GETC(),PEEKC(), and UNGETC()
need.
GETC() The GETC() macro returns the value of the next character (byte) in the regular-
expression pattern. Successive calls to GETC() return successive characters of
the regular expression.
PEEKC() The PEEKC() macro returns the next character (byte) in the regular expression.
Immediate subsequent calls to this macro return the same byte, which is also the
next character returned by the GETC() macro.
UNGETC(c)TheUNGETC() macro causes the c parameter to be returned by the next call to
the GETC( ) and PEEKC() macros. No more than one character of pushback is
ever needed because this character is guaranteed to be the last character read by
the GETC( ) macro. The value of the UNGETC() macro is always ignored.
RETURN(ptr)TheRETURN( ) macro is used for normal exit of the compile() macro. The |
value of the ptr parameter is a pointer to the character following the last charac-
ter of the compiled regular expression. This is useful in programs that manage
memory allocation.
ERROR(val)TheERROR() macro is the abnormal return from the compile() macro. This |
macro should never return from a call. In this macro, val is an error number,
which is described in the ERRORS section of this reference page.
NOTES
The compile() macro can be called by native processes only. |
The functionality provided by advance(), compile(), and step() is defined to be obsolete by |
POSIX. Functions such as regcomp() and regexec() should be used instead.
EXAMPLES
The following is an example of the regular expression macros and calls from the grep command:
#define INIT register char *sp=instring;
#define GETC( ) (*sp++)
#define PEEKC( ) (*sp)
#define UNGETC(c) (--sp)
#define RETURN(c) return;
#define ERROR(c) regerr( )
#include <regexp.h>
...
compile (patstr, expbuf, &expbuf[ESIZE], ’\0’);
...
if (step (linebuf, expbuf))
succeed( );
...
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