Rewrite arg.h

This was something I wanted to do for quite a while now.

The problem with the old arg.h is that it does not allow you to call ARGF() and
EARGF() multiple times without messing the argument up. This is an
unnecessary limitation and can lead to unexpected results for people not
aware of this problem.

	ARGBEGIN {
	case 'a':
		printf("1st call: %s\n", ARGF());
		printf("2nd call: %s\n", ARGF());
		break;
	default:
		break;
	}

	$ prog -a ARG
	1st call: ARG
	2nd call: RG

This is fixed now to properly print

	$ prog -a ARG
	1st call: ARG
	2nd call: ARG

The old version also used more local variables than necessary, as the
problem can be reduced to one single local variable within the second
loop, which expresses if the argument has been consumed or not.
The use of abort() within EARGF() was a bit drastic. exit(1) should
suffice here and align with what you expect from an e*-type function.
Additionally, the formatting I used should make readability easier and
the code deduplication in the *ARGF()-macros helps with maintainability.

The license used is ISC, which is compatible with MIT/X, GPL and so forth in
case you want to use it in your project. I explicitly added the license header
to the file making it easy to just drop it in.

There are no plans to support the obsolete ARGNUM, ARGNUMF, LNGARG syntaxes.

1 files changed, 48 insertions, 58 deletions

diff --git a/arg.h b/arg.h
index 0b23c53..77cf5be 100644
--- a/arg.h
+++ b/arg.h
@@ -1,65 +1,55 @@
 /*
- * Copy me if you can.
- * by 20h
+ * ISC-License
+ *
+ * (c) 2017 Laslo Hunhold <dev@frign.de>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
  */
-
-#ifndef ARG_H__
-#define ARG_H__
+#ifndef ARG_H
+#define ARG_H
 
 extern char *argv0;
 
-/* use main(int argc, char *argv[]) */
-#define ARGBEGIN	for (argv0 = *argv, argv++, argc--;\
-					argv[0] && argv[0][0] == '-'\
-					&& argv[0][1];\
-					argc--, argv++) {\
-				char argc_;\
-				char **argv_;\
-				int brk_;\
-				if (argv[0][1] == '-' && argv[0][2] == '\0') {\
-					argv++;\
-					argc--;\
-					break;\
-				}\
-				for (brk_ = 0, argv[0]++, argv_ = argv;\
-						argv[0][0] && !brk_;\
-						argv[0]++) {\
-					if (argv_ != argv)\
-						break;\
-					argc_ = argv[0][0];\
-					switch (argc_)
-
-/* Handles obsolete -NUM syntax */
-#define ARGNUM				case '0':\
-					case '1':\
-					case '2':\
-					case '3':\
-					case '4':\
-					case '5':\
-					case '6':\
-					case '7':\
-					case '8':\
-					case '9'
-
-#define ARGEND			}\
-			}
-
-#define ARGC()		argc_
-
-#define ARGNUMF()	(brk_ = 1, estrtonum(argv[0], 0, INT_MAX))
-
-#define EARGF(x)	((argv[0][1] == '\0' && argv[1] == NULL)?\
-				((x), abort(), (char *)0) :\
-				(brk_ = 1, (argv[0][1] != '\0')?\
-					(&argv[0][1]) :\
-					(argc--, argv++, argv[0])))
-
-#define ARGF()		((argv[0][1] == '\0' && argv[1] == NULL)?\
-				(char *)0 :\
-				(brk_ = 1, (argv[0][1] != '\0')?\
-					(&argv[0][1]) :\
-					(argc--, argv++, argv[0])))
-
-#define LNGARG()	&argv[0][0]
+/* int main(int argc, char *argv[]) */
+#define ARGBEGIN for (argv0 = *argv, argv++, argc--;                              \
+                      *argv && (*argv)[0] == '-' && (*argv)[1]; argc--, argv++) { \
+                 	int argparsed;                                            \
+                 	if ((*argv)[1] == '-' && (*argv)[2] == '\0') {            \
+                 		argc--, argv++;                                   \
+                 		break;                                            \
+                 	}                                                         \
+                 	for (argparsed = 0, (*argv)++; (*argv)[0]; (*argv)++) {   \
+                 		switch((*argv)[0])
+#define ARGEND   		if (argparsed) {                                  \
+                 			if ((*argv)[1] != '\0') {                 \
+                 				break;                            \
+                 			} else {                                  \
+                 				argc--, argv++;                   \
+                 				break;                            \
+                 			}                                         \
+                 		}                                                 \
+                 	}                                                         \
+                 }
+#define ARGC()   *argv[0]
+#define ARGF_(x) (((*argv)[1] == '\0' && !*(argv + 1)) ?       \
+                 	(x) :                                  \
+                 	(argparsed = 1, ((*argv)[1] != '\0') ? \
+                 		(&(*argv)[1]) :                \
+                 		(*(argv + 1))                  \
+                 	)                                      \
+                 )
+#define EARGF(x) ARGF_(((x), exit(1), (char *)0))
+#define ARGF()   ARGF_((char *)0)
 
 #endif