Extending log example code

This adds more command line processing to the example version of
log.  In particular, this adds the funky command line processing
that allows an arbitrary series of revisions followed by an
arbitrary number of paths and/or glob patterns.

The actual logging part still isn't implemented.

examples/log.c

@@ -32,24 +32,71 @@ static void usage(const char *message, const char *arg)
 
 int main(int argc, char *argv[])
 {
-	int i;
+	int i, j, last_nonoption, force_files = -1;
 	char *a;
 	const char *dir = ".";
 	git_repository *repo;
+	git_revwalk *walker;
+	git_revspec revs;
 
 	git_threads_init();
 
-	for (i = 1; i < argc; ++i) {
+	for (i = 1, last_nonoption = 1; i < argc; ++i) {
 		a = argv[i];
 
-		if (a[0] != '-') {
+		if (a[0] != '-' || force_files > 0) {
+			/* condense args not prefixed with '-' to start of argv */
+			if (last_nonoption != i)
+				argv[last_nonoption] = a;
+			last_nonoption++;
 		}
+		else if (!strcmp(a, "--"))
+			force_files = last_nonoption; /* copy all args as filenames */
 		else if (!check_str_param(a, "--git-dir=", &dir))
 			usage("Unknown argument", a);
 	}
 
 	check(git_repository_open_ext(&repo, dir, 0, NULL),
 		"Could not open repository");
+	check(git_revwalk_new(&walker, repo),
+		"Could not create revision walker");
+
+	if (force_files < 0)
+		force_files = last_nonoption;
+
+	for (i = 1; i < force_files; ) {
+		printf("option '%s'\n", argv[i]);
+
+		if (!git_revparse(&revs, repo, argv[i])) {
+			char str[GIT_OID_HEXSZ+1];
+
+			if (revs.from) {
+				git_oid_tostr(str, sizeof(str), git_object_id(revs.from));
+				printf("revwalk from %s\n", str);
+			}
+			if (revs.to) {
+				git_oid_tostr(str, sizeof(str), git_object_id(revs.to));
+				printf("revwalk to %s\n", str);
+			}
+
+			/* push / hide / merge-base in revwalker */
+
+			++i;
+		} else {
+			/* shift array down */
+			for (a = argv[i], j = i + 1; j < force_files; ++j)
+				argv[j - 1] = argv[j];
+			argv[--force_files] = a;
+		}
+	}
+
+	if (i == 1) {
+		/* no revs pushed so push HEAD */
+		printf("revwalk HEAD\n");
+	}
+
+	for (i = force_files; i < last_nonoption; ++i)
+		printf("file %s\n", argv[i]);
 
 	git_repository_free(repo);
 	git_threads_shutdown();