Reorganize rev-parse example

examples/rev-parse.c

-#include <stdio.h>
-#include <git2.h>
-#include <stdlib.h>
-#include <string.h>
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
 
-static void check(int error, const char *message, const char *arg)
+#include "common.h"
+
+
+/* Forward declarations for helpers */
+struct parse_state {
+	git_repository *repo;
+	const char *repodir;
+	const char *spec;
+	int not;
+};
+static void parse_opts(struct parse_state *ps, int argc, char *argv[]);
+static int parse_revision(struct parse_state *ps);
+
+
+int main(int argc, char *argv[])
 {
-	if (!error)
-		return;
-	if (arg)
-		fprintf(stderr, "%s %s (%d)\n", message, arg, error);
-	else
-		fprintf(stderr, "%s(%d)\n", message, error);
-	exit(1);
+	struct parse_state ps = {0};
+
+	git_threads_init();
+	parse_opts(&ps, argc, argv);
+
+	check_lg2(parse_revision(&ps), "Parsing", NULL);
+
+	git_repository_free(ps.repo);
+	git_threads_shutdown();
+
+	return 0;
 }
 
 static void usage(const char *message, const char *arg)
@@ -24,13 +44,25 @@ static void usage(const char *message, const char *arg)
 	exit(1);
 }
 
-struct parse_state {
-	git_repository *repo;
-	const char *repodir;
-	int not;
-};
+static void parse_opts(struct parse_state *ps, int argc, char *argv[])
+{
+	struct args_info args = ARGS_INFO_INIT;
 
-static int parse_revision(struct parse_state *ps, const char *revstr)
+	for (args.pos=1; args.pos < argc; ++args.pos) {
+		const char *a = argv[args.pos];
+
+		if (a[0] != '-') {
+			if (ps->spec)
+				usage("Too many specs", a);
+			ps->spec = a;
+		} else if (!strcmp(a, "--not"))
+			ps->not = !ps->not;
+		else if (!match_str_arg(&ps->repodir, &args, "--git-dir"))
+			usage("Cannot handle argument", a);
+	}
+}
+
+static int parse_revision(struct parse_state *ps)
 {
 	git_revspec rs;
 	char str[GIT_OID_HEXSZ + 1];
@@ -38,11 +70,11 @@ static int parse_revision(struct parse_state *ps, const char *revstr)
 	if (!ps->repo) {
 		if (!ps->repodir)
 			ps->repodir = ".";
-		check(git_repository_open_ext(&ps->repo, ps->repodir, 0, NULL),
+		check_lg2(git_repository_open_ext(&ps->repo, ps->repodir, 0, NULL),
 			"Could not open repository from", ps->repodir);
 	}
 
-	check(git_revparse(&rs, ps->repo, revstr), "Could not parse", revstr);
+	check_lg2(git_revparse(&rs, ps->repo, ps->spec), "Could not parse", ps->spec);
 
 	if ((rs.flags & GIT_REVPARSE_SINGLE) != 0) {
 		git_oid_tostr(str, sizeof(str), git_object_id(rs.from));
@@ -56,9 +88,9 @@ static int parse_revision(struct parse_state *ps, const char *revstr)
 
 		if ((rs.flags & GIT_REVPARSE_MERGE_BASE) != 0) {
 			git_oid base;
-			check(git_merge_base(&base, ps->repo,
-				git_object_id(rs.from), git_object_id(rs.to)),
-				"Could not find merge base", revstr);
+			check_lg2(git_merge_base(&base, ps->repo,
+						git_object_id(rs.from), git_object_id(rs.to)),
+					"Could not find merge base", ps->spec);
 
 			git_oid_tostr(str, sizeof(str), &base);
 			printf("%s\n", str);
@@ -69,38 +101,9 @@ static int parse_revision(struct parse_state *ps, const char *revstr)
 		git_object_free(rs.from);
 	}
 	else {
-		check(0, "Invalid results from git_revparse", revstr);
+		fatal("Invalid results from git_revparse", ps->spec);
 	}
 
 	return 0;
 }
 
-int main(int argc, char *argv[])
-{
-	int i;
-	char *a;
-	struct parse_state ps;
-
-	git_threads_init();
-
-	memset(&ps, 0, sizeof(ps));
-
-	for (i = 1; i < argc; ++i) {
-		a = argv[i];
-
-		if (a[0] != '-') {
-			if (parse_revision(&ps, a) != 0)
-				break;
-		} else if (!strcmp(a, "--not"))
-			ps.not = !ps.not;
-		else if (!strncmp(a, "--git-dir=", strlen("--git-dir=")))
-			ps.repodir = a + strlen("--git-dir=");
-		else
-			usage("Cannot handle argument", a);
-	}
-
-	git_repository_free(ps.repo);
-	git_threads_shutdown();
-
-	return 0;
-}