Implement simple topological sort algorithm for sortbydeps

Based on the "depth first search" algorithm, for more infos visit:
http://en.wikipedia.org/wiki/Topological_sorting

The previous algorithm used by sortbydeps was too slow, and to work around
it the number of steps needed to get correct result was reduced greatly.
So it produced wrong results in several cases :
1) smoke001.py
2) http://bugs.archlinux.org/task/7229

More here: http://archlinux.org/pipermail/pacman-dev/2007-April/008057.html

Signed-off-by: Chantry Xavier <shiningxc@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/libalpm/deps.h b/lib/libalpm/deps.h
index 8f3a9b91..132f21f4 100644
--- a/lib/libalpm/deps.h
+++ b/lib/libalpm/deps.h
@@ -42,6 +42,15 @@ struct __pmdepmissing_t {
 	pmdepend_t depend;
 };
 
+/* Graphs */
+struct __pmgraph_t {
+	int state; /* 0: untouched, -1: entered, other: leaving time */
+	void *data;
+	struct __pmgraph_t *parent; /* where did we come from? */
+	alpm_list_t *children;
+	alpm_list_t *childptr; /* points to a child in children list */
+};
+
 pmdepmissing_t *_alpm_depmiss_new(const char *target, pmdeptype_t type,
                                   pmdepmod_t depmod, const char *depname,
 																	const char *depversion);