# HG changeset patch
# User Sylvain Thénault <sylvain.thenault@logilab.fr>
# Date 1284019688 -7200
# Node ID f8dea560703fce8a82ae6656ea709414e0b847f2
# Parent  d8f0dce0b86df428d391406e554dfff2d612fbb4
add a small c-c shell script to detect cycle for a given relation

diff -r d8f0dce0b86d -r f8dea560703f misc/scripts/detect_cycle.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/misc/scripts/detect_cycle.py	Thu Sep 09 10:08:08 2010 +0200
@@ -0,0 +1,15 @@
+
+try:
+    rtype, = __args__
+except ValueError:
+    print 'USAGE: cubicweb-ctl shell <instance> detect_cycle.py -- <relation type>'
+    print
+
+graph = {}
+for fromeid, toeid in rql('Any X,Y WHERE X %s Y' % rtype):
+    graph.setdefault(fromeid, []).append(toeid)
+
+from logilab.common.graph import get_cycles
+
+for cycle in get_cycles(graph):
+    print 'cycle', '->'.join(str(n) for n in cycle)