2d440e36b0
git-svn-id: http://svn.openlayers.org/trunk/openlayers@359 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
261 lines
8.4 KiB
Python
261 lines
8.4 KiB
Python
#
|
|
# According to <http://www.vrplumber.com/programming/> this file
|
|
# is licensed under a BSD-style license. We only use the section
|
|
# originally by Tim Peters.
|
|
#
|
|
# TODO: The use of this code needs to be okayed by someone.
|
|
#
|
|
|
|
class RecursionError( OverflowError, ValueError ):
|
|
'''Unable to calculate result because of recursive structure'''
|
|
|
|
|
|
def sort(nodes, routes, noRecursion=1):
|
|
'''Passed a list of node IDs and a list of source,dest ID routes
|
|
attempt to create a list of stages where each sub list
|
|
is one stage in a process.
|
|
'''
|
|
children, parents = _buildChildrenLists(routes)
|
|
# first stage is those nodes
|
|
# having no incoming routes...
|
|
stage = []
|
|
stages = [stage]
|
|
taken = []
|
|
for node in nodes:
|
|
if (not parents.get(node)):
|
|
stage.append (node)
|
|
if nodes and not stage:
|
|
# there is no element which does not depend on
|
|
# some other element!!!
|
|
stage.append( nodes[0])
|
|
taken.extend( stage )
|
|
nodes = filter ( lambda x, l=stage: x not in l, nodes )
|
|
while nodes:
|
|
previousStageChildren = []
|
|
nodelen = len(nodes)
|
|
# second stage are those nodes
|
|
# which are direct children of the first stage
|
|
for node in stage:
|
|
for child in children.get (node, []):
|
|
if child not in previousStageChildren and child not in taken:
|
|
previousStageChildren.append(child)
|
|
elif child in taken and noRecursion:
|
|
raise RecursionError( (child, node) )
|
|
# unless they are children of other direct children...
|
|
# TODO, actually do that...
|
|
stage = previousStageChildren
|
|
removes = []
|
|
for current in stage:
|
|
currentParents = parents.get( current, [] )
|
|
for parent in currentParents:
|
|
if parent in stage and parent != current:
|
|
# might wind up removing current...
|
|
if not current in parents.get(parent, []):
|
|
# is not mutually dependent...
|
|
removes.append( current )
|
|
for remove in removes:
|
|
while remove in stage:
|
|
stage.remove( remove )
|
|
stages.append( stage)
|
|
taken.extend( stage )
|
|
nodes = filter ( lambda x, l=stage: x not in l, nodes )
|
|
if nodelen == len(nodes):
|
|
if noRecursion:
|
|
raise RecursionError( nodes )
|
|
else:
|
|
stages.append( nodes[:] )
|
|
nodes = []
|
|
return stages
|
|
|
|
def _buildChildrenLists (routes):
|
|
childrenTable = {}
|
|
parentTable = {}
|
|
for sourceID,destinationID in routes:
|
|
currentChildren = childrenTable.get( sourceID, [])
|
|
currentParents = parentTable.get( destinationID, [])
|
|
if not destinationID in currentChildren:
|
|
currentChildren.append ( destinationID)
|
|
if not sourceID in currentParents:
|
|
currentParents.append ( sourceID)
|
|
childrenTable[sourceID] = currentChildren
|
|
parentTable[destinationID] = currentParents
|
|
return childrenTable, parentTable
|
|
|
|
|
|
def toposort (nodes, routes, noRecursion=1):
|
|
'''Topological sort from Tim Peters, fairly efficient
|
|
in comparison (it seems).'''
|
|
#first calculate the recursion depth
|
|
|
|
dependencies = {}
|
|
inversedependencies = {}
|
|
if not nodes:
|
|
return []
|
|
if not routes:
|
|
return [nodes]
|
|
for node in nodes:
|
|
dependencies[ node ] = (0, node)
|
|
inversedependencies[ node ] = []
|
|
|
|
|
|
for depended, depends in routes:
|
|
# is it a null rule
|
|
try:
|
|
newdependencylevel, object = dependencies.get ( depends, (0, depends))
|
|
except TypeError:
|
|
print depends
|
|
raise
|
|
dependencies[ depends ] = (newdependencylevel + 1, depends)
|
|
# "dependency (existence) of depended-on"
|
|
newdependencylevel,object = dependencies.get ( depended, (0, depended) )
|
|
dependencies[ depended ] = (newdependencylevel, depended)
|
|
# Inverse dependency set up
|
|
dependencieslist = inversedependencies.get ( depended, [])
|
|
dependencieslist.append (depends)
|
|
inversedependencies[depended] = dependencieslist
|
|
### Now we do the actual sorting
|
|
# The first task is to create the sortable
|
|
# list of dependency-levels
|
|
sortinglist = dependencies.values()
|
|
sortinglist.sort ()
|
|
output = []
|
|
while sortinglist:
|
|
deletelist = []
|
|
generation = []
|
|
output.append( generation)
|
|
while sortinglist and sortinglist[0][0] == 0:
|
|
number, object = sortinglist[0]
|
|
generation.append ( object )
|
|
deletelist.append( object )
|
|
for inverse in inversedependencies.get(object, () ):
|
|
try:
|
|
oldcount, inverse = dependencies [ inverse]
|
|
if oldcount > 0:
|
|
# will be dealt with on later pass
|
|
dependencies [ inverse] = (oldcount-1, inverse)
|
|
else:
|
|
# will be dealt with on this pass,
|
|
# so needs not to be in the sorting list next time
|
|
deletelist.append( inverse )
|
|
# just in case a loop comes through
|
|
inversedependencies[object] = []
|
|
except KeyError:
|
|
# dealing with a recursion-breaking run...
|
|
pass
|
|
del sortinglist [0]
|
|
# if no elements could be deleted, then
|
|
# there is something which depends upon itself
|
|
if not deletelist:
|
|
if noRecursion:
|
|
raise RecursionError( sortinglist )
|
|
else:
|
|
# hack so that something gets deleted...
|
|
## import pdb
|
|
## pdb.set_trace()
|
|
dependencies[sortinglist[0][1]] = (0,sortinglist[0][1])
|
|
# delete the items that were dealt with
|
|
for item in deletelist:
|
|
try:
|
|
del dependencies [ item ]
|
|
except KeyError:
|
|
pass
|
|
# need to recreate the sortinglist
|
|
sortinglist = dependencies.values()
|
|
if not generation:
|
|
output.remove( generation )
|
|
sortinglist.sort ()
|
|
return output
|
|
|
|
|
|
|
|
|
|
|
|
if __name__ == "__main__":
|
|
|
|
nodes = ['a', 'b', 'c', 'd', 'e', 'f']
|
|
route = [('a', 'b'), ('b', 'c'), ('b', 'd'), ('e','f')]
|
|
|
|
for x in toposort( nodes, route):
|
|
for a in x:
|
|
print a
|
|
|
|
raise SystemExit
|
|
|
|
|
|
|
|
import pprint, traceback
|
|
nodes= [ 0,1,2,3,4,5 ]
|
|
testingValues = [
|
|
[ (0,1),(1,2),(2,3),(3,4),(4,5)],
|
|
[ (0,1),(0,2),(1,2),(3,4),(4,5)],
|
|
[
|
|
(0,1),
|
|
(0,2),
|
|
(0,2),
|
|
(2,4),
|
|
(2,5),
|
|
(3,2),
|
|
(0,3)],
|
|
[
|
|
(0,1), # 3-element cycle test, no orphan nodes
|
|
(1,2),
|
|
(2,0),
|
|
(2,4),
|
|
(2,5),
|
|
(3,2),
|
|
(0,3)],
|
|
[
|
|
(0,1),
|
|
(1,1),
|
|
(1,1),
|
|
(1,4),
|
|
(1,5),
|
|
(1,2),
|
|
(3,1),
|
|
(2,1),
|
|
(2,0)],
|
|
[
|
|
(0,1),
|
|
(1,0),
|
|
(0,2),
|
|
(0,3),
|
|
],
|
|
[
|
|
(0,1),
|
|
(1,0),
|
|
(0,2),
|
|
(3,1),
|
|
],
|
|
]
|
|
print 'sort, no recursion allowed'
|
|
for index in range(len(testingValues)):
|
|
## print ' %s -- %s'%( index, testingValues[index])
|
|
try:
|
|
print ' ', sort( nodes, testingValues[index] )
|
|
except:
|
|
print 'exception raised'
|
|
print 'toposort, no recursion allowed'
|
|
for index in range(len(testingValues)):
|
|
## print ' %s -- %s'%( index, testingValues[index])
|
|
try:
|
|
print ' ', toposort( nodes, testingValues[index] )
|
|
except:
|
|
print 'exception raised'
|
|
print 'sort, recursion allowed'
|
|
for index in range(len(testingValues)):
|
|
## print ' %s -- %s'%( index, testingValues[index])
|
|
try:
|
|
print ' ', sort( nodes, testingValues[index],0 )
|
|
except:
|
|
print 'exception raised'
|
|
print 'toposort, recursion allowed'
|
|
for index in range(len(testingValues)):
|
|
## print ' %s -- %s'%( index, testingValues[index])
|
|
try:
|
|
print ' ', toposort( nodes, testingValues[index],0 )
|
|
except:
|
|
print 'exception raised'
|
|
|
|
|
|
|