def test_add_edge_to_non_empty(self):
d = Digraph(3)
d.add_edge(1,2)
self.assertEquals(1, len(d.links(1)))
self.assertEquals(0, len(d.links(2)))
class SymbolDigraph(object):
"""Like digraph but operates with strings, you can never remove edges"""
def __init__(self,size=0):
self.symboltable = {}
self.names = []
self.digraph = Digraph(size)
def add_vertice(self, edge_from):
"""Add named vertice"""
index_from = self._check_index(edge_from)
self._check_digraph_size(index_from)
self.names[index_from] = edge_from
def add_edge(self, edge_from, edge_to):
"""Add named edge link"""
index_from = self._check_index(edge_from)
index_to = self._check_index(edge_to)
self._check_digraph_size(max(index_from, index_to))
self.digraph.add_edge(index_from, index_to)
def _check_index(self, key):
"""if exists, returns id, otherwise adds a new one and also returns"""
keyname = str(key)
#print "_check_index", key, "len(keyname)", len(keyname)
if key == None or not(len(keyname)):
raise Exception("Edge name cannot be none")
if self.index(keyname) == -1:
index = len(self.symboltable)
self.symboltable[keyname] = index
self._check_names_size(index)
self.names[index] = key
return self.symboltable[keyname]
def index(self, key):
"""returns internal index by key"""
if self.symboltable.has_key(key):
return self.symboltable[key]
return -1
def _check_digraph_size(self, index):
"""resizes graph accordingly"""
i = index - self.digraph.count_vertices()
while i >= 0:
self.digraph.add_vertice()
i -= 1
def _check_names_size(self, index):
"""resizes graph accordingly"""
i = index - len(self.names)
while i >= 0:
self.names.append(None)
i -= 1
def count_vertices(self):
"""returns number of vertices (nodes)"""
return self.digraph.count_vertices()
def count_edges(self):
"""returns number of edges(links)"""
return self.digraph.count_edges()
def vertices(self):
"Named vertices"
return self.names
def links(self, key):
"Links from node"
names = []
for linkid in self.digraph.links(self.index(key)):
names.append(self.name(linkid))
return names
def name(self, index):
"""Symbol by index"""
return self.names[index]