class Relation (IRelation,ILeftListRelation,IRightListRelation,ILinkRelation,IMutableRelation) :
"""
implementation of a relation
"""
def __init__ (self, idgenerator = "set") :
"""
constructor of an empty relation
"""
self._left_links=IdDict(idgenerator = idgenerator)
self._right_links=IdDict(idgenerator = idgenerator)
self._link_extremities=IdDict(idgenerator = idgenerator)
########################################################################
#
# Relation concept
#
########################################################################
def is_valid (self) :
return True
is_valid.__doc__=IRelation.is_valid.__doc__
def has_left (self, elmid) :
return elmid in self._left_links
has_left.__doc__=IRelation.has_left.__doc__
def has_right (self, elmid) :
return elmid in self._right_links
has_right.__doc__=IRelation.has_right.__doc__
def has_link (self, lid) :
return lid in self._link_extremities
has_link.__doc__=IRelation.has_link.__doc__
########################################################################
#
# Left list concept
#
########################################################################
def left_elements (self) :
return self._left_links.iterkeys()
left_elements.__doc__=ILeftListRelation.left_elements.__doc__
def nb_left_elements (self) :
return len(self._left_links)
nb_left_elements.__doc__=ILeftListRelation.nb_left_elements.__doc__
########################################################################
#
# Right list concept
#
########################################################################
def right_elements (self) :
return self._right_links.iterkeys()
right_elements.__doc__=IRightListRelation.right_elements.__doc__
def nb_right_elements (self) :
return len(self._right_links)
nb_right_elements.__doc__=IRightListRelation.nb_right_elements.__doc__
########################################################################
#
# Link Relation concept
#
########################################################################
def links (self) :
return self._link_extremities.iterkeys()
links.__doc__=ILinkRelation.links.__doc__
def from_left (self, elmid) :
try :
return iter(self._left_links[elmid])
except KeyError :
raise StrInvalidLeft(elmid)
from_left.__doc__=ILinkRelation.from_left.__doc__
def nb_links_from_left (self, elmid) :
try :
return len(self._left_links[elmid])
except KeyError :
raise StrInvalidLeft(elmid)
nb_links_from_left.__doc__=ILinkRelation.nb_links_from_left.__doc__
def from_right (self, elmid) :
try :
return iter(self._right_links[elmid])
except KeyError :
raise StrInvalidRight(elmid)
from_right.__doc__=ILinkRelation.from_right.__doc__
def nb_links_from_right (self, elmid) :
try :
return len(self._right_links[elmid])
except KeyError :
raise StrInvalidRight(elmid)
nb_links_from_right.__doc__=ILinkRelation.nb_links_from_right.__doc__
def left (self, lid) :
try :
return self._link_extremities[lid][0]
except KeyError :
raise StrInvalidLink(lid)
left.__doc__=ILinkRelation.left.__doc__
def right (self, lid) :
try :
return self._link_extremities[lid][1]
except KeyError :
raise StrInvalidLink(lid)
right.__doc__=ILinkRelation.right.__doc__
########################################################################
#
# Mutable relation concept
#
########################################################################
def add_left_element (self, elmid=None) :
return self._left_links.add(set(),elmid)
add_left_element.__doc__=IMutableRelation.add_left_element.__doc__
def remove_left_element (self, elmid) :
for lid in list(self.from_left(elmid)) :
self.remove_link(lid)
del self._left_links[elmid]
remove_left_element.__doc__=IMutableRelation.remove_left_element.__doc__
def add_right_element (self, elmid=None) :
return self._right_links.add(set(),elmid)
add_right_element.__doc__=IMutableRelation.add_right_element.__doc__
def remove_right_element (self, elmid) :
for lid in list(self.from_right(elmid)) :
self.remove_link(lid)
del self._right_links[elmid]
remove_right_element.__doc__=IMutableRelation.remove_right_element.__doc__
def add_link (self, left_elmid, right_elmid, lid=None) :
if not self.has_left(left_elmid) :
raise StrInvalidLeft(left_elmid)
if not self.has_right(right_elmid) :
raise StrInvalidRight(right_elmid)
lid=self._link_extremities.add( (left_elmid,right_elmid),lid )
self._left_links[left_elmid].add(lid)
self._right_links[right_elmid].add(lid)
return lid
add_link.__doc__=IMutableRelation.add_link.__doc__
def remove_link (self, lid) :
self._left_links[self.left(lid)].remove(lid)
self._right_links[self.right(lid)].remove(lid)
del self._link_extremities[lid]
remove_link.__doc__=IMutableRelation.remove_link.__doc__
