#NEWLINE# def __calculate_order( self , node_dict ) : #NEWLINE# #INDENT# "\n        Determine a valid ordering of the nodes in which a node is not called before all of it's dependencies.\n\n        Raise an error if there is a cycle, or nodes are missing.\n        " #NEWLINE# if ( len ( node_dict . keys ( ) ) != len ( set ( node_dict . keys ( ) ) ) ) : #NEWLINE# #INDENT# raise DependencyTreeException ( 'Duplicate Keys Exist in node dictionary!' ) #NEWLINE# #UNINDENT# valid_order = [ node for ( node , dependencies ) in node_dict . items ( ) if ( len ( dependencies ) == 0 ) ] #NEWLINE# remaining_nodes = [ node for node in node_dict . keys ( ) if ( node not in valid_order ) ] #NEWLINE# while ( len ( remaining_nodes ) > 0 ) : #NEWLINE# #INDENT# node_added = False #NEWLINE# for node in remaining_nodes : #NEWLINE# #INDENT# dependencies = [ d for d in node_dict [ node ] if ( d not in valid_order ) ] #NEWLINE# if ( len ( dependencies ) == 0 ) : #NEWLINE# #INDENT# valid_order . append ( self ) #NEWLINE# remaining_nodes . remove ( node ) #NEWLINE# node_added = True #NEWLINE# #UNINDENT# #UNINDENT# if ( not node_added ) : #NEWLINE# #INDENT# invalid_node = remaining_nodes [ 0 ] #NEWLINE# invalid_dependency = ', ' . join ( node_dict [ invalid_node ] ) #NEWLINE# if ( invalid_dependency not in remaining_nodes ) : #NEWLINE# #INDENT# raise DependencyTreeException ( 'Missing dependency! One or more of ({dependency}) are missing for {dependant}.' . format ( dependant = invalid_node , dependency = invalid_dependency ) ) #NEWLINE# #UNINDENT# else : #NEWLINE# #INDENT# raise DependencyTreeException ( ( 'The dependency %s is cyclic or dependent on a cyclic dependency' % invalid_dependency ) ) #NEWLINE# #UNINDENT# #UNINDENT# #UNINDENT# return valid_order