Solution for Code Kata # 18

gistfile1.py

import collections
from pprint import pformat

{
    'A': ['B', 'C'],
    'B': ['C', 'E'],
}


class Dependencies(object):
    tree = collections.defaultdict(set)

    def add_direct(self, node, dependencies):
        self.tree[node].update(dependencies)

    def dependencies_for(self, node, found_deps=None, root_node=None):
        # import pdb; pdb.set_trace()
        if not found_deps:
            root_node = node
            found_deps = set()

        for i in self.tree[node]:
            if i == root_node:
                raise Exception('Circular dependency')
            else:
                found_deps.update(i)
            self.dependencies_for(i, found_deps, root_node)
        return found_deps

    def __repr__(self):
        return pformat(self.tree)

    def __str__(self):
        return pformat(self.tree)


dep = Dependencies()
print('Tree after init', dep)

dep.add_direct('A', ['B', 'C'])
print('Tree after 1st insert:', dep)

dep.add_direct('B', ['C', 'E'])
print('Tree after 2nd insert:', dep)

print("A's dependencies: ", dep.dependencies_for('A'))