#!/usr/bin/env python
# Copyright (c) 2008 Florian Mayer
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
""" A simple dependency resolver """
def no_deps(items, deps, built):
""" Get items that have no unbuilt dependencies """
return [i for i in items if not depends_on_unbuilt(i, deps, built)]
def depends_on_unbuilt(item, deps, built):
""" See if item depends on any item not built """
if not item in deps:
return False
return any(d not in built for d in deps[item])
def resolve_paralell(items, deps):
""" Returns a list of sets of tasks that can be done paralelly """
items = set(items)
built = set()
out = []
while True:
if not items:
break
no_d = set(no_deps(items, deps, built))
items -= no_d
built |= no_d
out.append(no_d)
if set(sum(deps.values(), [])) == built:
out.append(items)
break
return out
if __name__ == '__main__':
jobs = ['a', 'b', 'c', 'd', 'e']
deps = {'a': ['b', 'c'], 'b': ['d', 'e']}
print resolve_paralell(jobs, deps)
