bpo-17005: Move topological sort functionality to its own module (GH-20558)
The topological sort functionality that was introduced initially in the
functools module has been moved to a new graphlib module to
better accommodate the new tools and keep the original scope of the
functools module.
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 72b7765..e726188 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -3,7 +3,7 @@
import collections
import collections.abc
import copy
-from itertools import permutations, chain
+from itertools import permutations
import pickle
from random import choice
import sys
@@ -1164,275 +1164,6 @@
return self.value == other.value
-class TestTopologicalSort(unittest.TestCase):
-
- def _test_graph(self, graph, expected):
-
- def static_order_with_groups(ts):
- ts.prepare()
- while ts.is_active():
- nodes = ts.get_ready()
- for node in nodes:
- ts.done(node)
- yield nodes
-
- ts = functools.TopologicalSorter(graph)
- self.assertEqual(list(static_order_with_groups(ts)), list(expected))
-
- ts = functools.TopologicalSorter(graph)
- self.assertEqual(list(ts.static_order()), list(chain(*expected)))
-
- def _assert_cycle(self, graph, cycle):
- ts = functools.TopologicalSorter()
- for node, dependson in graph.items():
- ts.add(node, *dependson)
- try:
- ts.prepare()
- except functools.CycleError as e:
- msg, seq = e.args
- self.assertIn(' '.join(map(str, cycle)),
- ' '.join(map(str, seq * 2)))
- else:
- raise
-
- def test_simple_cases(self):
- self._test_graph(
- {2: {11},
- 9: {11, 8},
- 10: {11, 3},
- 11: {7, 5},
- 8: {7, 3}},
- [(3, 5, 7), (11, 8), (2, 10, 9)]
- )
-
- self._test_graph({1: {}}, [(1,)])
-
- self._test_graph({x: {x+1} for x in range(10)},
- [(x,) for x in range(10, -1, -1)])
-
- self._test_graph({2: {3}, 3: {4}, 4: {5}, 5: {1},
- 11: {12}, 12: {13}, 13: {14}, 14: {15}},
- [(1, 15), (5, 14), (4, 13), (3, 12), (2, 11)])
-
- self._test_graph({
- 0: [1, 2],
- 1: [3],
- 2: [5, 6],
- 3: [4],
- 4: [9],
- 5: [3],
- 6: [7],
- 7: [8],
- 8: [4],
- 9: []
- },
- [(9,), (4,), (3, 8), (1, 5, 7), (6,), (2,), (0,)]
- )
-
- self._test_graph({
- 0: [1, 2],
- 1: [],
- 2: [3],
- 3: []
- },
- [(1, 3), (2,), (0,)]
- )
-
- self._test_graph({
- 0: [1, 2],
- 1: [],
- 2: [3],
- 3: [],
- 4: [5],
- 5: [6],
- 6: []
- },
- [(1, 3, 6), (2, 5), (0, 4)]
- )
-
- def test_no_dependencies(self):
- self._test_graph(
- {1: {2},
- 3: {4},
- 5: {6}},
- [(2, 4, 6), (1, 3, 5)]
- )
-
- self._test_graph(
- {1: set(),
- 3: set(),
- 5: set()},
- [(1, 3, 5)]
- )
-
- def test_the_node_multiple_times(self):
- # Test same node multiple times in dependencies
- self._test_graph({1: {2}, 3: {4}, 0: [2, 4, 4, 4, 4, 4]},
- [(2, 4), (1, 3, 0)])
-
- # Test adding the same dependency multiple times
- ts = functools.TopologicalSorter()
- ts.add(1, 2)
- ts.add(1, 2)
- ts.add(1, 2)
- self.assertEqual([*ts.static_order()], [2, 1])
-
- def test_graph_with_iterables(self):
- dependson = (2*x + 1 for x in range(5))
- ts = functools.TopologicalSorter({0: dependson})
- self.assertEqual(list(ts.static_order()), [1, 3, 5, 7, 9, 0])
-
- def test_add_dependencies_for_same_node_incrementally(self):
- # Test same node multiple times
- ts = functools.TopologicalSorter()
- ts.add(1, 2)
- ts.add(1, 3)
- ts.add(1, 4)
- ts.add(1, 5)
-
- ts2 = functools.TopologicalSorter({1: {2, 3, 4, 5}})
- self.assertEqual([*ts.static_order()], [*ts2.static_order()])
-
- def test_empty(self):
- self._test_graph({}, [])
-
- def test_cycle(self):
- # Self cycle
- self._assert_cycle({1: {1}}, [1, 1])
- # Simple cycle
- self._assert_cycle({1: {2}, 2: {1}}, [1, 2, 1])
- # Indirect cycle
- self._assert_cycle({1: {2}, 2: {3}, 3: {1}}, [1, 3, 2, 1])
- # not all elements involved in a cycle
- self._assert_cycle({1: {2}, 2: {3}, 3: {1}, 5: {4}, 4: {6}}, [1, 3, 2, 1])
- # Multiple cycles
- self._assert_cycle({1: {2}, 2: {1}, 3: {4}, 4: {5}, 6: {7}, 7: {6}},
- [1, 2, 1])
- # Cycle in the middle of the graph
- self._assert_cycle({1: {2}, 2: {3}, 3: {2, 4}, 4: {5}}, [3, 2])
-
- def test_calls_before_prepare(self):
- ts = functools.TopologicalSorter()
-
- with self.assertRaisesRegex(ValueError, r"prepare\(\) must be called first"):
- ts.get_ready()
- with self.assertRaisesRegex(ValueError, r"prepare\(\) must be called first"):
- ts.done(3)
- with self.assertRaisesRegex(ValueError, r"prepare\(\) must be called first"):
- ts.is_active()
-
- def test_prepare_multiple_times(self):
- ts = functools.TopologicalSorter()
- ts.prepare()
- with self.assertRaisesRegex(ValueError, r"cannot prepare\(\) more than once"):
- ts.prepare()
-
- def test_invalid_nodes_in_done(self):
- ts = functools.TopologicalSorter()
- ts.add(1, 2, 3, 4)
- ts.add(2, 3, 4)
- ts.prepare()
- ts.get_ready()
-
- with self.assertRaisesRegex(ValueError, "node 2 was not passed out"):
- ts.done(2)
- with self.assertRaisesRegex(ValueError, r"node 24 was not added using add\(\)"):
- ts.done(24)
-
- def test_done(self):
- ts = functools.TopologicalSorter()
- ts.add(1, 2, 3, 4)
- ts.add(2, 3)
- ts.prepare()
-
- self.assertEqual(ts.get_ready(), (3, 4))
- # If we don't mark anything as done, get_ready() returns nothing
- self.assertEqual(ts.get_ready(), ())
- ts.done(3)
- # Now 2 becomes available as 3 is done
- self.assertEqual(ts.get_ready(), (2,))
- self.assertEqual(ts.get_ready(), ())
- ts.done(4)
- ts.done(2)
- # Only 1 is missing
- self.assertEqual(ts.get_ready(), (1,))
- self.assertEqual(ts.get_ready(), ())
- ts.done(1)
- self.assertEqual(ts.get_ready(), ())
- self.assertFalse(ts.is_active())
-
- def test_is_active(self):
- ts = functools.TopologicalSorter()
- ts.add(1, 2)
- ts.prepare()
-
- self.assertTrue(ts.is_active())
- self.assertEqual(ts.get_ready(), (2,))
- self.assertTrue(ts.is_active())
- ts.done(2)
- self.assertTrue(ts.is_active())
- self.assertEqual(ts.get_ready(), (1,))
- self.assertTrue(ts.is_active())
- ts.done(1)
- self.assertFalse(ts.is_active())
-
- def test_not_hashable_nodes(self):
- ts = functools.TopologicalSorter()
- self.assertRaises(TypeError, ts.add, dict(), 1)
- self.assertRaises(TypeError, ts.add, 1, dict())
- self.assertRaises(TypeError, ts.add, dict(), dict())
-
- def test_order_of_insertion_does_not_matter_between_groups(self):
- def get_groups(ts):
- ts.prepare()
- while ts.is_active():
- nodes = ts.get_ready()
- ts.done(*nodes)
- yield set(nodes)
-
- ts = functools.TopologicalSorter()
- ts.add(3, 2, 1)
- ts.add(1, 0)
- ts.add(4, 5)
- ts.add(6, 7)
- ts.add(4, 7)
-
- ts2 = functools.TopologicalSorter()
- ts2.add(1, 0)
- ts2.add(3, 2, 1)
- ts2.add(4, 7)
- ts2.add(6, 7)
- ts2.add(4, 5)
-
- self.assertEqual(list(get_groups(ts)), list(get_groups(ts2)))
-
- def test_static_order_does_not_change_with_the_hash_seed(self):
- def check_order_with_hash_seed(seed):
- code = """if 1:
- import functools
- ts = functools.TopologicalSorter()
- ts.add('blech', 'bluch', 'hola')
- ts.add('abcd', 'blech', 'bluch', 'a', 'b')
- ts.add('a', 'a string', 'something', 'b')
- ts.add('bluch', 'hola', 'abcde', 'a', 'b')
- print(list(ts.static_order()))
- """
- env = os.environ.copy()
- # signal to assert_python not to do a copy
- # of os.environ on its own
- env['__cleanenv'] = True
- env['PYTHONHASHSEED'] = str(seed)
- out = assert_python_ok('-c', code, **env)
- return out
-
- run1 = check_order_with_hash_seed(1234)
- run2 = check_order_with_hash_seed(31415)
-
- self.assertNotEqual(run1, "")
- self.assertNotEqual(run2, "")
- self.assertEqual(run1, run2)
-
-
class TestCache:
# This tests that the pass-through is working as designed.
# The underlying functionality is tested in TestLRU.