dirstate-tree: Add tree traversal/iteration
Like Python’s, Rust’s iterators are "external" in that they are driven
by a caller who calls a `next` method. This is as opposed to "internal"
iterators who drive themselves and call a callback for each item.
Writing an internal iterator traversing a tree is easy with recursion,
but internal iterators cannot rely on the call stack in that way,
they must save in an explicit object all state that they need to be
preserved across two `next` calls.
This algorithm uses a `Vec` as a stack that contains what would be
local variables on the call stack if we could use recursion.
Differential Revision: https://phab.mercurial-scm.org/D10370
from __future__ import absolute_import
import unittest
try:
from mercurial import rustext
rustext.__name__ # trigger immediate actual import
except ImportError:
rustext = None
else:
from mercurial.rustext import revlog
# this would fail already without appropriate ancestor.__package__
from mercurial.rustext.ancestor import LazyAncestors
from mercurial.testing import revlog as revlogtesting
@unittest.skipIf(
rustext is None,
"rustext module revlog relies on is not available",
)
class RustRevlogIndexTest(revlogtesting.RevlogBasedTestBase):
def test_heads(self):
idx = self.parseindex()
rustidx = revlog.MixedIndex(idx)
self.assertEqual(rustidx.headrevs(), idx.headrevs())
def test_get_cindex(self):
# drop me once we no longer need the method for shortest node
idx = self.parseindex()
rustidx = revlog.MixedIndex(idx)
cidx = rustidx.get_cindex()
self.assertTrue(idx is cidx)
def test_len(self):
idx = self.parseindex()
rustidx = revlog.MixedIndex(idx)
self.assertEqual(len(rustidx), len(idx))
def test_ancestors(self):
idx = self.parseindex()
rustidx = revlog.MixedIndex(idx)
lazy = LazyAncestors(rustidx, [3], 0, True)
# we have two more references to the index:
# - in its inner iterator for __contains__ and __bool__
# - in the LazyAncestors instance itself (to spawn new iterators)
self.assertTrue(2 in lazy)
self.assertTrue(bool(lazy))
self.assertEqual(list(lazy), [3, 2, 1, 0])
# a second time to validate that we spawn new iterators
self.assertEqual(list(lazy), [3, 2, 1, 0])
# let's check bool for an empty one
self.assertFalse(LazyAncestors(idx, [0], 0, False))
if __name__ == '__main__':
import silenttestrunner
silenttestrunner.main(__name__)