Merge pull request #489 from chisholm/fix_xform_followedby_order

Fix observation expression DNF transformer to preserve FOLLOWEDBY order.
pull/1/head
Chris Lenk 2021-02-05 10:00:48 -05:00 committed by GitHub
commit 58b79597b6
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2 changed files with 29 additions and 12 deletions

View File

@ -282,6 +282,7 @@ class AbsorptionTransformer(
A or (A and B) = A
A or (A followedby B) = A
A or (B followedby A) = A
Other variants do not hold for observation expressions.
"""
@ -435,28 +436,35 @@ class DNFTransformer(ObservationExpressionTransformer):
A and (B or C) => (A and B) or (A and C)
A followedby (B or C) => (A followedby B) or (A followedby C)
(A or B) followedby C => (A followedby C) or (B followedby C)
"""
def __transform(self, ast):
root_type = type(ast) # will be AST class for AND or FOLLOWEDBY
changed = False
or_children = []
other_children = []
# If no OR children, nothing to do
if any(
isinstance(child, OrObservationExpression)
for child in ast.operands
):
# When we distribute FOLLOWEDBY over OR, it is important to
# preserve the original FOLLOWEDBY order! We don't need to do that
# for AND, but we do it anyway because it doesn't hurt, and we can
# use the same code for both.
iterables = []
for child in ast.operands:
if isinstance(child, OrObservationExpression):
or_children.append(child.operands)
iterables.append(child.operands)
else:
other_children.append(child)
iterables.append((child,))
if or_children:
root_type = type(ast) # will be AST class for AND or FOLLOWEDBY
distributed_children = [
root_type([
_dupe_ast(sub_ast) for sub_ast in itertools.chain(
other_children, prod_seq,
prod_seq,
)
])
for prod_seq in itertools.product(*or_children)
for prod_seq in itertools.product(*iterables)
]
# Need to recursively continue to distribute AND/FOLLOWEDBY over OR
@ -470,6 +478,7 @@ class DNFTransformer(ObservationExpressionTransformer):
else:
result = ast
changed = False
return result, changed

View File

@ -223,6 +223,10 @@ def test_obs_absorb_not_equivalent(patt1, patt2):
"([a:b=1] OR [a:b=2]) FOLLOWEDBY ([a:b=3] OR [a:b=4])",
"([a:b=1] FOLLOWEDBY [a:b=3]) OR ([a:b=1] FOLLOWEDBY [a:b=4]) OR ([a:b=2] FOLLOWEDBY [a:b=3]) OR ([a:b=2] FOLLOWEDBY [a:b=4])",
),
(
"([a:b=1] OR [a:b=2]) FOLLOWEDBY ([a:b=5] AND [a:b=6])",
"([a:b=1] FOLLOWEDBY ([a:b=5] AND [a:b=6])) OR ([a:b=2] FOLLOWEDBY ([a:b=5] AND [a:b=6]))",
),
],
)
def test_obs_dnf_equivalent(patt1, patt2):
@ -243,6 +247,10 @@ def test_obs_dnf_equivalent(patt1, patt2):
"[a:b=1] WITHIN 2 SECONDS",
"[a:b=1] REPEATS 2 TIMES",
),
(
"[a:b=1] FOLLOWEDBY ([a:b=2] OR [a:b=3])",
"([a:b=2] FOLLOWEDBY [a:b=1]) OR ([a:b=1] FOLLOWEDBY [a:b=3])",
),
],
)
def test_obs_not_equivalent(patt1, patt2):