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from typing import Dict, Optional
from jedi.parser_utils import get_flow_branch_keyword, is_scope, get_parent_scope
from jedi.inference.recursion import execution_allowed
from jedi.inference.helpers import is_big_annoying_library
class Status:
lookup_table: Dict[Optional[bool], 'Status'] = {}
def __init__(self, value: Optional[bool], name: str) -> None:
self._value = value
self._name = name
Status.lookup_table[value] = self
def invert(self):
if self is REACHABLE:
return UNREACHABLE
elif self is UNREACHABLE:
return REACHABLE
else:
return UNSURE
def __and__(self, other):
if UNSURE in (self, other):
return UNSURE
else:
return REACHABLE if self._value and other._value else UNREACHABLE
def __repr__(self):
return '<%s: %s>' % (type(self).__name__, self._name)
REACHABLE = Status(True, 'reachable')
UNREACHABLE = Status(False, 'unreachable')
UNSURE = Status(None, 'unsure')
def _get_flow_scopes(node):
while True:
node = get_parent_scope(node, include_flows=True)
if node is None or is_scope(node):
return
yield node
def reachability_check(context, value_scope, node, origin_scope=None):
if is_big_annoying_library(context) \
or not context.inference_state.flow_analysis_enabled:
return UNSURE
first_flow_scope = get_parent_scope(node, include_flows=True)
if origin_scope is not None:
origin_flow_scopes = list(_get_flow_scopes(origin_scope))
node_flow_scopes = list(_get_flow_scopes(node))
branch_matches = True
for flow_scope in origin_flow_scopes:
if flow_scope in node_flow_scopes:
node_keyword = get_flow_branch_keyword(flow_scope, node)
origin_keyword = get_flow_branch_keyword(flow_scope, origin_scope)
branch_matches = node_keyword == origin_keyword
if flow_scope.type == 'if_stmt':
if not branch_matches:
return UNREACHABLE
elif flow_scope.type == 'try_stmt':
if not branch_matches and origin_keyword == 'else' \
and node_keyword == 'except':
return UNREACHABLE
if branch_matches:
break
# Direct parents get resolved, we filter scopes that are separate
# branches. This makes sense for autocompletion and static analysis.
# For actual Python it doesn't matter, because we're talking about
# potentially unreachable code.
# e.g. `if 0:` would cause all name lookup within the flow make
# unaccessible. This is not a "problem" in Python, because the code is
# never called. In Jedi though, we still want to infer types.
while origin_scope is not None:
if first_flow_scope == origin_scope and branch_matches:
return REACHABLE
origin_scope = origin_scope.parent
return _break_check(context, value_scope, first_flow_scope, node)
def _break_check(context, value_scope, flow_scope, node):
reachable = REACHABLE
if flow_scope.type == 'if_stmt':
if flow_scope.is_node_after_else(node):
for check_node in flow_scope.get_test_nodes():
reachable = _check_if(context, check_node)
if reachable in (REACHABLE, UNSURE):
break
reachable = reachable.invert()
else:
flow_node = flow_scope.get_corresponding_test_node(node)
if flow_node is not None:
reachable = _check_if(context, flow_node)
elif flow_scope.type in ('try_stmt', 'while_stmt'):
return UNSURE
# Only reachable branches need to be examined further.
if reachable in (UNREACHABLE, UNSURE):
return reachable
if value_scope != flow_scope and value_scope != flow_scope.parent:
flow_scope = get_parent_scope(flow_scope, include_flows=True)
return reachable & _break_check(context, value_scope, flow_scope, node)
else:
return reachable
def _check_if(context, node):
with execution_allowed(context.inference_state, node) as allowed:
if not allowed:
return UNSURE
types = context.infer_node(node)
values = set(x.py__bool__() for x in types)
if len(values) == 1:
return Status.lookup_table[values.pop()]
else:
return UNSURE
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