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