forked from VimPlug/jedi
386 lines
15 KiB
Python
386 lines
15 KiB
Python
"""
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Searching for names with given scope and name. This is very central in Jedi and
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Python. The name resolution is quite complicated with descripter,
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``__getattribute__``, ``__getattr__``, ``global``, etc.
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If you want to understand name resolution, please read the first few chapters
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in http://blog.ionelmc.ro/2015/02/09/understanding-python-metaclasses/.
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Flow checks
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+++++++++++
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Flow checks are not really mature. There's only a check for ``isinstance``. It
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would check whether a flow has the form of ``if isinstance(a, type_or_tuple)``.
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Unfortunately every other thing is being ignored (e.g. a == '' would be easy to
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check for -> a is a string). There's big potential in these checks.
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"""
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from parso.python import tree
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from parso.tree import search_ancestor
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from jedi import debug
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from jedi.common import unite
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from jedi import settings
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from jedi.evaluate import representation as er
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from jedi.evaluate.instance import AbstractInstanceContext
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from jedi.evaluate import compiled
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from jedi.evaluate import pep0484
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from jedi.evaluate import iterable
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from jedi.evaluate import imports
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from jedi.evaluate import analysis
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from jedi.evaluate import flow_analysis
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from jedi.evaluate import param
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from jedi.evaluate import helpers
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from jedi.evaluate.filters import get_global_filters
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from jedi.evaluate.context import ContextualizedName, ContextualizedNode
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from jedi.parser_utils import is_scope, get_parent_scope
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class NameFinder(object):
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def __init__(self, evaluator, context, name_context, name_or_str, position=None):
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self._evaluator = evaluator
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# Make sure that it's not just a syntax tree node.
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self._context = context
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self._name_context = name_context
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self._name = name_or_str
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if isinstance(name_or_str, tree.Name):
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self._string_name = name_or_str.value
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else:
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self._string_name = name_or_str
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self._position = position
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self._found_predefined_types = None
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@debug.increase_indent
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def find(self, filters, attribute_lookup):
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"""
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:params bool attribute_lookup: Tell to logic if we're accessing the
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attribute or the contents of e.g. a function.
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"""
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names = self.filter_name(filters)
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if self._found_predefined_types is not None and names:
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check = flow_analysis.reachability_check(
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self._context, self._context.tree_node, self._name)
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if check is flow_analysis.UNREACHABLE:
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return set()
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return self._found_predefined_types
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types = self._names_to_types(names, attribute_lookup)
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if not names and not types \
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and not (isinstance(self._name, tree.Name) and
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isinstance(self._name.parent.parent, tree.Param)):
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if isinstance(self._name, tree.Name):
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if attribute_lookup:
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analysis.add_attribute_error(
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self._name_context, self._context, self._name)
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else:
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message = ("NameError: name '%s' is not defined."
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% self._string_name)
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analysis.add(self._name_context, 'name-error', self._name, message)
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return types
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def _get_origin_scope(self):
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if isinstance(self._name, tree.Name):
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scope = self._name
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while scope.parent is not None:
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# TODO why if classes?
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if not isinstance(scope, tree.Scope):
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break
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scope = scope.parent
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return scope
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else:
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return None
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def get_filters(self, search_global=False):
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origin_scope = self._get_origin_scope()
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if search_global:
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return get_global_filters(self._evaluator, self._context, self._position, origin_scope)
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else:
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return self._context.get_filters(search_global, self._position, origin_scope=origin_scope)
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def filter_name(self, filters):
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"""
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Searches names that are defined in a scope (the different
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``filters``), until a name fits.
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"""
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names = []
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if self._context.predefined_names:
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# TODO is this ok? node might not always be a tree.Name
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node = self._name
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while node is not None and not is_scope(node):
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node = node.parent
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if node.type in ("if_stmt", "for_stmt", "comp_for"):
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try:
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name_dict = self._context.predefined_names[node]
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types = name_dict[self._string_name]
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except KeyError:
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continue
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else:
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self._found_predefined_types = types
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break
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for filter in filters:
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names = filter.get(self._string_name)
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if names:
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break
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debug.dbg('finder.filter_name "%s" in (%s): %s@%s', self._string_name,
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self._context, names, self._position)
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return list(names)
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def _check_getattr(self, inst):
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"""Checks for both __getattr__ and __getattribute__ methods"""
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# str is important, because it shouldn't be `Name`!
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name = compiled.create(self._evaluator, self._string_name)
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# This is a little bit special. `__getattribute__` is in Python
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# executed before `__getattr__`. But: I know no use case, where
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# this could be practical and where Jedi would return wrong types.
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# If you ever find something, let me know!
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# We are inversing this, because a hand-crafted `__getattribute__`
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# could still call another hand-crafted `__getattr__`, but not the
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# other way around.
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names = (inst.get_function_slot_names('__getattr__') or
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inst.get_function_slot_names('__getattribute__'))
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return inst.execute_function_slots(names, name)
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def _names_to_types(self, names, attribute_lookup):
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types = set()
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types = unite(name.infer() for name in names)
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debug.dbg('finder._names_to_types: %s -> %s', names, types)
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if not names and isinstance(self._context, AbstractInstanceContext):
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# handling __getattr__ / __getattribute__
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return self._check_getattr(self._context)
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# Add isinstance and other if/assert knowledge.
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if not types and isinstance(self._name, tree.Name) and \
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not isinstance(self._name_context, AbstractInstanceContext):
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flow_scope = self._name
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base_node = self._name_context.tree_node
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if base_node.type == 'comp_for':
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return types
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while True:
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flow_scope = get_parent_scope(flow_scope, include_flows=True)
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n = _check_flow_information(self._name_context, flow_scope,
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self._name, self._position)
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if n is not None:
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return n
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if flow_scope == base_node:
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break
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return types
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def _name_to_types(evaluator, context, tree_name):
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types = []
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node = tree_name.get_definition()
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typ = node.type
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if typ == 'for_stmt':
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types = pep0484.find_type_from_comment_hint_for(context, node, tree_name)
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if types:
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return types
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if typ == 'with_stmt':
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types = pep0484.find_type_from_comment_hint_with(context, node, tree_name)
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if types:
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return types
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if typ in ('for_stmt', 'comp_for'):
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try:
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types = context.predefined_names[node][tree_name.value]
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except KeyError:
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cn = ContextualizedNode(context, node.children[3])
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for_types = iterable.py__iter__types(evaluator, cn.infer(), cn)
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c_node = ContextualizedName(context, tree_name)
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types = check_tuple_assignments(evaluator, c_node, for_types)
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elif typ == 'expr_stmt':
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types = _remove_statements(evaluator, context, node, tree_name)
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elif typ == 'with_stmt':
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types = context.eval_node(node.get_context_manager_from_name(tree_name))
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elif typ in ('import_from', 'import_name'):
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types = imports.infer_import(context, tree_name)
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elif typ in ('funcdef', 'classdef'):
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types = _apply_decorators(evaluator, context, node)
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elif typ == 'global_stmt':
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context = evaluator.create_context(context, tree_name)
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finder = NameFinder(evaluator, context, context, tree_name.value)
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filters = finder.get_filters(search_global=True)
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# For global_stmt lookups, we only need the first possible scope,
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# which means the function itself.
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filters = [next(filters)]
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types += finder.find(filters, attribute_lookup=False)
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elif typ == 'try_stmt':
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# TODO an exception can also be a tuple. Check for those.
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# TODO check for types that are not classes and add it to
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# the static analysis report.
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exceptions = context.eval_node(tree_name.get_previous_sibling().get_previous_sibling())
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types = unite(
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evaluator.execute(t, param.ValuesArguments([]))
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for t in exceptions
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)
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else:
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raise ValueError("Should not happen.")
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return types
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def _apply_decorators(evaluator, context, node):
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"""
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Returns the function, that should to be executed in the end.
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This is also the places where the decorators are processed.
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"""
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if node.type == 'classdef':
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decoratee_context = er.ClassContext(
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evaluator,
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parent_context=context,
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classdef=node
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)
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else:
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decoratee_context = er.FunctionContext(
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evaluator,
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parent_context=context,
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funcdef=node
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)
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initial = values = set([decoratee_context])
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for dec in reversed(node.get_decorators()):
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debug.dbg('decorator: %s %s', dec, values)
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dec_values = context.eval_node(dec.children[1])
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trailer_nodes = dec.children[2:-1]
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if trailer_nodes:
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# Create a trailer and evaluate it.
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trailer = tree.PythonNode('trailer', trailer_nodes)
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trailer.parent = dec
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dec_values = evaluator.eval_trailer(context, dec_values, trailer)
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if not len(dec_values):
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debug.warning('decorator not found: %s on %s', dec, node)
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return initial
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values = unite(dec_value.execute(param.ValuesArguments([values]))
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for dec_value in dec_values)
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if not len(values):
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debug.warning('not possible to resolve wrappers found %s', node)
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return initial
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debug.dbg('decorator end %s', values)
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return values
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def _remove_statements(evaluator, context, stmt, name):
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"""
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This is the part where statements are being stripped.
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Due to lazy evaluation, statements like a = func; b = a; b() have to be
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evaluated.
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"""
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types = set()
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check_instance = None
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pep0484types = \
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pep0484.find_type_from_comment_hint_assign(context, stmt, name)
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if pep0484types:
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return pep0484types
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types |= context.eval_stmt(stmt, seek_name=name)
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if check_instance is not None:
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# class renames
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types = set([er.get_instance_el(evaluator, check_instance, a, True)
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if isinstance(a, er.Function) else a for a in types])
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return types
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def _check_flow_information(context, flow, search_name, pos):
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""" Try to find out the type of a variable just with the information that
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is given by the flows: e.g. It is also responsible for assert checks.::
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if isinstance(k, str):
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k. # <- completion here
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ensures that `k` is a string.
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"""
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if not settings.dynamic_flow_information:
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return None
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result = None
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if is_scope(flow):
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# Check for asserts.
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module_node = flow.get_root_node()
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try:
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names = module_node.get_used_names()[search_name.value]
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except KeyError:
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return None
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names = reversed([
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n for n in names
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if flow.start_pos <= n.start_pos < (pos or flow.end_pos)
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])
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for name in names:
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ass = search_ancestor(name, 'assert_stmt')
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if ass is not None:
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result = _check_isinstance_type(context, ass.assertion, search_name)
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if result is not None:
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return result
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if flow.type in ('if_stmt', 'while_stmt'):
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potential_ifs = [c for c in flow.children[1::4] if c != ':']
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for if_test in reversed(potential_ifs):
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if search_name.start_pos > if_test.end_pos:
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return _check_isinstance_type(context, if_test, search_name)
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return result
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def _check_isinstance_type(context, element, search_name):
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try:
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assert element.type in ('power', 'atom_expr')
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# this might be removed if we analyze and, etc
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assert len(element.children) == 2
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first, trailer = element.children
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assert first.type == 'name' and first.value == 'isinstance'
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assert trailer.type == 'trailer' and trailer.children[0] == '('
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assert len(trailer.children) == 3
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# arglist stuff
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arglist = trailer.children[1]
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args = param.TreeArguments(context.evaluator, context, arglist, trailer)
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param_list = list(args.unpack())
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# Disallow keyword arguments
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assert len(param_list) == 2
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(key1, lazy_context_object), (key2, lazy_context_cls) = param_list
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assert key1 is None and key2 is None
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call = helpers.call_of_leaf(search_name)
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is_instance_call = helpers.call_of_leaf(lazy_context_object.data)
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# Do a simple get_code comparison. They should just have the same code,
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# and everything will be all right.
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assert is_instance_call.normalize() == call.normalize()
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except AssertionError:
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return None
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result = set()
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for cls_or_tup in lazy_context_cls.infer():
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if isinstance(cls_or_tup, iterable.AbstractSequence) and \
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cls_or_tup.array_type == 'tuple':
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for lazy_context in cls_or_tup.py__iter__():
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for context in lazy_context.infer():
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result |= context.execute_evaluated()
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else:
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result |= cls_or_tup.execute_evaluated()
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return result
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def check_tuple_assignments(evaluator, contextualized_name, types):
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"""
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Checks if tuples are assigned.
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"""
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lazy_context = None
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for index, node in contextualized_name.assignment_indexes():
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cn = ContextualizedNode(contextualized_name.context, node)
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iterated = iterable.py__iter__(evaluator, types, cn)
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for _ in range(index + 1):
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try:
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lazy_context = next(iterated)
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except StopIteration:
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# We could do this with the default param in next. But this
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# would allow this loop to run for a very long time if the
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# index number is high. Therefore break if the loop is
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# finished.
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return set()
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types = lazy_context.infer()
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return types
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