""" Evaluation of Python code in |jedi| is based on three assumptions: * The code uses as least side effects as possible. Jedi understands certain list/tuple/set modifications, but there's no guarantee that Jedi detects everything (list.append in different modules for example). * No magic is being used: - metaclasses - ``setattr()`` / ``__import__()`` - writing to ``globals()``, ``locals()``, ``object.__dict__`` * The programmer is not a total dick, e.g. like `this `_ :-) The actual algorithm is based on a principle called lazy evaluation. If you don't know about it, google it. That said, the typical entry point for static analysis is calling ``eval_statement``. There's separate logic for autocompletion in the API, the evaluator is all about evaluating an expression. Now you need to understand what follows after ``eval_statement``. Let's make an example:: import datetime datetime.date.toda# <-- cursor here First of all, this module doesn't care about completion. It really just cares about ``datetime.date``. At the end of the procedure ``eval_statement`` will return the ``date`` class. To *visualize* this (simplified): - ``Evaluator.eval_statement`` doesn't do much, because there's no assignment. - ``Evaluator.eval_element`` cares for resolving the dotted path - ``Evaluator.find_types`` searches for global definitions of datetime, which it finds in the definition of an import, by scanning the syntax tree. - Using the import logic, the datetime module is found. - Now ``find_types`` is called again by ``eval_element`` to find ``date`` inside the datetime module. Now what would happen if we wanted ``datetime.date.foo.bar``? Two more calls to ``find_types``. However the second call would be ignored, because the first one would return nothing (there's no foo attribute in ``date``). What if the import would contain another ``ExprStmt`` like this:: from foo import bar Date = bar.baz Well... You get it. Just another ``eval_statement`` recursion. It's really easy. Python can obviously get way more complicated then this. To understand tuple assignments, list comprehensions and everything else, a lot more code had to be written. Jedi has been tested very well, so you can just start modifying code. It's best to write your own test first for your "new" feature. Don't be scared of breaking stuff. As long as the tests pass, you're most likely to be fine. I need to mention now that lazy evaluation is really good because it only *evaluates* what needs to be *evaluated*. All the statements and modules that are not used are just being ignored. """ import copy import sys from jedi.parser.python import tree from jedi import debug from jedi.common import unite from jedi.evaluate import representation as er from jedi.evaluate import imports from jedi.evaluate import recursion from jedi.evaluate import iterable from jedi.evaluate.cache import memoize_default from jedi.evaluate import stdlib from jedi.evaluate import finder from jedi.evaluate import compiled from jedi.evaluate import precedence from jedi.evaluate import param from jedi.evaluate import helpers from jedi.evaluate import pep0484 from jedi.evaluate.filters import TreeNameDefinition, ParamName from jedi.evaluate.instance import AnonymousInstance, BoundMethod from jedi.evaluate.context import ContextualizedName, ContextualizedNode class Evaluator(object): def __init__(self, grammar, sys_path=None): self.grammar = grammar self.memoize_cache = {} # for memoize decorators # To memorize modules -> equals `sys.modules`. self.modules = {} # like `sys.modules`. self.compiled_cache = {} # see `evaluate.compiled.create()` self.mixed_cache = {} # see `evaluate.compiled.mixed.create()` self.analysis = [] self.dynamic_params_depth = 0 self.is_analysis = False self.python_version = sys.version_info[:2] if sys_path is None: sys_path = sys.path self.sys_path = copy.copy(sys_path) try: self.sys_path.remove('') except ValueError: pass self.reset_recursion_limitations() # Constants self.BUILTINS = compiled.get_special_object(self, 'BUILTINS') def reset_recursion_limitations(self): self.recursion_detector = recursion.RecursionDetector() self.execution_recursion_detector = recursion.ExecutionRecursionDetector(self) def find_types(self, context, name_or_str, name_context, position=None, search_global=False, is_goto=False): """ This is the search function. The most important part to debug. `remove_statements` and `filter_statements` really are the core part of this completion. :param position: Position of the last statement -> tuple of line, column :return: List of Names. Their parents are the types. """ f = finder.NameFinder(self, context, name_context, name_or_str, position) filters = f.get_filters(search_global) if is_goto: return f.filter_name(filters) return f.find(filters, attribute_lookup=not search_global) def eval_statement(self, context, stmt, seek_name=None): with recursion.execution_allowed(self, stmt) as allowed: if allowed or context.get_root_context() == self.BUILTINS: return self._eval_stmt(context, stmt, seek_name) return set() #@memoize_default(default=[], evaluator_is_first_arg=True) @debug.increase_indent def _eval_stmt(self, context, stmt, seek_name=None): """ The starting point of the completion. A statement always owns a call list, which are the calls, that a statement does. In case multiple names are defined in the statement, `seek_name` returns the result for this name. :param stmt: A `tree.ExprStmt`. """ debug.dbg('eval_statement %s (%s)', stmt, seek_name) rhs = stmt.get_rhs() types = self.eval_element(context, rhs) if seek_name: c_node = ContextualizedName(context, seek_name) types = finder.check_tuple_assignments(self, c_node, types) first_operation = stmt.first_operation() if first_operation not in ('=', None) and first_operation.type == 'operator': # `=` is always the last character in aug assignments -> -1 operator = copy.copy(first_operation) operator.value = operator.value[:-1] name = str(stmt.get_defined_names()[0]) left = context.py__getattribute__( name, position=stmt.start_pos, search_global=True) for_stmt = tree.search_ancestor(stmt, 'for_stmt') if for_stmt is not None and for_stmt.type == 'for_stmt' and types \ and for_stmt.defines_one_name(): # Iterate through result and add the values, that's possible # only in for loops without clutter, because they are # predictable. Also only do it, if the variable is not a tuple. node = for_stmt.get_input_node() cn = ContextualizedNode(context, node) ordered = list(iterable.py__iter__(self, cn.infer(), cn)) for lazy_context in ordered: dct = {str(for_stmt.children[1]): lazy_context.infer()} with helpers.predefine_names(context, for_stmt, dct): t = self.eval_element(context, rhs) left = precedence.calculate(self, context, left, operator, t) types = left else: types = precedence.calculate(self, context, left, operator, types) debug.dbg('eval_statement result %s', types) return types def eval_element(self, context, element): if isinstance(context, iterable.CompForContext): return self._eval_element_not_cached(context, element) if_stmt = element while if_stmt is not None: if_stmt = if_stmt.parent if if_stmt.type in ('if_stmt', 'for_stmt'): break if if_stmt.is_scope(): if_stmt = None break predefined_if_name_dict = context.predefined_names.get(if_stmt) if predefined_if_name_dict is None and if_stmt and if_stmt.type == 'if_stmt': if_stmt_test = if_stmt.children[1] name_dicts = [{}] # If we already did a check, we don't want to do it again -> If # context.predefined_names is filled, we stop. # We don't want to check the if stmt itself, it's just about # the content. if element.start_pos > if_stmt_test.end_pos: # Now we need to check if the names in the if_stmt match the # names in the suite. if_names = helpers.get_names_of_node(if_stmt_test) element_names = helpers.get_names_of_node(element) str_element_names = [str(e) for e in element_names] if any(str(i) in str_element_names for i in if_names): for if_name in if_names: definitions = self.goto_definitions(context, if_name) # Every name that has multiple different definitions # causes the complexity to rise. The complexity should # never fall below 1. if len(definitions) > 1: if len(name_dicts) * len(definitions) > 16: debug.dbg('Too many options for if branch evaluation %s.', if_stmt) # There's only a certain amount of branches # Jedi can evaluate, otherwise it will take to # long. name_dicts = [{}] break original_name_dicts = list(name_dicts) name_dicts = [] for definition in definitions: new_name_dicts = list(original_name_dicts) for i, name_dict in enumerate(new_name_dicts): new_name_dicts[i] = name_dict.copy() new_name_dicts[i][str(if_name)] = set([definition]) name_dicts += new_name_dicts else: for name_dict in name_dicts: name_dict[str(if_name)] = definitions if len(name_dicts) > 1: result = set() for name_dict in name_dicts: with helpers.predefine_names(context, if_stmt, name_dict): result |= self._eval_element_not_cached(context, element) return result else: return self._eval_element_if_evaluated(context, element) else: if predefined_if_name_dict: return self._eval_element_not_cached(context, element) else: return self._eval_element_if_evaluated(context, element) def _eval_element_if_evaluated(self, context, element): """ TODO This function is temporary: Merge with eval_element. """ parent = element while parent is not None: parent = parent.parent predefined_if_name_dict = context.predefined_names.get(parent) if predefined_if_name_dict is not None: return self._eval_element_not_cached(context, element) return self._eval_element_cached(context, element) @memoize_default(default=set(), evaluator_is_first_arg=True) def _eval_element_cached(self, context, element): return self._eval_element_not_cached(context, element) @debug.increase_indent def _eval_element_not_cached(self, context, element): debug.dbg('eval_element %s@%s', element, element.start_pos) types = set() typ = element.type if typ in ('name', 'number', 'string', 'atom'): types = self.eval_atom(context, element) elif typ == 'keyword': # For False/True/None if element.value in ('False', 'True', 'None'): types.add(compiled.builtin_from_name(self, element.value)) # else: print e.g. could be evaluated like this in Python 2.7 elif typ == 'lambda': types = set([er.FunctionContext(self, context, element)]) elif typ == 'expr_stmt': types = self.eval_statement(context, element) elif typ in ('power', 'atom_expr'): first_child = element.children[0] if not (first_child.type == 'keyword' and first_child.value == 'await'): types = self.eval_atom(context, first_child) for trailer in element.children[1:]: if trailer == '**': # has a power operation. right = self.eval_element(context, element.children[2]) types = set(precedence.calculate(self, context, types, trailer, right)) break types = self.eval_trailer(context, types, trailer) elif typ in ('testlist_star_expr', 'testlist',): # The implicit tuple in statements. types = set([iterable.SequenceLiteralContext(self, context, element)]) elif typ in ('not_test', 'factor'): types = self.eval_element(context, element.children[-1]) for operator in element.children[:-1]: types = set(precedence.factor_calculate(self, types, operator)) elif typ == 'test': # `x if foo else y` case. types = (self.eval_element(context, element.children[0]) | self.eval_element(context, element.children[-1])) elif typ == 'operator': # Must be an ellipsis, other operators are not evaluated. assert element.value == '...' types = set([compiled.create(self, Ellipsis)]) elif typ == 'dotted_name': types = self.eval_atom(context, element.children[0]) for next_name in element.children[2::2]: # TODO add search_global=True? types = unite( typ.py__getattribute__(next_name, name_context=context) for typ in types ) types = types elif typ == 'eval_input': types = self._eval_element_not_cached(context, element.children[0]) elif typ == 'annassign': types = pep0484._evaluate_for_annotation(context, element.children[1]) else: types = precedence.calculate_children(self, context, element.children) debug.dbg('eval_element result %s', types) return types def eval_atom(self, context, atom): """ Basically to process ``atom`` nodes. The parser sometimes doesn't generate the node (because it has just one child). In that case an atom might be a name or a literal as well. """ if atom.type == 'name': # This is the first global lookup. stmt = atom.get_definition() if stmt.type == 'comp_for': stmt = tree.search_ancestor(stmt, ('expr_stmt', 'lambda', 'funcdef', 'classdef')) if stmt is None or stmt.type != 'expr_stmt': # We only need to adjust the start_pos for statements, because # there the name cannot be used. stmt = atom return context.py__getattribute__( name_or_str=atom, position=stmt.start_pos, search_global=True ) elif isinstance(atom, tree.Literal): return set([compiled.create(self, atom.eval())]) else: c = atom.children if c[0].type == 'string': # Will be one string. types = self.eval_atom(context, c[0]) for string in c[1:]: right = self.eval_atom(context, string) types = precedence.calculate(self, context, types, '+', right) return types # Parentheses without commas are not tuples. elif c[0] == '(' and not len(c) == 2 \ and not(c[1].type == 'testlist_comp' and len(c[1].children) > 1): return self.eval_element(context, c[1]) try: comp_for = c[1].children[1] except (IndexError, AttributeError): pass else: if comp_for == ':': # Dict comprehensions have a colon at the 3rd index. try: comp_for = c[1].children[3] except IndexError: pass if comp_for.type == 'comp_for': return set([iterable.Comprehension.from_atom(self, context, atom)]) # It's a dict/list/tuple literal. array_node = c[1] try: array_node_c = array_node.children except AttributeError: array_node_c = [] if c[0] == '{' and (array_node == '}' or ':' in array_node_c): context = iterable.DictLiteralContext(self, context, atom) else: context = iterable.SequenceLiteralContext(self, context, atom) return set([context]) def eval_trailer(self, context, types, trailer): trailer_op, node = trailer.children[:2] if node == ')': # `arglist` is optional. node = () new_types = set() if trailer_op == '[': new_types |= iterable.py__getitem__(self, context, types, trailer) else: for typ in types: debug.dbg('eval_trailer: %s in scope %s', trailer, typ) if trailer_op == '.': new_types |= typ.py__getattribute__( name_context=context, name_or_str=node ) elif trailer_op == '(': arguments = param.TreeArguments(self, context, node, trailer) new_types |= self.execute(typ, arguments) return new_types @debug.increase_indent def execute(self, obj, arguments): if not isinstance(arguments, param.AbstractArguments): raise NotImplementedError arguments = param.Arguments(self, arguments) if self.is_analysis: arguments.eval_all() debug.dbg('execute: %s %s', obj, arguments) try: # Some stdlib functions like super(), namedtuple(), etc. have been # hard-coded in Jedi to support them. return stdlib.execute(self, obj, arguments) except stdlib.NotInStdLib: pass try: func = obj.py__call__ except AttributeError: debug.warning("no execution possible %s", obj) return set() else: types = func(arguments) debug.dbg('execute result: %s in %s', types, obj) return types def goto_definitions(self, context, name): def_ = name.get_definition() is_simple_name = name.parent.type not in ('power', 'trailer') if is_simple_name: if name.parent.type == 'classdef' and name.parent.name == name: return [er.ClassContext(self, name.parent, context)] elif name.parent.type == 'funcdef': return [er.FunctionContext(self, context, name.parent)] elif name.parent.type == 'file_input': raise NotImplementedError if def_.type == 'expr_stmt' and name in def_.get_defined_names(): return self.eval_statement(context, def_, name) elif def_.type == 'for_stmt': container_types = self.eval_element(context, def_.children[3]) cn = ContextualizedNode(context, def_.children[3]) for_types = iterable.py__iter__types(self, container_types, cn) c_node = ContextualizedName(context, name) return finder.check_tuple_assignments(self, c_node, for_types) elif def_.type in ('import_from', 'import_name'): return imports.infer_import(context, name) return helpers.evaluate_call_of_leaf(context, name) def goto(self, context, name): stmt = name.get_definition() par = name.parent if par.type == 'argument' and par.children[1] == '=' and par.children[0] == name: # Named param goto. trailer = par.parent if trailer.type == 'arglist': trailer = trailer.parent if trailer.type != 'classdef': if trailer.type == 'decorator': types = self.eval_element(context, trailer.children[1]) else: i = trailer.parent.children.index(trailer) to_evaluate = trailer.parent.children[:i] types = self.eval_element(context, to_evaluate[0]) for trailer in to_evaluate[1:]: types = self.eval_trailer(context, types, trailer) param_names = [] for typ in types: try: get_param_names = typ.get_param_names except AttributeError: pass else: for param_name in get_param_names(): if param_name.string_name == name.value: param_names.append(param_name) return param_names elif par.type == 'expr_stmt' and name in par.get_defined_names(): # Only take the parent, because if it's more complicated than just # a name it's something you can "goto" again. return [TreeNameDefinition(context, name)] elif par.type == 'param' and par.name: return [ParamName(context, name)] elif isinstance(par, (tree.Param, tree.Function, tree.Class)) and par.name is name: return [TreeNameDefinition(context, name)] elif isinstance(stmt, tree.Import): module_names = imports.infer_import(context, name, is_goto=True) return module_names elif par.type == 'dotted_name': # Is a decorator. index = par.children.index(name) if index > 0: new_dotted = helpers.deep_ast_copy(par) new_dotted.children[index - 1:] = [] values = self.eval_element(context, new_dotted) return unite( value.py__getattribute__(name, name_context=context, is_goto=True) for value in values ) if par.type == 'trailer' and par.children[0] == '.': values = helpers.evaluate_call_of_leaf(context, name, cut_own_trailer=True) return unite( value.py__getattribute__(name, name_context=context, is_goto=True) for value in values ) else: if stmt.type != 'expr_stmt': # We only need to adjust the start_pos for statements, because # there the name cannot be used. stmt = name return context.py__getattribute__( name, position=stmt.start_pos, search_global=True, is_goto=True ) def create_context(self, base_context, node, node_is_context=False, node_is_object=False): def parent_scope(node): while True: node = node.parent if node.is_scope(): return node elif node.type in ('argument', 'testlist_comp'): if node.children[1].type == 'comp_for': return node.children[1] elif node.type == 'dictorsetmaker': for n in node.children[1:4]: # In dictionaries it can be pretty much anything. if n.type == 'comp_for': return n def from_scope_node(scope_node, child_is_funcdef=None, is_nested=True, node_is_object=False): if scope_node == base_node: return base_context is_funcdef = scope_node.type in ('funcdef', 'lambda') parent_scope = scope_node.get_parent_scope() parent_context = from_scope_node(parent_scope, child_is_funcdef=is_funcdef) if is_funcdef: if isinstance(parent_context, AnonymousInstance): func = BoundMethod( self, parent_context, parent_context.class_context, parent_context.parent_context, scope_node ) else: func = er.FunctionContext( self, parent_context, scope_node ) if is_nested and not node_is_object: return func.get_function_execution() return func elif scope_node.type == 'classdef': class_context = er.ClassContext(self, scope_node, parent_context) if child_is_funcdef: # anonymous instance return AnonymousInstance(self, parent_context, class_context) else: return class_context elif scope_node.type == 'comp_for': if node.start_pos >= scope_node.children[-1].start_pos: return parent_context return iterable.CompForContext.from_comp_for(parent_context, scope_node) raise Exception("There's a scope that was not managed.") base_node = base_context.tree_node if node_is_context and node.is_scope(): scope_node = node else: if node.parent.type in ('funcdef', 'classdef'): # When we're on class/function names/leafs that define the # object itself and not its contents. node = node.parent scope_node = parent_scope(node) return from_scope_node(scope_node, is_nested=True, node_is_object=node_is_object)