""" 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. That said, the typical entry point for static analysis is calling ``eval_expr_stmt``. There's separate logic for autocompletion in the API, the evaluator is all about evaluating an expression. TODO this paragraph is not what jedi does anymore, it's similar, but not the same. Now you need to understand what follows after ``eval_expr_stmt``. 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_expr_stmt`` will return the ``date`` class. To *visualize* this (simplified): - ``Evaluator.eval_expr_stmt`` doesn't do much, because there's no assignment. - ``Context.eval_node`` 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_node`` 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_expr_stmt`` 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. """ from parso.python import tree import parso from parso import python_bytes_to_unicode from jedi import debug from jedi import parser_utils from jedi.evaluate.utils import unite from jedi.evaluate import imports from jedi.evaluate import recursion from jedi.evaluate.cache import evaluator_function_cache from jedi.evaluate import compiled from jedi.evaluate import helpers from jedi.evaluate.filters import TreeNameDefinition, ParamName from jedi.evaluate.base_context import ContextualizedName, ContextualizedNode, \ ContextSet, NO_CONTEXTS, iterate_contexts from jedi.evaluate.context import ClassContext, FunctionContext, \ AnonymousInstance, BoundMethod from jedi.evaluate.context.iterable import CompForContext from jedi.evaluate.syntax_tree import eval_trailer, eval_expr_stmt, \ eval_node, check_tuple_assignments class Evaluator(object): def __init__(self, project, environment=None, script_path=None): if environment is None: environment = project.get_environment() self.environment = environment self.script_path = script_path self.compiled_subprocess = environment.get_evaluator_subprocess(self) self.grammar = environment.get_grammar() self.latest_grammar = parso.load_grammar(version='3.6') self.memoize_cache = {} # for memoize decorators self.module_cache = imports.ModuleCache() # does the job of `sys.modules`. self.compiled_cache = {} # see `evaluate.compiled.create()` self.inferred_element_counts = {} self.mixed_cache = {} # see `evaluate.compiled.mixed._create()` self.analysis = [] self.dynamic_params_depth = 0 self.is_analysis = False self.project = project self.access_cache = {} # This setting is only temporary to limit the work we have to do with # tensorflow and others. self.infer_enabled = True self.reset_recursion_limitations() self.allow_different_encoding = True @property @evaluator_function_cache() def builtins_module(self): return compiled.get_special_object(self, u'BUILTINS') def reset_recursion_limitations(self): self.recursion_detector = recursion.RecursionDetector() self.execution_recursion_detector = recursion.ExecutionRecursionDetector(self) def get_sys_path(self): """Convenience function""" return self.project._get_sys_path(self, environment=self.environment) def eval_element(self, context, element): if not self.infer_enabled: return NO_CONTEXTS if isinstance(context, CompForContext): return eval_node(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 parser_utils.is_scope(if_stmt): if_stmt = None break predefined_if_name_dict = context.predefined_names.get(if_stmt) # TODO there's a lot of issues with this one. We actually should do # this in a different way. Caching should only be active in certain # cases and this all sucks. if predefined_if_name_dict is None and if_stmt \ and if_stmt.type == 'if_stmt' and self.is_analysis: 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 = [e.value for e in element_names] if any(i.value 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][if_name.value] = ContextSet(definition) name_dicts += new_name_dicts else: for name_dict in name_dicts: name_dict[if_name.value] = definitions if len(name_dicts) > 1: result = ContextSet() for name_dict in name_dicts: with helpers.predefine_names(context, if_stmt, name_dict): result |= eval_node(context, element) return result else: return self._eval_element_if_evaluated(context, element) else: if predefined_if_name_dict: return eval_node(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 eval_node(context, element) return self._eval_element_cached(context, element) @evaluator_function_cache(default=NO_CONTEXTS) def _eval_element_cached(self, context, element): return eval_node(context, element) def goto_definitions(self, context, name): def_ = name.get_definition(import_name_always=True) if def_ is not None: type_ = def_.type if type_ == 'classdef': return [ClassContext(self, context, name.parent)] elif type_ == 'funcdef': return [FunctionContext.from_context(context, name.parent)] if type_ == 'expr_stmt': is_simple_name = name.parent.type not in ('power', 'trailer') if is_simple_name: return eval_expr_stmt(context, def_, name) if type_ == 'for_stmt': container_types = context.eval_node(def_.children[3]) cn = ContextualizedNode(context, def_.children[3]) for_types = iterate_contexts(container_types, cn) c_node = ContextualizedName(context, name) return check_tuple_assignments(self, c_node, for_types) if 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): definition = name.get_definition(import_name_always=True) if definition is not None: type_ = definition.type if type_ == 'expr_stmt': # Only take the parent, because if it's more complicated than just # a name it's something you can "goto" again. is_simple_name = name.parent.type not in ('power', 'trailer') if is_simple_name: return [TreeNameDefinition(context, name)] elif type_ == 'param': return [ParamName(context, name)] elif type_ in ('funcdef', 'classdef'): return [TreeNameDefinition(context, name)] elif type_ in ('import_from', 'import_name'): module_names = imports.infer_import(context, name, is_goto=True) return module_names par = name.parent node_type = par.type if node_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': context_set = context.eval_node(trailer.children[1]) else: i = trailer.parent.children.index(trailer) to_evaluate = trailer.parent.children[:i] if to_evaluate[0] == 'await': to_evaluate.pop(0) context_set = context.eval_node(to_evaluate[0]) for trailer in to_evaluate[1:]: context_set = eval_trailer(context, context_set, trailer) param_names = [] for context in context_set: try: get_param_names = context.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 node_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 = context.eval_node(new_dotted) return unite( value.py__getattribute__(name, name_context=context, is_goto=True) for value in values ) if node_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: stmt = tree.search_ancestor( name, 'expr_stmt', 'lambdef' ) or name if stmt.type == 'lambdef': 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 parser_utils.is_scope(node): 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', 'lambdef') parent_scope = parser_utils.get_parent_scope(scope_node) parent_context = from_scope_node(parent_scope, child_is_funcdef=is_funcdef) if is_funcdef: func = FunctionContext.from_context( parent_context, scope_node ) if isinstance(parent_context, AnonymousInstance): func = BoundMethod( instance=parent_context, klass=parent_context.class_context, function=func ) if is_nested and not node_is_object: return func.get_function_execution() return func elif scope_node.type == 'classdef': class_context = ClassContext(self, parent_context, scope_node) 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 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 parser_utils.is_scope(node): scope_node = node else: if node.parent.type in ('funcdef', 'classdef') and node.parent.name == node: # 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) def parse_and_get_code(self, code=None, path=None, encoding='utf-8', **kwargs): if self.allow_different_encoding: if code is None: with open(path, 'rb') as f: code = f.read() code = python_bytes_to_unicode(code, encoding=encoding, errors='replace') return self.grammar.parse(code=code, path=path, **kwargs), code def parse(self, *args, **kwargs): return self.parse_and_get_code(*args, **kwargs)[0]