From 174eff58758a6ee57add114ce6fc5f735afbc19a Mon Sep 17 00:00:00 2001
From: Dave Halter <davidhalter88@gmail.com>
Date: Mon, 25 Sep 2017 23:08:59 +0200
Subject: [PATCH] Replace a lot more of empty sets and unite calls.

---
 jedi/common/context.py      |  3 +++
 jedi/evaluate/__init__.py   |  2 +-
 jedi/evaluate/docstrings.py | 10 ++++++--
 jedi/evaluate/dynamic.py    |  7 +++---
 jedi/evaluate/filters.py    |  6 ++---
 jedi/evaluate/finder.py     |  8 ++-----
 jedi/evaluate/imports.py    | 13 ++++-------
 jedi/evaluate/instance.py   | 11 ++++-----
 jedi/evaluate/iterable.py   | 17 +++++++-------
 jedi/evaluate/param.py      |  3 ++-
 jedi/evaluate/pep0484.py    |  5 ++--
 jedi/evaluate/precedence.py |  4 ++--
 jedi/evaluate/recursion.py  |  3 ++-
 jedi/evaluate/stdlib.py     | 46 +++++++++++++++++++------------------
 14 files changed, 72 insertions(+), 66 deletions(-)

diff --git a/jedi/common/context.py b/jedi/common/context.py
index b29b7c2f..95c4671b 100644
--- a/jedi/common/context.py
+++ b/jedi/common/context.py
@@ -35,6 +35,9 @@ class ContextSet(object):
     def __bool__(self):
         return bool(self._set)
 
+    def __len__(self):
+        return len(self._set)
+
     def __repr__(self):
         return '%s(%s)' % (self.__class__.__name__, ', '.join(str(s) for s in self._set))
 
diff --git a/jedi/evaluate/__init__.py b/jedi/evaluate/__init__.py
index 7cff98d4..35c4256e 100644
--- a/jedi/evaluate/__init__.py
+++ b/jedi/evaluate/__init__.py
@@ -433,7 +433,7 @@ class Evaluator(object):
             node = ()
 
         if trailer_op == '[':
-            return ContextSet(iterable.py__getitem__(self, context, types, trailer))
+            return iterable.py__getitem__(self, context, types, trailer)
         else:
             context_set = ContextSet()
             for typ in types:
diff --git a/jedi/evaluate/docstrings.py b/jedi/evaluate/docstrings.py
index 43c950ed..ea471811 100644
--- a/jedi/evaluate/docstrings.py
+++ b/jedi/evaluate/docstrings.py
@@ -223,7 +223,10 @@ def _execute_types_in_stmt(module_context, stmt):
     contain is executed. (Used as type information).
     """
     definitions = module_context.eval_node(stmt)
-    return unite(_execute_array_values(module_context.evaluator, d) for d in definitions)
+    return ContextSet.from_sets(
+        _execute_array_values(module_context.evaluator, d)
+        for d in definitions
+    )
 
 
 def _execute_array_values(evaluator, array):
@@ -234,7 +237,10 @@ def _execute_array_values(evaluator, array):
     if isinstance(array, SequenceLiteralContext):
         values = []
         for lazy_context in array.py__iter__():
-            objects = unite(_execute_array_values(evaluator, typ) for typ in lazy_context.infer())
+            objects = ContextSet.from_sets(
+                _execute_array_values(evaluator, typ)
+                for typ in lazy_context.infer()
+            )
             values.append(context.LazyKnownContexts(objects))
         return set([FakeSequence(evaluator, array.array_type, values)])
     else:
diff --git a/jedi/evaluate/dynamic.py b/jedi/evaluate/dynamic.py
index fb179b58..946d81e2 100644
--- a/jedi/evaluate/dynamic.py
+++ b/jedi/evaluate/dynamic.py
@@ -24,7 +24,8 @@ from jedi.evaluate.cache import evaluator_function_cache
 from jedi.evaluate import imports
 from jedi.evaluate.param import TreeArguments, create_default_params
 from jedi.evaluate.helpers import is_stdlib_path
-from jedi.evaluate.utils import to_list, unite
+from jedi.evaluate.utils import to_list
+from jedi.common import ContextSet
 from jedi.parser_utils import get_parent_scope
 
 
@@ -50,7 +51,7 @@ class MergedExecutedParams(object):
         self._executed_params = executed_params
 
     def infer(self):
-        return unite(p.infer() for p in self._executed_params)
+        return ContextSet.from_sets(p.infer() for p in self._executed_params)
 
 
 @debug.increase_indent
@@ -103,7 +104,7 @@ def search_params(evaluator, execution_context, funcdef):
         evaluator.dynamic_params_depth -= 1
 
 
-@evaluator_function_cache(default=[])
+@evaluator_function_cache(default=None)
 @to_list
 def _search_function_executions(evaluator, module_context, funcdef):
     """
diff --git a/jedi/evaluate/filters.py b/jedi/evaluate/filters.py
index c94f9758..e3edb1eb 100644
--- a/jedi/evaluate/filters.py
+++ b/jedi/evaluate/filters.py
@@ -6,9 +6,9 @@ from abc import abstractmethod
 
 from parso.tree import search_ancestor
 from jedi.evaluate import flow_analysis
-from jedi.evaluate.utils import to_list, unite
 from jedi.common import ContextSet
 from jedi.parser_utils import get_parent_scope
+from jedi.evaluate.utils import to_list
 
 
 class AbstractNameDefinition(object):
@@ -36,10 +36,10 @@ class AbstractNameDefinition(object):
         return '<%s: %s@%s>' % (self.__class__.__name__, self.string_name, self.start_pos)
 
     def execute(self, arguments):
-        return unite(context.execute(arguments) for context in self.infer())
+        return self.infer().execute(arguments)
 
     def execute_evaluated(self, *args, **kwargs):
-        return unite(context.execute_evaluated(*args, **kwargs) for context in self.infer())
+        return self.infer().execute_evaluated(*args, **kwargs)
 
     @property
     def api_type(self):
diff --git a/jedi/evaluate/finder.py b/jedi/evaluate/finder.py
index 3e5e2ef5..15d45108 100644
--- a/jedi/evaluate/finder.py
+++ b/jedi/evaluate/finder.py
@@ -233,10 +233,7 @@ def _name_to_types(evaluator, context, tree_name):
         # TODO check for types that are not classes and add it to
         # the static analysis report.
         exceptions = context.eval_node(tree_name.get_previous_sibling().get_previous_sibling())
-        types = unite(
-            evaluator.execute(t, param.ValuesArguments([]))
-            for t in exceptions
-        )
+        types = exceptions.execute_evaluated()
     else:
         raise ValueError("Should not happen.")
     return types
@@ -274,8 +271,7 @@ def _apply_decorators(evaluator, context, node):
             debug.warning('decorator not found: %s on %s', dec, node)
             return initial
 
-        values = unite(dec_value.execute(param.ValuesArguments([values]))
-                       for dec_value in dec_values)
+        values = dec_values.execute(param.ValuesArguments([values]))
         if not len(values):
             debug.warning('not possible to resolve wrappers found %s', node)
             return initial
diff --git a/jedi/evaluate/imports.py b/jedi/evaluate/imports.py
index 75139d15..5d69e931 100644
--- a/jedi/evaluate/imports.py
+++ b/jedi/evaluate/imports.py
@@ -24,7 +24,6 @@ from parso import python_bytes_to_unicode
 from jedi._compatibility import find_module, unicode, ImplicitNSInfo
 from jedi import debug
 from jedi import settings
-from jedi.evaluate.utils import unite
 from jedi.evaluate import sys_path
 from jedi.evaluate import helpers
 from jedi.evaluate import compiled
@@ -67,13 +66,11 @@ def infer_import(context, tree_name, is_goto=False):
         return NO_CONTEXTS
 
     if from_import_name is not None:
-        types = unite(
-            t.py__getattribute__(
-                from_import_name,
-                name_context=context,
-                is_goto=is_goto,
-                analysis_errors=False
-            ) for t in types
+        types = types.py__getattribute__(
+            from_import_name,
+            name_context=context,
+            is_goto=is_goto,
+            analysis_errors=False
         )
 
         if not types:
diff --git a/jedi/evaluate/instance.py b/jedi/evaluate/instance.py
index f8df7a1b..f1116707 100644
--- a/jedi/evaluate/instance.py
+++ b/jedi/evaluate/instance.py
@@ -1,7 +1,6 @@
 from abc import abstractproperty
 
 from jedi._compatibility import is_py3
-from jedi.evaluate.utils import unite
 from jedi import debug
 from jedi.evaluate import compiled
 from jedi.evaluate import filters
@@ -11,7 +10,7 @@ from jedi.evaluate.param import AbstractArguments, AnonymousArguments
 from jedi.cache import memoize_method
 from jedi.evaluate import representation as er
 from jedi.evaluate import iterable
-from jedi.common import ContextSet, iterator_to_context_set
+from jedi.common import ContextSet, iterator_to_context_set, NO_CONTEXTS
 from jedi.parser_utils import get_parent_scope
 
 
@@ -59,7 +58,7 @@ class AbstractInstanceContext(Context):
             raise AttributeError
 
         def execute(arguments):
-            return unite(name.execute(arguments) for name in names)
+            return ContextSet.from_sets(name.execute(arguments) for name in names)
 
         return execute
 
@@ -81,7 +80,7 @@ class AbstractInstanceContext(Context):
         return []
 
     def execute_function_slots(self, names, *evaluated_args):
-        return unite(
+        return ContextSet.from_sets(
             name.execute_evaluated(*evaluated_args)
             for name in names
         )
@@ -97,7 +96,7 @@ class AbstractInstanceContext(Context):
                 none_obj = compiled.create(self.evaluator, None)
                 return self.execute_function_slots(names, none_obj, obj)
         else:
-            return set([self])
+            return ContextSet(self)
 
     def get_filters(self, search_global=None, until_position=None,
                     origin_scope=None, include_self_names=True):
@@ -123,7 +122,7 @@ class AbstractInstanceContext(Context):
             names = self.get_function_slot_names('__getitem__')
         except KeyError:
             debug.warning('No __getitem__, cannot access the array.')
-            return set()
+            return NO_CONTEXTS
         else:
             index_obj = compiled.create(self.evaluator, index)
             return self.execute_function_slots(names, index_obj)
diff --git a/jedi/evaluate/iterable.py b/jedi/evaluate/iterable.py
index cee0879b..dcc2b939 100644
--- a/jedi/evaluate/iterable.py
+++ b/jedi/evaluate/iterable.py
@@ -144,7 +144,7 @@ class GeneratorMixin(object):
     @register_builtin_method('__next__', python_version_match=3)
     def py__next__(self):
         # TODO add TypeError if params are given.
-        return unite(lazy_context.infer() for lazy_context in self.py__iter__())
+        return ContextSet.from_sets(lazy_context.infer() for lazy_context in self.py__iter__())
 
     def get_filters(self, search_global, until_position=None, origin_scope=None):
         gen_obj = compiled.get_special_object(self.evaluator, 'GENERATOR_OBJECT')
@@ -297,7 +297,8 @@ class ArrayMixin(object):
         return self.evaluator.BUILTINS
 
     def dict_values(self):
-        return unite(self._defining_context.eval_node(v) for k, v in self._items())
+        return ContextSet.from_sets(self._defining_context.eval_node(v)
+                                    for k, v in self._items())
 
 
 class ListComprehension(ArrayMixin, Comprehension):
@@ -335,7 +336,7 @@ class DictComprehension(ArrayMixin, Comprehension):
         return self.dict_values()
 
     def dict_values(self):
-        return unite(values for keys, values in self._iterate())
+        return ContextSet.from_sets(values for keys, values in self._iterate())
 
     @register_builtin_method('values')
     def _imitate_values(self):
@@ -414,7 +415,7 @@ class SequenceLiteralContext(ArrayMixin, AbstractSequence):
     def _values(self):
         """Returns a list of a list of node."""
         if self.array_type == 'dict':
-            return unite(v for k, v in self._items())
+            return ContextSet.from_sets(v for k, v in self._items())
         else:
             return self._items()
 
@@ -532,7 +533,7 @@ class FakeDict(_FakeArray):
         return self._dct[index].infer()
 
     def dict_values(self):
-        return unite(lazy_context.infer() for lazy_context in self._dct.values())
+        return ContextSet.from_sets(lazy_context.infer() for lazy_context in self._dct.values())
 
     def _items(self):
         raise DeprecationWarning
@@ -555,7 +556,7 @@ class MergedArray(_FakeArray):
                 yield lazy_context
 
     def py__getitem__(self, index):
-        return unite(lazy_context.infer() for lazy_context in self.py__iter__())
+        return ContextSet.from_sets(lazy_context.infer() for lazy_context in self.py__iter__())
 
     def _items(self):
         for array in self._arrays:
@@ -633,7 +634,7 @@ def py__iter__types(evaluator, types, contextualized_node=None):
     Calls `py__iter__`, but ignores the ordering in the end and just returns
     all types that it contains.
     """
-    return unite(
+    return ContextSet.from_sets(
         lazy_context.infer()
         for lazy_context in py__iter__(evaluator, types, contextualized_node)
     )
@@ -740,7 +741,7 @@ def _check_array_additions(context, sequence):
     is_list = sequence.name.string_name == 'list'
     search_names = (['append', 'extend', 'insert'] if is_list else ['add', 'update'])
 
-    added_types = NO_CONTEXTS()
+    added_types = NO_CONTEXTS
     for add_name in search_names:
         try:
             possible_names = module_context.tree_node.get_used_names()[add_name]
diff --git a/jedi/evaluate/param.py b/jedi/evaluate/param.py
index 04d93d42..a914d81a 100644
--- a/jedi/evaluate/param.py
+++ b/jedi/evaluate/param.py
@@ -10,6 +10,7 @@ from jedi.evaluate import context
 from jedi.evaluate import docstrings
 from jedi.evaluate import pep0484
 from jedi.evaluate.filters import ParamName
+from jedi.common import NO_CONTEXTS
 
 
 def add_argument_issue(parent_context, error_name, lazy_context, message):
@@ -51,7 +52,7 @@ class AbstractArguments():
                 debug.warning('TypeError: %s expected at least %s arguments, got %s',
                               name, len(parameters), i)
                 raise ValueError
-            values = set() if argument is None else argument.infer()
+            values = NO_CONTEXTS if argument is None else argument.infer()
 
             if not values and not optional:
                 # For the stdlib we always want values. If we don't get them,
diff --git a/jedi/evaluate/pep0484.py b/jedi/evaluate/pep0484.py
index 8e741fb0..0fa7ca41 100644
--- a/jedi/evaluate/pep0484.py
+++ b/jedi/evaluate/pep0484.py
@@ -25,11 +25,10 @@ import re
 from parso import ParserSyntaxError
 from parso.python import tree
 
-from jedi.evaluate.utils import unite
 from jedi.evaluate.cache import evaluator_method_cache
 from jedi.evaluate import compiled
 from jedi.evaluate.context import LazyTreeContext
-from jedi.common import NO_CONTEXTS
+from jedi.common import NO_CONTEXTS, ContextSet
 from jedi import debug
 from jedi import _compatibility
 from jedi import parser_utils
@@ -146,7 +145,7 @@ def py__getitem__(context, typ, node):
     if type_name in ("Union", '_Union'):
         # In Python 3.6 it's still called typing.Union but it's an instance
         # called _Union.
-        return unite(context.eval_node(node) for node in nodes)
+        return ContextSet.from_sets(context.eval_node(node) for node in nodes)
     if type_name in ("Optional", '_Optional'):
         # Here we have the same issue like in Union. Therefore we also need to
         # check for the instance typing._Optional (Python 3.6).
diff --git a/jedi/evaluate/precedence.py b/jedi/evaluate/precedence.py
index 5d6aef13..72b7a432 100644
--- a/jedi/evaluate/precedence.py
+++ b/jedi/evaluate/precedence.py
@@ -7,7 +7,7 @@ from jedi._compatibility import unicode
 from jedi import debug
 from jedi.evaluate.compiled import CompiledObject, create, builtin_from_name
 from jedi.evaluate import analysis
-from jedi.common import ContextSet
+from jedi.common import ContextSet, NO_CONTEXTS
 
 # Maps Python syntax to the operator module.
 COMPARISON_OPERATORS = {
@@ -162,7 +162,7 @@ def _element_calculate(evaluator, context, left, operator, right):
         else:
             return ContextSet(create(evaluator, result))
     elif operator == 'in':
-        return set()
+        return NO_CONTEXTS
 
     def check(obj):
         """Checks if a Jedi object is either a float or an int."""
diff --git a/jedi/evaluate/recursion.py b/jedi/evaluate/recursion.py
index 85499496..ebc71f09 100644
--- a/jedi/evaluate/recursion.py
+++ b/jedi/evaluate/recursion.py
@@ -29,6 +29,7 @@ therefore the quality might not always be maximal.
 from contextlib import contextmanager
 
 from jedi import debug
+from jedi.common import NO_CONTEXTS
 
 
 recursion_limit = 15
@@ -71,7 +72,7 @@ def execution_allowed(evaluator, node):
         pushed_nodes.pop()
 
 
-def execution_recursion_decorator(default=set()):
+def execution_recursion_decorator(default=NO_CONTEXTS):
     def decorator(func):
         def wrapper(execution, **kwargs):
             detector = execution.evaluator.execution_recursion_detector
diff --git a/jedi/evaluate/stdlib.py b/jedi/evaluate/stdlib.py
index f2878e71..053f2b9c 100644
--- a/jedi/evaluate/stdlib.py
+++ b/jedi/evaluate/stdlib.py
@@ -24,6 +24,7 @@ from jedi.evaluate import precedence
 from jedi.evaluate import param
 from jedi.evaluate import analysis
 from jedi.evaluate.context import LazyTreeContext, ContextualizedNode
+from jedi.common import NO_CONTEXTS, ContextSet
 
 # Now this is all part of fake tuples in Jedi. However super doesn't work on
 # __init__ and __new__ doesn't work at all. So adding this to nametuples is
@@ -77,7 +78,7 @@ def _follow_param(evaluator, arguments, index):
     try:
         key, lazy_context = list(arguments.unpack())[index]
     except IndexError:
-        return set()
+        return NO_CONTEXTS
     else:
         return lazy_context.infer()
 
@@ -109,7 +110,7 @@ def argument_clinic(string, want_obj=False, want_context=False, want_arguments=F
             try:
                 lst = list(arguments.eval_argument_clinic(clinic_args))
             except ValueError:
-                return set()
+                return NO_CONTEXTS
             else:
                 kwargs = {}
                 if want_context:
@@ -137,15 +138,16 @@ def builtins_next(evaluator, iterators, defaults):
     else:
         name = '__next__'
 
-    types = set()
+    context_set = NO_CONTEXTS
     for iterator in iterators:
         if isinstance(iterator, AbstractInstanceContext):
-            for filter in iterator.get_filters(include_self_names=True):
-                for n in filter.get(name):
-                    for context in n.infer():
-                        types |= context.execute_evaluated()
-    if types:
-        return types
+            context_set = ContextSet.from_sets(
+                n.infer()
+                for filter in iterator.get_filters(include_self_names=True)
+                for n in filter.get(name)
+            ).execute_evaluated()
+    if context_set:
+        return context_set
     return defaults
 
 
@@ -159,16 +161,16 @@ def builtins_getattr(evaluator, objects, names, defaults=None):
             else:
                 debug.warning('getattr called without str')
                 continue
-    return set()
+    return NO_CONTEXTS
 
 
 @argument_clinic('object[, bases, dict], /')
 def builtins_type(evaluator, objects, bases, dicts):
     if bases or dicts:
         # It's a type creation... maybe someday...
-        return set()
+        return NO_CONTEXTS
     else:
-        return set([o.py__class__() for o in objects])
+        return ContextSet.from_iterable(o.py__class__() for o in objects)
 
 
 class SuperInstance(AbstractInstanceContext):
@@ -185,7 +187,7 @@ def builtins_super(evaluator, types, objects, context):
                             AnonymousInstanceFunctionExecution)):
         su = context.instance.py__class__().py__bases__()
         return unite(context.execute_evaluated() for context in su[0].infer())
-    return set()
+    return NO_CONTEXTS
 
 
 @argument_clinic('sequence, /', want_obj=True, want_arguments=True)
@@ -207,12 +209,12 @@ def builtins_reversed(evaluator, sequences, obj, arguments):
     # just returned the result directly.
     seq = iterable.FakeSequence(evaluator, 'list', rev)
     arguments = param.ValuesArguments([[seq]])
-    return set([CompiledInstance(evaluator, evaluator.BUILTINS, obj, arguments)])
+    return ContextSet(CompiledInstance(evaluator, evaluator.BUILTINS, obj, arguments))
 
 
 @argument_clinic('obj, type, /', want_arguments=True)
 def builtins_isinstance(evaluator, objects, types, arguments):
-    bool_results = set([])
+    bool_results = set()
     for o in objects:
         try:
             mro_func = o.py__class__().py__mro__
@@ -220,7 +222,7 @@ def builtins_isinstance(evaluator, objects, types, arguments):
             # This is temporary. Everything should have a class attribute in
             # Python?! Maybe we'll leave it here, because some numpy objects or
             # whatever might not.
-            return set([compiled.create(True), compiled.create(False)])
+            return ContextSet(compiled.create(True), compiled.create(False))
 
         mro = mro_func()
 
@@ -244,7 +246,7 @@ def builtins_isinstance(evaluator, objects, types, arguments):
                               'not %s.' % cls_or_tup
                     analysis.add(lazy_context._context, 'type-error-isinstance', node, message)
 
-    return set(compiled.create(evaluator, x) for x in bool_results)
+    return ContextSet.from_iterable(compiled.create(evaluator, x) for x in bool_results)
 
 
 def collections_namedtuple(evaluator, obj, arguments):
@@ -259,7 +261,7 @@ def collections_namedtuple(evaluator, obj, arguments):
     """
     # Namedtuples are not supported on Python 2.6
     if not hasattr(collections, '_class_template'):
-        return set()
+        return NO_CONTEXTS
 
     # Process arguments
     # TODO here we only use one of the types, we should use all.
@@ -274,7 +276,7 @@ def collections_namedtuple(evaluator, obj, arguments):
             for v in lazy_context.infer() if hasattr(v, 'obj')
         ]
     else:
-        return set()
+        return NO_CONTEXTS
 
     base = collections._class_template
     base += _NAMEDTUPLE_INIT
@@ -293,7 +295,7 @@ def collections_namedtuple(evaluator, obj, arguments):
     module = evaluator.grammar.parse(source)
     generated_class = next(module.iter_classdefs())
     parent_context = er.ModuleContext(evaluator, module, '')
-    return set([er.ClassContext(evaluator, generated_class, parent_context)])
+    return ContextSet(er.ClassContext(evaluator, generated_class, parent_context))
 
 
 @argument_clinic('first, /')
@@ -314,8 +316,8 @@ _implemented = {
         'deepcopy': _return_first_param,
     },
     'json': {
-        'load': lambda *args: set(),
-        'loads': lambda *args: set(),
+        'load': lambda *args: NO_CONTEXTS,
+        'loads': lambda *args: NO_CONTEXTS,
     },
     'collections': {
         'namedtuple': collections_namedtuple,