8th day of python challenges 111-117

venv/lib/python3.6/site-packages/pylint/checkers/async.py

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+# Copyright (c) 2015-2018 Claudiu Popa <pcmanticore@gmail.com>
+# Copyright (c) 2017 Derek Gustafson <degustaf@gmail.com>
+
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/master/COPYING
+
+"""Checker for anything related to the async protocol (PEP 492)."""
+
+import sys
+
+import astroid
+from astroid import bases
+from astroid import exceptions
+
+from pylint import checkers
+from pylint.checkers import utils as checker_utils
+from pylint import interfaces
+from pylint import utils
+from pylint.checkers.utils import decorated_with
+
+
+class AsyncChecker(checkers.BaseChecker):
+    __implements__ = interfaces.IAstroidChecker
+    name = "async"
+    msgs = {
+        "E1700": (
+            "Yield inside async function",
+            "yield-inside-async-function",
+            "Used when an `yield` or `yield from` statement is "
+            "found inside an async function.",
+            {"minversion": (3, 5)},
+        ),
+        "E1701": (
+            "Async context manager '%s' doesn't implement __aenter__ and __aexit__.",
+            "not-async-context-manager",
+            "Used when an async context manager is used with an object "
+            "that does not implement the async context management protocol.",
+            {"minversion": (3, 5)},
+        ),
+    }
+
+    def open(self):
+        self._ignore_mixin_members = utils.get_global_option(
+            self, "ignore-mixin-members"
+        )
+        self._async_generators = ["contextlib.asynccontextmanager"]
+
+    @checker_utils.check_messages("yield-inside-async-function")
+    def visit_asyncfunctiondef(self, node):
+        for child in node.nodes_of_class(astroid.Yield):
+            if child.scope() is node and (
+                sys.version_info[:2] == (3, 5) or isinstance(child, astroid.YieldFrom)
+            ):
+                self.add_message("yield-inside-async-function", node=child)
+
+    @checker_utils.check_messages("not-async-context-manager")
+    def visit_asyncwith(self, node):
+        for ctx_mgr, _ in node.items:
+            inferred = checker_utils.safe_infer(ctx_mgr)
+            if inferred is None or inferred is astroid.Uninferable:
+                continue
+
+            if isinstance(inferred, bases.AsyncGenerator):
+                # Check if we are dealing with a function decorated
+                # with contextlib.asynccontextmanager.
+                if decorated_with(inferred.parent, self._async_generators):
+                    continue
+            else:
+                try:
+                    inferred.getattr("__aenter__")
+                    inferred.getattr("__aexit__")
+                except exceptions.NotFoundError:
+                    if isinstance(inferred, astroid.Instance):
+                        # If we do not know the bases of this class,
+                        # just skip it.
+                        if not checker_utils.has_known_bases(inferred):
+                            continue
+                        # Just ignore mixin classes.
+                        if self._ignore_mixin_members:
+                            if inferred.name[-5:].lower() == "mixin":
+                                continue
+                else:
+                    continue
+
+            self.add_message(
+                "not-async-context-manager", node=node, args=(inferred.name,)
+            )
+
+
+def register(linter):
+    """required method to auto register this checker"""
+    linter.register_checker(AsyncChecker(linter))