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# Copyright (c) 2016-2020 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2016 Moises Lopez <moylop260@vauxoo.com>
# Copyright (c) 2017, 2020 hippo91 <guillaume.peillex@gmail.com>
# Copyright (c) 2019, 2021 Pierre Sassoulas <pierre.sassoulas@gmail.com>
# Copyright (c) 2019 Hugo van Kemenade <hugovk@users.noreply.github.com>
# Copyright (c) 2020 Anthony Sottile <asottile@umich.edu>
# 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
"""Module to add McCabe checker class for pylint. """
from mccabe import PathGraph as Mccabe_PathGraph
from mccabe import PathGraphingAstVisitor as Mccabe_PathGraphingAstVisitor
from pylint import checkers
from pylint.checkers.utils import check_messages
from pylint.interfaces import HIGH, IAstroidChecker
class PathGraph(Mccabe_PathGraph):
def __init__(self, node):
super().__init__(name="", entity="", lineno=1)
self.root = node
class PathGraphingAstVisitor(Mccabe_PathGraphingAstVisitor):
def __init__(self):
super().__init__()
self._bottom_counter = 0
def default(self, node, *args):
for child in node.get_children():
self.dispatch(child, *args)
def dispatch(self, node, *args):
self.node = node
klass = node.__class__
meth = self._cache.get(klass)
if meth is None:
class_name = klass.__name__
meth = getattr(self.visitor, "visit" + class_name, self.default)
self._cache[klass] = meth
return meth(node, *args)
def visitFunctionDef(self, node):
if self.graph is not None:
# closure
pathnode = self._append_node(node)
self.tail = pathnode
self.dispatch_list(node.body)
bottom = "%s" % self._bottom_counter
self._bottom_counter += 1
self.graph.connect(self.tail, bottom)
self.graph.connect(node, bottom)
self.tail = bottom
else:
self.graph = PathGraph(node)
self.tail = node
self.dispatch_list(node.body)
self.graphs[f"{self.classname}{node.name}"] = self.graph
self.reset()
visitAsyncFunctionDef = visitFunctionDef
def visitSimpleStatement(self, node):
self._append_node(node)
visitAssert = (
visitAssign
) = (
visitAugAssign
) = (
visitDelete
) = (
visitPrint
) = (
visitRaise
) = (
visitYield
) = (
visitImport
) = (
visitCall
) = (
visitSubscript
) = (
visitPass
) = (
visitContinue
) = (
visitBreak
) = visitGlobal = visitReturn = visitExpr = visitAwait = visitSimpleStatement
def visitWith(self, node):
self._append_node(node)
self.dispatch_list(node.body)
visitAsyncWith = visitWith
def _append_node(self, node):
if not self.tail:
return None
self.graph.connect(self.tail, node)
self.tail = node
return node
def _subgraph(self, node, name, extra_blocks=()):
"""create the subgraphs representing any `if` and `for` statements"""
if self.graph is None:
# global loop
self.graph = PathGraph(node)
self._subgraph_parse(node, node, extra_blocks)
self.graphs[f"{self.classname}{name}"] = self.graph
self.reset()
else:
self._append_node(node)
self._subgraph_parse(node, node, extra_blocks)
def _subgraph_parse(self, node, pathnode, extra_blocks):
"""parse the body and any `else` block of `if` and `for` statements"""
loose_ends = []
self.tail = node
self.dispatch_list(node.body)
loose_ends.append(self.tail)
for extra in extra_blocks:
self.tail = node
self.dispatch_list(extra.body)
loose_ends.append(self.tail)
if node.orelse:
self.tail = node
self.dispatch_list(node.orelse)
loose_ends.append(self.tail)
else:
loose_ends.append(node)
if node:
bottom = "%s" % self._bottom_counter
self._bottom_counter += 1
for end in loose_ends:
self.graph.connect(end, bottom)
self.tail = bottom
class McCabeMethodChecker(checkers.BaseChecker):
"""Checks McCabe complexity cyclomatic threshold in methods and functions
to validate a too complex code.
"""
__implements__ = IAstroidChecker
name = "design"
msgs = {
"R1260": (
"%s is too complex. The McCabe rating is %d",
"too-complex",
"Used when a method or function is too complex based on "
"McCabe Complexity Cyclomatic",
)
}
options = (
(
"max-complexity",
{
"default": 10,
"type": "int",
"metavar": "<int>",
"help": "McCabe complexity cyclomatic threshold",
},
),
)
@check_messages("too-complex")
def visit_module(self, node):
"""visit an astroid.Module node to check too complex rating and
add message if is greather than max_complexity stored from options"""
visitor = PathGraphingAstVisitor()
for child in node.body:
visitor.preorder(child, visitor)
for graph in visitor.graphs.values():
complexity = graph.complexity()
node = graph.root
if hasattr(node, "name"):
node_name = "'%s'" % node.name
else:
node_name = "This '%s'" % node.__class__.__name__.lower()
if complexity <= self.config.max_complexity:
continue
self.add_message(
"too-complex", node=node, confidence=HIGH, args=(node_name, complexity)
)
def register(linter):
"""Required method to auto register this checker.
:param linter: Main interface object for Pylint plugins
:type linter: Pylint object
"""
linter.register_checker(McCabeMethodChecker(linter))
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