226 lines
7.3 KiB
Python
226 lines
7.3 KiB
Python
# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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# For details: https://github.com/pylint-dev/pylint/blob/main/LICENSE
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# Copyright (c) https://github.com/pylint-dev/pylint/blob/main/CONTRIBUTORS.txt
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"""Module to add McCabe checker class for pylint."""
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from __future__ import annotations
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from collections.abc import Sequence
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from typing import TYPE_CHECKING, Any, TypeAlias, TypeVar
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from astroid import nodes
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from mccabe import PathGraph as Mccabe_PathGraph
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from mccabe import PathGraphingAstVisitor as Mccabe_PathGraphingAstVisitor
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from pylint import checkers
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from pylint.checkers.utils import only_required_for_messages
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from pylint.interfaces import HIGH
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if TYPE_CHECKING:
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from pylint.lint import PyLinter
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_StatementNodes: TypeAlias = (
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nodes.Assert
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| nodes.Assign
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| nodes.AugAssign
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| nodes.Delete
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| nodes.Raise
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| nodes.Yield
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| nodes.Import
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| nodes.Call
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| nodes.Subscript
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| nodes.Pass
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| nodes.Continue
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| nodes.Break
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| nodes.Global
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| nodes.Return
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| nodes.Expr
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| nodes.Await
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)
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_SubGraphNodes: TypeAlias = nodes.If | nodes.Try | nodes.For | nodes.While | nodes.Match
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_AppendableNodeT = TypeVar(
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"_AppendableNodeT", bound=_StatementNodes | nodes.While | nodes.FunctionDef
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)
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class PathGraph(Mccabe_PathGraph): # type: ignore[misc]
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def __init__(self, node: _SubGraphNodes | nodes.FunctionDef):
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super().__init__(name="", entity="", lineno=1)
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self.root = node
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class PathGraphingAstVisitor(Mccabe_PathGraphingAstVisitor): # type: ignore[misc]
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def __init__(self) -> None:
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super().__init__()
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self._bottom_counter = 0
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self.graph: PathGraph | None = None
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def default(self, node: nodes.NodeNG, *args: Any) -> None:
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for child in node.get_children():
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self.dispatch(child, *args)
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def dispatch(self, node: nodes.NodeNG, *args: Any) -> Any:
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self.node = node
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klass = node.__class__
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meth = self._cache.get(klass)
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if meth is None:
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class_name = klass.__name__
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meth = getattr(self.visitor, "visit" + class_name, self.default)
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self._cache[klass] = meth
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return meth(node, *args)
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def visitFunctionDef(self, node: nodes.FunctionDef) -> None:
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if self.graph is not None:
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# closure
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pathnode = self._append_node(node)
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self.tail = pathnode
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self.dispatch_list(node.body)
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bottom = f"{self._bottom_counter}"
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self._bottom_counter += 1
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self.graph.connect(self.tail, bottom)
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self.graph.connect(node, bottom)
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self.tail = bottom
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else:
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self.graph = PathGraph(node)
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self.tail = node
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self.dispatch_list(node.body)
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self.graphs[f"{self.classname}{node.name}"] = self.graph
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self.reset()
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visitAsyncFunctionDef = visitFunctionDef
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def visitSimpleStatement(self, node: _StatementNodes) -> None:
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self._append_node(node)
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visitAssert = visitAssign = visitAugAssign = visitDelete = visitRaise = (
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visitYield
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) = visitImport = visitCall = visitSubscript = visitPass = visitContinue = (
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visitBreak
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) = visitGlobal = visitReturn = visitExpr = visitAwait = visitSimpleStatement
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def visitWith(self, node: nodes.With) -> None:
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self._append_node(node)
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self.dispatch_list(node.body)
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visitAsyncWith = visitWith
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def visitMatch(self, node: nodes.Match) -> None:
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self._subgraph(node, f"match_{id(node)}", node.cases)
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def _append_node(self, node: _AppendableNodeT) -> _AppendableNodeT | None:
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if not (self.tail and self.graph):
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return None
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self.graph.connect(self.tail, node)
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self.tail = node
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return node
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def _subgraph(
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self,
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node: _SubGraphNodes,
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name: str,
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extra_blocks: Sequence[nodes.ExceptHandler | nodes.MatchCase] = (),
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) -> None:
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"""Create the subgraphs representing any `if`, `for` or `match` statements."""
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if self.graph is None:
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# global loop
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self.graph = PathGraph(node)
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self._subgraph_parse(node, node, extra_blocks)
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self.graphs[f"{self.classname}{name}"] = self.graph
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self.reset()
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else:
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self._append_node(node)
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self._subgraph_parse(node, node, extra_blocks)
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def _subgraph_parse(
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self,
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node: _SubGraphNodes,
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pathnode: _SubGraphNodes,
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extra_blocks: Sequence[nodes.ExceptHandler | nodes.MatchCase],
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) -> None:
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"""Parse `match`/`case` blocks, or the body and `else` block of `if`/`for`
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statements.
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"""
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loose_ends = []
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if isinstance(node, nodes.Match):
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for case in extra_blocks:
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if isinstance(case, nodes.MatchCase):
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self.tail = node
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self.dispatch_list(case.body)
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loose_ends.append(self.tail)
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loose_ends.append(node)
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else:
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self.tail = node
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self.dispatch_list(node.body)
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loose_ends.append(self.tail)
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for extra in extra_blocks:
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self.tail = node
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self.dispatch_list(extra.body)
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loose_ends.append(self.tail)
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if node.orelse:
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self.tail = node
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self.dispatch_list(node.orelse)
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loose_ends.append(self.tail)
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else:
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loose_ends.append(node)
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if node and self.graph:
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bottom = f"{self._bottom_counter}"
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self._bottom_counter += 1
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for end in loose_ends:
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self.graph.connect(end, bottom)
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self.tail = bottom
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class McCabeMethodChecker(checkers.BaseChecker):
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"""Checks McCabe complexity cyclomatic threshold in methods and functions
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to validate a too complex code.
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"""
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name = "design"
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msgs = {
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"R1260": (
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"%s is too complex. The McCabe rating is %d",
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"too-complex",
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"Used when a method or function is too complex based on "
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"McCabe Complexity Cyclomatic",
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)
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}
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options = (
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(
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"max-complexity",
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{
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"default": 10,
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"type": "int",
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"metavar": "<int>",
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"help": "McCabe complexity cyclomatic threshold",
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},
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),
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)
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@only_required_for_messages("too-complex")
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def visit_module(self, node: nodes.Module) -> None:
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"""Visit an nodes.Module node to check too complex rating and
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add message if is greater than max_complexity stored from options.
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"""
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visitor = PathGraphingAstVisitor()
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for child in node.body:
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visitor.preorder(child, visitor)
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for graph in visitor.graphs.values():
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complexity = graph.complexity()
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node = graph.root
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if hasattr(node, "name"):
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node_name = f"'{node.name}'"
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else:
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node_name = f"This '{node.__class__.__name__.lower()}'"
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if complexity <= self.linter.config.max_complexity:
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continue
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self.add_message(
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"too-complex", node=node, confidence=HIGH, args=(node_name, complexity)
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)
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def register(linter: PyLinter) -> None:
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linter.register_checker(McCabeMethodChecker(linter))
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