[mccabe] Remove unused code that was used to draw graphics originally

Author: Pierre-Sassoulas

doc/whatsnew/fragments/10551.internal

@@ -0,0 +1,4 @@
+The dependency to mccabe was removed and its content is now vendored in pylint. Optimization were done as a result
+because mccabe was a code to dot graph generator and pylint only need to calculate the mccabe score not draw graphics.
+
+Refs #10551

pylint/extensions/mccabe.py

@@ -2,9 +2,6 @@
 # For details: https://github.com/pylint-dev/pylint/blob/main/LICENSE
 # Copyright (c) https://github.com/pylint-dev/pylint/blob/main/CONTRIBUTORS.txt
 
-# mypy: ignore-errors
-# pylint: disable=unused-argument,consider-using-generator
-
 """Module to add McCabe checker class for pylint.
 
 Based on:
@@ -15,8 +12,7 @@
 
 from __future__ import annotations
 
-from collections.abc import Sequence
-from typing import TYPE_CHECKING, Any, TypeAlias, TypeVar
+from typing import TYPE_CHECKING, Any
 
 from astroid import nodes
 
@@ -28,51 +24,24 @@
     from pylint.lint import PyLinter
 
 
-_StatementNodes: TypeAlias = (
-    nodes.Assert
-    | nodes.Assign
-    | nodes.AugAssign
-    | nodes.Delete
-    | nodes.Raise
-    | nodes.Yield
-    | nodes.Import
-    | nodes.Call
-    | nodes.Subscript
-    | nodes.Pass
-    | nodes.Continue
-    | nodes.Break
-    | nodes.Global
-    | nodes.Return
-    | nodes.Expr
-    | nodes.Await
-)
-
-_SubGraphNodes: TypeAlias = nodes.If | nodes.Try | nodes.For | nodes.While | nodes.Match
-_AppendableNodeT = TypeVar(
-    "_AppendableNodeT", bound=_StatementNodes | nodes.While | nodes.FunctionDef
-)
-
-
 class PathGraph:
-    def __init__(self, node: _SubGraphNodes | nodes.FunctionDef):
-        self.name = ""
-        self.root = node
-        self.nodes = {}
+    def __init__(self) -> None:
+        self.nodes: dict[Any, list[Any]] = {}
 
-    def connect(self, n1, n2):
+    def connect(self, n1: Any, n2: Any) -> None:
         if n1 not in self.nodes:
             self.nodes[n1] = []
         self.nodes[n1].append(n2)
         # Ensure that the destination node is always counted.
         if n2 not in self.nodes:
             self.nodes[n2] = []
 
-    def complexity(self):
+    def complexity(self) -> int:
         """Return the McCabe complexity for the graph.
 
         V-E+2
         """
-        num_edges = sum([len(n) for n in self.nodes.values()])
+        num_edges = sum(len(n) for n in self.nodes.values())
         num_nodes = len(self.nodes)
         return num_edges - num_nodes + 2
 
@@ -83,155 +52,119 @@ class PathGraphingAstVisitor:
     """
 
     def __init__(self) -> None:
-        self.classname = ""
-        self.graphs = {}
-        self._cache = {}
+        self.graphs: dict[str, tuple[PathGraph, nodes.NodeNG]] = {}
         self._bottom_counter = 0
         self.graph: PathGraph | None = None
-        self.tail = None
+        self.tail: Any = None
 
-    def reset(self):
-        self.graph = None
-        self.tail = None
+    def dispatch(self, node: nodes.NodeNG) -> None:
+        meth = getattr(self, "visit" + node.__class__.__name__, self.default)
+        meth(node)
 
-    def default(self, node: nodes.NodeNG, *args: Any) -> None:
+    def default(self, node: nodes.NodeNG) -> None:
         for child in node.get_children():
-            self.dispatch(child, *args)
-
-    def dispatch(self, node: nodes.NodeNG, *args: Any) -> Any:
-        klass = node.__class__
-        meth = self._cache.get(klass)
-        if meth is None:
-            class_name = klass.__name__
-            meth = getattr(self, "visit" + class_name, self.default)
-            self._cache[klass] = meth
-        return meth(node, *args)
-
-    def preorder(self, tree, visitor):
-        """Do preorder walk of tree using visitor."""
-        self.dispatch(tree)
-
-    def dispatch_list(self, node_list):
-        for node in node_list:
-            self.dispatch(node)
+            self.dispatch(child)
 
     def visitFunctionDef(self, node: nodes.FunctionDef) -> None:
         if self.graph is not None:
             # closure
-            pathnode = self._append_node(node)
-            self.tail = pathnode
-            self.dispatch_list(node.body)
+            self.graph.connect(self.tail, node)
+            self.tail = node
+            for child in node.body:
+                self.dispatch(child)
             bottom = f"{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.graph = PathGraph()
             self.tail = node
-            self.dispatch_list(node.body)
-            self.graphs[f"{self.classname}{node.name}"] = self.graph
-            self.reset()
+            for child in node.body:
+                self.dispatch(child)
+            self.graphs[node.name] = (self.graph, node)
+            self.graph = None
+            self.tail = None
 
     visitAsyncFunctionDef = visitFunctionDef
 
-    def visitClassDef(self, node: nodes.ClassDef) -> None:
-        old_classname = self.classname
-        self.classname += node.name + "."
-        self.dispatch_list(node.body)
-        self.classname = old_classname
-
-    def visitSimpleStatement(self, node: _StatementNodes) -> None:
-        self._append_node(node)
+    def visitAssert(self, node: nodes.NodeNG) -> None:
+        if self.tail and self.graph:
+            self.graph.connect(self.tail, node)
+            self.tail = node
 
-    visitAssert = visitAssign = visitAugAssign = visitDelete = visitRaise = (
-        visitYield
-    ) = visitImport = visitCall = visitSubscript = visitPass = visitContinue = (
-        visitBreak
-    ) = visitGlobal = visitReturn = visitExpr = visitAwait = visitSimpleStatement
+    visitAssign = visitAugAssign = visitDelete = visitRaise = visitYield = (
+        visitImport
+    ) = visitCall = visitSubscript = visitPass = visitContinue = visitBreak = (
+        visitGlobal
+    ) = visitReturn = visitExpr = visitAwait = visitAssert
 
     def visitWith(self, node: nodes.With) -> None:
-        self._append_node(node)
-        self.dispatch_list(node.body)
+        if self.tail and self.graph:
+            self.graph.connect(self.tail, node)
+            self.tail = node
+        for child in node.body:
+            self.dispatch(child)
 
     visitAsyncWith = visitWith
 
-    def visitLoop(self, node: nodes.For | nodes.While) -> None:
-        name = f"loop_{id(node)}"
-        self._subgraph(node, name)
-
-    visitAsyncFor = visitFor = visitWhile = visitLoop
+    def visitFor(self, node: nodes.For | nodes.While) -> None:
+        self._subgraph(node, node.handlers if isinstance(node, nodes.Try) else [])
 
-    def visitIf(self, node: nodes.If) -> None:
-        name = f"if_{id(node)}"
-        self._subgraph(node, name)
+    visitAsyncFor = visitWhile = visitIf = visitFor
 
-    def visitTryExcept(self, node: nodes.Try) -> None:
-        name = f"try_{id(node)}"
-        self._subgraph(node, name, extra_blocks=node.handlers)
-
-    visitTry = visitTryExcept
+    def visitTry(self, node: nodes.Try) -> None:
+        self._subgraph(node, node.handlers)
 
     def visitMatch(self, node: nodes.Match) -> None:
-        self._subgraph(node, f"match_{id(node)}", node.cases)
-
-    def _append_node(self, node: _AppendableNodeT) -> _AppendableNodeT | None:
-        if not self.tail or not self.graph:
-            return None
-        self.graph.connect(self.tail, node)
-        self.tail = node
-        return node
+        self._subgraph(node, node.cases)
 
     def _subgraph(
-        self,
-        node: _SubGraphNodes,
-        name: str,
-        extra_blocks: Sequence[nodes.ExceptHandler | nodes.MatchCase] = (),
+        self, node: nodes.NodeNG, extra_blocks: list[nodes.NodeNG] | None = None
     ) -> None:
-        """Create the subgraphs representing any `if`, `for` or `match` statements."""
+        if extra_blocks is None:
+            extra_blocks = []
         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()
+            self.graph = PathGraph()
+            self._parse(node, extra_blocks)
+            self.graphs[f"loop_{id(node)}"] = (self.graph, node)
+            self.graph = None
+            self.tail = None
         else:
-            self._append_node(node)
-            self._subgraph_parse(node, node, extra_blocks)
-
-    def _subgraph_parse(
-        self,
-        node: _SubGraphNodes,
-        pathnode: _SubGraphNodes,
-        extra_blocks: Sequence[nodes.ExceptHandler | nodes.MatchCase],
-    ) -> None:
-        """Parse `match`/`case` blocks, or the body and `else` block of `if`/`for`
-        statements.
-        """
+            if self.tail:
+                self.graph.connect(self.tail, node)
+                self.tail = node
+            self._parse(node, extra_blocks)
+
+    def _parse(self, node: nodes.NodeNG, extra_blocks: list[nodes.NodeNG]) -> None:
         loose_ends = []
         if isinstance(node, nodes.Match):
             for case in extra_blocks:
                 if isinstance(case, nodes.MatchCase):
                     self.tail = node
-                    self.dispatch_list(case.body)
+                    for child in case.body:
+                        self.dispatch(child)
                     loose_ends.append(self.tail)
             loose_ends.append(node)
         else:
             self.tail = node
-            self.dispatch_list(node.body)
+            for child in node.body:
+                self.dispatch(child)
             loose_ends.append(self.tail)
             for extra in extra_blocks:
                 self.tail = node
-                self.dispatch_list(extra.body)
+                for child in extra.body:
+                    self.dispatch(child)
                 loose_ends.append(self.tail)
-            if node.orelse:
+            if hasattr(node, "orelse") and node.orelse:
                 self.tail = node
-                self.dispatch_list(node.orelse)
+                for child in node.orelse:
+                    self.dispatch(child)
                 loose_ends.append(self.tail)
             else:
                 loose_ends.append(node)
 
-        if node and self.graph:
+        if self.graph:
             bottom = f"{self._bottom_counter}"
             self._bottom_counter += 1
             for end in loose_ends:
@@ -267,16 +200,15 @@ class McCabeMethodChecker(checkers.BaseChecker):
     )
 
     @only_required_for_messages("too-complex")
-    def visit_module(self, node: nodes.Module) -> None:
+    def visit_module(self, module: nodes.Module) -> None:
         """Visit an astroid.Module node to check too complex rating and
         add message if is greater than max_complexity stored from options.
         """
         visitor = PathGraphingAstVisitor()
-        for child in node.body:
-            visitor.preorder(child, visitor)
-        for graph in visitor.graphs.values():
+        for child in module.body:
+            visitor.dispatch(child)
+        for graph, node in visitor.graphs.values():
             complexity = graph.complexity()
-            node = graph.root
             if hasattr(node, "name"):
                 node_name = f"'{node.name}'"
             else: