Plugins/CheckerPlugins/CodeStyleChecker/mccabe.py

""" Meager code path measurement tool.
    Ned Batchelder
    http://nedbatchelder.com/blog/200803/python_code_complexity_microtool.html
    MIT License.
"""
from __future__ import with_statement

import collections
import ast

__version__ = '0.3.1_eric6'


class ASTVisitor(object):
    """Performs a depth-first walk of the AST."""

    def __init__(self):
        self.node = None
        self._cache = {}

    def default(self, node, *args):
        for child in ast.iter_child_nodes(node):
            self.dispatch(child, *args)

    def dispatch(self, node, *args):
        self.node = node
        klass = node.__class__
        meth = self._cache.get(klass)
        if meth is None:
            className = klass.__name__
            meth = getattr(self.visitor, 'visit' + className, self.default)
            self._cache[klass] = meth
        return meth(node, *args)

    def preorder(self, tree, visitor, *args):
        """Do preorder walk of tree using visitor"""
        self.visitor = visitor
        visitor.visit = self.dispatch
        self.dispatch(tree, *args)  # XXX *args make sense?


class PathNode(object):
    def __init__(self, name, look="circle"):
        self.name = name
        self.look = look

    def to_dot(self):
        print('node [shape=%s,label="%s"] %d;' % (
            self.look, self.name, self.dot_id()))

    def dot_id(self):
        return id(self)


class PathGraph(object):
    def __init__(self, name, entity, lineno):
        self.name = name
        self.entity = entity
        self.lineno = lineno
        self.nodes = collections.defaultdict(list)

    def connect(self, n1, n2):
        self.nodes[n1].append(n2)
        # Ensure that the destination node is always counted.
        self.nodes[n2] = []

    def to_dot(self):
        print('subgraph {')
        for node in self.nodes:
            node.to_dot()
        for node, nexts in self.nodes.items():
            for next in nexts:
                print('%s -- %s;' % (node.dot_id(), next.dot_id()))
        print('}')

    def complexity(self):
        """ Return the McCabe complexity for the graph.
            V-E+2
        """
        num_edges = sum([len(n) for n in self.nodes.values()])
        num_nodes = len(self.nodes)
        return num_edges - num_nodes + 2


class PathGraphingAstVisitor(ASTVisitor):
    """ A visitor for a parsed Abstract Syntax Tree which finds executable
        statements.
    """

    def __init__(self):
        super(PathGraphingAstVisitor, self).__init__()
        self.classname = ""
        self.graphs = {}
        self.reset()

    def reset(self):
        self.graph = None
        self.tail = None

    def dispatch_list(self, node_list):
        for node in node_list:
            self.dispatch(node)

    def visitFunctionDef(self, node):

        if self.classname:
            entity = '%s%s' % (self.classname, node.name)
        else:
            entity = node.name

        name = '%d:1: %r' % (node.lineno, entity)

        if self.graph is not None:
            # closure
            pathnode = self.appendPathNode(name)
            self.tail = pathnode
            self.dispatch_list(node.body)
            bottom = PathNode("", look='point')
            self.graph.connect(self.tail, bottom)
            self.graph.connect(pathnode, bottom)
            self.tail = bottom
        else:
            self.graph = PathGraph(name, entity, node.lineno)
            pathnode = PathNode(name)
            self.tail = pathnode
            self.dispatch_list(node.body)
            self.graphs["%s%s" % (self.classname, node.name)] = self.graph
            self.reset()

    visitAsyncFunctionDef = visitFunctionDef

    def visitClassDef(self, node):
        old_classname = self.classname
        self.classname += node.name + "."
        self.dispatch_list(node.body)
        self.classname = old_classname

    def appendPathNode(self, name):
        if not self.tail:
            return
        pathnode = PathNode(name)
        self.graph.connect(self.tail, pathnode)
        self.tail = pathnode
        return pathnode

    def visitSimpleStatement(self, node):
        if node.lineno is None:
            lineno = 0
        else:
            lineno = node.lineno
        name = "Stmt %d" % lineno
        self.appendPathNode(name)

    visitAssert = visitAssign = visitAugAssign = visitDelete = visitPrint = \
        visitRaise = visitYield = visitImport = visitCall = visitSubscript = \
        visitPass = visitContinue = visitBreak = visitGlobal = visitReturn = \
        visitSimpleStatement

    def visitLoop(self, node):
        name = "Loop %d" % node.lineno
        self._subgraph(node, name)

    visitFor = visitAsyncFor = visitWhile = visitLoop

    def visitIf(self, node):
        name = "If %d" % node.lineno
        self._subgraph(node, name)

    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(name, name, node.lineno)
            pathnode = PathNode(name)
            self._subgraph_parse(node, pathnode, extra_blocks)
            self.graphs["%s%s" % (self.classname, name)] = self.graph
            self.reset()
        else:
            pathnode = self.appendPathNode(name)
            self._subgraph_parse(node, pathnode, 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 = pathnode
        self.dispatch_list(node.body)
        loose_ends.append(self.tail)
        for extra in extra_blocks:
            self.tail = pathnode
            self.dispatch_list(extra.body)
            loose_ends.append(self.tail)
        if node.orelse:
            self.tail = pathnode
            self.dispatch_list(node.orelse)
            loose_ends.append(self.tail)
        else:
            loose_ends.append(pathnode)
        if pathnode:
            bottom = PathNode("", look='point')
            for le in loose_ends:
                self.graph.connect(le, bottom)
            self.tail = bottom

    def visitTryExcept(self, node):
        name = "TryExcept %d" % node.lineno
        self._subgraph(node, name, extra_blocks=node.handlers)

    visitTry = visitTryExcept

    def visitWith(self, node):
        name = "With %d" % node.lineno
        self.appendPathNode(name)
        self.dispatch_list(node.body)
    
    visitAsyncWith = visitWith