File Content: 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 optparse import sys import tokenize from collections import defaultdict try: import ast from ast import iter_child_nodes except ImportError: # Python 2.5 from flake8.util import ast, iter_child_nodes __version__ = '0.7.0' 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 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, column=0): self.name = name self.entity = entity self.lineno = lineno self.column = column self.nodes = 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:%d: %r' % (node.lineno, node.col_offset, 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, node.col_offset) 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) def default(self, node, *args): if isinstance(node, ast.stmt): self.visitSimpleStatement(node) else: super(PathGraphingAstVisitor, self).default(node, *args) def visitLoop(self, node): name = "Loop %d" % node.lineno self._subgraph(node, name) visitAsyncFor = visitFor = 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, node.col_offset) 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 class McCabeChecker(object): """McCabe cyclomatic complexity checker.""" name = 'mccabe' version = __version__ _code = 'C901' _error_tmpl = "C901 %r is too complex (%d)" max_complexity = -1 def __init__(self, tree, filename): self.tree = tree @classmethod def add_options(cls, parser): flag = '--max-complexity' kwargs = { 'default': -1, 'action': 'store', 'type': int, 'help': 'McCabe complexity threshold', 'parse_from_config': 'True', } config_opts = getattr(parser, 'config_options', None) if isinstance(config_opts, list): # Flake8 2.x kwargs.pop('parse_from_config') parser.add_option(flag, **kwargs) parser.config_options.append('max-complexity') else: parser.add_option(flag, **kwargs) @classmethod def parse_options(cls, options): cls.max_complexity = int(options.max_complexity) def run(self): if self.max_complexity < 0: return visitor = PathGraphingAstVisitor() visitor.preorder(self.tree, visitor) for graph in visitor.graphs.values(): if graph.complexity() > self.max_complexity: text = self._error_tmpl % (graph.entity, graph.complexity()) yield graph.lineno, graph.column, text, type(self) def get_code_complexity(code, threshold=7, filename='stdin'): try: tree = compile(code, filename, "exec", ast.PyCF_ONLY_AST) except SyntaxError: e = sys.exc_info()[1] sys.stderr.write("Unable to parse %s: %s\n" % (filename, e)) return 0 complx = [] McCabeChecker.max_complexity = threshold for lineno, offset, text, check in McCabeChecker(tree, filename).run(): complx.append('%s:%d:1: %s' % (filename, lineno, text)) if len(complx) == 0: return 0 print('\n'.join(complx)) return len(complx) def get_module_complexity(module_path, threshold=7): """Returns the complexity of a module""" code = _read(module_path) return get_code_complexity(code, threshold, filename=module_path) def _read(filename): if (2, 5) < sys.version_info < (3, 0): with open(filename, 'rU') as f: return f.read() elif (3, 0) <= sys.version_info < (4, 0): """Read the source code.""" try: with open(filename, 'rb') as f: (encoding, _) = tokenize.detect_encoding(f.readline) except (LookupError, SyntaxError, UnicodeError): # Fall back if file encoding is improperly declared with open(filename, encoding='latin-1') as f: return f.read() with open(filename, 'r', encoding=encoding) as f: return f.read() def main(argv=None): if argv is None: argv = sys.argv[1:] opar = optparse.OptionParser() opar.add_option("-d", "--dot", dest="dot", help="output a graphviz dot file", action="store_true") opar.add_option("-m", "--min", dest="threshold", help="minimum complexity for output", type="int", default=1) options, args = opar.parse_args(argv) code = _read(args[0]) tree = compile(code, args[0], "exec", ast.PyCF_ONLY_AST) visitor = PathGraphingAstVisitor() visitor.preorder(tree, visitor) if options.dot: print('graph {') for graph in visitor.graphs.values(): if (not options.threshold or graph.complexity() >= options.threshold): graph.to_dot() print('}') else: for graph in visitor.graphs.values(): if graph.complexity() >= options.threshold: print(graph.name, graph.complexity()) if __name__ == '__main__': main(sys.argv[1:]) Submit