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""" 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:])
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