Add pylint to depot_tools.

third_party/pylint/checkers/design_analysis.py

+# Copyright (c) 2003-2006 LOGILAB S.A. (Paris, FRANCE).
+# http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any later
+# version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+"""check for signs of poor design
+
+
+ see http://intranet.logilab.fr/jpl/view?rql=Any%20X%20where%20X%20eid%201243
+ FIXME: missing 13, 15, 16
+"""
+
+from logilab.astng import Function, If, InferenceError
+
+from pylint.interfaces import IASTNGChecker
+from pylint.checkers import BaseChecker
+
+import re
+
+# regexp for ignored argument name
+IGNORED_ARGUMENT_NAMES = re.compile('_.*')
+
+def class_is_abstract(klass):
+    """return true if the given class node should be considered as an abstract
+    class
+    """
+    for attr in klass.values():
+        if isinstance(attr, Function):
+            if attr.is_abstract(pass_is_abstract=False):
+                return True
+    return False
+
+
+MSGS = {
+    'R0901': ('Too many ancestors (%s/%s)',
+              'Used when class has too many parent classes, try to reduce \
+              this to get a more simple (and so easier to use) class.'),
+    'R0902': ('Too many instance attributes (%s/%s)',
+              'Used when class has too many instance attributes, try to reduce \
+              this to get a more simple (and so easier to use) class.'),
+    'R0903': ('Too few public methods (%s/%s)',
+              'Used when class has too few public methods, so be sure it\'s \
+              really worth it.'),
+    'R0904': ('Too many public methods (%s/%s)',
+              'Used when class has too many public methods, try to reduce \
+              this to get a more simple (and so easier to use) class.'),
+    
+    'R0911': ('Too many return statements (%s/%s)',
+              'Used when a function or method has too many return statement, \
+              making it hard to follow.'),
+    'R0912': ('Too many branches (%s/%s)',
+              'Used when a function or method has too many branches, \
+              making it hard to follow.'),
+    'R0913': ('Too many arguments (%s/%s)',
+              'Used when a function or method takes too many arguments.'),
+    'R0914': ('Too many local variables (%s/%s)',
+              'Used when a function or method has too many local variables.'),
+    'R0915': ('Too many statements (%s/%s)',
+              'Used when a function or method has too many statements. You \
+              should then split it in smaller functions / methods.'),
+    
+    'R0921': ('Abstract class not referenced',
+              'Used when an abstract class is not used as ancestor anywhere.'),
+    'R0922': ('Abstract class is only referenced %s times',
+              'Used when an abstract class is used less than X times as \
+              ancestor.'),
+    'R0923': ('Interface not implemented',
+              'Used when an interface class is not implemented anywhere.'),
+    }
+
+
+class MisdesignChecker(BaseChecker):
+    """checks for sign of poor/misdesign:                                      
+    * number of methods, attributes, local variables...                        
+    * size, complexity of functions, methods                                   
+    """
+    
+    __implements__ = (IASTNGChecker,)
+
+    # configuration section name
+    name = 'design'
+    # messages
+    msgs = MSGS
+    priority = -2
+    # configuration options
+    options = (('max-args',
+                {'default' : 5, 'type' : 'int', 'metavar' : '<int>',
+                 'help': 'Maximum number of arguments for function / method'}
+                ),
+               ('ignored-argument-names',
+                {'default' : IGNORED_ARGUMENT_NAMES,
+                 'type' :'regexp', 'metavar' : '<regexp>',
+                 'help' : 'Argument names that match this expression will be '
+                          'ignored. Default to name with leading underscore'}
+                ),
+               ('max-locals',
+                {'default' : 15, 'type' : 'int', 'metavar' : '<int>',
+                 'help': 'Maximum number of locals for function / method body'}
+                ),
+               ('max-returns',
+                {'default' : 6, 'type' : 'int', 'metavar' : '<int>',
+                 'help': 'Maximum number of return / yield for function / '
+                         'method body'}
+                ),
+               ('max-branchs',
+                {'default' : 12, 'type' : 'int', 'metavar' : '<int>',
+                 'help': 'Maximum number of branch for function / method body'}
+                ),
+               ('max-statements',
+                {'default' : 50, 'type' : 'int', 'metavar' : '<int>',
+                 'help': 'Maximum number of statements in function / method '
+                         'body'}
+                ),
+               ('max-parents',
+                {'default' : 7,
+                 'type' : 'int',
+                 'metavar' : '<num>',
+                 'help' : 'Maximum number of parents for a class (see R0901).'}
+                ),
+               ('max-attributes',
+                {'default' : 7,
+                 'type' : 'int',
+                 'metavar' : '<num>',
+                 'help' : 'Maximum number of attributes for a class \
+(see R0902).'}
+                ),
+               ('min-public-methods',
+                {'default' : 2,
+                 'type' : 'int',
+                 'metavar' : '<num>',
+                 'help' : 'Minimum number of public methods for a class \
+(see R0903).'}
+                ),
+               ('max-public-methods',
+                {'default' : 20,
+                 'type' : 'int',
+                 'metavar' : '<num>',
+                 'help' : 'Maximum number of public methods for a class \
+(see R0904).'}
+                ),
+               )
+
+    def __init__(self, linter=None):
+        BaseChecker.__init__(self, linter)
+        self.stats = None
+        self._returns = None
+        self._branchs = None
+        self._used_abstracts = None
+        self._used_ifaces = None
+        self._abstracts = None
+        self._ifaces = None
+        self._stmts = 0
+        
+    def open(self):
+        """initialize visit variables"""
+        self.stats = self.linter.add_stats()
+        self._returns = []
+        self._branchs = []
+        self._used_abstracts = {}
+        self._used_ifaces = {}
+        self._abstracts = []
+        self._ifaces = []
+
+    def close(self):
+        """check that abstract/interface classes are used"""
+        for abstract in self._abstracts:
+            if not abstract in self._used_abstracts:
+                self.add_message('R0921', node=abstract)
+            elif self._used_abstracts[abstract] < 2:
+                self.add_message('R0922', node=abstract,
+                                 args=self._used_abstracts[abstract])
+        for iface in self._ifaces:
+            if not iface in self._used_ifaces:
+                self.add_message('R0923', node=iface)
+                
+    def visit_class(self, node):
+        """check size of inheritance hierarchy and number of instance attributes
+        """
+        self._inc_branch()
+        # Is the total inheritance hierarchy is 7 or less?
+        nb_parents = len(list(node.ancestors()))
+        if nb_parents > self.config.max_parents:
+            self.add_message('R0901', node=node,
+                             args=(nb_parents, self.config.max_parents))
+        # Does the class contain less than 20 attributes for
+        # non-GUI classes (40 for GUI)?
+        # FIXME detect gui classes
+        if len(node.instance_attrs) > self.config.max_attributes:
+            self.add_message('R0902', node=node,
+                             args=(len(node.instance_attrs),
+                                   self.config.max_attributes))
+        # update abstract / interface classes structures
+        if class_is_abstract(node):
+            self._abstracts.append(node)
+        elif node.type == 'interface' and node.name != 'Interface':
+            self._ifaces.append(node)
+            for parent in node.ancestors(False):
+                if parent.name == 'Interface':
+                    continue
+                self._used_ifaces[parent] = 1
+        try:
+            for iface in node.interfaces():
+                self._used_ifaces[iface] = 1
+        except InferenceError:
+            # XXX log ? 
+            pass
+        for parent in node.ancestors():
+            try:
+                self._used_abstracts[parent] += 1
+            except KeyError:
+                self._used_abstracts[parent] = 1
+            
+    def leave_class(self, node):
+        """check number of public methods"""
+        nb_public_methods = 0
+        for method in node.methods():
+            if not method.name.startswith('_'):
+                nb_public_methods += 1
+        # Does the class contain less than 20 public methods ?
+        if nb_public_methods > self.config.max_public_methods:
+            self.add_message('R0904', node=node,
+                             args=(nb_public_methods,
+                                   self.config.max_public_methods))
+        # stop here for exception, metaclass and interface classes
+        if node.type != 'class':
+            return
+        # Does the class contain more than 5 public methods ?
+        if nb_public_methods < self.config.min_public_methods:
+            self.add_message('R0903', node=node,
+                             args=(nb_public_methods,
+                                   self.config.min_public_methods))
+
+        
+    def visit_function(self, node):
+        """check function name, docstring, arguments, redefinition,
+        variable names, max locals
+        """
+        self._inc_branch()
+        # init branch and returns counters
+        self._returns.append(0)
+        self._branchs.append(0)
+        # check number of arguments
+        args = node.args.args
+        if args is not None:
+            ignored_args_num = len(
+                [arg for arg in args
+                 if self.config.ignored_argument_names.match(arg.name)])
+            argnum = len(args) - ignored_args_num
+            if  argnum > self.config.max_args:
+                self.add_message('R0913', node=node,
+                                 args=(len(args), self.config.max_args))
+        else:
+            ignored_args_num = 0
+        # check number of local variables
+        locnum = len(node.locals) - ignored_args_num
+        if locnum > self.config.max_locals:
+            self.add_message('R0914', node=node,
+                             args=(locnum, self.config.max_locals))
+        # init statements counter
+        self._stmts = 1
+
+    def leave_function(self, node):
+        """most of the work is done here on close:
+        checks for max returns, branch, return in __init__
+        """
+        returns = self._returns.pop()
+        if returns > self.config.max_returns:
+            self.add_message('R0911', node=node,
+                             args=(returns, self.config.max_returns))
+        branchs = self._branchs.pop()
+        if branchs > self.config.max_branchs:
+            self.add_message('R0912', node=node,
+                             args=(branchs, self.config.max_branchs))
+        # check number of statements
+        if self._stmts > self.config.max_statements:
+            self.add_message('R0915', node=node,
+                             args=(self._stmts, self.config.max_statements))
+
+    def visit_return(self, _):
+        """count number of returns"""
+        if not self._returns:
+            return # return outside function, reported by the base checker
+        self._returns[-1] += 1
+        
+    def visit_default(self, node):
+        """default visit method -> increments the statements counter if
+        necessary
+        """
+        if node.is_statement:
+            self._stmts += 1
+
+    def visit_tryexcept(self, node):
+        """increments the branchs counter"""
+        branchs = len(node.handlers)
+        if node.orelse:
+            branchs += 1
+        self._inc_branch(branchs)
+        self._stmts += branchs
+        
+    def visit_tryfinally(self, _):
+        """increments the branchs counter"""
+        self._inc_branch(2)
+        self._stmts += 2
+        
+    def visit_if(self, node):
+        """increments the branchs counter"""
+        branchs = 1
+        # don't double count If nodes coming from some 'elif'
+        if node.orelse and (len(node.orelse)>1 or
+                            not isinstance(node.orelse[0], If)):
+            branchs += 1
+        self._inc_branch(branchs)
+        self._stmts += branchs
+        
+    def visit_while(self, node):
+        """increments the branchs counter"""
+        branchs = 1
+        if node.orelse:
+            branchs += 1
+        self._inc_branch(branchs)
+        
+    visit_for = visit_while
+
+    def _inc_branch(self, branchsnum=1):
+        """increments the branchs counter"""
+        branchs = self._branchs
+        for i in xrange(len(branchs)):
+            branchs[i] += branchsnum
+
+    # FIXME: make a nice report...
+
+def register(linter):
+    """required method to auto register this checker """
+    linter.register_checker(MisdesignChecker(linter))