path: root/pylint/utils.py

# Copyright (c) 2003-2014 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.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
"""some various utilities and helper classes, most of them used in the
main pylint class
"""
from __future__ import print_function

import collections
import os
from os.path import dirname, basename, splitext, exists, isdir, join, normpath
import re
import sys
import tokenize
import warnings
import textwrap

import six
from six.moves import zip  # pylint: disable=redefined-builtin

from astroid import nodes, Module
from astroid.modutils import modpath_from_file, get_module_files, \
    file_from_modpath, load_module_from_file

from pylint.interfaces import IRawChecker, ITokenChecker, UNDEFINED, implements
from pylint.reporters.ureports.nodes import Section


class UnknownMessage(Exception):
    """raised when a unregistered message id is encountered"""

class EmptyReport(Exception):
    """raised when a report is empty and so should not be displayed"""


MSG_TYPES = {
    'I' : 'info',
    'C' : 'convention',
    'R' : 'refactor',
    'W' : 'warning',
    'E' : 'error',
    'F' : 'fatal'
    }
MSG_TYPES_LONG = {v: k for k, v in six.iteritems(MSG_TYPES)}

MSG_TYPES_STATUS = {
    'I' : 0,
    'C' : 16,
    'R' : 8,
    'W' : 4,
    'E' : 2,
    'F' : 1
    }

DEPRECATED_ALIASES = {
    # New name, deprecated name.
    'repr': 'backquote',
    'expr': 'discard',
    'assignname': 'assname',
    'assignattr': 'assattr',
    'attribute': 'getattr',
    'call': 'callfunc',
    'importfrom': 'from',
    'classdef': 'class',
    'functiondef': 'function',
    'generatorexp': 'genexpr',
}

_MSG_ORDER = 'EWRCIF'
MSG_STATE_SCOPE_CONFIG = 0
MSG_STATE_SCOPE_MODULE = 1
MSG_STATE_CONFIDENCE = 2

# Allow stopping after the first semicolon encountered,
# so that an option can be continued with the reasons
# why it is active or disabled.
OPTION_RGX = re.compile(r'\s*#.*\bpylint:\s*([^;]+);{0,1}')

# The line/node distinction does not apply to fatal errors and reports.
_SCOPE_EXEMPT = 'FR'

class WarningScope(object):
    LINE = 'line-based-msg'
    NODE = 'node-based-msg'

_MsgBase = collections.namedtuple(
    '_MsgBase',
    ['msg_id', 'symbol', 'msg', 'C', 'category', 'confidence',
     'abspath', 'path', 'module', 'obj', 'line', 'column'])


class Message(_MsgBase):
    """This class represent a message to be issued by the reporters"""
    def __new__(cls, msg_id, symbol, location, msg, confidence):
        return _MsgBase.__new__(
            cls, msg_id, symbol, msg, msg_id[0], MSG_TYPES[msg_id[0]],
            confidence, *location)

    def format(self, template):
        """Format the message according to the given template.

        The template format is the one of the format method :
        cf. http://docs.python.org/2/library/string.html#formatstrings
        """
        # For some reason, _asdict on derived namedtuples does not work with
        # Python 3.4. Needs some investigation.
        return template.format(**dict(zip(self._fields, self)))


def get_module_and_frameid(node):
    """return the module name and the frame id in the module"""
    frame = node.frame()
    module, obj = '', []
    while frame:
        if isinstance(frame, Module):
            module = frame.name
        else:
            obj.append(getattr(frame, 'name', '<lambda>'))
        try:
            frame = frame.parent.frame()
        except AttributeError:
            frame = None
    obj.reverse()
    return module, '.'.join(obj)

def category_id(cid):
    cid = cid.upper()
    if cid in MSG_TYPES:
        return cid
    return MSG_TYPES_LONG.get(cid)


def _decoding_readline(stream, encoding):
    return lambda: stream.readline().decode(encoding, 'replace')


def tokenize_module(module):
    with module.stream() as stream:
        readline = stream.readline
        if sys.version_info < (3, 0):
            if module.file_encoding is not None:
                readline = _decoding_readline(stream, module.file_encoding)

            return list(tokenize.generate_tokens(readline))
        return list(tokenize.tokenize(readline))

def build_message_def(checker, msgid, msg_tuple):
    if implements(checker, (IRawChecker, ITokenChecker)):
        default_scope = WarningScope.LINE
    else:
        default_scope = WarningScope.NODE
    options = {}
    if len(msg_tuple) > 3:
        (msg, symbol, descr, options) = msg_tuple
    elif len(msg_tuple) > 2:
        (msg, symbol, descr) = msg_tuple[:3]
    else:
        # messages should have a symbol, but for backward compatibility
        # they may not.
        (msg, descr) = msg_tuple
        warnings.warn("[pylint 0.26] description of message %s doesn't include "
                      "a symbolic name" % msgid, DeprecationWarning)
        symbol = None
    options.setdefault('scope', default_scope)
    return MessageDefinition(checker, msgid, msg, descr, symbol, **options)


class MessageDefinition(object):
    def __init__(self, checker, msgid, msg, descr, symbol, scope,
                 minversion=None, maxversion=None, old_names=None):
        self.checker = checker
        assert len(msgid) == 5, 'Invalid message id %s' % msgid
        assert msgid[0] in MSG_TYPES, \
               'Bad message type %s in %r' % (msgid[0], msgid)
        self.msgid = msgid
        self.msg = msg
        self.descr = descr
        self.symbol = symbol
        self.scope = scope
        self.minversion = minversion
        self.maxversion = maxversion
        self.old_names = old_names or []

    def may_be_emitted(self):
        """return True if message may be emitted using the current interpreter"""
        if self.minversion is not None and self.minversion > sys.version_info:
            return False
        if self.maxversion is not None and self.maxversion <= sys.version_info:
            return False
        return True

    def format_help(self, checkerref=False):
        """return the help string for the given message id"""
        desc = self.descr
        if checkerref:
            desc += ' This message belongs to the %s checker.' % \
                   self.checker.name
        title = self.msg
        if self.symbol:
            msgid = '%s (%s)' % (self.symbol, self.msgid)
        else:
            msgid = self.msgid
        if self.minversion or self.maxversion:
            restr = []
            if self.minversion:
                restr.append('< %s' % '.'.join([str(n) for n in self.minversion]))
            if self.maxversion:
                restr.append('>= %s' % '.'.join([str(n) for n in self.maxversion]))
            restr = ' or '.join(restr)
            if checkerref:
                desc += " It can't be emitted when using Python %s." % restr
            else:
                desc += " This message can't be emitted when using Python %s." % restr
        desc = _normalize_text(' '.join(desc.split()), indent='  ')
        if title != '%s':
            title = title.splitlines()[0]
            return ':%s: *%s*\n%s' % (msgid, title, desc)
        return ':%s:\n%s' % (msgid, desc)


class MessagesHandlerMixIn(object):
    """a mix-in class containing all the messages related methods for the main
    lint class
    """

    def __init__(self):
        self._msgs_state = {}
        self.msg_status = 0

    def _checker_messages(self, checker):
        for checker in self._checkers[checker.lower()]:
            for msgid in checker.msgs:
                yield msgid

    def disable(self, msgid, scope='package', line=None, ignore_unknown=False):
        """don't output message of the given id"""
        assert scope in ('package', 'module')
        # handle disable=all by disabling all categories
        if msgid == 'all':
            for msgid in MSG_TYPES:
                self.disable(msgid, scope, line)
            return
        # msgid is a category?
        catid = category_id(msgid)
        if catid is not None:
            for _msgid in self.msgs_store._msgs_by_category.get(catid):
                self.disable(_msgid, scope, line)
            return
        # msgid is a checker name?
        if msgid.lower() in self._checkers:
            msgs_store = self.msgs_store
            for checker in self._checkers[msgid.lower()]:
                for _msgid in checker.msgs:
                    if _msgid in msgs_store._alternative_names:
                        self.disable(_msgid, scope, line)
            return
        # msgid is report id?
        if msgid.lower().startswith('rp'):
            self.disable_report(msgid)
            return

        try:
            # msgid is a symbolic or numeric msgid.
            msg = self.msgs_store.check_message_id(msgid)
        except UnknownMessage:
            if ignore_unknown:
                return
            raise

        if scope == 'module':
            self.file_state.set_msg_status(msg, line, False)
            if msg.symbol != 'locally-disabled':
                self.add_message('locally-disabled', line=line,
                                 args=(msg.symbol, msg.msgid))

        else:
            msgs = self._msgs_state
            msgs[msg.msgid] = False
            # sync configuration object
            self.config.disable = [self._message_symbol(mid)
                                   for mid, val in six.iteritems(msgs)
                                   if not val]

    def _message_symbol(self, msgid):
        """Get the message symbol of the given message id

        Return the original message id if the message does not
        exist.
        """
        try:
            return self.msgs_store.check_message_id(msgid).symbol
        except UnknownMessage:
            return msgid

    def enable(self, msgid, scope='package', line=None, ignore_unknown=False):
        """reenable message of the given id"""
        assert scope in ('package', 'module')
        if msgid == 'all':
            for msgid_ in MSG_TYPES:
                self.enable(msgid_, scope=scope, line=line)
            if not self._python3_porting_mode:
                # Don't activate the python 3 porting checker if it
                # wasn't activated explicitly.
                self.disable('python3')
            return
        catid = category_id(msgid)
        # msgid is a category?
        if catid is not None:
            for msgid in self.msgs_store._msgs_by_category.get(catid):
                self.enable(msgid, scope, line)
            return
        # msgid is a checker name?
        if msgid.lower() in self._checkers:
            for checker in self._checkers[msgid.lower()]:
                for msgid_ in checker.msgs:
                    self.enable(msgid_, scope, line)
            return
        # msgid is report id?
        if msgid.lower().startswith('rp'):
            self.enable_report(msgid)
            return

        try:
            # msgid is a symbolic or numeric msgid.
            msg = self.msgs_store.check_message_id(msgid)
        except UnknownMessage:
            if ignore_unknown:
                return
            raise

        if scope == 'module':
            self.file_state.set_msg_status(msg, line, True)
            self.add_message('locally-enabled', line=line, args=(msg.symbol, msg.msgid))
        else:
            msgs = self._msgs_state
            msgs[msg.msgid] = True
            # sync configuration object
            self.config.enable = [mid for mid, val in six.iteritems(msgs) if val]

    def get_message_state_scope(self, msgid, line=None, confidence=UNDEFINED):
        """Returns the scope at which a message was enabled/disabled."""
        if self.config.confidence and confidence.name not in self.config.confidence:
            return MSG_STATE_CONFIDENCE
        try:
            if line in self.file_state._module_msgs_state[msgid]:
                return MSG_STATE_SCOPE_MODULE
        except (KeyError, TypeError):
            return MSG_STATE_SCOPE_CONFIG

    def is_message_enabled(self, msg_descr, line=None, confidence=None):
        """return true if the message associated to the given message id is
        enabled

        msgid may be either a numeric or symbolic message id.
        """
        if self.config.confidence and confidence:
            if confidence.name not in self.config.confidence:
                return False
        try:
            msgid = self.msgs_store.check_message_id(msg_descr).msgid
        except UnknownMessage:
            # The linter checks for messages that are not registered
            # due to version mismatch, just treat them as message IDs
            # for now.
            msgid = msg_descr
        if line is None:
            return self._msgs_state.get(msgid, True)
        try:
            return self.file_state._module_msgs_state[msgid][line]
        except KeyError:
            return self._msgs_state.get(msgid, True)

    def add_message(self, msg_descr, line=None, node=None, args=None, confidence=UNDEFINED):
        """Adds a message given by ID or name.

        If provided, the message string is expanded using args

        AST checkers should must the node argument (but may optionally
        provide line if the line number is different), raw and token checkers
        must provide the line argument.
        """
        msg_info = self.msgs_store.check_message_id(msg_descr)
        msgid = msg_info.msgid
        # backward compatibility, message may not have a symbol
        symbol = msg_info.symbol or msgid
        # Fatal messages and reports are special, the node/scope distinction
        # does not apply to them.
        if msgid[0] not in _SCOPE_EXEMPT:
            if msg_info.scope == WarningScope.LINE:
                assert node is None and line is not None, (
                    'Message %s must only provide line, got line=%s, node=%s' % (msgid, line, node))
            elif msg_info.scope == WarningScope.NODE:
                # Node-based warnings may provide an override line.
                assert node is not None, 'Message %s must provide Node, got None'

        if line is None and node is not None:
            line = node.fromlineno
        if hasattr(node, 'col_offset'):
            col_offset = node.col_offset # XXX measured in bytes for utf-8, divide by two for chars?
        else:
            col_offset = None
        # should this message be displayed
        if not self.is_message_enabled(msgid, line, confidence):
            self.file_state.handle_ignored_message(
                self.get_message_state_scope(msgid, line, confidence),
                msgid, line, node, args, confidence)
            return
        # update stats
        msg_cat = MSG_TYPES[msgid[0]]
        self.msg_status |= MSG_TYPES_STATUS[msgid[0]]
        self.stats[msg_cat] += 1
        self.stats['by_module'][self.current_name][msg_cat] += 1
        try:
            self.stats['by_msg'][symbol] += 1
        except KeyError:
            self.stats['by_msg'][symbol] = 1
        # expand message ?
        msg = msg_info.msg
        if args:
            msg %= args
        # get module and object
        if node is None:
            module, obj = self.current_name, ''
            abspath = self.current_file
        else:
            module, obj = get_module_and_frameid(node)
            abspath = node.root().file
        path = abspath.replace(self.reporter.path_strip_prefix, '')
        # add the message
        self.reporter.handle_message(
            Message(msgid, symbol,
                    (abspath, path, module, obj, line or 1, col_offset or 0), msg, confidence))

    def print_full_documentation(self):
        """output a full documentation in ReST format"""
        print("Pylint global options and switches")
        print("----------------------------------")
        print("")
        print("Pylint provides global options and switches.")
        print("")

        by_checker = {}
        for checker in self.get_checkers():
            if checker.name == 'master':
                if checker.options:
                    for section, options in checker.options_by_section():
                        if section is None:
                            title = 'General options'
                        else:
                            title = '%s options' % section.capitalize()
                        print(title)
                        print('~' * len(title))
                        _rest_format_section(sys.stdout, None, options)
                        print("")
            else:
                try:
                    by_checker[checker.name][0] += checker.options_and_values()
                    by_checker[checker.name][1].update(checker.msgs)
                    by_checker[checker.name][2] += checker.reports
                except KeyError:
                    by_checker[checker.name] = [list(checker.options_and_values()),
                                                dict(checker.msgs),
                                                list(checker.reports)]

        print("Pylint checkers' options and switches")
        print("-------------------------------------")
        print("")
        print("Pylint checkers can provide three set of features:")
        print("")
        print("* options that control their execution,")
        print("* messages that they can raise,")
        print("* reports that they can generate.")
        print("")
        print("Below is a list of all checkers and their features.")
        print("")

        for checker, (options, msgs, reports) in six.iteritems(by_checker):
            title = '%s checker' % (checker.replace("_", " ").title())
            print(title)
            print('~' * len(title))
            print("")
            print("Verbatim name of the checker is ``%s``." % checker)
            print("")
            if options:
                title = 'Options'
                print(title)
                print('^' * len(title))
                _rest_format_section(sys.stdout, None, options)
                print("")
            if msgs:
                title = 'Messages'
                print(title)
                print('~' * len(title))
                for msgid, msg in sorted(six.iteritems(msgs),
                                         key=lambda kv: (_MSG_ORDER.index(kv[0][0]), kv[1])):
                    msg = build_message_def(checker, msgid, msg)
                    print(msg.format_help(checkerref=False))
                print("")
            if reports:
                title = 'Reports'
                print(title)
                print('~' * len(title))
                for report in reports:
                    print(':%s: %s' % report[:2])
                print("")
            print("")


class FileState(object):
    """Hold internal state specific to the currently analyzed file"""

    def __init__(self, modname=None):
        self.base_name = modname
        self._module_msgs_state = {}
        self._raw_module_msgs_state = {}
        self._ignored_msgs = collections.defaultdict(set)
        self._suppression_mapping = {}

    def collect_block_lines(self, msgs_store, module_node):
        """Walk the AST to collect block level options line numbers."""
        for msg, lines in six.iteritems(self._module_msgs_state):
            self._raw_module_msgs_state[msg] = lines.copy()
        orig_state = self._module_msgs_state.copy()
        self._module_msgs_state = {}
        self._suppression_mapping = {}
        self._collect_block_lines(msgs_store, module_node, orig_state)

    def _collect_block_lines(self, msgs_store, node, msg_state):
        """Recursivly walk (depth first) AST to collect block level options line
        numbers.
        """
        for child in node.get_children():
            self._collect_block_lines(msgs_store, child, msg_state)
        first = node.fromlineno
        last = node.tolineno
        # first child line number used to distinguish between disable
        # which are the first child of scoped node with those defined later.
        # For instance in the code below:
        #
        # 1.   def meth8(self):
        # 2.        """test late disabling"""
        # 3.        # pylint: disable=E1102
        # 4.        print self.blip
        # 5.        # pylint: disable=E1101
        # 6.        print self.bla
        #
        # E1102 should be disabled from line 1 to 6 while E1101 from line 5 to 6
        #
        # this is necessary to disable locally messages applying to class /
        # function using their fromlineno
        if (isinstance(node, (nodes.Module, nodes.ClassDef, nodes.FunctionDef))
                and node.body):
            firstchildlineno = node.body[0].fromlineno
        else:
            firstchildlineno = last
        for msgid, lines in six.iteritems(msg_state):
            for lineno, state in list(lines.items()):
                original_lineno = lineno
                if first > lineno or last < lineno:
                    continue
                # Set state for all lines for this block, if the
                # warning is applied to nodes.
                if  msgs_store.check_message_id(msgid).scope == WarningScope.NODE:
                    if lineno > firstchildlineno:
                        state = True
                    first_, last_ = node.block_range(lineno)
                else:
                    first_ = lineno
                    last_ = last
                for line in range(first_, last_+1):
                    # do not override existing entries
                    if line in self._module_msgs_state.get(msgid, ()):
                        continue
                    if line in lines: # state change in the same block
                        state = lines[line]
                        original_lineno = line
                    if not state:
                        self._suppression_mapping[(msgid, line)] = original_lineno
                    try:
                        self._module_msgs_state[msgid][line] = state
                    except KeyError:
                        self._module_msgs_state[msgid] = {line: state}
                del lines[lineno]

    def set_msg_status(self, msg, line, status):
        """Set status (enabled/disable) for a given message at a given line"""
        assert line > 0
        try:
            self._module_msgs_state[msg.msgid][line] = status
        except KeyError:
            self._module_msgs_state[msg.msgid] = {line: status}

    def handle_ignored_message(self, state_scope, msgid, line,
                               node, args, confidence): # pylint: disable=unused-argument
        """Report an ignored message.

        state_scope is either MSG_STATE_SCOPE_MODULE or MSG_STATE_SCOPE_CONFIG,
        depending on whether the message was disabled locally in the module,
        or globally. The other arguments are the same as for add_message.
        """
        if state_scope == MSG_STATE_SCOPE_MODULE:
            try:
                orig_line = self._suppression_mapping[(msgid, line)]
                self._ignored_msgs[(msgid, orig_line)].add(line)
            except KeyError:
                pass

    def iter_spurious_suppression_messages(self, msgs_store):
        for warning, lines in six.iteritems(self._raw_module_msgs_state):
            for line, enable in six.iteritems(lines):
                if not enable and (warning, line) not in self._ignored_msgs:
                    yield 'useless-suppression', line, \
                        (msgs_store.get_msg_display_string(warning),)
        # don't use iteritems here, _ignored_msgs may be modified by add_message
        for (warning, from_), lines in list(self._ignored_msgs.items()):
            for line in lines:
                yield 'suppressed-message', line, \
                    (msgs_store.get_msg_display_string(warning), from_)


class MessagesStore(object):
    """The messages store knows information about every possible message but has
    no particular state during analysis.
    """

    def __init__(self):
        # Primary registry for all active messages (i.e. all messages
        # that can be emitted by pylint for the underlying Python
        # version). It contains the 1:1 mapping from symbolic names
        # to message definition objects.
        self._messages = {}
        # Maps alternative names (numeric IDs, deprecated names) to
        # message definitions. May contain several names for each definition
        # object.
        self._alternative_names = {}
        self._msgs_by_category = collections.defaultdict(list)

    @property
    def messages(self):
        """The list of all active messages."""
        return six.itervalues(self._messages)

    def add_renamed_message(self, old_id, old_symbol, new_symbol):
        """Register the old ID and symbol for a warning that was renamed.

        This allows users to keep using the old ID/symbol in suppressions.
        """
        msg = self.check_message_id(new_symbol)
        msg.old_names.append((old_id, old_symbol))
        self._alternative_names[old_id] = msg
        self._alternative_names[old_symbol] = msg

    def register_messages(self, checker):
        """register a dictionary of messages

        Keys are message ids, values are a 2-uple with the message type and the
        message itself

        message ids should be a string of len 4, where the two first characters
        are the checker id and the two last the message id in this checker
        """
        chkid = None
        for msgid, msg_tuple in six.iteritems(checker.msgs):
            msg = build_message_def(checker, msgid, msg_tuple)
            assert msg.symbol not in self._messages, \
                    'Message symbol %r is already defined' % msg.symbol
            # avoid duplicate / malformed ids
            assert msg.msgid not in self._alternative_names, \
                   'Message id %r is already defined' % msgid
            assert chkid is None or chkid == msg.msgid[1:3], \
                   'Inconsistent checker part in message id %r' % msgid
            chkid = msg.msgid[1:3]
            self._messages[msg.symbol] = msg
            self._alternative_names[msg.msgid] = msg
            for old_id, old_symbol in msg.old_names:
                self._alternative_names[old_id] = msg
                self._alternative_names[old_symbol] = msg
            self._msgs_by_category[msg.msgid[0]].append(msg.msgid)

    def check_message_id(self, msgid):
        """returns the Message object for this message.

        msgid may be either a numeric or symbolic id.

        Raises UnknownMessage if the message id is not defined.
        """
        if msgid[1:].isdigit():
            msgid = msgid.upper()
        for source in (self._alternative_names, self._messages):
            try:
                return source[msgid]
            except KeyError:
                pass
        raise UnknownMessage('No such message id %s' % msgid)

    def get_msg_display_string(self, msgid):
        """Generates a user-consumable representation of a message.

        Can be just the message ID or the ID and the symbol.
        """
        return repr(self.check_message_id(msgid).symbol)

    def help_message(self, msgids):
        """display help messages for the given message identifiers"""
        for msgid in msgids:
            try:
                print(self.check_message_id(msgid).format_help(checkerref=True))
                print("")
            except UnknownMessage as ex:
                print(ex)
                print("")
                continue

    def list_messages(self):
        """output full messages list documentation in ReST format"""
        msgs = sorted(six.itervalues(self._messages), key=lambda msg: msg.msgid)
        for msg in msgs:
            if not msg.may_be_emitted():
                continue
            print(msg.format_help(checkerref=False))
        print("")


class ReportsHandlerMixIn(object):
    """a mix-in class containing all the reports and stats manipulation
    related methods for the main lint class
    """
    def __init__(self):
        self._reports = collections.defaultdict(list)
        self._reports_state = {}

    def report_order(self):
        """ Return a list of reports, sorted in the order
        in which they must be called.
        """
        return list(self._reports)

    def register_report(self, reportid, r_title, r_cb, checker):
        """register a report

        reportid is the unique identifier for the report
        r_title the report's title
        r_cb the method to call to make the report
        checker is the checker defining the report
        """
        reportid = reportid.upper()
        self._reports[checker].append((reportid, r_title, r_cb))

    def enable_report(self, reportid):
        """disable the report of the given id"""
        reportid = reportid.upper()
        self._reports_state[reportid] = True

    def disable_report(self, reportid):
        """disable the report of the given id"""
        reportid = reportid.upper()
        self._reports_state[reportid] = False

    def report_is_enabled(self, reportid):
        """return true if the report associated to the given identifier is
        enabled
        """
        return self._reports_state.get(reportid, True)

    def make_reports(self, stats, old_stats):
        """render registered reports"""
        sect = Section('Report',
                       '%s statements analysed.'% (self.stats['statement']))
        for checker in self.report_order():
            for reportid, r_title, r_cb in self._reports[checker]:
                if not self.report_is_enabled(reportid):
                    continue
                report_sect = Section(r_title)
                try:
                    r_cb(report_sect, stats, old_stats)
                except EmptyReport:
                    continue
                report_sect.report_id = reportid
                sect.append(report_sect)
        return sect

    def add_stats(self, **kwargs):
        """add some stats entries to the statistic dictionary
        raise an AssertionError if there is a key conflict
        """
        for key, value in six.iteritems(kwargs):
            if key[-1] == '_':
                key = key[:-1]
            assert key not in self.stats
            self.stats[key] = value
        return self.stats


def expand_modules(files_or_modules, black_list):
    """take a list of files/modules/packages and return the list of tuple
    (file, module name) which have to be actually checked
    """
    result = []
    errors = []
    for something in files_or_modules:
        if exists(something):
            # this is a file or a directory
            try:
                modname = '.'.join(modpath_from_file(something))
            except ImportError:
                modname = splitext(basename(something))[0]
            if isdir(something):
                filepath = join(something, '__init__.py')
            else:
                filepath = something
        else:
            # suppose it's a module or package
            modname = something
            try:
                filepath = file_from_modpath(modname.split('.'))
                if filepath is None:
                    continue
            except (ImportError, SyntaxError) as ex:
                # FIXME p3k : the SyntaxError is a Python bug and should be
                # removed as soon as possible http://bugs.python.org/issue10588
                errors.append({'key': 'fatal', 'mod': modname, 'ex': ex})
                continue
        filepath = normpath(filepath)
        result.append({'path': filepath, 'name': modname, 'isarg': True,
                       'basepath': filepath, 'basename': modname})
        if not (modname.endswith('.__init__') or modname == '__init__') \
                and '__init__.py' in filepath:
            for subfilepath in get_module_files(dirname(filepath), black_list):
                if filepath == subfilepath:
                    continue
                submodname = '.'.join(modpath_from_file(subfilepath))
                result.append({'path': subfilepath, 'name': submodname,
                               'isarg': False,
                               'basepath': filepath, 'basename': modname})
    return result, errors


class PyLintASTWalker(object):

    def __init__(self, linter):
        # callbacks per node types
        self.nbstatements = 0
        self.visit_events = collections.defaultdict(list)
        self.leave_events = collections.defaultdict(list)
        self.linter = linter

    def _is_method_enabled(self, method):
        if not hasattr(method, 'checks_msgs'):
            return True
        for msg_desc in method.checks_msgs:
            if self.linter.is_message_enabled(msg_desc):
                return True
        return False

    def add_checker(self, checker):
        """walk to the checker's dir and collect visit and leave methods"""
        # XXX : should be possible to merge needed_checkers and add_checker
        vcids = set()
        lcids = set()
        visits = self.visit_events
        leaves = self.leave_events
        for member in dir(checker):
            cid = member[6:]
            if cid == 'default':
                continue
            if member.startswith('visit_'):
                v_meth = getattr(checker, member)
                # don't use visit_methods with no activated message:
                if self._is_method_enabled(v_meth):
                    visits[cid].append(v_meth)
                    vcids.add(cid)
            elif member.startswith('leave_'):
                l_meth = getattr(checker, member)
                # don't use leave_methods with no activated message:
                if self._is_method_enabled(l_meth):
                    leaves[cid].append(l_meth)
                    lcids.add(cid)
        visit_default = getattr(checker, 'visit_default', None)
        if visit_default:
            for cls in nodes.ALL_NODE_CLASSES:
                cid = cls.__name__.lower()
                if cid not in vcids:
                    visits[cid].append(visit_default)
        # for now we have no "leave_default" method in Pylint

    def walk(self, astroid):
        """call visit events of astroid checkers for the given node, recurse on
        its children, then leave events.
        """
        cid = astroid.__class__.__name__.lower()

        # Detect if the node is a new name for a deprecated alias.
        # In this case, favour the methods for the deprecated
        # alias if any,  in order to maintain backwards
        # compatibility. If both of them are present,
        # only the old ones will be called.
        old_cid = DEPRECATED_ALIASES.get(cid)
        visit_events = ()
        leave_events = ()

        if old_cid:
            visit_events = self.visit_events.get(old_cid)
            leave_events = self.leave_events.get(old_cid)
            if visit_events or leave_events:
                msg = ("Implemented method {meth}_{old} instead of {meth}_{new}. "
                       "This will be supported until Pylint 2.0.")
                if visit_events:
                    warnings.warn(msg.format(meth="visit", old=old_cid, new=cid),
                                  PendingDeprecationWarning)
                if leave_events:
                    warnings.warn(msg.format(meth="leave", old=old_cid, new=cid),
                                  PendingDeprecationWarning)

        if not visit_events:
            visit_events = self.visit_events.get(cid)
        if not leave_events:
            leave_events = self.leave_events.get(cid)

        if astroid.is_statement:
            self.nbstatements += 1
        # generate events for this node on each checker
        for cb in visit_events or ():
            cb(astroid)
        # recurse on children
        for child in astroid.get_children():
            self.walk(child)
        for cb in leave_events or ():
            cb(astroid)


PY_EXTS = ('.py', '.pyc', '.pyo', '.pyw', '.so', '.dll')

def register_plugins(linter, directory):
    """load all module and package in the given directory, looking for a
    'register' function in each one, used to register pylint checkers
    """
    imported = {}
    for filename in os.listdir(directory):
        base, extension = splitext(filename)
        if base in imported or base == '__pycache__':
            continue
        if extension in PY_EXTS and base != '__init__' or (
                not extension and isdir(join(directory, base))):
            try:
                module = load_module_from_file(join(directory, filename))
            except ValueError:
                # empty module name (usually emacs auto-save files)
                continue
            except ImportError as exc:
                print("Problem importing module %s: %s" % (filename, exc),
                      file=sys.stderr)
            else:
                if hasattr(module, 'register'):
                    module.register(linter)
                    imported[base] = 1

def get_global_option(checker, option, default=None):
    """ Retrieve an option defined by the given *checker* or
    by all known option providers.

    It will look in the list of all options providers
    until the given *option* will be found.
    If the option wasn't found, the *default* value will be returned.
    """
    # First, try in the given checker's config.
    # After that, look in the options providers.

    try:
        return getattr(checker.config, option.replace("-", "_"))
    except AttributeError:
        pass
    for provider in checker.linter.options_providers:
        for options in provider.options:
            if options[0] == option:
                return getattr(provider.config, option.replace("-", "_"))
    return default


def deprecated_option(shortname=None, opt_type=None, help_msg=None):
    def _warn_deprecated(option, optname, *args): # pylint: disable=unused-argument
        msg = ("Warning: option %s is obsolete and "
               "it is slated for removal in Pylint 1.6.\n")
        sys.stderr.write(msg % (optname,))

    option = {
        'help': help_msg,
        'hide': True,
        'type': opt_type,
        'action': 'callback',
        'callback': _warn_deprecated,
        'deprecated': True
    }
    if shortname:
        option['shortname'] = shortname
    return option


def _splitstrip(string, sep=','):
    """return a list of stripped string by splitting the string given as
    argument on `sep` (',' by default). Empty string are discarded.

    >>> _splitstrip('a, b, c   ,  4,,')
    ['a', 'b', 'c', '4']
    >>> _splitstrip('a')
    ['a']
    >>>

    :type string: str or unicode
    :param string: a csv line

    :type sep: str or unicode
    :param sep: field separator, default to the comma (',')

    :rtype: str or unicode
    :return: the unquoted string (or the input string if it wasn't quoted)
    """
    return [word.strip() for word in string.split(sep) if word.strip()]


def _unquote(string):
    """remove optional quotes (simple or double) from the string

    :type string: str or unicode
    :param string: an optionally quoted string

    :rtype: str or unicode
    :return: the unquoted string (or the input string if it wasn't quoted)
    """
    if not string:
        return string
    if string[0] in '"\'':
        string = string[1:]
    if string[-1] in '"\'':
        string = string[:-1]
    return string


def _normalize_text(text, line_len=80, indent=''):
    """Wrap the text on the given line length."""
    return '\n'.join(textwrap.wrap(text, width=line_len, initial_indent=indent,
                                   subsequent_indent=indent))


def _check_csv(value):
    if isinstance(value, (list, tuple)):
        return value
    return _splitstrip(value)


if six.PY2:
    def _encode(string, encoding):
        # pylint: disable=undefined-variable
        if isinstance(string, unicode):
            return string.encode(encoding)
        return str(string)
else:
    def _encode(string, _):
        return str(string)

def _get_encoding(encoding, stream):
    encoding = encoding or getattr(stream, 'encoding', None)
    if not encoding:
        import locale
        encoding = locale.getpreferredencoding()
    return encoding


def _comment(string):
    """return string as a comment"""
    lines = [line.strip() for line in string.splitlines()]
    return '# ' + ('%s# ' % os.linesep).join(lines)


def _format_option_value(optdict, value):
    """return the user input's value from a 'compiled' value"""
    if isinstance(value, (list, tuple)):
        value = ','.join(value)
    elif isinstance(value, dict):
        value = ','.join('%s:%s' % (k, v) for k, v in value.items())
    elif hasattr(value, 'match'): # optdict.get('type') == 'regexp'
        # compiled regexp
        value = value.pattern
    elif optdict.get('type') == 'yn':
        value = value and 'yes' or 'no'
    elif isinstance(value, six.string_types) and value.isspace():
        value = "'%s'" % value
    return value


def _ini_format_section(stream, section, options, encoding=None, doc=None):
    """format an options section using the INI format"""
    encoding = _get_encoding(encoding, stream)
    if doc:
        print(_encode(_comment(doc), encoding), file=stream)
    print('[%s]' % section, file=stream)
    _ini_format(stream, options, encoding)


def _ini_format(stream, options, encoding):
    """format options using the INI format"""
    for optname, optdict, value in options:
        value = _format_option_value(optdict, value)
        help = optdict.get('help')
        if help:
            help = _normalize_text(help, line_len=79, indent='# ')
            print(file=stream)
            print(_encode(help, encoding), file=stream)
        else:
            print(file=stream)
        if value is None:
            print('#%s=' % optname, file=stream)
        else:
            value = _encode(value, encoding).strip()
            print('%s=%s' % (optname, value), file=stream)

format_section = _ini_format_section


def _rest_format_section(stream, section, options, encoding=None, doc=None):
    """format an options section using as ReST formatted output"""
    encoding = _get_encoding(encoding, stream)
    if section:
        print('%s\n%s' % (section, "'"*len(section)), file=stream)
    if doc:
        print(_encode(_normalize_text(doc, line_len=79, indent=''), encoding), file=stream)
        print(file=stream)
    for optname, optdict, value in options:
        help = optdict.get('help')
        print(':%s:' % optname, file=stream)
        if help:
            help = _normalize_text(help, line_len=79, indent='  ')
            print(_encode(help, encoding), file=stream)
        if value:
            value = _encode(_format_option_value(optdict, value), encoding)
            print(file=stream)
            print('  Default: ``%s``' % value.replace("`` ", "```` ``"), file=stream)