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# Copyright (c) 2009-2010 Arista Networks, Inc. - James Lingard
# Copyright (c) 2004-2010 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.
"""Checker for string formatting operations.
"""
from logilab import astng
from pylint.interfaces import IASTNGChecker
from pylint.checkers import BaseChecker
from pylint.checkers import utils
MSGS = {
'E1300': ("Unsupported format character %r (%#02x) at index %d",
"bad-format-character",
"Used when a unsupported format character is used in a format\
string."),
'E1301': ("Format string ends in middle of conversion specifier",
"truncated-format-string",
"Used when a format string terminates before the end of a \
conversion specifier."),
'E1302': ("Mixing named and unnamed conversion specifiers in format string",
"mixed-format-string",
"Used when a format string contains both named (e.g. '%(foo)d') \
and unnamed (e.g. '%d') conversion specifiers. This is also \
used when a named conversion specifier contains * for the \
minimum field width and/or precision."),
'E1303': ("Expected mapping for format string, not %s",
"format-needs-mapping",
"Used when a format string that uses named conversion specifiers \
is used with an argument that is not a mapping."),
'W1300': ("Format string dictionary key should be a string, not %s",
"bad-format-string-key",
"Used when a format string that uses named conversion specifiers \
is used with a dictionary whose keys are not all strings."),
'W1301': ("Unused key %r in format string dictionary",
"unused-format-string-key",
"Used when a format string that uses named conversion specifiers \
is used with a dictionary that conWtains keys not required by the \
format string."),
'E1304': ("Missing key %r in format string dictionary",
"missing-format-string-key",
"Used when a format string that uses named conversion specifiers \
is used with a dictionary that doesn't contain all the keys \
required by the format string."),
'E1305': ("Too many arguments for format string",
"too-many-format-args",
"Used when a format string that uses unnamed conversion \
specifiers is given too few arguments."),
'E1306': ("Not enough arguments for format string",
"too-few-format-args",
"Used when a format string that uses unnamed conversion \
specifiers is given too many arguments"),
}
OTHER_NODES = (astng.Const, astng.List, astng.Backquote,
astng.Lambda, astng.Function,
astng.ListComp, astng.SetComp, astng.GenExpr)
class StringFormatChecker(BaseChecker):
"""Checks string formatting operations to ensure that the format string
is valid and the arguments match the format string.
"""
__implements__ = (IASTNGChecker,)
name = 'string_format'
msgs = MSGS
def visit_binop(self, node):
if node.op != '%':
return
left = node.left
args = node.right
if not (isinstance(left, astng.Const)
and isinstance(left.value, basestring)):
return
format_string = left.value
try:
required_keys, required_num_args = \
utils.parse_format_string(format_string)
except utils.UnsupportedFormatCharacter, e:
c = format_string[e.index]
self.add_message('E1300', node=node, args=(c, ord(c), e.index))
return
except utils.IncompleteFormatString:
self.add_message('E1301', node=node)
return
if required_keys and required_num_args:
# The format string uses both named and unnamed format
# specifiers.
self.add_message('E1302', node=node)
elif required_keys:
# The format string uses only named format specifiers.
# Check that the RHS of the % operator is a mapping object
# that contains precisely the set of keys required by the
# format string.
if isinstance(args, astng.Dict):
keys = set()
unknown_keys = False
for k, _ in args.items:
if isinstance(k, astng.Const):
key = k.value
if isinstance(key, basestring):
keys.add(key)
else:
self.add_message('W1300', node=node, args=key)
else:
# One of the keys was something other than a
# constant. Since we can't tell what it is,
# supress checks for missing keys in the
# dictionary.
unknown_keys = True
if not unknown_keys:
for key in required_keys:
if key not in keys:
self.add_message('E1304', node=node, args=key)
for key in keys:
if key not in required_keys:
self.add_message('W1301', node=node, args=key)
elif isinstance(args, OTHER_NODES + (astng.Tuple,)):
type_name = type(args).__name__
self.add_message('E1303', node=node, args=type_name)
# else:
# The RHS of the format specifier is a name or
# expression. It may be a mapping object, so
# there's nothing we can check.
else:
# The format string uses only unnamed format specifiers.
# Check that the number of arguments passed to the RHS of
# the % operator matches the number required by the format
# string.
if isinstance(args, astng.Tuple):
num_args = len(args.elts)
elif isinstance(args, OTHER_NODES + (astng.Dict, astng.DictComp)):
num_args = 1
else:
# The RHS of the format specifier is a name or
# expression. It could be a tuple of unknown size, so
# there's nothing we can check.
num_args = None
if num_args is not None:
if num_args > required_num_args:
self.add_message('E1305', node=node)
elif num_args < required_num_args:
self.add_message('E1306', node=node)
def register(linter):
"""required method to auto register this checker """
linter.register_checker(StringFormatChecker(linter))
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