| # Copyright (c) 2009-2010 Arista Networks, Inc. - James Lingard |
| # Copyright (c) 2004-2013 LOGILAB S.A. (Paris, FRANCE). |
| # Copyright 2012 Google Inc. |
| # |
| # 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. |
| """Checker for string formatting operations. |
| """ |
| |
| import sys |
| import tokenize |
| import string |
| import numbers |
| |
| import astroid |
| |
| from pylint.interfaces import ITokenChecker, IAstroidChecker, IRawChecker |
| from pylint.checkers import BaseChecker, BaseTokenChecker |
| from pylint.checkers import utils |
| from pylint.checkers.utils import check_messages |
| |
| import six |
| |
| |
| _PY3K = sys.version_info[:2] >= (3, 0) |
| _PY27 = sys.version_info[:2] == (2, 7) |
| |
| 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 many 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 few arguments"), |
| |
| 'W1302': ("Invalid format string", |
| "bad-format-string", |
| "Used when a PEP 3101 format string is invalid.", |
| {'minversion': (2, 7)}), |
| 'W1303': ("Missing keyword argument %r for format string", |
| "missing-format-argument-key", |
| "Used when a PEP 3101 format string that uses named fields " |
| "doesn't receive one or more required keywords.", |
| {'minversion': (2, 7)}), |
| 'W1304': ("Unused format argument %r", |
| "unused-format-string-argument", |
| "Used when a PEP 3101 format string that uses named " |
| "fields is used with an argument that " |
| "is not required by the format string.", |
| {'minversion': (2, 7)}), |
| 'W1305': ("Format string contains both automatic field numbering " |
| "and manual field specification", |
| "format-combined-specification", |
| "Usen when a PEP 3101 format string contains both automatic " |
| "field numbering (e.g. '{}') and manual field " |
| "specification (e.g. '{0}').", |
| {'minversion': (2, 7)}), |
| 'W1306': ("Missing format attribute %r in format specifier %r", |
| "missing-format-attribute", |
| "Used when a PEP 3101 format string uses an " |
| "attribute specifier ({0.length}), but the argument " |
| "passed for formatting doesn't have that attribute.", |
| {'minversion': (2, 7)}), |
| 'W1307': ("Using invalid lookup key %r in format specifier %r", |
| "invalid-format-index", |
| "Used when a PEP 3101 format string uses a lookup specifier " |
| "({a[1]}), but the argument passed for formatting " |
| "doesn't contain or doesn't have that key as an attribute.", |
| {'minversion': (2, 7)}) |
| } |
| |
| OTHER_NODES = (astroid.Const, astroid.List, astroid.Backquote, |
| astroid.Lambda, astroid.Function, |
| astroid.ListComp, astroid.SetComp, astroid.GenExpr) |
| |
| if _PY3K: |
| import _string |
| |
| def split_format_field_names(format_string): |
| return _string.formatter_field_name_split(format_string) |
| else: |
| def _field_iterator_convertor(iterator): |
| for is_attr, key in iterator: |
| if isinstance(key, numbers.Number): |
| yield is_attr, int(key) |
| else: |
| yield is_attr, key |
| |
| def split_format_field_names(format_string): |
| keyname, fielditerator = format_string._formatter_field_name_split() |
| # it will return longs, instead of ints, which will complicate |
| # the output |
| return keyname, _field_iterator_convertor(fielditerator) |
| |
| |
| def collect_string_fields(format_string): |
| """ Given a format string, return an iterator |
| of all the valid format fields. It handles nested fields |
| as well. |
| """ |
| |
| formatter = string.Formatter() |
| try: |
| parseiterator = formatter.parse(format_string) |
| for result in parseiterator: |
| if all(item is None for item in result[1:]): |
| # not a replacement format |
| continue |
| name = result[1] |
| nested = result[2] |
| yield name |
| if nested: |
| for field in collect_string_fields(nested): |
| yield field |
| except ValueError: |
| # probably the format string is invalid |
| # should we check the argument of the ValueError? |
| raise utils.IncompleteFormatString(format_string) |
| |
| def parse_format_method_string(format_string): |
| """ |
| Parses a PEP 3101 format string, returning a tuple of |
| (keys, num_args, manual_pos_arg), |
| where keys is the set of mapping keys in the format string, num_args |
| is the number of arguments required by the format string and |
| manual_pos_arg is the number of arguments passed with the position. |
| """ |
| keys = [] |
| num_args = 0 |
| manual_pos_arg = set() |
| for name in collect_string_fields(format_string): |
| if name and str(name).isdigit(): |
| manual_pos_arg.add(str(name)) |
| elif name: |
| keyname, fielditerator = split_format_field_names(name) |
| if isinstance(keyname, numbers.Number): |
| # In Python 2 it will return long which will lead |
| # to different output between 2 and 3 |
| manual_pos_arg.add(keyname) |
| keyname = int(keyname) |
| keys.append((keyname, list(fielditerator))) |
| else: |
| num_args += 1 |
| return keys, num_args, len(manual_pos_arg) |
| |
| def get_args(callfunc): |
| """ Get the arguments from the given `CallFunc` node. |
| Return a tuple, where the first element is the |
| number of positional arguments and the second element |
| is the keyword arguments in a dict. |
| """ |
| positional = 0 |
| named = {} |
| |
| for arg in callfunc.args: |
| if isinstance(arg, astroid.Keyword): |
| named[arg.arg] = utils.safe_infer(arg.value) |
| else: |
| positional += 1 |
| return positional, named |
| |
| def get_access_path(key, parts): |
| """ Given a list of format specifiers, returns |
| the final access path (e.g. a.b.c[0][1]). |
| """ |
| path = [] |
| for is_attribute, specifier in parts: |
| if is_attribute: |
| path.append(".{}".format(specifier)) |
| else: |
| path.append("[{!r}]".format(specifier)) |
| return str(key) + "".join(path) |
| |
| |
| class StringFormatChecker(BaseChecker): |
| """Checks string formatting operations to ensure that the format string |
| is valid and the arguments match the format string. |
| """ |
| |
| __implements__ = (IAstroidChecker,) |
| name = 'string' |
| msgs = MSGS |
| |
| @check_messages(*(MSGS.keys())) |
| def visit_binop(self, node): |
| if node.op != '%': |
| return |
| left = node.left |
| args = node.right |
| |
| if not (isinstance(left, astroid.Const) |
| and isinstance(left.value, six.string_types)): |
| return |
| format_string = left.value |
| try: |
| required_keys, required_num_args = \ |
| utils.parse_format_string(format_string) |
| except utils.UnsupportedFormatCharacter as e: |
| c = format_string[e.index] |
| self.add_message('bad-format-character', |
| node=node, args=(c, ord(c), e.index)) |
| return |
| except utils.IncompleteFormatString: |
| self.add_message('truncated-format-string', node=node) |
| return |
| if required_keys and required_num_args: |
| # The format string uses both named and unnamed format |
| # specifiers. |
| self.add_message('mixed-format-string', 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, astroid.Dict): |
| keys = set() |
| unknown_keys = False |
| for k, _ in args.items: |
| if isinstance(k, astroid.Const): |
| key = k.value |
| if isinstance(key, six.string_types): |
| keys.add(key) |
| else: |
| self.add_message('bad-format-string-key', |
| 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('missing-format-string-key', |
| node=node, args=key) |
| for key in keys: |
| if key not in required_keys: |
| self.add_message('unused-format-string-key', |
| node=node, args=key) |
| elif isinstance(args, OTHER_NODES + (astroid.Tuple,)): |
| type_name = type(args).__name__ |
| self.add_message('format-needs-mapping', |
| 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, astroid.Tuple): |
| num_args = len(args.elts) |
| elif isinstance(args, OTHER_NODES + (astroid.Dict, astroid.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('too-many-format-args', node=node) |
| elif num_args < required_num_args: |
| self.add_message('too-few-format-args', node=node) |
| |
| |
| class StringMethodsChecker(BaseChecker): |
| __implements__ = (IAstroidChecker,) |
| name = 'string' |
| msgs = { |
| 'E1310': ("Suspicious argument in %s.%s call", |
| "bad-str-strip-call", |
| "The argument to a str.{l,r,}strip call contains a" |
| " duplicate character, "), |
| } |
| |
| @check_messages(*(MSGS.keys())) |
| def visit_callfunc(self, node): |
| func = utils.safe_infer(node.func) |
| if (isinstance(func, astroid.BoundMethod) |
| and isinstance(func.bound, astroid.Instance) |
| and func.bound.name in ('str', 'unicode', 'bytes')): |
| if func.name in ('strip', 'lstrip', 'rstrip') and node.args: |
| arg = utils.safe_infer(node.args[0]) |
| if not isinstance(arg, astroid.Const): |
| return |
| if len(arg.value) != len(set(arg.value)): |
| self.add_message('bad-str-strip-call', node=node, |
| args=(func.bound.name, func.name)) |
| elif func.name == 'format': |
| if _PY27 or _PY3K: |
| self._check_new_format(node, func) |
| |
| def _check_new_format(self, node, func): |
| """ Check the new string formatting. """ |
| # TODO: skip (for now) format nodes which don't have |
| # an explicit string on the left side of the format operation. |
| # We do this because our inference engine can't properly handle |
| # redefinitions of the original string. |
| # For more details, see issue 287. |
| # |
| # Note that there may not be any left side at all, if the format method |
| # has been assigned to another variable. See issue 351. For example: |
| # |
| # fmt = 'some string {}'.format |
| # fmt('arg') |
| if (isinstance(node.func, astroid.Getattr) |
| and not isinstance(node.func.expr, astroid.Const)): |
| return |
| try: |
| strnode = next(func.bound.infer()) |
| except astroid.InferenceError: |
| return |
| if not isinstance(strnode, astroid.Const): |
| return |
| if node.starargs or node.kwargs: |
| # TODO: Don't complicate the logic, skip these for now. |
| return |
| try: |
| positional, named = get_args(node) |
| except astroid.InferenceError: |
| return |
| try: |
| fields, num_args, manual_pos = parse_format_method_string(strnode.value) |
| except utils.IncompleteFormatString: |
| self.add_message('bad-format-string', node=node) |
| return |
| |
| named_fields = set(field[0] for field in fields |
| if isinstance(field[0], six.string_types)) |
| if num_args and manual_pos: |
| self.add_message('format-combined-specification', |
| node=node) |
| return |
| |
| check_args = False |
| # Consider "{[0]} {[1]}" as num_args. |
| num_args += sum(1 for field in named_fields |
| if field == '') |
| if named_fields: |
| for field in named_fields: |
| if field not in named and field: |
| self.add_message('missing-format-argument-key', |
| node=node, |
| args=(field, )) |
| for field in named: |
| if field not in named_fields: |
| self.add_message('unused-format-string-argument', |
| node=node, |
| args=(field, )) |
| # num_args can be 0 if manual_pos is not. |
| num_args = num_args or manual_pos |
| if positional or num_args: |
| empty = any(True for field in named_fields |
| if field == '') |
| if named or empty: |
| # Verify the required number of positional arguments |
| # only if the .format got at least one keyword argument. |
| # This means that the format strings accepts both |
| # positional and named fields and we should warn |
| # when one of the them is missing or is extra. |
| check_args = True |
| else: |
| check_args = True |
| if check_args: |
| # num_args can be 0 if manual_pos is not. |
| num_args = num_args or manual_pos |
| if positional > num_args: |
| self.add_message('too-many-format-args', node=node) |
| elif positional < num_args: |
| self.add_message('too-few-format-args', node=node) |
| |
| self._check_new_format_specifiers(node, fields, named) |
| |
| def _check_new_format_specifiers(self, node, fields, named): |
| """ |
| Check attribute and index access in the format |
| string ("{0.a}" and "{0[a]}"). |
| """ |
| for key, specifiers in fields: |
| # Obtain the argument. If it can't be obtained |
| # or infered, skip this check. |
| if key == '': |
| # {[0]} will have an unnamed argument, defaulting |
| # to 0. It will not be present in `named`, so use the value |
| # 0 for it. |
| key = 0 |
| if isinstance(key, numbers.Number): |
| try: |
| argname = utils.get_argument_from_call(node, key) |
| except utils.NoSuchArgumentError: |
| continue |
| else: |
| if key not in named: |
| continue |
| argname = named[key] |
| if argname in (astroid.YES, None): |
| continue |
| try: |
| argument = next(argname.infer()) |
| except astroid.InferenceError: |
| continue |
| if not specifiers or argument is astroid.YES: |
| # No need to check this key if it doesn't |
| # use attribute / item access |
| continue |
| if argument.parent and isinstance(argument.parent, astroid.Arguments): |
| # Ignore any object coming from an argument, |
| # because we can't infer its value properly. |
| continue |
| previous = argument |
| parsed = [] |
| for is_attribute, specifier in specifiers: |
| if previous is astroid.YES: |
| break |
| parsed.append((is_attribute, specifier)) |
| if is_attribute: |
| try: |
| previous = previous.getattr(specifier)[0] |
| except astroid.NotFoundError: |
| if (hasattr(previous, 'has_dynamic_getattr') and |
| previous.has_dynamic_getattr()): |
| # Don't warn if the object has a custom __getattr__ |
| break |
| path = get_access_path(key, parsed) |
| self.add_message('missing-format-attribute', |
| args=(specifier, path), |
| node=node) |
| break |
| else: |
| warn_error = False |
| if hasattr(previous, 'getitem'): |
| try: |
| previous = previous.getitem(specifier) |
| except (IndexError, TypeError): |
| warn_error = True |
| else: |
| try: |
| # Lookup __getitem__ in the current node, |
| # but skip further checks, because we can't |
| # retrieve the looked object |
| previous.getattr('__getitem__') |
| break |
| except astroid.NotFoundError: |
| warn_error = True |
| if warn_error: |
| path = get_access_path(key, parsed) |
| self.add_message('invalid-format-index', |
| args=(specifier, path), |
| node=node) |
| break |
| |
| try: |
| previous = next(previous.infer()) |
| except astroid.InferenceError: |
| # can't check further if we can't infer it |
| break |
| |
| |
| |
| class StringConstantChecker(BaseTokenChecker): |
| """Check string literals""" |
| __implements__ = (ITokenChecker, IRawChecker) |
| name = 'string_constant' |
| msgs = { |
| 'W1401': ('Anomalous backslash in string: \'%s\'. ' |
| 'String constant might be missing an r prefix.', |
| 'anomalous-backslash-in-string', |
| 'Used when a backslash is in a literal string but not as an ' |
| 'escape.'), |
| 'W1402': ('Anomalous Unicode escape in byte string: \'%s\'. ' |
| 'String constant might be missing an r or u prefix.', |
| 'anomalous-unicode-escape-in-string', |
| 'Used when an escape like \\u is encountered in a byte ' |
| 'string where it has no effect.'), |
| } |
| |
| # Characters that have a special meaning after a backslash in either |
| # Unicode or byte strings. |
| ESCAPE_CHARACTERS = 'abfnrtvx\n\r\t\\\'\"01234567' |
| |
| # TODO(mbp): Octal characters are quite an edge case today; people may |
| # prefer a separate warning where they occur. \0 should be allowed. |
| |
| # Characters that have a special meaning after a backslash but only in |
| # Unicode strings. |
| UNICODE_ESCAPE_CHARACTERS = 'uUN' |
| |
| def process_module(self, module): |
| self._unicode_literals = 'unicode_literals' in module.future_imports |
| |
| def process_tokens(self, tokens): |
| for (tok_type, token, (start_row, _), _, _) in tokens: |
| if tok_type == tokenize.STRING: |
| # 'token' is the whole un-parsed token; we can look at the start |
| # of it to see whether it's a raw or unicode string etc. |
| self.process_string_token(token, start_row) |
| |
| def process_string_token(self, token, start_row): |
| for i, c in enumerate(token): |
| if c in '\'\"': |
| quote_char = c |
| break |
| # pylint: disable=undefined-loop-variable |
| prefix = token[:i].lower() # markers like u, b, r. |
| after_prefix = token[i:] |
| if after_prefix[:3] == after_prefix[-3:] == 3 * quote_char: |
| string_body = after_prefix[3:-3] |
| else: |
| string_body = after_prefix[1:-1] # Chop off quotes |
| # No special checks on raw strings at the moment. |
| if 'r' not in prefix: |
| self.process_non_raw_string_token(prefix, string_body, start_row) |
| |
| def process_non_raw_string_token(self, prefix, string_body, start_row): |
| """check for bad escapes in a non-raw string. |
| |
| prefix: lowercase string of eg 'ur' string prefix markers. |
| string_body: the un-parsed body of the string, not including the quote |
| marks. |
| start_row: integer line number in the source. |
| """ |
| # Walk through the string; if we see a backslash then escape the next |
| # character, and skip over it. If we see a non-escaped character, |
| # alert, and continue. |
| # |
| # Accept a backslash when it escapes a backslash, or a quote, or |
| # end-of-line, or one of the letters that introduce a special escape |
| # sequence <http://docs.python.org/reference/lexical_analysis.html> |
| # |
| # TODO(mbp): Maybe give a separate warning about the rarely-used |
| # \a \b \v \f? |
| # |
| # TODO(mbp): We could give the column of the problem character, but |
| # add_message doesn't seem to have a way to pass it through at present. |
| i = 0 |
| while True: |
| i = string_body.find('\\', i) |
| if i == -1: |
| break |
| # There must be a next character; having a backslash at the end |
| # of the string would be a SyntaxError. |
| next_char = string_body[i+1] |
| match = string_body[i:i+2] |
| if next_char in self.UNICODE_ESCAPE_CHARACTERS: |
| if 'u' in prefix: |
| pass |
| elif (_PY3K or self._unicode_literals) and 'b' not in prefix: |
| pass # unicode by default |
| else: |
| self.add_message('anomalous-unicode-escape-in-string', |
| line=start_row, args=(match, )) |
| elif next_char not in self.ESCAPE_CHARACTERS: |
| self.add_message('anomalous-backslash-in-string', |
| line=start_row, args=(match, )) |
| # Whether it was a valid escape or not, backslash followed by |
| # another character can always be consumed whole: the second |
| # character can never be the start of a new backslash escape. |
| i += 2 |
| |
| |
| |
| def register(linter): |
| """required method to auto register this checker """ |
| linter.register_checker(StringFormatChecker(linter)) |
| linter.register_checker(StringMethodsChecker(linter)) |
| linter.register_checker(StringConstantChecker(linter)) |
