pylint: upgrade to 1.3.1

third_party/pylint/checkers/strings.py

+# 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
+try:
+    import numbers
+except ImportError:
+    numbers = None
+
+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
+
+_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()
+    parseiterator = formatter.parse(format_string)
+    try:
+        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
+                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, 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('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, basestring):
+                            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.
+        if not isinstance(node.func.expr, astroid.Const):
+            return
+        try:
+            strnode = func.bound.infer().next()
+        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
+
+        manual_fields = set(field[0] for field in fields
+                            if isinstance(field[0], numbers.Number))
+        named_fields = set(field[0] for field in fields
+                           if isinstance(field[0], basestring))
+        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:
+                # We can have two possibilities:
+                # * "{0} {1}".format(a, b)
+                # * "{} {} {}".format(a, b, c, d)
+                # We can check the manual keys for the first one.
+                if len(manual_fields) != positional:
+                    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 = argname.infer().next()
+            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):
+                # Check to see if our argument is kwarg or vararg,
+                # and skip the check for this argument if so, because when inferring,
+                # astroid will return empty objects (dicts and tuples) and
+                # that can lead to false positives.
+                if argname.name in (argument.parent.kwarg, argument.parent.vararg):
+                    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 = previous.infer().next()
+                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, start_col), _, _) 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, start_col)
+
+    def process_string_token(self, token, start_row, start_col):
+        for i, c in enumerate(token):
+            if c in '\'\"':
+                quote_char = c
+                break
+        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, start_col)
+
+    def process_non_raw_string_token(self, prefix, string_body, start_row,
+                                     start_col):
+        """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.
+        start_col: integer column 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))