def bind_arguments(func, args, kwargs):
    """Bind the arguments provided into a dict.  When passed a function,
    a tuple of arguments and a dict of keyword arguments `bind_arguments`
    returns a dict of names as the function would see it.  This can be useful
    to implement a cache decorator that uses the function arguments to build
    the cache key based on the values of the arguments.

    :param func: the function the arguments should be bound for.
    :param args: tuple of positional arguments.
    :param kwargs: a dict of keyword arguments.
    :return: a :class:`dict` of bound keyword arguments.
    """
    args, kwargs, missing, extra, extra_positional, \
        arg_spec, vararg_var, kwarg_var = _parse_signature(func)(args, kwargs)
    values = {}
    for (name, has_default, default), value in zip(arg_spec, args):
        values[name] = value
    if vararg_var is not None:
        values[vararg_var] = tuple(extra_positional)
    elif extra_positional:
        raise TypeError('too many positional arguments')
    if kwarg_var is not None:
        multikw = set(extra) & set([x[0] for x in arg_spec])
        if multikw:
            raise TypeError('got multiple values for keyword argument ' +
                            repr(iter(multikw).next()))
        values[kwarg_var] = extra
    elif extra:
        raise TypeError('got unexpected keyword argument ' +
                        repr(iter(extra).next()))
    return values

def validate_arguments(func, args, kwargs, drop_extra = True):
    parser = _parse_signature(func)
    args, kwargs, missing, extra, extra_positional = parser(args, kwargs)[:5]
    if missing:
        raise ArgumentValidationError(tuple(missing))
    elif (extra or extra_positional) and not drop_extra:
        raise ArgumentValidationError(None, extra, extra_positional)
    return (tuple(args), kwargs)

def validate_arguments(func, args, kwargs, drop_extra=True):
    """Check if the function accepts the arguments and keyword arguments.
    Returns a new ``(args, kwargs)`` tuple that can savely be passed to
    the function without causing a `TypeError` because the function signature
    is incompatible.  If `drop_extra` is set to `True` (which is the default)
    any extra positional or keyword arguments are dropped automatically.

    The exception raised provides three attributes:

    `missing`
        A set of argument names that the function expected but where
        missing.

    `extra`
        A dict of keyword arguments that the function can not handle but
        where provided.

    `extra_positional`
        A list of values that where given by positional argument but the
        function cannot accept.

    This can be useful for decorators that forward user submitted data to
    a view function::

        from werkzeug import ArgumentValidationError, validate_arguments

        def sanitize(f):
            def proxy(request):
                data = request.values.to_dict()
                try:
                    args, kwargs = validate_arguments(f, (request,), data)
                except ArgumentValidationError:
                    raise BadRequest('The browser failed to transmit all '
                                     'the data expected.')
                return f(*args, **kwargs)
            return proxy

    :param func: the function the validation is performed against.
    :param args: a tuple of positional arguments.
    :param kwargs: a dict of keyword arguments.
    :param drop_extra: set to `False` if you don't want extra arguments
                       to be silently dropped.
    :return: tuple in the form ``(args, kwargs)``.
    """
    parser = _parse_signature(func)
    args, kwargs, missing, extra, extra_positional = parser(args, kwargs)[:5]
    if missing:
        raise ArgumentValidationError(tuple(missing))
    elif (extra or extra_positional) and not drop_extra:
        raise ArgumentValidationError(None, extra, extra_positional)
    return tuple(args), kwargs

def bind_arguments(func, args, kwargs):
    args, kwargs, missing, extra, extra_positional, arg_spec, vararg_var, kwarg_var = _parse_signature(func)(args, kwargs)
    values = {}
    for (name, has_default, default), value in zip(arg_spec, args):
        values[name] = value

    if vararg_var is not None:
        values[vararg_var] = tuple(extra_positional)
    elif extra_positional:
        raise TypeError('too many positional arguments')
    if kwarg_var is not None:
        multikw = set(extra) & set([ x[0] for x in arg_spec ])
        if multikw:
            raise TypeError('got multiple values for keyword argument ' + repr(iter(multikw).next()))
        values[kwarg_var] = extra
    elif extra:
        raise TypeError('got unexpected keyword argument ' + repr(iter(extra).next()))
    return values