filters.py 文件源码

def prepare_map(args, kwargs):
    context = args[0]
    seq = args[1]

    if len(args) == 2 and 'attribute' in kwargs:
        attribute = kwargs.pop('attribute')
        if kwargs:
            raise FilterArgumentError('Unexpected keyword argument %r' %
                next(iter(kwargs)))
        func = make_attrgetter(context.environment, attribute)
    else:
        try:
            name = args[2]
            args = args[3:]
        except LookupError:
            raise FilterArgumentError('map requires a filter argument')
        func = lambda item: context.environment.call_filter(
            name, item, args, kwargs, context=context)

    return seq, func