grep.py

def grep(pattern_str):
    ''' Using yield receive data inside generator

    :param pattern_str: rex string

    Demo::
        >>> finder = grep('target \d+')
        >>> next(finder)
        >>> print(finder.send('target 1234'))
        target 1234
        >>> print(finder.send('salt 1234'))
        None
        >>> print(finder.send('salt target 1234'))
        salt target 1234
    '''
    sre = re.compile(pattern_str)
    while True:
        message = yield
        sre_search = sre.search(message)
        yield sre_search and message