name : protocol_hwgrep.py #! python # # This module implements a special URL handler that uses the port listing to # find ports by searching the string descriptions. # # This file is part of pySerial. https://github.com/pyserial/pyserial # (C) 2011-2015 Chris Liechti <cliechti@gmx.net> # # SPDX-License-Identifier: BSD-3-Clause # # URL format: hwgrep://<regexp>&<option> # # where <regexp> is a Python regexp according to the re module # # violating the normal definition for URLs, the charachter `&` is used to # separate parameters from the arguments (instead of `?`, but the question mark # is heavily used in regexp'es) # # options: # n=<N> pick the N'th entry instead of the first one (numbering starts at 1) # skip_busy tries to open port to check if it is busy, fails on posix as ports are not locked! from __future__ import absolute_import import serial import serial.tools.list_ports try: basestring except NameError: basestring = str # python 3 pylint: disable=redefined-builtin class Serial(serial.Serial): """Just inherit the native Serial port implementation and patch the port property.""" # pylint: disable=no-member @serial.Serial.port.setter def port(self, value): """translate port name before storing it""" if isinstance(value, basestring) and value.startswith('hwgrep://'): serial.Serial.port.__set__(self, self.from_url(value)) else: serial.Serial.port.__set__(self, value) def from_url(self, url): """extract host and port from an URL string""" if url.lower().startswith("hwgrep://"): url = url[9:] n = 0 test_open = False args = url.split('&') regexp = args.pop(0) for arg in args: if '=' in arg: option, value = arg.split('=', 1) else: option = arg value = None if option == 'n': # pick n'th element n = int(value) - 1 if n < 1: raise ValueError('option "n" expects a positive integer larger than 1: {!r}'.format(value)) elif option == 'skip_busy': # open to test if port is available. not the nicest way.. test_open = True else: raise ValueError('unknown option: {!r}'.format(option)) # use a for loop to get the 1st element from the generator for port, desc, hwid in sorted(serial.tools.list_ports.grep(regexp)): if test_open: try: s = serial.Serial(port) except serial.SerialException: # it has some error, skip this one continue else: s.close() if n: n -= 1 continue return port else: raise serial.SerialException('no ports found matching regexp {!r}'.format(url)) # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - if __name__ == '__main__': s = Serial(None) s.port = 'hwgrep://ttyS0' print(s)