introduce command handlers
A command handler can be used to deal with parameters which have a common command for querying and writing to the hardware. Support for parsing and formatting commands is included. Change-Id: I79a1b6c9daf3af3be2e1875875ced41ec1a1829d Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/21946 Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de> Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
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264
secop/commandhandler.py
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264
secop/commandhandler.py
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#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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# *****************************************************************************
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# This program is free software; you can redistribute it and/or modify it under
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# the terms of the GNU General Public License as published by the Free Software
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# Foundation; either version 2 of the License, or (at your option) any later
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# version.
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#
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# This program is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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# details.
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#
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# You should have received a copy of the GNU General Public License along with
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# this program; if not, write to the Free Software Foundation, Inc.,
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# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#
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# Module authors:
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# Markus Zolliker <markus.zolliker@psi.ch>
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# *****************************************************************************
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"""command handler
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utility class for cases, where multiple parameters are treated with a common command.
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The support for LakeShore and similar protocols is already included.
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"""
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import re
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from secop.metaclass import Done
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class CmdParser:
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"""helper for parsing replies
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using a subset of old style python formatting
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the same format can be used or formatting command arguments
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"""
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# make a map of cast functions
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CAST_MAP = {letter: cast
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for letters, cast in (
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('d', int),
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('s', str), # 'c' is treated separately
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('o', lambda x:int(x, 8)),
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('xX', lambda x:int(x, 16)),
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('eEfFgG', float),
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) for letter in letters
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}
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# pattern for chacaters to be escaped
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ESC_PAT = re.compile('([\\%s])' % '\\'.join('|^$-.+*?()[]{}<>'))
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# format pattern
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FMT_PAT = re.compile('(%%|%[^diouxXfFgGeEcrsa]*(?:.|$))')
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def __init__(self, argformat):
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# replace named patterns
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self.fmt = argformat
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spl = self.FMT_PAT.split(argformat)
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spl_iter = iter(spl)
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def escaped(text):
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return self.ESC_PAT.sub(lambda x: '\\' + x.group(1), text)
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casts = []
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# the first item in spl is just plain text
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pat = [escaped(next(spl_iter))]
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todofmt = None # format set aside to be treated in next loop
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# loop over found formats and separators
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for fmt, sep in zip(spl_iter,spl_iter):
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if fmt == '%%':
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if todofmt is None:
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pat.append('%' + escaped(sep)) # plain text
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continue
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fmt = todofmt
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todofmt = None
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sep = '%' + sep
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elif todofmt:
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raise ValueError("a separator must follow '%s'" % todofmt)
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cast = self.CAST_MAP.get(fmt[-1], None)
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if cast is None: # special or unknown case
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if fmt != '%c':
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raise ValueError("unsupported format: '%s'" % fmt)
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# we do not need a separator after %c
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pat.append('(.)')
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casts.append(str)
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pat.append(escaped(sep))
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continue
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if sep == '': # missing separator. postpone handling for '%%' case or end of pattern
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todofmt = fmt
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continue
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casts.append(cast)
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# accepting everything up to a separator
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pat.append('([^%s]*)' % escaped(sep[0]) + escaped(sep))
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if todofmt:
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casts.append(cast)
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pat.append('(.*)')
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self.casts = casts
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self.pat = re.compile(''.join(pat))
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try:
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argformat % ((0,) * len(casts)) # validate argformat
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except ValueError as e:
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raise ValueError("%s in %r" % (e, argformat))
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def format(self, *values):
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return self.fmt % values
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def parse(self, reply):
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match = self.pat.match(reply)
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if not match:
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raise ValueError('reply "%s" does not match pattern "%s"' % (reply, self.fmt))
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return [c(v) for c, v in zip(self.casts, match.groups())]
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class ChangeWrapper:
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"""store parameter changes before they are applied"""
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def __init__(self, module, pname, value):
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self._module = module
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setattr(self, pname, value)
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def __getattr__(self, key):
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"""get values from module for unknown keys"""
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return getattr(self._module, key)
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def apply(self, module):
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"""set only changed values"""
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for k, v in self.__dict__.items():
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if k != '_module' and v != getattr(module, k):
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setattr(module, k, v)
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def __repr__(self):
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return ', '.join('%s=%r' % (k, v) for k, v in self.__dict__.items() if k != '_module')
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class CmdHandlerBase:
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"""generic command handler"""
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# def __init__(self, group, ...):
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# init must at least initialize self.group, which is is relevant for calling the
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# proper analyze_<group> and change_<group> methods
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def parse_reply(self, reply):
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"""return values from a raw reply"""
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raise NotImplementedError
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def make_query(self, module):
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"""make a query"""
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raise NotImplementedError
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def make_change(self, module, *values):
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"""make a change command from values"""
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raise NotImplementedError
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def send_command(self, module, changecmd=''):
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"""send a command (query or change+query) and parse the reply into a list
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If changecmd is given, it is prepended before the query.
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"""
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querycmd = self.make_query(module)
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reply = module.sendRecv((changecmd + querycmd))
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return self.parse_reply(reply)
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def send_change(self, module, *values):
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"""compose and send a command from values
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and send a query afterwards. This method might be overriden, if the change command
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can be combined with a query command, or if the change command already includes
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a reply.
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"""
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changecmd = self.make_change(module, *values)
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module.sendRecv(changecmd) # ignore result
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return self.send_command(module)
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def get_read_func(self, pname):
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"""returns the read function passed to the metaclass"""
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return self.read
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def read(self, module):
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"""the read function passed to the metaclass
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overwrite with None if not used
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"""
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# do a read of the current hw values
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reply = self.send_command(module)
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# convert them to parameters
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getattr(module, 'analyze_' + self.group)(*reply)
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return Done # parameters should be updated already
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def get_write_func(self, pname):
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"""returns the write function passed to the metaclass
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return None if not used.
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"""
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def wfunc(module, value, cmd=self, pname=pname):
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# do a read of the current hw values
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values = cmd.send_command(module)
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# convert them to parameters
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analyze = getattr(module, 'analyze_' + cmd.group)
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analyze(*values)
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# create wrapper object 'new' with changed parameter 'pname'
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new = ChangeWrapper(module, pname, value)
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# call change_* for calculation new hw values
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values = getattr(module, 'change_' + cmd.group)(new, *values)
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# send the change command and a query command
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analyze(*cmd.send_change(module, *values))
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# update only changed values
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new.apply(module)
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return Done # parameter 'pname' should be changed already
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return wfunc
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class CmdHandler(CmdHandlerBase):
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"""more evolved command handler
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this command handler works for a syntax, where the change command syntax can be
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build from the query command syntax, with the to be changed items at the second
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part of the command, using the same format as for the reply.
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Examples: devices from LakeShore, PPMS
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implementing classes have to define/override the following:
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"""
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CMDARGS = [] # list of properties or parameters to be used for building
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# some of the the query and change commands
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CMDSEPARATOR = ';' # if given, it is valid to join a command a a query with
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# the given separator
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def __init__(self, group, querycmd, replyfmt):
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"""initialize the command handler
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group: the handler group (used for analyze_<group> and change_<group>)
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querycmd: the command for a query, may contain named formats for cmdargs
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replyfmt: the format for reading the reply with some scanf like behaviour
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"""
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self.group = group
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self.querycmd = querycmd
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self.replyfmt = CmdParser(replyfmt)
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def parse_reply(self, reply):
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"""return values from a raw reply"""
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return self.replyfmt.parse(reply)
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def make_query(self, module):
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"""make a query"""
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return self.querycmd % {k: getattr(module, k, None) for k in self.CMDARGS}
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def make_change(self, module, *values):
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"""make a change command from a query command"""
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changecmd = self.querycmd.replace('?', ' ')
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if not self.querycmd.endswith('?'):
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changecmd += ','
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changecmd %= {k: getattr(module, k, None) for k in self.CMDARGS}
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return changecmd + self.replyfmt.format(*values)
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def send_change(self, module, *values):
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"""join change and query commands"""
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if self.CMDSEPARATOR is None:
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return super().send_change(module, *values)
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return self.send_command(module, self.make_change(module, *values) + self.CMDSEPARATOR)
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