118 lines
3.5 KiB
Python
118 lines
3.5 KiB
Python
""" ESC/POS configuration manager.
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This module contains the implentations of abstract base class :py:class:`Config`.
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"""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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from __future__ import unicode_literals
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import os
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import appdirs
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import yaml
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from . import printer
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from . import exceptions
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class Config(object):
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""" Configuration handler class.
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This class loads configuration from a default or specificed directory. It
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can create your defined printer and return it to you.
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"""
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_app_name = 'python-escpos'
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_config_file = 'config.yaml'
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def __init__(self):
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""" Initialize configuration.
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Remember to add anything that needs to be reset between configurations
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to self._reset_config
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"""
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self._has_loaded = False
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self._printer = None
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self._printer_name = None
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self._printer_config = None
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def _reset_config(self):
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""" Clear the loaded configuration.
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If we are loading a changed config, we don't want to have leftover
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data.
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"""
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self._has_loaded = False
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self._printer = None
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self._printer_name = None
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self._printer_config = None
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def load(self, config_path=None):
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""" Load and parse the configuration file using pyyaml
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:param config_path: An optional file path, file handle, or byte string
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for the configuration file.
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"""
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self._reset_config()
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if not config_path:
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config_path = os.path.join(
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appdirs.user_config_dir(self._app_name),
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self._config_file
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)
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try:
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# First check if it's file like. If it is, pyyaml can load it.
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# I'm checking type instead of catching excpetions to keep the
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# exception handling simple
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if hasattr(config_path, 'read'):
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config = yaml.safe_load(config_path)
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else:
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# If it isn't, it's a path. We have to open it first.
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with open(config_path, 'rb') as config_file:
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config = yaml.safe_load(config_file)
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except EnvironmentError:
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raise exceptions.ConfigNotFoundError('Couldn\'t read config at {config_path}'.format(
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config_path=str(config_path),
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))
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except yaml.YAMLError:
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raise exceptions.ConfigSyntaxError('Error parsing YAML')
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if 'printer' in config:
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self._printer_config = config['printer']
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self._printer_name = self._printer_config.pop('type').title()
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if not self._printer_name or not hasattr(printer, self._printer_name):
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raise exceptions.ConfigSyntaxError(
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'Printer type "{printer_name}" is invalid'.format(
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printer_name=self._printer_name,
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)
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)
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self._has_loaded = True
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def printer(self):
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""" Returns a printer that was defined in the config, or throws an
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exception.
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This method loads the default config if one hasn't beeen already loaded.
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"""
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if not self._has_loaded:
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self.load()
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if not self._printer_name:
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raise exceptions.ConfigSectionMissingError('printer')
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if not self._printer:
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# We could catch init errors and make them a ConfigSyntaxError,
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# but I'll just let them pass
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self._printer = getattr(printer, self._printer_name)(**self._printer_config)
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return self._printer
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