buildstream/_options/option.py

#!/usr/bin/env python3
#
#  Copyright (C) 2017 Codethink Limited
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU Lesser General Public
#  License as published by the Free Software Foundation; either
#  version 2 of the License, or (at your option) any later version.
#
#  This library is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
#  Lesser General Public License for more details.
#
#  You should have received a copy of the GNU Lesser General Public
#  License along with this library. If not, see <http://www.gnu.org/licenses/>.
#
#  Authors:
#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>

from .. import _yaml


# Shared symbols for validation purposes
#
OPTION_SYMBOLS = [
    'type',
    'description',
    'variable'
]


# Option()
#
# An abstract class representing a project option.
#
# Concrete classes must be created to handle option types,
# the loaded project options is a collection of typed Option
# instances.
#
class Option():

    # Subclasses use this to specify the type name used
    # for the yaml format and error messages
    OPTION_TYPE = None

    def __init__(self, name, definition, pool):
        self.name = name
        self.description = None
        self.variable = None
        self.value = None
        self.pool = pool
        self.load(definition)

    # load()
    #
    # Loads the option attributes from the descriptions
    # in the project.conf
    #
    # Args:
    #    node (dict): The loaded YAML dictionary describing
    #                 the option
    def load(self, node):
        self.description = _yaml.node_get(node, str, 'description')
        self.variable = _yaml.node_get(node, str, 'variable', default_value='') or None

    # load_value()
    #
    # Loads the value of the option in string form.
    #
    # Args:
    #    node (Mapping): The YAML loaded key/value dictionary
    #                    to load the value from
    #    transform (callbable): Transform function for variable substitution
    #
    def load_value(self, node, *, transform=None):
        pass  # pragma: nocover

    # set_value()
    #
    # Sets the value of an option from a string passed
    # to buildstream on the command line
    #
    # Args:
    #    value (str): The value in string form
    #
    def set_value(self, value):
        pass  # pragma: nocover

    # get_value()
    #
    # Gets the value of an option in string form, this
    # is for the purpose of exporting option values to
    # variables which must be in string form.
    #
    # Returns:
    #    (str): The value in string form
    #
    def get_value(self):
        pass  # pragma: nocover

    # resolve()
    #
    # Called on each option once, after all configuration
    # and cli options have been passed.
    #
    def resolve(self):
        pass  # pragma: nocover