Source code for fastoad.io.xml.variable_io_standard

"""
Defines how OpenMDAO variables are serialized to XML
"""
#  This file is part of FAST-OAD : A framework for rapid Overall Aircraft Design
#  Copyright (C) 2020  ONERA & ISAE-SUPAERO
#  FAST is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#  This program 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 General Public License for more details.
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <https://www.gnu.org/licenses/>.
import logging
from typing import Union, IO

from fastoad.openmdao.variables import VariableList
from .exceptions import FastXPathEvalError
from .translator import VarXpathTranslator
from .variable_io_base import VariableXmlBaseFormatter

_LOGGER = logging.getLogger(__name__)  # Logger for this module


class VariableXmlStandardFormatter(VariableXmlBaseFormatter):
    """
    Standard XML formatter for variables

    Assuming self.path_separator is defined as ``:`` (default), a variable named like
    ``foo:bar`` with units ``m/s`` will be read and written as:

    .. code:: xml

        <aircraft>
            <foo>
                <bar units="m/s" >`42.0</bar>
            </foo>
        <aircraft>

    When writing outputs of a model, OpenMDAO component hierarchy may be used by defining

     .. code:: python

        self.path_separator = '.'  # Discouraged for reading !
        self.use_promoted_names = False

    This way, a variable like ``componentA.subcomponent2.my_var`` will be written as:

    .. code:: xml

        <aircraft>
            <componentA>
                <subcomponent2>
                    <my_var units="m/s" >72.0</my_var>
                </subcomponent2>
            <componentA>
        <aircraft>
    """

    def __init__(self):
        super().__init__(BasicVarXpathTranslator(":"))

    @property
    def path_separator(self):
        """
        The separator that will be used in OpenMDAO variable names to match XML path.
        Warning: The dot "." can be used when writing, but not when reading.
        """
        return self._translator.path_separator

    @path_separator.setter
    def path_separator(self, separator):
        self._translator.path_separator = separator

    def read_variables(self, data_source: Union[str, IO]) -> VariableList:
        # Check separator, as OpenMDAO won't accept the dot.
        if self.path_separator == ".":
            _LOGGER.warning(
                "Usage of dot (.) is discouraged, because it won't be accepted by OpenMDAO."
            )
        return super().read_variables(data_source)

    def write_variables(self, data_source: Union[str, IO], variables: VariableList):
        try:
            super().write_variables(data_source, variables)
        except FastXPathEvalError as err:
            # Trying to help...
            raise FastXPathEvalError(
                err.args[0] + ' : self.path_separator is "%s". It is correct?' % self.path_separator
            )


class BasicVarXpathTranslator(VarXpathTranslator):
    """
    Dedicated VarXpathTranslator that builds variable names by simply converting
    the '/' separator of XPaths into the desired separator.
    """

    def __init__(self, path_separator):
        super().__init__()
        self.path_separator = path_separator

    def get_variable_name(self, xpath: str) -> str:
        path_components = xpath.split("/")
        name = self.path_separator.join(path_components)
        return name

    def get_xpath(self, var_name: str) -> str:
        path_components = var_name.split(self.path_separator)
        xpath = "/".join(path_components)
        return xpath