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#!/usr/bin/env python3
#
# override-default: preprocessor for XML interface definitions to interpret
# redundant entries (relative to path) with tag 'defaultValue' as an override
# directive. Must be called before build-command-templates, as the schema
# disallows redundancy.
#
# Copyright (C) 2021 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# 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 <http://www.gnu.org/licenses/>.
#
#
# Use lxml xpath capability to find multiple elements with tag defaultValue
# relative to path; replace and remove to override the value.
import sys
import glob
import logging
from lxml import etree
debug = False
logger = logging.getLogger(__name__)
logs_handler = logging.StreamHandler()
logger.addHandler(logs_handler)
if debug:
logger.setLevel(logging.DEBUG)
else:
logger.setLevel(logging.INFO)
def override_element(l: list):
"""
Allow multiple override elements; use the final one (in document order).
"""
if len(l) < 2:
logger.debug("passing list of single element to override_element")
return
# assemble list of leafNodes of overriding defaultValues, for later removal
parents = []
for el in l[1:]:
parents.append(el.getparent())
# replace element with final override
l[0].getparent().replace(l[0], l[-1])
# remove all but overridden element
for el in parents:
el.getparent().remove(el)
def collect_and_override(dir_name):
"""
Collect elements with defaultValue tag into dictionary indexed by tuple
of (name, str(ancestor path)); the second component must be immutable for
tuple to act as key, hence str().
"""
for fname in glob.glob(f'{dir_name}/*.xml'):
tree = etree.parse(fname)
root = tree.getroot()
defv = {}
xpath_str = f'//defaultValue'
xp = tree.xpath(xpath_str)
for element in xp:
ap = element.xpath('ancestor::*[@name]')
defv.setdefault((ap[-1].get("name"), str(ap[:-1])), []).append(element)
for k, v in defv.items():
if len(v) > 1:
logger.debug(f'overridding default in {k[0]}')
override_element(v)
revised_str = etree.tostring(root, encoding='unicode', pretty_print=True)
with open(f'{fname}', 'w') as f:
f.write(revised_str)
def main():
if len(sys.argv) < 2:
logger.critical('Must specify XML directory!')
sys.exit(1)
dir_name = sys.argv[1]
collect_and_override(dir_name)
if __name__ == '__main__':
main()
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