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# Copyright 2012 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
class ParseError(Exception):
def __init__(self, message, lineno, line):
self.msg = message
self.line = line
self.lineno = lineno
def __str__(self):
return 'at line %d, %s: %r' % (self.lineno, self.msg, self.line)
class BaseParser:
lineno = 0
parse_exc = ParseError
def _assignment(self, key, value):
self.assignment(key, value)
return None, []
def _get_section(self, line):
if not line.endswith(']'):
return self.error_no_section_end_bracket(line)
if len(line) <= 2:
return self.error_no_section_name(line)
return line[1:-1]
def _split_key_value(self, line):
colon = line.find(':')
equal = line.find('=')
if colon < 0 and equal < 0:
return self.error_invalid_assignment(line)
if colon < 0 or (equal >= 0 and equal < colon):
key, value = line[:equal], line[equal + 1:]
else:
key, value = line[:colon], line[colon + 1:]
value = value.strip()
if value and value[0] == value[-1] and value.startswith(("\"", "'")):
value = value[1:-1]
return key.strip(), [value]
def parse(self, lineiter):
key = None
value = []
for line in lineiter:
self.lineno += 1
line = line.rstrip()
if not line:
# Blank line, ends multi-line values
if key:
key, value = self._assignment(key, value)
continue
elif line.startswith((' ', '\t')):
# Continuation of previous assignment
if key is None:
self.error_unexpected_continuation(line)
else:
value.append(line.lstrip())
continue
if key:
# Flush previous assignment, if any
key, value = self._assignment(key, value)
if line.startswith('['):
# Section start
section = self._get_section(line)
if section:
self.new_section(section)
elif line.startswith(('#', ';')):
self.comment(line[1:].lstrip())
else:
key, value = self._split_key_value(line)
if not key:
return self.error_empty_key(line)
if key:
# Flush previous assignment, if any
self._assignment(key, value)
def assignment(self, key, value):
"""Called when a full assignment is parsed."""
raise NotImplementedError()
def new_section(self, section):
"""Called when a new section is started."""
raise NotImplementedError()
def comment(self, comment):
"""Called when a comment is parsed."""
pass
def error_invalid_assignment(self, line):
raise self.parse_exc("No ':' or '=' found in assignment",
self.lineno, line)
def error_empty_key(self, line):
raise self.parse_exc('Key cannot be empty', self.lineno, line)
def error_unexpected_continuation(self, line):
raise self.parse_exc('Unexpected continuation line',
self.lineno, line)
def error_no_section_end_bracket(self, line):
raise self.parse_exc('Invalid section (must end with ])',
self.lineno, line)
def error_no_section_name(self, line):
raise self.parse_exc('Empty section name', self.lineno, line)
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