/usr/lib/python2.7/dist-packages/configglue/parser.py is in python-configglue 1.1.2-0ubuntu2.
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#
# configglue -- glue for your apps' configuration
#
# A library for simple, DRY configuration of applications
#
# (C) 2009--2013 by Canonical Ltd.
# by John R. Lenton <john.lenton@canonical.com>
# and Ricardo Kirkner <ricardo.kirkner@canonical.com>
#
# Released under the BSD License (see the file LICENSE)
#
# For bug reports, support, and new releases: http://launchpad.net/configglue
#
###############################################################################
import codecs
import collections
import copy
import logging
import os
import re
from functools import reduce
from ._compat import BaseConfigParser, text_type, string_types
from ._compat import (
DEFAULTSECT,
InterpolationMissingOptionError,
NoOptionError,
NoSectionError,
)
__all__ = [
'SchemaValidationError',
'SchemaConfigParser',
]
CONFIG_FILE_ENCODING = 'utf-8'
class NullHandler(logging.Handler):
def emit(self, record):
pass
logger = logging.getLogger(__name__)
logger.addHandler(NullHandler())
class SchemaValidationError(Exception):
"""Exception class raised for any schema validation error."""
class SchemaConfigParser(BaseConfigParser, object):
"""A ConfigParser that validates against a Schema
The way to use this class is:
config = SchemaConfigParser(MySchema())
config.read('mysystemconfig.cfg', 'mylocalconfig.cfg', ...)
config.parse_all()
...
profit!
"""
def __init__(self, schema):
super(SchemaConfigParser, self).__init__()
# validate schema
if not schema.is_valid():
# TODO: add error details
raise SchemaValidationError()
self.schema = schema
self._location = {}
self.extra_sections = set()
self._basedir = ''
self._dirty = collections.defaultdict(
lambda: collections.defaultdict(dict))
def is_valid(self, report=False):
"""Return if the state of the parser is valid.
This is useful to detect errors in configuration files, like type
errors or missing required options.
"""
valid = True
errors = []
try:
# validate structure
config_sections = set(self.sections())
schema_sections = set(s.name for s in self.schema.sections())
skip_sections = self.extra_sections
magic_sections = set(['__main__', '__noschema__'])
# test1: no undefined implicit sections
unmatched_sections = (skip_sections - config_sections)
if unmatched_sections:
error_msg = "Undefined sections in configuration: %s"
error_value = ', '.join(unmatched_sections)
errors.append(error_msg % error_value)
valid = False
# remove sections to skip from config sections
config_sections.difference_update(skip_sections)
# test2: no extra sections that are not implicit sections
unmatched_sections = (
config_sections - magic_sections - schema_sections)
if unmatched_sections:
error_msg = "Sections in configuration are missing from schema: %s"
error_value = ', '.join(unmatched_sections)
errors.append(error_msg % error_value)
valid = False
for name in config_sections.union(schema_sections):
if name not in skip_sections:
if not self.schema.has_section(name):
# this should have been reported before
# so skip bogus section
continue
section = self.schema.section(name)
try:
parsed_options = set(self.options(name))
except NoSectionError:
parsed_options = set([])
schema_options = set(section.options())
fatal_options = set(opt.name for opt in schema_options
if opt.fatal)
# all fatal options are included
fatal_included = parsed_options.issuperset(fatal_options)
if not fatal_included:
error_msg = ("Configuration missing required options"
" for section '%s': %s")
error_value = ', '.join(list(fatal_options -
parsed_options))
errors.append(error_msg % (name, error_value))
valid &= fatal_included
# remaining parsed options are valid schema options
other_options = parsed_options - fatal_options
schema_opt_names = set(opt.name for opt in schema_options)
# add the default section special includes option
if name == '__main__':
schema_opt_names.add('includes')
schema_options = other_options.issubset(schema_opt_names)
if not schema_options:
error_msg = ("Configuration includes invalid options"
" for section '%s': %s")
error_value = ', '.join(list(other_options -
schema_opt_names))
errors.append(error_msg % (name, error_value))
valid &= schema_options
# structure validates, validate content
self.parse_all()
except Exception as e:
errors.append(text_type(e))
valid = False
if report:
return valid, errors
else:
return valid
def items(self, section, raw=False, vars=None):
"""Return the list of all options in a section.
The returned value is a list of tuples of (name, value) for each
option in the section.
All % interpolations are expanded in the return values, based on the
defaults passed into the constructor, unless the optional argument
`raw' is true. Additional substitutions may be provided using the
`vars' argument, which must be a dictionary whose contents overrides
any pre-existing defaults.
The section __main__ is special as it's implicitly defined and used
for options not explicitly included in any section.
"""
d = self._defaults.copy()
try:
d.update(self._sections[section])
except KeyError:
if section != DEFAULTSECT:
raise NoSectionError(section)
# Update with the entry specific variables
if vars:
for key, value in vars.items():
d[self.optionxform(key)] = value
options = d.keys()
if "__name__" in options:
options.remove("__name__")
if raw:
return [(option, d[option])
for option in options]
else:
items = []
for option in options:
try:
value = self._interpolate(section, option, d[option], d)
except InterpolationMissingOptionError as e:
# interpolation failed, because key was not found in
# section. try other sections before bailing out
value = self._interpolate_value(section, option)
if value is None:
# this should be a string, so None indicates an error
raise e
items.append((option, value))
return items
def values(self, section=None, parse=True):
"""Returns multiple values in a dict.
This method can return the value of multiple options in a single call,
unlike get() that returns a single option's value.
If section=None, return all options from all sections.
If section is specified, return all options from that section only.
Section is to be specified *by name*, not by
passing in real Section objects.
"""
values = collections.defaultdict(dict)
if section is None:
sections = self.schema.sections()
else:
sections = [self.schema.section(section)]
for sect in sections:
for opt in sect.options():
values[sect.name][opt.name] = self.get(
sect.name, opt.name, parse=parse)
if section is not None:
return values[section]
else:
return values
def read(self, filenames, already_read=None):
"""Like ConfigParser.read, but consider files we've already read."""
if already_read is None:
already_read = set()
if isinstance(filenames, string_types):
filenames = [filenames]
read_ok = []
for filename in filenames:
path = os.path.join(self._basedir, filename)
if path in already_read:
continue
try:
fp = codecs.open(path, 'r', encoding=CONFIG_FILE_ENCODING)
except IOError:
logger.warn(
'File {0} could not be read. Skipping.'.format(path))
continue
self._read(fp, path, already_read=already_read)
fp.close()
read_ok.append(path)
self._last_location = filename
return read_ok
def readfp(self, fp, filename=None):
"""Like ConfigParser.readfp, but consider the encoding."""
# wrap the StringIO so it can read encoded text
decoded_fp = codecs.getreader(CONFIG_FILE_ENCODING)(fp)
self._read(decoded_fp, filename)
def _read(self, fp, fpname, already_read=None):
# read file content
self._update(fp, fpname)
if already_read is None:
already_read = set()
already_read.add(fpname)
if self.has_option('__main__', 'includes'):
old_basedir, self._basedir = self._basedir, os.path.dirname(
fpname)
includes = self.get('__main__', 'includes')
filenames = [text_type.strip(x) for x in includes]
self.read(filenames, already_read=already_read)
self._basedir = old_basedir
if filenames:
# re-read the file to override included options with
# local values
fp.seek(0)
self._update(fp, fpname)
def _update(self, fp, fpname):
# remember current values
old_sections = copy.deepcopy(self._sections)
# read in new file
super(SchemaConfigParser, self)._read(fp, fpname)
# update location of changed values
self._update_location(old_sections, fpname)
def _update_location(self, old_sections, filename):
# keep list of valid options to include locations for
option_names = [x.name for x in self.schema.options()]
# new values
sections = self._sections
# update locations
for section, options in sections.items():
old_section = old_sections.get(section)
if old_section is not None:
# update options in existing section
for option, value in options.items():
valid_option = option in option_names
option_changed = (option not in old_section or
value != old_section[option])
if valid_option and option_changed:
self._location[option] = filename
else:
# complete section is new
for option, value in options.items():
valid_option = option in option_names
if valid_option:
self._location[option] = filename
def parse(self, section, option, value):
"""Parse the value of an option.
This method raises NoSectionError if an invalid section name is
passed in.
This method raises ValueError if the value is not parseable.
"""
if section == '__main__':
option_obj = getattr(self.schema, option, None)
else:
section_obj = getattr(self.schema, section, None)
if section_obj is not None:
option_obj = getattr(section_obj, option, None)
else:
raise NoSectionError(section)
if option_obj is not None:
kwargs = {}
if option_obj.require_parser:
kwargs = {'parser': self}
try:
value = option_obj.parse(value, **kwargs)
except ValueError as e:
raise ValueError("Invalid value '%s' for %s '%s' in"
" section '%s'. Original exception was: %s" %
(value, option_obj.__class__.__name__, option,
section, e))
return value
def parse_all(self):
"""Go through all sections and options attempting to parse each one.
If any options are omitted from the config file, provide the
default value from the schema.
In the case of an NoSectionError or NoOptionError, raise it if the
option has *fatal* set to *True*.
"""
for section in self.schema.sections():
for option in section.options():
try:
self.get(section.name, option.name, raw=option.raw)
except (NoSectionError, NoOptionError):
if option.fatal:
raise
def locate(self, option=None):
"""Return the location (file) where the option was last defined."""
return self._location.get(option)
def _extract_interpolation_keys(self, item):
if isinstance(item, (list, tuple)):
keys = [self._extract_interpolation_keys(x) for x in item]
keys = reduce(set.union, keys, set())
else:
keys = set(self._interpolation._KEYCRE.findall(item))
# remove invalid key
if '' in keys:
keys.remove('')
return keys
def _get_interpolation_keys(self, section, option):
rawval = super(SchemaConfigParser, self).get(section, option, raw=True)
try:
opt = self.schema.section(section).option(option)
value = opt.parse(rawval, raw=True)
except:
value = rawval
keys = self._extract_interpolation_keys(value)
return rawval, keys
def _interpolate(self, *args, **kwargs):
"""Helper method for transition to configparser."""
return self._interpolation.before_get(self, *args, **kwargs)
def _interpolate_value(self, section, option):
rawval, keys = self._get_interpolation_keys(section, option)
if not keys:
# interpolation keys are not valid
return
values = {}
# iterate over the other sections
for key in keys:
# we want the unparsed value
try:
value = self.get(section, key, parse=False)
except (NoSectionError, NoOptionError):
# value of key not found in config, so try in special
# sections
for section in ('__main__', '__noschema__'):
try:
value = super(SchemaConfigParser, self).get(section,
key)
break
except:
continue
else:
return
values[key] = value
# replace holders with values
result = rawval % values
assert isinstance(result, string_types)
return result
def interpolate_environment(self, rawval, raw=False):
"""Interpolate environment variables"""
if raw:
return rawval
# this allows both nested and mutliple environment variable
# interpolation in a single value
pattern = re.sub(r'\${([A-Z_]+)}', r'%(\1)s', rawval)
pattern = re.sub(r'\$([A-Z_]+)', r'%(\1)s', pattern)
# counter to protect against infinite loops
num_interpolations = 0
# save simple result in case we need it
simple_pattern = pattern
# handle complex case of env vars with defaults
env = os.environ.copy()
env_re = re.compile(r'\${(?P<name>[A-Z_]+):-(?P<default>.*?)}')
match = env_re.search(pattern)
while match and num_interpolations < 50:
groups = match.groupdict()
name = groups['name']
pattern = pattern.replace(match.group(), '%%(%s)s' % name)
if name not in env and groups['default'] is not None:
# interpolate defaults as well to allow ${FOO:-$BAR}
env[name] = groups['default'] % os.environ
num_interpolations += 1
match = env_re.search(pattern)
if num_interpolations >= 50:
# blown loop, restore earlier simple interpolation
pattern = simple_pattern
keys = self._extract_interpolation_keys(pattern)
if not keys:
# interpolation keys are not valid
return rawval
return pattern % env
def _get_default(self, section, option):
# cater for 'special' sections
if section == '__noschema__':
value = super(SchemaConfigParser, self).get(section, option)
return value
# any other section
opt = self.schema.section(section).option(option)
if not opt.fatal:
value = opt.default
return value
# no default value found, raise an error
raise NoOptionError(option, section)
def get(self, section, option, raw=False, vars=None, parse=True):
"""Return the parsed value of an option.
If *raw* is True, return the value as it's stored in the parser,
without parsing it.
Extra *vars* can be passed in to be evaluated during parsing.
If *parse* is False, return the string representation of the value.
"""
try:
# get option's raw mode setting
try:
option_obj = self._get_option(section, option)
raw = option_obj.raw or raw
except:
pass
# value is defined entirely in current section
value = super(SchemaConfigParser, self).get(section, option,
raw=raw, vars=vars)
except InterpolationMissingOptionError as e:
# interpolation key not in same section
value = self._interpolate_value(section, option)
if value is None:
# this should be a string, so None indicates an error
raise e
except (NoSectionError, NoOptionError) as e:
# option not found in config, try to get its default value from
# schema
value = self._get_default(section, option)
# interpolate environment variables
if isinstance(value, string_types):
try:
value = self.interpolate_environment(value, raw=raw)
if parse:
value = self.parse(section, option, value)
except KeyError:
# interpolation failed, fallback to default value
value = self._get_default(section, option)
return value
def _get_option(self, section, option):
section_obj = self.schema.section(section)
option_obj = section_obj.option(option)
return option_obj
def set(self, section, option, value):
"""Set an option's raw value."""
option_obj = self._get_option(section, option)
# make sure the value is of the right type for the option
if not option_obj.validate(value):
raise TypeError("{0} is not a valid {1} value.".format(
value, type(option_obj).__name__))
# cast value to a string because SafeConfigParser only allows
# strings to be set
str_value = option_obj.to_string(value)
if not self.has_section(section):
# Don't call .add_section here because 2.6 complains
# about sections called '__main__'
self._sections[section] = {}
super(SchemaConfigParser, self).set(section, option, str_value)
filename = self.locate(option)
self._dirty[filename][section][option] = str_value
def write(self, fp):
"""Write an .ini-format representation of the configuration state."""
# make sure the parser is populated
self._fill_parser()
if self._defaults:
fp.write("[%s]\n" % DEFAULTSECT)
for (key, value) in self._defaults.items():
fp.write("%s = %s\n" % (key, value.replace('\n', '\n\t')))
fp.write("\n")
for section in self._sections:
fp.write("[%s]\n" % section)
for (key, value) in self._sections[section].items():
if key == "__name__":
continue
if (value is not None) or (self._optcre == self.OPTCRE):
key = " = ".join((key, value.replace('\n', '\n\t')))
fp.write("%s\n" % (key))
fp.write("\n")
def save(self, fp=None):
"""Save the parser contents to a file.
The data will be saved as a ini file.
"""
if fp is not None:
if isinstance(fp, string_types):
fp = codecs.open(fp, 'w', encoding=CONFIG_FILE_ENCODING)
self.write(fp)
else:
# write to the original files
for filename, sections in self._dirty.items():
if filename is None:
# default option was overridden. figure out where to
# save it
if not getattr(self, '_last_location', None):
# no files where read, there is no possible
# location for the customized setting.
raise ValueError("No config files where read and no "
"location was specified for writing the "
"configuration.")
else:
filename = self._last_location
parser = BaseConfigParser()
parser.read(filename)
for section, options in sections.items():
for option, value in options.items():
parser.set(section, option, value)
# write to new file
parser.write(codecs.open("%s.new" % filename, 'w',
encoding=CONFIG_FILE_ENCODING))
# rename old file
if os.path.exists(filename):
os.rename(filename, "%s.old" % filename)
# rename new file
os.rename("%s.new" % filename, filename)
def _fill_parser(self):
"""Populate parser with current values for each option."""
values = self.values()
for section, options in values.items():
for option, value in options.items():
self.set(section, option, value)
# make sure having set the options didn't change anything
assert values == self.values()
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