"""Configuration file updater.
A configuration file consists of sections, lead by a "[section]" header,
and followed by "name: value" entries, with continuations and such in
the style of RFC 822.
The basic idea of ConfigUpdater is that a configuration file consists of
three kinds of building blocks: sections, comments and spaces for separation.
A section itself consists of three kinds of blocks: options, comments and
spaces. This gives us the corresponding data structures to describe a
configuration file.
A general block object contains the lines which were parsed and make up
the block. If a block object was not changed then during writing the same
lines that were parsed will be used to express the block. In case a block,
e.g. an option, was changed, it is marked as `updated` and its values will
be transformed into a corresponding string during an update of a
configuration file.
.. note::
ConfigUpdater was created by starting from Python's ConfigParser source
code and changing it according to my needs. Thus this source code
is subject to the PSF License in a way but I am not a lawyer.
"""
import io
import os
import re
import sys
from abc import ABC
from collections import OrderedDict as _default_dict
from collections.abc import MutableMapping
from configparser import (ConfigParser, DuplicateOptionError,
DuplicateSectionError, Error,
MissingSectionHeaderError, NoOptionError,
NoSectionError, ParsingError)
__all__ = ["NoSectionError", "DuplicateOptionError", "DuplicateSectionError",
"NoOptionError", "NoConfigFileReadError", "ParsingError",
"MissingSectionHeaderError", "ConfigUpdater"]
[docs]class NoConfigFileReadError(Error):
"""Raised when no configuration file was read but update requested."""
def __init__(self):
super().__init__(
"No configuration file was yet read! Use .read(...) first.")
# Used in parser getters to indicate the default behaviour when a specific
# option is not found it to raise an exception. Created to enable 'None' as
# a valid fallback value.
_UNSET = object()
class Container(ABC):
"""Abstract Mixin Class
"""
def __init__(self, **kwargs):
self._structure = list()
super().__init__(**kwargs)
@property
def structure(self):
return self._structure
@property
def last_item(self):
if self._structure:
return self._structure[-1]
else:
return None
class Block(ABC):
"""Abstract Block type holding lines
Block objects hold original lines from the configuration file and hold
a reference to a container wherein the object resides.
"""
def __init__(self, container=None, **kwargs):
self._container = container
self.lines = []
self._updated = False
super().__init__(**kwargs)
def __str__(self):
return ''.join(self.lines)
def __len__(self):
return len(self.lines)
def __eq__(self, other):
if isinstance(other, self.__class__):
return self.lines == other.lines
else:
return False
def add_line(self, line):
"""Add a line to the current block
Args:
line (str): one line to add
"""
self.lines.append(line)
return self
@property
def container(self):
return self._container
@property
def add_before(self):
"""Returns a builder inserting a new block before the current block"""
idx = self._container.structure.index(self)
return BlockBuilder(self._container, idx)
@property
def add_after(self):
"""Returns a builder inserting a new block after the current block"""
idx = self._container.structure.index(self)
return BlockBuilder(self._container, idx+1)
class BlockBuilder(object):
"""Builder that injects blocks at a given index position."""
def __init__(self, container, idx):
self._container = container
self._idx = idx
def comment(self, text, comment_prefix='#'):
"""Creates a comment block
Args:
text (str): content of comment without \#
comment_prefix (str): character indicating start of comment
Returns:
self for chaining
"""
comment = Comment(self._container)
if not text.startswith(comment_prefix):
text = "{} {}".format(comment_prefix, text)
if not text.endswith(os.linesep):
text = "{}{}".format(text, os.linesep)
comment.add_line(text)
self._container.structure.insert(self._idx, comment)
self._idx += 1
return self
def section(self, section):
"""Creates a section block
Args:
section (str or :class:`Section`): name of section or object
Returns:
self for chaining
"""
if not isinstance(self._container, ConfigUpdater):
raise ValueError("Sections can only be added at section level!")
if isinstance(section, str):
# create a new section
section = Section(section, container=self._container)
elif not isinstance(section, Section):
raise ValueError("Parameter must be a string or Section type!")
if section.name in [block.name for block in self._container
if isinstance(block, Section)]:
raise DuplicateSectionError(section.name)
self._container.structure.insert(self._idx, section)
self._idx += 1
return self
def space(self, newlines=1):
"""Creates a vertical space of newlines
Args:
newlines (int): number of empty lines
Returns:
self for chaining
"""
space = Space()
for line in range(newlines):
space.add_line(os.linesep)
self._container.structure.insert(self._idx, space)
self._idx += 1
return self
def option(self, key, value=None, **kwargs):
"""Creates a new option inside a section
Args:
key (str): key of the option
value (str or None): value of the option
**kwargs: are passed to the constructor of :class:`Option`
Returns:
self for chaining
"""
if not isinstance(self._container, Section):
raise ValueError("Options can only be added inside a section!")
option = Option(key, value, container=self._container, **kwargs)
option.value = value
self._container.structure.insert(self._idx, option)
self._idx += 1
return self
class Comment(Block):
"""Comment block"""
def __init__(self, container=None):
super().__init__(container=container)
def __repr__(self):
return '<Comment>'
class Space(Block):
"""Vertical space block of new lines"""
def __init__(self, container=None):
super().__init__(container=container)
def __repr__(self):
return '<Space>'
class Section(Block, Container, MutableMapping):
"""Section block holding options
Attributes:
name (str): name of the section
updated (bool): indicates name change or a new section
"""
def __init__(self, name, container, **kwargs):
self._name = name
self._structure = list()
self._updated = False
super().__init__(container=container, **kwargs)
def add_option(self, entry):
"""Add an Option object to the section
Used during initial parsing mainly
Args:
entry (Option): key value pair as Option object
"""
self._structure.append(entry)
return self
def add_comment(self, line):
"""Add a Comment object to the section
Used during initial parsing mainly
Args:
line (str): one line in the comment
"""
if not isinstance(self.last_item, Comment):
comment = Comment(self._structure)
self._structure.append(comment)
self.last_item.add_line(line)
return self
def add_space(self, line):
"""Add a Space object to the section
Used during initial parsing mainly
Args:
line (str): one line that defines the space, maybe whitespaces
"""
if not isinstance(self.last_item, Space):
space = Space(self._structure)
self._structure.append(space)
self.last_item.add_line(line)
return self
def _get_option_idx(self, key):
idx = [i for i, entry in enumerate(self._structure)
if isinstance(entry, Option) and entry.key == key]
if idx:
return idx[0]
else:
raise ValueError
def __str__(self):
if not self.updated:
s = super().__str__()
else:
s = "[{}]\n".format(self._name)
for entry in self._structure:
s += str(entry)
return s
def __repr__(self):
return '<Section: {}>'.format(self.name)
def __getitem__(self, key):
if key not in self.options():
raise KeyError(key)
return self._structure[self._get_option_idx(key=key)]
def __setitem__(self, key, value):
if key in self:
option = self.__getitem__(key)
option.value = value
else:
option = Option(key, value, container=self)
option.value = value
self._structure.append(option)
def __delitem__(self, key):
if key not in self.options():
raise KeyError(key)
idx = self._get_option_idx(key=key)
del self._structure[idx]
def __contains__(self, key):
return key in self.options()
def __len__(self):
return len(self._structure)
def __iter__(self):
"""Return all entries, not just options"""
return self._structure.__iter__()
def __eq__(self, other):
if isinstance(other, self.__class__):
return (self.name == other.name and
self._structure == other._structure)
else:
return False
def option_blocks(self):
"""Returns option blocks
Returns:
list: list of :class:`Option` blocks
"""
return [entry for entry in self._structure
if isinstance(entry, Option)]
def options(self):
"""Returns option names
Returns:
list: list of option names as strings
"""
return [option.key for option in self.option_blocks()]
def to_dict(self):
"""Transform to dictionary
Returns:
dict: dictionary with same content
"""
return {key: self.__getitem__(key).value for key in self.options()}
@property
def updated(self):
"""Returns if the option was changed/updated"""
# if no lines were added, treat it as updated since we added it
return self._updated or not self.lines
@property
def name(self):
return self._name
@name.setter
def name(self, value):
self._name = str(value)
self._updated = True
def set(self, option, value=None):
"""Set an option for chaining.
Args:
option (str): option name
value (str): value, default None
"""
option = self._container.optionxform(option)
if option in self.options():
self.__getitem__(option).value = value
else:
self.__setitem__(option, value)
return self
def insert_at(self, idx):
"""Returns a builder inserting a new block at the given index
Args:
idx (int): index where to insert
"""
return BlockBuilder(self, idx)
class Option(Block):
"""Option block holding a key/value pair.
Attributes:
key (str): name of the key
value (str): stored value
updated (bool): indicates name change or a new section
"""
def __init__(self, key, value, container, delimiter='=',
space_around_delimiters=True, line=None):
super().__init__(container=container)
self._key = key
self._values = [value]
self._value_is_none = value is None
self._delimiter = delimiter
self._value = None # will be filled after join_multiline_value
self._updated = False
self._multiline_value_joined = False
self._space_around_delimiters = space_around_delimiters
if line:
self.lines.append(line)
def add_line(self, line):
super().add_line(line)
self._values.append(line.strip())
def _join_multiline_value(self):
if not self._multiline_value_joined and not self._value_is_none:
# do what `_join_multiline_value` in ConfigParser would do
self._value = os.linesep.join(self._values).rstrip()
self._multiline_value_joined = True
def __str__(self):
if not self.updated:
return super().__str__()
if self._value is None:
return "{}{}".format(self._key, os.linesep)
if self._space_around_delimiters:
# no space is needed if we use multi-line arguments
suffix = '' if str(self._value).startswith(os.linesep) else ' '
delim = " {}{}".format(self._delimiter, suffix)
else:
delim = self._delimiter
return "{}{}{}{}".format(self._key, delim, self._value, os.linesep)
def __repr__(self):
return '<Option: {} = {}>'.format(self.key, self.value)
@property
def updated(self):
"""Returns if the option was changed/updated"""
# if no lines were added, treat it as updated since we added it
return self._updated or not self.lines
@property
def key(self):
return self._key
@key.setter
def key(self, value):
self._join_multiline_value()
self._key = value
self._updated = True
@property
def value(self):
self._join_multiline_value()
return self._value
@value.setter
def value(self, value):
self._updated = True
self._multiline_value_joined = True
self._value = value
self._values = [value]
def set_values(self, values, separator=os.linesep, indent=4*' '):
"""Sets the value to a given list of options, e.g. multi-line values
Args:
values (list): list of values
separator (str): separator for values, default: line separator
indent (str): indentation depth in case of line separator
"""
self._updated = True
self._multiline_value_joined = True
self._values = values
if separator == os.linesep:
values.insert(0, '')
separator = separator + indent
self._value = separator.join(values)
[docs]class ConfigUpdater(Container, MutableMapping):
"""Parser for updating configuration files.
ConfigUpdater follows the API of ConfigParser with some differences:
* inline comments are treated as part of a key's value,
* only a single config file can be updated at a time,
* empty lines in values are not valid,
* the original case of sections and keys are kept,
* control over the position of a new section/key.
Following features are **deliberately not** implemented:
* interpolation of values,
* propagation of parameters from the default section,
* conversions of values,
* passing key/value-pairs with ``default`` argument,
* non-strict mode allowing duplicate sections and keys.
"""
# Regular expressions for parsing section headers and options
_SECT_TMPL = r"""
\[ # [
(?P<header>[^]]+) # very permissive!
\] # ]
"""
_OPT_TMPL = r"""
(?P<option>.*?) # very permissive!
\s*(?P<vi>{delim})\s* # any number of space/tab,
# followed by any of the
# allowed delimiters,
# followed by any space/tab
(?P<value>.*)$ # everything up to eol
"""
_OPT_NV_TMPL = r"""
(?P<option>.*?) # very permissive!
\s*(?: # any number of space/tab,
(?P<vi>{delim})\s* # optionally followed by
# any of the allowed
# delimiters, followed by any
# space/tab
(?P<value>.*))?$ # everything up to eol
"""
# Compiled regular expression for matching sections
SECTCRE = re.compile(_SECT_TMPL, re.VERBOSE)
# Compiled regular expression for matching options with typical separators
OPTCRE = re.compile(_OPT_TMPL.format(delim="=|:"), re.VERBOSE)
# Compiled regular expression for matching options with optional values
# delimited using typical separators
OPTCRE_NV = re.compile(_OPT_NV_TMPL.format(delim="=|:"), re.VERBOSE)
# Compiled regular expression for matching leading whitespace in a line
NONSPACECRE = re.compile(r"\S")
def __init__(self, allow_no_value=False, *, delimiters=('=', ':'),
comment_prefixes=('#', ';'), inline_comment_prefixes=None,
strict=True, space_around_delimiters=True):
"""Constructor of ConfigUpdater
Args:
allow_no_value (bool): allow keys without a value, default False
delimiters (tuple): delimiters for key/value pairs, default =, :
comment_prefixes (tuple): prefix of comments, default # and ;
inline_comment_prefixes (tuple): prefix of inline comment,
default None
strict (bool): each section must be unique as well as every key
within a section, default True
space_around_delimiters (bool): add a space before and after the
delimiter, default True
"""
self._filename = None
self._space_around_delimiters = space_around_delimiters
self._dict = _default_dict # no reason to let the user change this
# keeping _sections to keep code aligned with ConfigParser but
# _structure takes the actual role instead. Only use self._structure!
self._sections = self._dict()
self._structure = []
self._delimiters = tuple(delimiters)
if delimiters == ('=', ':'):
self._optcre = self.OPTCRE_NV if allow_no_value else self.OPTCRE
else:
d = "|".join(re.escape(d) for d in delimiters)
if allow_no_value:
self._optcre = re.compile(self._OPT_NV_TMPL.format(delim=d),
re.VERBOSE)
else:
self._optcre = re.compile(self._OPT_TMPL.format(delim=d),
re.VERBOSE)
self._comment_prefixes = tuple(comment_prefixes or ())
self._inline_comment_prefixes = tuple(inline_comment_prefixes or ())
self._strict = strict
self._allow_no_value = allow_no_value
# Options from ConfigParser that we need to set constantly
self._empty_lines_in_values = False
super().__init__()
def _get_section_idx(self, name):
idx = [i for i, entry in enumerate(self._structure)
if isinstance(entry, Section) and entry.name == name]
if idx:
return idx[0]
else:
raise ValueError
[docs] def read(self, filename, encoding=None):
"""Read and parse a filename.
Args:
filename (str): path to file
encoding (str): encoding of file, default None
"""
with open(filename, encoding=encoding) as fp:
self._read(fp, filename)
self._filename = os.path.abspath(filename)
[docs] def read_file(self, f, source=None):
"""Like read() but the argument must be a file-like object.
The ``f`` argument must be iterable, returning one line at a time.
Optional second argument is the ``source`` specifying the name of the
file being read. If not given, it is taken from f.name. If ``f`` has no
``name`` attribute, ``<???>`` is used.
Args:
f: file like object
source (str): reference name for file object, default None
"""
if source is None:
try:
source = f.name
except AttributeError:
source = '<???>'
self._read(f, source)
[docs] def read_string(self, string, source='<string>'):
"""Read configuration from a given string.
Args:
string (str): string containing a configuration
source (str): reference name for file object, default '<string>'
"""
sfile = io.StringIO(string)
self.read_file(sfile, source)
def _update_curr_block(self, block_type):
if not isinstance(self.last_item, block_type):
new_block = block_type(container=self)
self._structure.append(new_block)
def _add_comment(self, line):
if isinstance(self.last_item, Section):
self.last_item.add_comment(line)
else:
self._update_curr_block(Comment)
self.last_item.add_line(line)
def _add_section(self, sectname, line):
new_section = Section(sectname, container=self)
new_section.add_line(line)
self._structure.append(new_section)
def _add_option(self, key, vi, value, line):
entry = Option(
key, value,
delimiter=vi,
container=self.last_item,
space_around_delimiters=self._space_around_delimiters,
line=line)
self.last_item.add_option(entry)
def _add_space(self, line):
if isinstance(self.last_item, Section):
self.last_item.add_space(line)
else:
self._update_curr_block(Space)
self.last_item.add_line(line)
def _read(self, fp, fpname):
"""Parse a sectioned configuration file.
Each section in a configuration file contains a header, indicated by
a name in square brackets (`[]`), plus key/value options, indicated by
`name` and `value` delimited with a specific substring (`=` or `:` by
default).
Values can span multiple lines, as long as they are indented deeper
than the first line of the value. Depending on the parser's mode, blank
lines may be treated as parts of multiline values or ignored.
Configuration files may include comments, prefixed by specific
characters (`#` and `;` by default). Comments may appear on their own
in an otherwise empty line or may be entered in lines holding values or
section names.
Note: This method was borrowed from ConfigParser and we keep this
mess here as close as possible to the original messod (pardon
this german pun) for consistency reasons and later upgrades.
"""
self._structure = []
elements_added = set()
cursect = None # None, or a dictionary
sectname = None
optname = None
lineno = 0
indent_level = 0
e = None # None, or an exception
for lineno, line in enumerate(fp, start=1):
comment_start = sys.maxsize
# strip inline comments
inline_prefixes = {p: -1 for p in self._inline_comment_prefixes}
while comment_start == sys.maxsize and inline_prefixes:
next_prefixes = {}
for prefix, index in inline_prefixes.items():
index = line.find(prefix, index+1)
if index == -1:
continue
next_prefixes[prefix] = index
if index == 0 or (index > 0 and line[index-1].isspace()):
comment_start = min(comment_start, index)
inline_prefixes = next_prefixes
# strip full line comments
for prefix in self._comment_prefixes:
if line.strip().startswith(prefix):
comment_start = 0
self._add_comment(line) # HOOK
break
if comment_start == sys.maxsize:
comment_start = None
value = line[:comment_start].strip()
if not value:
if self._empty_lines_in_values:
# add empty line to the value, but only if there was no
# comment on the line
if (comment_start is None and
cursect is not None and
optname and
cursect[optname] is not None):
cursect[optname].append('') # newlines added at join
self.last_item.last_item.add_line(line) # HOOK
else:
# empty line marks end of value
indent_level = sys.maxsize
if comment_start is None:
self._add_space(line)
continue
# continuation line?
first_nonspace = self.NONSPACECRE.search(line)
cur_indent_level = first_nonspace.start() if first_nonspace else 0
if (cursect is not None and optname and
cur_indent_level > indent_level):
cursect[optname].append(value)
self.last_item.last_item.add_line(line) # HOOK
# a section header or option header?
else:
indent_level = cur_indent_level
# is it a section header?
mo = self.SECTCRE.match(value)
if mo:
sectname = mo.group('header')
if sectname in self._sections:
if self._strict and sectname in elements_added:
raise DuplicateSectionError(sectname, fpname,
lineno)
cursect = self._sections[sectname]
elements_added.add(sectname)
else:
cursect = self._dict()
self._sections[sectname] = cursect
elements_added.add(sectname)
# So sections can't start with a continuation line
optname = None
self._add_section(sectname, line) # HOOK
# no section header in the file?
elif cursect is None:
raise MissingSectionHeaderError(fpname, lineno, line)
# an option line?
else:
mo = self._optcre.match(value)
if mo:
optname, vi, optval = mo.group('option', 'vi', 'value')
if not optname:
e = self._handle_error(e, fpname, lineno, line)
optname = self.optionxform(optname.rstrip())
if (self._strict and
(sectname, optname) in elements_added):
raise DuplicateOptionError(sectname, optname,
fpname, lineno)
elements_added.add((sectname, optname))
# This check is fine because the OPTCRE cannot
# match if it would set optval to None
if optval is not None:
optval = optval.strip()
cursect[optname] = [optval]
else:
# valueless option handling
cursect[optname] = None
self._add_option(optname, vi, optval, line) # HOOK
else:
# a non-fatal parsing error occurred. set up the
# exception but keep going. the exception will be
# raised at the end of the file and will contain a
# list of all bogus lines
e = self._handle_error(e, fpname, lineno, line)
# if any parsing errors occurred, raise an exception
if e:
raise e
def _handle_error(self, exc, fpname, lineno, line):
if not exc:
exc = ParsingError(fpname)
exc.append(lineno, repr(line))
return exc
[docs] def write(self, fp):
"""Write an .ini-format representation of the configuration state.
Args:
fp (file-like object): open file handle
"""
fp.write(str(self))
[docs] def update_file(self):
"""Update the read-in configuration file.
"""
if self._filename is None:
raise NoConfigFileReadError()
with open(self._filename, 'w') as fb:
self.write(fb)
[docs] def sections_blocks(self):
"""Returns all section blocks
Returns:
list: list of :class:`Section` blocks
"""
return [block for block in self._structure
if isinstance(block, Section)]
[docs] def sections(self):
"""Return a list of section names
Returns:
list: list of section names
"""
return [section.name for section in self.sections_blocks()]
def __str__(self):
return ''.join(str(block) for block in self._structure)
def __getitem__(self, key):
for section in self.sections_blocks():
if section.name == key:
return section
else:
raise KeyError(key)
def __setitem__(self, key, value):
if not isinstance(value, Section):
raise ValueError("Value must be of type Section!")
if isinstance(key, str) and key in self:
idx = self._get_section_idx(key)
del self._structure[idx]
self._structure.insert(idx, value)
else:
# name the section by the key
value.name = key
self.add_section(value)
def __delitem__(self, section):
if not self.has_section(section):
raise KeyError(section)
self.remove_section(section)
def __contains__(self, key):
return self.has_section(key)
def __len__(self):
"""Number of all blocks, not just sections"""
return len(self._structure)
def __iter__(self):
"""Iterate over all blocks, not just sections"""
return self._structure.__iter__()
def __eq__(self, other):
if isinstance(other, self.__class__):
return self._structure == other._structure
else:
return False
[docs] def add_section(self, section):
"""Create a new section in the configuration.
Raise DuplicateSectionError if a section by the specified name
already exists. Raise ValueError if name is DEFAULT.
Args:
section (str or :class:`Section`): name or Section type
"""
if section in self.sections():
raise DuplicateSectionError(section)
if isinstance(section, str):
# create a new section
section = Section(section, container=self)
elif not isinstance(section, Section):
raise ValueError("Parameter must be a string or Section type!")
self._structure.append(section)
[docs] def has_section(self, section):
"""Returns whether the given section exists.
Args:
section (str): name of section
Returns:
bool: wether the section exists
"""
return section in self.sections()
[docs] def options(self, section):
"""Returns list of configuration options for the named section.
Args:
section (str): name of section
Returns:
list: list of option names
"""
if not self.has_section(section):
raise NoSectionError(section) from None
return self.__getitem__(section).options()
[docs] def get(self, section, option):
"""Gets an option value for a given section.
Args:
section (str): section name
option (str): option name
Returns:
:class:`Option`: Option object holding key/value pair
"""
if not self.has_section(section):
raise NoSectionError(section) from None
section = self.__getitem__(section)
option = self.optionxform(option)
try:
value = section[option]
except KeyError:
raise NoOptionError(option, section)
return value
[docs] def items(self, section=_UNSET):
"""Return a list of (name, value) tuples for options or sections.
If section is given, return a list of tuples with (name, value) for
each option in the section. Otherwise, return a list of tuples with
(section_name, section_type) for each section.
Args:
section (str): optional section name, default UNSET
Returns:
list: list of :class:`Section` or :class:`Option` objects
"""
if section is _UNSET:
return [(sect.name, sect) for sect in self.sections_blocks()]
section = self.__getitem__(section)
return [(opt.key, opt) for opt in section.option_blocks()]
[docs] def has_option(self, section, option):
"""Checks for the existence of a given option in a given section.
Args:
section (str): name of section
option (str): name of option
Returns:
bool: whether the option exists in the given section
"""
if section not in self.sections():
return False
else:
option = self.optionxform(option)
return option in self[section]
[docs] def set(self, section, option, value=None):
"""Set an option.
Args:
section (str): section name
option (str): option name
value (str): value, default None
"""
try:
section = self.__getitem__(section)
except KeyError:
raise NoSectionError(section) from None
option = self.optionxform(option)
if option in section:
section[option].value = value
else:
section[option] = value
return self
[docs] def remove_option(self, section, option):
"""Remove an option.
Args:
section (str): section name
option (str): option name
Returns:
bool: whether the option was actually removed
"""
try:
section = self.__getitem__(section)
except KeyError:
raise NoSectionError(section) from None
option = self.optionxform(option)
existed = option in section.options()
if existed:
del section[option]
return existed
[docs] def remove_section(self, name):
"""Remove a file section.
Args:
name: name of the section
Returns:
bool: whether the section was actually removed
"""
existed = self.has_section(name)
if existed:
idx = self._get_section_idx(name)
del self._structure[idx]
return existed
[docs] def to_dict(self):
"""Transform to dictionary
Returns:
dict: dictionary with same content
"""
return {sect: self.__getitem__(sect).to_dict()
for sect in self.sections()}