Re: [Configobj-develop] Merging configs (setting default values)

[Fuzzyman <fuz...@vo...>]

# configobj.py
# A config file reader/writer that supports nested sections in config files.
# Copyright (C) 2005 Michael Foord, Nicola Larosa
# E-mail: fuzzyman AT voidspace DOT org DOT uk
#         nico AT tekNico DOT net

# ConfigObj 4

# Released subject to the BSD License
# Please see http://www.voidspace.org.uk/python/license.shtml

# Scripts maintained at http://www.voidspace.org.uk/python/index.shtml
# For information about bugfixes, updates and support, please join the
# ConfigObj mailing list:
# http://lists.sourceforge.net/lists/listinfo/configobj-develop
# Comments, suggestions and bug reports welcome.

"""
    >>> z = ConfigObj()
    >>> z['a'] = 'a'
    >>> z['sect'] = {
    ...    'subsect': {
    ...         'a': 'fish',
    ...         'b': 'wobble',
    ...     },
    ...     'member': 'value',
    ... }
    >>> x = ConfigObj(z.write())
    >>> z == x
    1
"""

import sys
INTP_VER = sys.version_info[:2]
if INTP_VER < (2, 2):
    raise RuntimeError("Python v.2.2 or later needed")

import os, re
from types import StringTypes

# the UTF8 BOM - from codecs module
BOM_UTF8 = '\xef\xbb\xbf'

__version__ = '4.0.3'

__revision__ = '$Id: configobj.py 147 2005-11-08 12:08:49Z fuzzyman $'

__docformat__ = "restructuredtext en"

__all__ = (
    '__version__',
    'BOM_UTF8',
    'DEFAULT_INDENT_TYPE',
    'NUM_INDENT_SPACES',
    'MAX_INTERPOL_DEPTH',
    'ConfigObjError',
    'NestingError',
    'ParseError',
    'DuplicateError',
    'ConfigspecError',
    'ConfigObj',
    'SimpleVal',
    'InterpolationError',
    'InterpolationDepthError',
    'MissingInterpolationOption',
    'RepeatSectionError',
    '__docformat__',
    'flatten_errors',
)

DEFAULT_INDENT_TYPE = ' '
NUM_INDENT_SPACES = 4
MAX_INTERPOL_DEPTH = 10

OPTION_DEFAULTS = {
    'interpolation': True,
    'raise_errors': False,
    'list_values': True,
    'create_empty': False,
    'file_error': False,
    'configspec': None,
    'stringify': True,
    # option may be set to one of ('', ' ', '\t')
    'indent_type': None,
}

class ConfigObjError(SyntaxError):
    """
    This is the base class for all errors that ConfigObj raises.
    It is a subclass of SyntaxError.
    
    >>> raise ConfigObjError
    Traceback (most recent call last):
    ConfigObjError
    """
    def __init__(self, message='', line_number=None, line=''):
        self.line = line
        self.line_number = line_number
        self.message = message
        SyntaxError.__init__(self, message)

class NestingError(ConfigObjError):
    """
    This error indicates a level of nesting that doesn't match.
    
    >>> raise NestingError
    Traceback (most recent call last):
    NestingError
    """

class ParseError(ConfigObjError):
    """
    This error indicates that a line is badly written.
    It is neither a valid ``key = value`` line,
    nor a valid section marker line.
    
    >>> raise ParseError
    Traceback (most recent call last):
    ParseError
    """

class DuplicateError(ConfigObjError):
    """
    The keyword or section specified already exists.
    
    >>> raise DuplicateError
    Traceback (most recent call last):
    DuplicateError
    """

class ConfigspecError(ConfigObjError):
    """
    An error occured whilst parsing a configspec.
    
    >>> raise ConfigspecError
    Traceback (most recent call last):
    ConfigspecError
    """

class InterpolationError(ConfigObjError):
    """Base class for the two interpolation errors."""

class InterpolationDepthError(InterpolationError):
    """Maximum interpolation depth exceeded in string interpolation."""

    def __init__(self, option):
        """
        >>> raise InterpolationDepthError('yoda')
        Traceback (most recent call last):
        InterpolationDepthError: max interpolation depth exceeded in value "yoda".
        """
        InterpolationError.__init__(
            self,
            'max interpolation depth exceeded in value "%s".' % option)

class RepeatSectionError(ConfigObjError):
    """
    This error indicates additional sections in a section with a
    ``__many__`` (repeated) section.
    
    >>> raise RepeatSectionError
    Traceback (most recent call last):
    RepeatSectionError
    """

class MissingInterpolationOption(InterpolationError):
    """A value specified for interpolation was missing."""

    def __init__(self, option):
        """
        >>> raise MissingInterpolationOption('yoda')
        Traceback (most recent call last):
        MissingInterpolationOption: missing option "yoda" in interpolation.
        """
        InterpolationError.__init__(
            self,
            'missing option "%s" in interpolation.' % option)

class Section(dict):
    """
    A dictionary-like object that represents a section in a config file.
    
    It does string interpolation if the 'interpolate' attribute
    of the 'main' object is set to True.
    
    Interpolation is tried first from the 'DEFAULT' section of this object,
    next from the 'DEFAULT' section of the parent, lastly the main object.
    
    A Section will behave like an ordered dictionary - following the
    order of the ``scalars`` and ``sections`` attributes.
    You can use this to change the order of members.
    
    Iteration follows the order: scalars, then sections.
    """

    _KEYCRE = re.compile(r"%\(([^)]*)\)s|.")

    def __init__(self, parent, depth, main, indict=None, name=None):
        """
        * parent is the section above
        * depth is the depth level of this section
        * main is the main ConfigObj
        * indict is a dictionary to initialise the section with
        """
        if indict is None:
            indict = {}
        dict.__init__(self)
        # used for nesting level *and* interpolation
        self.parent = parent
        # used for the interpolation attribute
        self.main = main
        # level of nesting depth of this Section
        self.depth = depth
        # the sequence of scalar values in this Section
        self.scalars = []
        # the sequence of sections in this Section
        self.sections = []
        # purely for information
        self.name = name
        # for comments :-)
        self.comments = {}
        self.inline_comments = {}
        # for the configspec
        self.configspec = {}
        # for defaults
        self.defaults = []
        #
        # we do this explicitly so that __setitem__ is used properly
        # (rather than just passing to ``dict.__init__``)
        for entry in indict:
            self[entry] = indict[entry]

    def _interpolate(self, value):
        """Nicked from ConfigParser."""
        depth = MAX_INTERPOL_DEPTH
        # loop through this until it's done
        while depth:
            depth -= 1
            if value.find("%(") != -1:
                value = self._KEYCRE.sub(self._interpolation_replace, value)
            else:
                break
        else:
            raise InterpolationDepthError(value)
        return value

    def _interpolation_replace(self, match):
        """ """
        s = match.group(1)
        if s is None:
            return match.group()
        else:
            # switch off interpolation before we try and fetch anything !
            self.main.interpolation = False
            # try the 'DEFAULT' member of *this section* first
            val = self.get('DEFAULT', {}).get(s)
            # try the 'DEFAULT' member of the *parent section* next
            if val is None:
                val = self.parent.get('DEFAULT', {}).get(s)
            # last, try the 'DEFAULT' member of the *main section*
            if val is None:
                val = self.main.get('DEFAULT', {}).get(s)
            self.main.interpolation = True
            if val is None:
                raise MissingInterpolationOption(s)
            return val

    def __getitem__(self, key):
        """Fetch the item and do string interpolation."""
        val = dict.__getitem__(self, key)
        if self.main.interpolation and isinstance(val, StringTypes):
            return self._interpolate(val)
        return val

    def __setitem__(self, key, value):
        """
        Correctly set a value.
        
        Making dictionary values Section instances.
        (We have to special case 'Section' instances - which are also dicts)
        
        Keys must be strings.
        Values need only be strings (or lists of strings) if
        ``main.stringify`` is set.
        """
        if not isinstance(key, StringTypes):
            raise ValueError, 'The key "%s" is not a string.' % key
        # add the comment
        if not self.comments.has_key(key):
            self.comments[key] = []
            self.inline_comments[key] = ''
        # remove the entry from defaults
        if key in self.defaults:
            self.defaults.remove(key)
        #
        if isinstance(value, Section):
            if not self.has_key(key):
                self.sections.append(key)
            dict.__setitem__(self, key, value)
        elif isinstance(value, dict):
            # First create the new depth level,
            # then create the section
            if not self.has_key(key):
                self.sections.append(key)
            new_depth = self.depth + 1
            dict.__setitem__(
                self,
                key,
                Section(
                    self,
                    new_depth,
                    self.main,
                    indict=value,
                    name=key))
        else:
            if not self.has_key(key):
                self.scalars.append(key)
            if not self.main.stringify:
                if isinstance(value, StringTypes):
                    pass
                elif isinstance(value, (list, tuple)):
                    for entry in value:
                        if not isinstance(entry, StringTypes):
                            raise TypeError, (
                                'Value is not a string "%s".' % entry)
                else:
                    raise TypeError, 'Value is not a string "%s".' % value
            dict.__setitem__(self, key, value)

    def __delitem__(self, key):
        """Remove items from the sequence when deleting."""
        dict. __delitem__(self, key)
        if key in self.scalars:
            self.scalars.remove(key)
        else:
            self.sections.remove(key)
        del self.comments[key]
        del self.inline_comments[key]

    def get(self, key, default=None):
        """A version of ``get`` that doesn't bypass string interpolation."""
        try:
            return self[key]
        except KeyError:
            return default

    def update(self, indict):
        """
        A version of update that uses our ``__setitem__``.
        """
        for entry in indict:
            self[entry] = indict[entry]


    def pop(self, key, *args):
        """ """
        val = dict.pop(self, key, *args)
        if key in self.scalars:
            del self.comments[key]
            del self.inline_comments[key]
            self.scalars.remove(key)
        elif key in self.sections:
            del self.comments[key]
            del self.inline_comments[key]
            self.sections.remove(key)
        if self.main.interpolation and isinstance(val, StringTypes):
            return self._interpolate(val)
        return val

    def popitem(self):
        """Pops the first (key,val)"""
        sequence = (self.scalars + self.sections)
        if not sequence:
            raise KeyError, ": 'popitem(): dictionary is empty'"
        key = sequence[0]
        val =  self[key]
        del self[key]
        return key, val

    def clear(self):
        """
        A version of clear that also affects scalars/sections
        Also clears comments and configspec.
        
        Leaves other attributes alone :
            depth/main/parent are not affected
        """
        dict.clear(self)
        self.scalars = []
        self.sections = []
        self.comments = {}
        self.inline_comments = {}
        self.configspec = {}

    def setdefault(self, key, default=None):
        """A version of setdefault that sets sequence if appropriate."""
        try:
            return self[key]
        except KeyError:
            self[key] = default
            return self[key]

    def items(self):
        """ """
        return zip((self.scalars + self.sections), self.values())

    def keys(self):
        """ """
        return (self.scalars + self.sections)

    def values(self):
        """ """
        return [self[key] for key in (self.scalars + self.sections)]

    def iteritems(self):
        """ """
        return iter(self.items())

    def iterkeys(self):
        """ """
        return iter((self.scalars + self.sections))

    __iter__ = iterkeys

    def itervalues(self):
        """ """
        return iter(self.values())

    def __repr__(self):
        return '{%s}' % ', '.join([('%s: %s' % (repr(key), repr(self[key])))
            for key in (self.scalars + self.sections)])

    __str__ = __repr__

    # Extra methods - not in a normal dictionary

    def dict(self):
        """
        Return a deepcopy of self as a dictionary.
        
        All members that are ``Section`` instances are recursively turned to
        ordinary dictionaries - by calling their ``dict`` method.
        
        >>> n = a.dict()
        >>> n == a
        1
        >>> n is a
        0
        """
        newdict = {}
        for entry in self:
            this_entry = self[entry]
            if isinstance(this_entry, Section):
                this_entry = this_entry.dict()
            elif isinstance(this_entry, (list, tuple)):
                # create a copy rather than a reference
                this_entry = list(this_entry)
            newdict[entry] = this_entry
        return newdict

    def merge(self, indict):
        """
        A recursive update - useful for merging config files.
        
        >>> a = '''[section1]
        ...     option1 = True
        ...     [[subsection]]
        ...     more_options = False
        ...     # end of file'''.splitlines()
        >>> b = '''# File is user.ini
        ...     [section1]
        ...     option1 = False
        ...     # end of file'''.splitlines()
        >>> c1 = ConfigObj(b)
        >>> c2 = ConfigObj(a)
        >>> c2.merge(c1)
        >>> c2
        {'section1': {'option1': 'False', 'subsection': {'more_options': 'False'}}}
        """
        for key, val in indict.items():
            if (key in self and isinstance(self[key], dict) and
                                isinstance(val, dict)):
                self[key].merge(val)
            else:   
                self[key] = val

    def rename(self, oldkey, newkey):
        """
        Change a keyname to another, without changing position in sequence.
        
        Implemented so that transformations can be made on keys,
        as well as on values. (used by encode and decode)
        
        Also renames comments.
        """
        if oldkey in self.scalars:
            the_list = self.scalars
        elif oldkey in self.sections:
            the_list = self.sections
        else:
            raise KeyError, 'Key "%s" not found.' % oldkey
        pos = the_list.index(oldkey)
        #
        val = self[oldkey]
        dict.__delitem__(self, oldkey)
        dict.__setitem__(self, newkey, val)
        the_list.remove(oldkey)
        the_list.insert(pos, newkey)
        comm = self.comments[oldkey]
        inline_comment = self.inline_comments[oldkey]
        del self.comments[oldkey]
        del self.inline_comments[oldkey]
        self.comments[newkey] = comm
        self.inline_comments[newkey] = inline_comment

    def walk(self, function, raise_errors=True,
            call_on_sections=False, **keywargs):
        """
        Walk every member and call a function on the keyword and value.
        
        Return a dictionary of the return values
        
        If the function raises an exception, raise the errror
        unless ``raise_errors=False``, in which case set the return value to
        ``False``.
        
        Any unrecognised keyword arguments you pass to walk, will be pased on
        to the function you pass in.
        
        Note: if ``call_on_sections`` is ``True`` then - on encountering a
        subsection, *first* the function is called for the *whole* subsection,
        and then recurses into it's members. This means your function must be
        able to handle strings, dictionaries and lists. This allows you
        to change the key of subsections as well as for ordinary members. The
        return value when called on the whole subsection has to be discarded.
        
        See  the encode and decode methods for examples, including functions.
        
        .. caution::
        
            You can use ``walk`` to transform the names of members of a section
            but you mustn't add or delete members.
        
        >>> config = '''[XXXXsection]
        ... XXXXkey = XXXXvalue'''.splitlines()
        >>> cfg = ConfigObj(config)
        >>> cfg
        {'XXXXsection': {'XXXXkey': 'XXXXvalue'}}
        >>> def transform(section, key):
        ...     val = section[key]
        ...     newkey = key.replace('XXXX', 'CLIENT1')
        ...     section.rename(key, newkey)
        ...     if isinstance(val, (tuple, list, dict)):
        ...         pass
        ...     else:
        ...         val = val.replace('XXXX', 'CLIENT1')
        ...         section[newkey] = val
        >>> cfg.walk(transform, call_on_sections=True)
        {'CLIENT1section': {'CLIENT1key': None}}
        >>> cfg
        {'CLIENT1section': {'CLIENT1key': 'CLIENT1value'}}
        """
        out = {}
        # scalars first
        for i in range(len(self.scalars)):
            entry = self.scalars[i]
            try:
                val = function(self, entry, **keywargs)
                # bound again in case name has changed
                entry = self.scalars[i]
                out[entry] = val
            except Exception:
                if raise_errors:
                    raise
                else:
                    entry = self.scalars[i]
                    out[entry] = False
        # then sections
        for i in range(len(self.sections)):
            entry = self.sections[i]
            if call_on_sections:
                try:
                    function(self, entry, **keywargs)
                except Exception:
                    if raise_errors:
                        raise
                    else:
                        entry = self.sections[i]
                        out[entry] = False
                # bound again in case name has changed
                entry = self.sections[i]
            # previous result is discarded
            out[entry] = self[entry].walk(
                function,
                raise_errors=raise_errors,
                call_on_sections=call_on_sections,
                **keywargs)
        return out

    def decode(self, encoding):
        """
        Decode all strings and values to unicode, using the specified encoding.
        
        Works with subsections and list values.
        
        Uses the ``walk`` method.
        
        Testing ``encode`` and ``decode``.
        >>> m = ConfigObj(a)
        >>> m.decode('ascii')
        >>> def testuni(val):
        ...     for entry in val:
        ...         if not isinstance(entry, unicode):
        ...             print >> sys.stderr, type(entry)
        ...             raise AssertionError, 'decode failed.'
        ...         if isinstance(val[entry], dict):
        ...             testuni(val[entry])
        ...         elif not isinstance(val[entry], unicode):
        ...             raise AssertionError, 'decode failed.'
        >>> testuni(m)
        >>> m.encode('ascii')
        >>> a == m
        1
        """
        def decode(section, key, encoding=encoding):
            """ """
            val = section[key]
            if isinstance(val, (list, tuple)):
                newval = []
                for entry in val:
                    newval.append(entry.decode(encoding))
            elif isinstance(val, dict):
                newval = val
            else:
                newval = val.decode(encoding)
            newkey = key.decode(encoding)
            section.rename(key, newkey)
            section[newkey] = newval
        # using ``call_on_sections`` allows us to modify section names
        self.walk(decode, call_on_sections=True)

    def encode(self, encoding):
        """
        Encode all strings and values from unicode,
        using the specified encoding.
        
        Works with subsections and list values.
        Uses the ``walk`` method.
        """
        def encode(section, key, encoding=encoding):
            """ """
            val = section[key]
            if isinstance(val, (list, tuple)):
                newval = []
                for entry in val:
                    newval.append(entry.encode(encoding))
            elif isinstance(val, dict):
                newval = val
            else:
                newval = val.encode(encoding)
            newkey = key.encode(encoding)
            section.rename(key, newkey)
            section[newkey] = newval
        self.walk(encode, call_on_sections=True)

    def istrue(self, key):
        """
        Accepts a key as input. The corresponding value must be a string or
        the objects (``True`` or 1) or (``False`` or 0). We allow 0 and 1 to
        retain compatibility with Python 2.2.
        
        If the string is one of  ``True``, ``On``, ``Yes``, or ``1`` it returns 
        ``True``.
        
        If the string is one of  ``False``, ``Off``, ``No``, or ``0`` it returns 
        ``False``.
        
        ``istrue`` is not case sensitive.
        
        Any other input will raise a ``ValueError``. 
        """
        val = self[key]
        if val == True:
            return True
        elif val == False:
            return False
        else:
            try:
                if not isinstance(val, StringTypes):
                    raise KeyError
                else:
                    return self.main._bools[val.lower()]
            except KeyError:
                raise ValueError('Value "%s" is neither True nor False' % val)

class ConfigObj(Section):
    """
    An object to read, create, and write config files.
    
    Testing with duplicate keys and sections.
    
    >>> c = '''
    ... [hello]
    ... member = value
    ... [hello again]
    ... member = value
    ... [ "hello" ]
    ... member = value
    ... '''
    >>> ConfigObj(c.split('\\n'), raise_errors = True)
    Traceback (most recent call last):
    DuplicateError: Duplicate section name at line 5.
    
    >>> d = '''
    ... [hello]
    ... member = value
    ... [hello again]
    ... member1 = value
    ... member2 = value
    ... 'member1' = value
    ... [ "and again" ]
    ... member = value
    ... '''
    >>> ConfigObj(d.split('\\n'), raise_errors = True)
    Traceback (most recent call last):
    DuplicateError: Duplicate keyword name at line 6.
    """

    _keyword = re.compile(r'''^ # line start
        (\s*)                   # indentation
        (                       # keyword
            (?:".*?")|          # double quotes
            (?:'.*?')|          # single quotes
            (?:[^'"=].*?)       # no quotes
        )
        \s*=\s*                 # divider
        (.*)                    # value (including list values and comments)
        $   # line end
        ''',
        re.VERBOSE)

    _sectionmarker = re.compile(r'''^
        (\s*)                     # 1: indentation
        ((?:\[\s*)+)              # 2: section marker open
        (                         # 3: section name open
            (?:"\s*\S.*?\s*")|    # at least one non-space with double quotes
            (?:'\s*\S.*?\s*')|    # at least one non-space with single quotes
            (?:[^'"\s].*?)        # at least one non-space unquoted
        )                         # section name close
        ((?:\s*\])+)              # 4: section marker close
        \s*(\#.*)?                # 5: optional comment
        $''',
        re.VERBOSE)

    # this regexp pulls list values out as a single string
    # or single values and comments
    _valueexp = re.compile(r'''^
        (?:
            (?:
                (
                    (?:
                        (?:
                            (?:".*?")|              # double quotes
                            (?:'.*?')|              # single quotes
                            (?:[^'",\#][^,\#]*?)       # unquoted
                        )
                        \s*,\s*                     # comma
                    )*      # match all list items ending in a comma (if any)
                )
                (
                    (?:".*?")|                      # double quotes
                    (?:'.*?')|                      # single quotes
                    (?:[^'",\#\s][^,]*?)             # unquoted
                )?          # last item in a list - or string value
            )|
            (,)             # alternatively a single comma - empty list
        )
        \s*(\#.*)?          # optional comment
        $''',
        re.VERBOSE)

    # use findall to get the members of a list value
    _listvalueexp = re.compile(r'''
        (
            (?:".*?")|          # double quotes
            (?:'.*?')|          # single quotes
            (?:[^'",\#].*?)       # unquoted
        )
        \s*,\s*                 # comma
        ''',
        re.VERBOSE)

    # this regexp is used for the value
    # when lists are switched off
    _nolistvalue = re.compile(r'''^
        (
            (?:".*?")|          # double quotes
            (?:'.*?')|          # single quotes
            (?:[^'"\#].*?)      # unquoted
        )
        \s*(\#.*)?              # optional comment
        $''',
        re.VERBOSE)

    # regexes for finding triple quoted values on one line
    _single_line_single = re.compile(r"^'''(.*?)'''\s*(#.*)?$")
    _single_line_double = re.compile(r'^"""(.*?)"""\s*(#.*)?$')
    _multi_line_single = re.compile(r"^(.*?)'''\s*(#.*)?$")
    _multi_line_double = re.compile(r'^(.*?)"""\s*(#.*)?$')

    _triple_quote = {
        "'''": (_single_line_single, _multi_line_single),
        '"""': (_single_line_double, _multi_line_double),
    }

    # Used by the ``istrue`` Section method
    _bools = {
        'yes': True, 'no': False,
        'on': True, 'off': False,
        '1': True, '0': False,
        'true': True, 'false': False,
        }

    def __init__(self, infile=None, options=None, **kwargs):
        """
        Parse or create a config file object.
        
        ``ConfigObj(infile=None, options=None, **kwargs)``
        """
        if infile is None:
            infile = []
        if options is None:
            options = {}
        # keyword arguments take precedence over an options dictionary
        options.update(kwargs)
        # init the superclass
        Section.__init__(self, self, 0, self)
        #
        defaults = OPTION_DEFAULTS.copy()
        for entry in options.keys():
            if entry not in defaults.keys():
                raise TypeError, 'Unrecognised option "%s".' % entry
        # TODO: check the values too
        # add the explicit options to the defaults
        defaults.update(options)
        #
        # initialise a few variables
        self._errors = []
        self.raise_errors = defaults['raise_errors']
        self.interpolation = defaults['interpolation']
        self.list_values = defaults['list_values']
        self.create_empty = defaults['create_empty']
        self.file_error = defaults['file_error']
        self.stringify = defaults['stringify']
        self.indent_type = defaults['indent_type']
        # used by the write method
        self.BOM = None
        #
        self.initial_comment = []
        self.final_comment = []
        #
        if isinstance(infile, StringTypes):
            self.filename = os.path.abspath(infile)
            if os.path.isfile(self.filename):
                infile = open(self.filename).readlines()
            elif self.file_error:
                # raise an error if the file doesn't exist
                raise IOError, 'Config file not found: "%s".' % self.filename
            else:
                # file doesn't already exist
                if self.create_empty:
                    # this is a good test that the filename specified
                    # isn't impossible - like on a non existent device
                    h = open(self.filename, 'w')
                    h.write('')
                    h.close()
                infile = []
        elif isinstance(infile, (list, tuple)):
            self.filename = None
        elif isinstance(infile, dict):
            # initialise self
            # the Section class handles creating subsections
            if isinstance(infile, ConfigObj):
                # get a copy of our ConfigObj
                infile = infile.dict()
            for entry in infile:
                self[entry] = infile[entry]
            self.filename = None
            del self._errors
            if defaults['configspec'] is not None:
                self._handle_configspec(defaults['configspec'])
            else:
                self.configspec = None
            return
        elif hasattr(infile, 'seek'):
            # this supports StringIO instances and even file objects
            self.filename = infile
            infile.seek(0)
            infile = infile.readlines()
            self.filename.seek(0)
        else:
            raise TypeError, ('infile must be a filename,'
                ' StringIO instance, or a file as a list.')
        #
        # strip trailing '\n' from lines
        infile = [line.rstrip('\n') for line in infile]
        #
        # remove the UTF8 BOM if it is there
        # FIXME: support other BOM
        if infile and infile[0].startswith(BOM_UTF8):
            infile[0] = infile[0][3:]
            self.BOM = BOM_UTF8
        else:
            self.BOM = None
        #
        self._parse(infile)
        # if we had any errors, now is the time to raise them
        if self._errors:
            error = ConfigObjError("Parsing failed.")
            # set the errors attribute; it's a list of tuples:
            # (error_type, message, line_number)
            error.errors = self._errors
            # set the config attribute
            error.config = self
            raise error
        # delete private attributes
        del self._errors
        #
        if defaults['configspec'] is None:
            self.configspec = None
        else:
            self._handle_configspec(defaults['configspec'])

    def _parse(self, infile):
        """
        Actually parse the config file
        
        Testing Interpolation
        
        >>> c = ConfigObj()
        >>> c['DEFAULT'] = {
        ...     'b': 'goodbye',
        ...     'userdir': 'c:\\\\home',
        ...     'c': '%(d)s',
        ...     'd': '%(c)s'
        ... }
        >>> c['section'] = {
        ...     'a': '%(datadir)s\\\\some path\\\\file.py',
        ...     'b': '%(userdir)s\\\\some path\\\\file.py',
        ...     'c': 'Yo %(a)s',
        ...     'd': '%(not_here)s',
        ...     'e': '%(c)s',
        ... }
        >>> c['section']['DEFAULT'] = {
        ...     'datadir': 'c:\\\\silly_test',
        ...     'a': 'hello - %(b)s',
        ... }
        >>> c['section']['a'] == 'c:\\\\silly_test\\\\some path\\\\file.py'
        1
        >>> c['section']['b'] == 'c:\\\\home\\\\some path\\\\file.py'
        1
        >>> c['section']['c'] == 'Yo hello - goodbye'
        1
        
        Switching Interpolation Off
        
        >>> c.interpolation = False
        >>> c['section']['a'] == '%(datadir)s\\\\some path\\\\file.py'
        1
        >>> c['section']['b'] == '%(userdir)s\\\\some path\\\\file.py'
        1
        >>> c['section']['c'] == 'Yo %(a)s'
        1
        
        Testing the interpolation errors.
        
        >>> c.interpolation = True
        >>> c['section']['d']
        Traceback (most recent call last):
        MissingInterpolationOption: missing option "not_here" in interpolation.
        >>> c['section']['e']
        Traceback (most recent call last):
        InterpolationDepthError: max interpolation depth exceeded in value "%(c)s".
        
        Testing our quoting.
        
        >>> i._quote('\"""\'\'\'')
        Traceback (most recent call last):
        SyntaxError: EOF while scanning triple-quoted string
        >>> try:
        ...     i._quote('\\n', multiline=False)
        ... except ConfigObjError, e:
        ...    e.msg
        'Value "\\n" cannot be safely quoted.'
        >>> k._quote(' "\' ', multiline=False)
        Traceback (most recent call last):
        SyntaxError: EOL while scanning single-quoted string
        
        Testing with "stringify" off.
        >>> c.stringify = False
        >>> c['test'] = 1
        Traceback (most recent call last):
        TypeError: Value is not a string "1".
        """
        comment_list = []
        done_start = False
        this_section = self
        maxline = len(infile) - 1
        cur_index = -1
        reset_comment = False
        while cur_index < maxline:
            if reset_comment:
                comment_list = []
            cur_index += 1
            line = infile[cur_index]
            sline = line.strip()
            # do we have anything on the line ?
            if not sline or sline.startswith('#'):
                reset_comment = False
                comment_list.append(line)
                continue
            if not done_start:
                # preserve initial comment
                self.initial_comment = comment_list
                comment_list = []
                done_start = True
            reset_comment = True
            # first we check if it's a section marker
            mat = self._sectionmarker.match(line)
##            print >> sys.stderr, sline, mat
            if mat is not None:
                # is a section line
                (indent, sect_open, sect_name, sect_close, comment) = (
                    mat.groups())
                if indent and (self.indent_type is None):
                    self.indent_type = indent[0]
                cur_depth = sect_open.count('[')
                if cur_depth != sect_close.count(']'):
                    self._handle_error(
                        "Cannot compute the section depth at line %s.",
                        NestingError, infile, cur_index)
                    continue
                if cur_depth < this_section.depth:
                    # the new section is dropping back to a previous level
                    try:
                        parent = self._match_depth(
                            this_section,
                            cur_depth).parent
                    except SyntaxError:
                        self._handle_error(
                            "Cannot compute nesting level at line %s.",
                            NestingError, infile, cur_index)
                        continue
                elif cur_depth == this_section.depth:
                    # the new section is a sibling of the current section
                    parent = this_section.parent
                elif cur_depth == this_section.depth + 1:
                    # the new section is a child the current section
                    parent = this_section
                else:
                    self._handle_error(
                        "Section too nested at line %s.",
                        NestingError, infile, cur_index)
                #
                sect_name = self._unquote(sect_name)
                if parent.has_key(sect_name):
##                    print >> sys.stderr, sect_name
                    self._handle_error(
                        'Duplicate section name at line %s.',
                        DuplicateError, infile, cur_index)
                    continue
                # create the new section
                this_section = Section(
                    parent,
                    cur_depth,
                    self,
                    name=sect_name)
                parent[sect_name] = this_section
                parent.inline_comments[sect_name] = comment
                parent.comments[sect_name] = comment_list
##                print >> sys.stderr, parent[sect_name] is this_section
                continue
            #
            # it's not a section marker,
            # so it should be a valid ``key = value`` line
            mat = self._keyword.match(line)
##            print >> sys.stderr, sline, mat
            if mat is not None:
                # is a keyword value
                # value will include any inline comment
                (indent, key, value) = mat.groups()
                if indent and (self.indent_type is None):
                    self.indent_type = indent[0]
                # check for a multiline value
                if value[:3] in ['"""', "'''"]:
                    try:
                        (value, comment, cur_index) = self._multiline(
                            value, infile, cur_index, maxline)
                    except SyntaxError:
                        self._handle_error(
                            'Parse error in value at line %s.',
                            ParseError, infile, cur_index)
                        continue
                else:
                    # extract comment and lists
                    try:
                        (value, comment) = self._handle_value(value)
                    except SyntaxError:
                        self._handle_error(
                            'Parse error in value at line %s.',
                            ParseError, infile, cur_index)
                        continue
                #
##                print >> sys.stderr, sline
                key = self._unquote(key)
                if this_section.has_key(key):
                    self._handle_error(
                        'Duplicate keyword name at line %s.',
                        DuplicateError, infile, cur_index)
                    continue
                # add the key
##                print >> sys.stderr, this_section.name
                this_section[key] = value
                this_section.inline_comments[key] = comment
                this_section.comments[key] = comment_list
##                print >> sys.stderr, key, this_section[key]
##                if this_section.name is not None:
##                    print >> sys.stderr, this_section
##                    print >> sys.stderr, this_section.parent
##                    print >> sys.stderr, this_section.parent[this_section.name]
                continue
            #
            # it neither matched as a keyword
            # or a section marker
            self._handle_error(
                'Invalid line at line "%s".',
                ParseError, infile, cur_index)
        if self.indent_type is None:
            # no indentation used, set the type accordingly
            self.indent_type = ''
        # preserve the final comment
        self.final_comment = comment_list

    def _match_depth(self, sect, depth):
        """
        Given a section and a depth level, walk back through the sections
        parents to see if the depth level matches a previous section.
        
        Return a reference to the right section,
        or raise a SyntaxError.
        """
        while depth < sect.depth:
            if sect is sect.parent:
                # we've reached the top level already
                raise SyntaxError
            sect = sect.parent
        if sect.depth == depth:
            return sect
        # shouldn't get here
        raise SyntaxError

    def _handle_error(self, text, ErrorClass, infile, cur_index):
        """
        Handle an error according to the error settings.
        
        Either raise the error or store it.
        The error will have occured at ``cur_index``
        """
        line = infile[cur_index]
        message = text % cur_index
        error = ErrorClass(message, cur_index, line)
        if self.raise_errors:
            # raise the error - parsing stops here
            raise error
        # store the error
        # reraise when parsing has finished
        self._errors.append(error)

    def _unquote(self, value):
        """Return an unquoted version of a value"""
        if (value[0] == value[-1]) and (value[0] in ('"', "'")):
            value = value[1:-1]
        return value

    def _quote(self, value, multiline=True):
        """
        Return a safely quoted version of a value.
        
        Raise a ConfigObjError if the value cannot be safely quoted.
        If multiline is ``True`` (default) then use triple quotes
        if necessary.
        
        Don't quote values that don't need it.
        Recursively quote members of a list and return a comma joined list.
        Multiline is ``False`` for lists.
        Obey list syntax for empty and single member lists.
        
        If ``list_values=False`` then the value is only quoted if it contains
        a ``\n`` (is multiline).
        """
        if isinstance(value, (list, tuple)):
            if not value:
                return ','
            elif len(value) == 1:
                return self._quote(value[0], multiline=False) + ','
            return ', '.join([self._quote(val, multiline=False)
                for val in value])
        if not isinstance(value, StringTypes):
            if self.stringify:
                value = str(value)
            else:
                raise TypeError, 'Value "%s" is not a string.' % value
        squot = "'%s'"
        dquot = '"%s"'
        noquot = "%s"
        wspace_plus = ' \r\t\n\v\t\'"'
        tsquot = '"""%s"""'
        tdquot = "'''%s'''"
        if not value:
            return '""'
        if (not self.list_values and '\n' not in value) or not (multiline and
                ((("'" in value) and ('"' in value)) or ('\n' in value))):
            if not self.list_values:
                # we don't quote if ``list_values=False``
                quot = noquot
            # for normal values either single or double quotes will do
            elif '\n' in value:
                # will only happen if multiline is off - e.g. '\n' in key
                raise ConfigObjError, ('Value "%s" cannot be safely quoted.' %
                    value)
            elif ((value[0] not in wspace_plus) and
                    (value[-1] not in wspace_plus) and
                    (',' not in value)):
                quot = noquot
            else:
                if ("'" in value) and ('"' in value):
                    raise ConfigObjError, (
                        'Value "%s" cannot be safely quoted.' % value)
                elif '"' in value:
                    quot = squot
                else:
                    quot = dquot
        else:
            # if value has '\n' or "'" *and* '"', it will need triple quotes
            if (value.find('"""') != -1) and (value.find("'''") != -1):
                raise ConfigObjError, (
                    'Value "%s" cannot be safely quoted.' % value)
            if value.find('"""') == -1:
                quot = tdquot
            else:
                quot = tsquot
        return quot % value

    def _handle_value(self, value):
        """
        Given a value string, unquote, remove comment,
        handle lists. (including empty and single member lists)
        
        Testing list values.
        
        >>> testconfig3 = '''
        ... a = ,
        ... b = test,
        ... c = test1, test2   , test3
        ... d = test1, test2, test3,
        ... '''
        >>> d = ConfigObj(testconfig3.split('\\n'), raise_errors=True)
        >>> d['a'] == []
        1
        >>> d['b'] == ['test']
        1
        >>> d['c'] == ['test1', 'test2', 'test3']
        1
        >>> d['d'] == ['test1', 'test2', 'test3']
        1
        
        Testing with list values off.
        
        >>> e = ConfigObj(
        ...     testconfig3.split('\\n'),
        ...     raise_errors=True,
        ...     list_values=False)
        >>> e['a'] == ','
        1
        >>> e['b'] == 'test,'
        1
        >>> e['c'] == 'test1, test2   , test3'
        1
        >>> e['d'] == 'test1, test2, test3,'
        1
        
        Testing creating from a dictionary.
        
        >>> f = {
        ...     'key1': 'val1',
        ...     'key2': 'val2',
        ...     'section 1': {
        ...         'key1': 'val1',
        ...         'key2': 'val2',
        ...         'section 1b': {
        ...             'key1': 'val1',
        ...             'key2': 'val2',
        ...         },
        ...     },
        ...     'section 2': {
        ...         'key1': 'val1',
        ...         'key2': 'val2',
        ...         'section 2b': {
        ...             'key1': 'val1',
        ...             'key2': 'val2',
        ...         },
        ...     },
        ...      'key3': 'val3',
        ... }
        >>> g = ConfigObj(f)
        >>> f == g
        1
        
        Testing we correctly detect badly built list values (4 of them).
        
        >>> testconfig4 = '''
        ... config = 3,4,,
        ... test = 3,,4
        ... fish = ,,
        ... dummy = ,,hello, goodbye
        ... '''
        >>> try:
        ...     ConfigObj(testconfig4.split('\\n'))
        ... except ConfigObjError, e:
        ...     len(e.errors)
        4
        
        Testing we correctly detect badly quoted values (4 of them).
        
        >>> testconfig5 = '''
        ... config = "hello   # comment
        ... test = 'goodbye
        ... fish = 'goodbye   # comment
        ... dummy = "hello again
        ... '''
        >>> try:
        ...     ConfigObj(testconfig5.split('\\n'))
        ... except ConfigObjError, e:
        ...     len(e.errors)
        4
        """
        # do we look for lists in values ?
        if not self.list_values:
            mat = self._nolistvalue.match(value)
            if mat is None:
                raise SyntaxError
            (value, comment) = mat.groups()
            # NOTE: we don't unquote here
            return (value, comment)
        mat = self._valueexp.match(value)
        if mat is None:
            # the value is badly constructed, probably badly quoted,
            # or an invalid list
            raise SyntaxError
        (list_values, single, empty_list, comment) = mat.groups()
        if (list_values == '') and (single is None):
            # change this if you want to accept empty values
            raise SyntaxError
        # NOTE: note there is no error handling from here if the regex
        # is wrong: then incorrect values will slip through
        if empty_list is not None:
            # the single comma - meaning an empty list
            return ([], comment)
        if single is not None:
            single = self._unquote(single)
        if list_values == '':
            # not a list value
            return (single, comment)
        the_list = self._listvalueexp.findall(list_values)
        the_list = [self._unquote(val) for val in the_list]
        if single is not None:
            the_list += [single]
        return (the_list, comment)

    def _multiline(self, value, infile, cur_index, maxline):
        """
        Extract the value, where we are in a multiline situation
        
        Testing multiline values.
        
        >>> i == {
        ...     'name4': ' another single line value ',
        ...     'multi section': {
        ...         'name4': '\\n        Well, this is a\\n        multiline '
        ...             'value\\n        ',
        ...         'name2': '\\n        Well, this is a\\n        multiline '
        ...             'value\\n        ',
        ...         'name3': '\\n        Well, this is a\\n        multiline '
        ...             'value\\n        ',
        ...         'name1': '\\n        Well, this is a\\n        multiline '
        ...             'value\\n        ',
        ...     },
        ...     'name2': ' another single line value ',
        ...     'name3': ' a single line value ',
        ...     'name1': ' a single line value ',
        ... }
        1
        """
        quot = value[:3]
        newvalue = value[3:]
        single_line = self._triple_quote[quot][0]
        multi_line = self._triple_quote[quot][1]
        mat = single_line.match(value)
        if mat is not None:
            retval = list(mat.groups())
            retval.append(cur_index)
            return retval
        elif newvalue.find(quot) != -1:
            # somehow the triple quote is missing
            raise SyntaxError
        #
        while cur_index < maxline:
            cur_index += 1
            newvalue += '\n'
            line = infile[cur_index]
            if line.find(quot) == -1:
                newvalue += line
            else:
                # end of multiline, process it
                break
        else:
            # we've got to the end of the config, oops...
            raise SyntaxError
        mat = multi_line.match(line)
        if mat is None:
            # a badly formed line
            raise SyntaxError
        (value, comment) = mat.groups()
        return (newvalue + value, comment, cur_index)

    def _handle_configspec(self, configspec):
        """Parse the configspec."""
        try:
            configspec = ConfigObj(
                configspec,
                raise_errors=True,
                file_error=True,
                list_values=False)
        except ConfigObjError, e:
            # FIXME: Should these errors have a reference
            # to the already parsed ConfigObj ?
            raise ConfigspecError('Parsing configspec failed: %s' % e)
        except IOError, e:
            raise IOError('Reading configspec failed: %s' % e)
        self._set_configspec_value(configspec, self)

    def _set_configspec_value(self, configspec, section):
        """Used to recursively set configspec values."""
        if '__many__' in configspec.sections:
            section.configspec['__many__'] = configspec['__many__']
            if len(configspec.sections) > 1:
                # FIXME: can we supply any useful information here ?
                raise RepeatSectionError
        for entry in configspec.scalars:
            section.configspec[entry] = configspec[entry]
        for entry in configspec.sections:
            if entry == '__many__':
                continue
            if not section.has_key(entry):
                section[entry] = {}
            self._set_configspec_value(configspec[entry], section[entry])

    def _handle_repeat(self, section, configspec):
        """Dynamically assign configspec for repeated section."""
        try:
            section_keys = configspec.sections
            scalar_keys = configspec.scalars
        except AttributeError:
            section_keys = [entry for entry in configspec 
                                if isinstance(configspec[entry], dict)]
            scalar_keys = [entry for entry in configspec 
                                if not isinstance(configspec[entry], dict)]
        if '__many__' in section_keys and len(section_keys) > 1:
            # FIXME: can we supply any useful information here ?
            raise RepeatSectionError
        scalars = {}
        sections = {}
        for entry in scalar_keys:
            val = configspec[entry]
            scalars[entry] = val
        for entry in section_keys:
            val = configspec[entry]
            if entry == '__many__':
                scalars[entry] = val
                continue
            sections[entry] = val
        #
        section.configspec = scalars
        for entry in sections:
            if not section.has_key(entry):
                section[entry] = {}
            self._handle_repeat(section[entry], sections[entry])

    def _write_line(self, indent_string, entry, this_entry, comment):
        """Write an individual line, for the write method"""
        return '%s%s = %s%s' % (
            indent_string,
            self._quote(entry, multiline=False),
            self._quote(this_entry),
            comment)

    def _write_marker(self, indent_string, depth, entry, comment):
        """Write a section marker line"""
        return '%s%s%s%s%s' % (
            indent_string,
            '[' * depth,
            self._quote(entry, multiline=False),
            ']' * depth,
            comment)

    def _handle_comment(self, comment):
        """
        Deal with a comment.
        
        >>> filename = a.filename
        >>> a.filename = None
        >>> values = a.write()
        >>> index = 0
        >>> while index < 23:
        ...     index += 1
        ...     line = values[index-1]
        ...     assert line.endswith('# comment ' + str(index))
        >>> a.filename = filename
        
        >>> start_comment = ['# Initial Comment', '', '#']
        >>> end_comment = ['', '#', '# Final Comment']
        >>> newconfig = start_comment + testconfig1.split('\\n') + end_comment
        >>> nc = ConfigObj(newconfig)
        >>> nc.initial_comment
        ['# Initial Comment', '', '#']
        >>> nc.final_comment
        ['', '#', '# Final Comment']
        >>> nc.initial_comment == start_comment
        1
        >>> nc.final_comment == end_comment
        1
        """
        if not comment:
            return ''
        if self.indent_type == '\t':
            start = '\t'
        else:
            start = ' ' * NUM_INDENT_SPACES
        if not comment.startswith('#'):
            start += '# '
        return (start + comment)

    def _compute_indent_string(self, depth):
        """
        Compute the indent string, according to current indent_type and depth
        """
        if self.indent_type == '':
            # no indentation at all
            return ''
        if self.indent_type == '\t':
            return '\t' * depth
        if self.indent_type == ' ':
            return ' ' * NUM_INDENT_SPACES * depth
        raise SyntaxError

    # Public methods

    def write(self, section=None):
        """
        Write the current ConfigObj as a file
        
        tekNico: FIXME: use StringIO instead of real files
        
        >>> filename = a.filename
        >>> a.filename = 'test.ini'
        >>> a.write()
        >>> a.filename = filename
        >>> a == ConfigObj('test.ini', raise_errors=True)
        1
        >>> os.remove('test.ini')
        >>> b.filename = 'test.ini'
        >>> b.write()
        >>> b == ConfigObj('test.ini', raise_errors=True)
        1
        >>> os.remove('test.ini')
        >>> i.filename = 'test.ini'
        >>> i.write()
        >>> i == ConfigObj('test.ini', raise_errors=True)
        1
        >>> os.remove('test.ini')
        >>> a = ConfigObj()
        >>> a['DEFAULT'] = {'a' : 'fish'}
        >>> a['a'] = '%(a)s'
        >>> a.write()
        ['a = %(a)s', '[DEFAULT]', 'a = fish']
        """
        int_val = 'test'
        if self.indent_type is None:
            # this can be true if initialised from a dictionary
            self.indent_type = DEFAULT_INDENT_TYPE
        #
        out = []
        return_list = True
        if section is None:
            int_val = self.interpolation
            self.interpolation = False
            section = self
            return_list = False
            for line in self.initial_comment:
                stripped_line = line.strip()
                if stripped_line and not stripped_line.startswith('#'):
                    line = '# ' + line
                out.append(line)
        #
        indent_string = self._compute_indent_string(section.depth)
        for entry in (section.scalars + section.sections):
            if entry in section.defaults:
                # don't write out default values
                continue
            for comment_line in section.comments[entry]:
                comment_line = comment_line.lstrip()
                if comment_line and not comment_line.startswith('#'):
                    comment_line = '#' + comment_line
                out.append(indent_string + comment_line)
            this_entry = section[entry]
            comment = self._handle_comment(section.inline_comments[entry])
            #
            if isinstance(this_entry, dict):
                # a section
                out.append(self._write_marker(
                    indent_string,
                    this_entry.depth,
                    entry,
                    comment))
                out.extend(self.write(this_entry))
            else:
                out.append(self._write_line(
                    indent_string,
                    entry,
                    this_entry,
                    comment))
        #
        if not return_list:
            for line in self.final_comment:
                stripped_line = line.strip()
                if stripped_line and not stripped_line.startswith('#'):
                    line = '# ' + line
                out.append(line)
        #
        if int_val != 'test':
            self.interpolation = int_val
        #
        if (return_list) or (self.filename is None):
            return out
        #
        if isinstance(self.filename, StringTypes):
            h = open(self.filename, 'w')
            h.write(self.BOM or '')
            h.write('\n'.join(out))
            h.close()
        else:
            self.filename.seek(0)
            self.filename.write(self.BOM or '')
            self.filename.write('\n'.join(out))
            # if we have a stored file object (or StringIO)
            # we *don't* close it

    def validate(self, validator, section=None, preserve_errors=False):
        """
        Test the ConfigObj against a configspec.
        
        It uses the ``validator`` object from *validate.py*.
        
        To run ``validate`` on the current ConfigObj, call: ::
        
            test = config.validate(validator)
        
        (Normally having previously passed in the configspec when the ConfigObj
        was created - you can dynamically assign a dictionary of checks to the
        ``configspec`` attribute of a section though).
        
        It returns ``True`` if everything passes, or a dictionary of
        pass/fails (True/False). If every member of a subsection passes, it
        will just have the value ``True``. (It also returns ``False`` if all
        members fail).
        
        In addition, it converts the values from strings to their native
        types if their checks pass (and ``stringify`` is set).
        
        If ``preserve_errors`` is ``True`` (``False`` is default) then instead
        of a marking a fail with a ``False``, it will preserve the actual
        exception object. This can contain info about the reason for failure.
        For example the ``VdtValueTooSmallError`` indeicates that the value
        supplied was too small. If a value (or section) is missing it will
        still be marked as ``False``.
        
        You can then use the ``flatten_errors`` function to turn your nested
        results dictionary into a flattened list of failures - useful for
        displaying meaningful error messages.
        
        >>> try:
        ...     from validate import Validator
        ... except ImportError:
        ...     print >> sys.stderr, 'Cannot import the Validator object, skipping the related tests'
        ... else:
        ...     config = '''
        ...     test1=40
        ...     test2=hello
        ...     test3=3
        ...     test4=5.0
        ...     [section]
        ...         test1=40
        ...         test2=hello
        ...         test3=3
        ...         test4=5.0
        ...         [[sub section]]
        ...             test1=40
        ...             test2=hello
        ...             test3=3
        ...             test4=5.0
        ... '''.split('\\n')
        ...     configspec = '''
        ...     test1= integer(30,50)
        ...     test2= string
        ...     test3=integer
        ...     test4=float(6.0)
        ...     [section ]
        ...         test1=integer(30,50)
        ...         test2=string
        ...         test3=intege...
 
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