mirror of https://github.com/evilhero/mylar
352 lines
11 KiB
Python
Executable File
352 lines
11 KiB
Python
Executable File
"""Generic configuration system using unrepr.
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Configuration data may be supplied as a Python dictionary, as a filename,
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or as an open file object. When you supply a filename or file, Python's
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builtin ConfigParser is used (with some extensions).
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Namespaces
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----------
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Configuration keys are separated into namespaces by the first "." in the key.
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The only key that cannot exist in a namespace is the "environment" entry.
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This special entry 'imports' other config entries from a template stored in
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the Config.environments dict.
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You can define your own namespaces to be called when new config is merged
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by adding a named handler to Config.namespaces. The name can be any string,
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and the handler must be either a callable or a context manager.
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"""
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try:
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# Python 3.0+
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from configparser import ConfigParser
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except ImportError:
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from ConfigParser import ConfigParser
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try:
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set
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except NameError:
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from sets import Set as set
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import sys
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def as_dict(config):
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"""Return a dict from 'config' whether it is a dict, file, or filename."""
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if isinstance(config, basestring):
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config = Parser().dict_from_file(config)
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elif hasattr(config, 'read'):
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config = Parser().dict_from_file(config)
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return config
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class NamespaceSet(dict):
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"""A dict of config namespace names and handlers.
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Each config entry should begin with a namespace name; the corresponding
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namespace handler will be called once for each config entry in that
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namespace, and will be passed two arguments: the config key (with the
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namespace removed) and the config value.
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Namespace handlers may be any Python callable; they may also be
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Python 2.5-style 'context managers', in which case their __enter__
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method should return a callable to be used as the handler.
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See cherrypy.tools (the Toolbox class) for an example.
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"""
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def __call__(self, config):
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"""Iterate through config and pass it to each namespace handler.
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config
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A flat dict, where keys use dots to separate
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namespaces, and values are arbitrary.
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The first name in each config key is used to look up the corresponding
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namespace handler. For example, a config entry of {'tools.gzip.on': v}
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will call the 'tools' namespace handler with the args: ('gzip.on', v)
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"""
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# Separate the given config into namespaces
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ns_confs = {}
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for k in config:
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if "." in k:
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ns, name = k.split(".", 1)
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bucket = ns_confs.setdefault(ns, {})
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bucket[name] = config[k]
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# I chose __enter__ and __exit__ so someday this could be
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# rewritten using Python 2.5's 'with' statement:
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# for ns, handler in self.iteritems():
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# with handler as callable:
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# for k, v in ns_confs.get(ns, {}).iteritems():
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# callable(k, v)
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for ns, handler in self.items():
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exit = getattr(handler, "__exit__", None)
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if exit:
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callable = handler.__enter__()
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no_exc = True
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try:
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try:
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for k, v in ns_confs.get(ns, {}).items():
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callable(k, v)
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except:
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# The exceptional case is handled here
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no_exc = False
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if exit is None:
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raise
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if not exit(*sys.exc_info()):
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raise
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# The exception is swallowed if exit() returns true
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finally:
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# The normal and non-local-goto cases are handled here
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if no_exc and exit:
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exit(None, None, None)
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else:
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for k, v in ns_confs.get(ns, {}).items():
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handler(k, v)
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def __repr__(self):
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return "%s.%s(%s)" % (self.__module__, self.__class__.__name__,
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dict.__repr__(self))
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def __copy__(self):
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newobj = self.__class__()
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newobj.update(self)
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return newobj
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copy = __copy__
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class Config(dict):
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"""A dict-like set of configuration data, with defaults and namespaces.
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May take a file, filename, or dict.
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"""
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defaults = {}
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environments = {}
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namespaces = NamespaceSet()
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def __init__(self, file=None, **kwargs):
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self.reset()
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if file is not None:
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self.update(file)
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if kwargs:
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self.update(kwargs)
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def reset(self):
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"""Reset self to default values."""
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self.clear()
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dict.update(self, self.defaults)
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def update(self, config):
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"""Update self from a dict, file or filename."""
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if isinstance(config, basestring):
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# Filename
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config = Parser().dict_from_file(config)
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elif hasattr(config, 'read'):
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# Open file object
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config = Parser().dict_from_file(config)
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else:
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config = config.copy()
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self._apply(config)
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def _apply(self, config):
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"""Update self from a dict."""
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which_env = config.get('environment')
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if which_env:
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env = self.environments[which_env]
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for k in env:
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if k not in config:
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config[k] = env[k]
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dict.update(self, config)
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self.namespaces(config)
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def __setitem__(self, k, v):
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dict.__setitem__(self, k, v)
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self.namespaces({k: v})
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class Parser(ConfigParser):
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"""Sub-class of ConfigParser that keeps the case of options and that
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raises an exception if the file cannot be read.
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"""
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def optionxform(self, optionstr):
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return optionstr
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def read(self, filenames):
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if isinstance(filenames, basestring):
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filenames = [filenames]
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for filename in filenames:
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# try:
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# fp = open(filename)
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# except IOError:
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# continue
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fp = open(filename)
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try:
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self._read(fp, filename)
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finally:
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fp.close()
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def as_dict(self, raw=False, vars=None):
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"""Convert an INI file to a dictionary"""
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# Load INI file into a dict
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result = {}
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for section in self.sections():
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if section not in result:
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result[section] = {}
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for option in self.options(section):
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value = self.get(section, option, raw, vars)
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try:
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value = unrepr(value)
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except Exception, x:
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msg = ("Config error in section: %r, option: %r, "
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"value: %r. Config values must be valid Python." %
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(section, option, value))
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raise ValueError(msg, x.__class__.__name__, x.args)
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result[section][option] = value
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return result
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def dict_from_file(self, file):
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if hasattr(file, 'read'):
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self.readfp(file)
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else:
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self.read(file)
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return self.as_dict()
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# public domain "unrepr" implementation, found on the web and then improved.
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class _Builder:
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def build(self, o):
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m = getattr(self, 'build_' + o.__class__.__name__, None)
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if m is None:
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raise TypeError("unrepr does not recognize %s" %
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repr(o.__class__.__name__))
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return m(o)
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def build_Subscript(self, o):
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expr, flags, subs = o.getChildren()
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expr = self.build(expr)
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subs = self.build(subs)
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return expr[subs]
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def build_CallFunc(self, o):
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children = map(self.build, o.getChildren())
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callee = children.pop(0)
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kwargs = children.pop() or {}
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starargs = children.pop() or ()
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args = tuple(children) + tuple(starargs)
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return callee(*args, **kwargs)
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def build_List(self, o):
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return map(self.build, o.getChildren())
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def build_Const(self, o):
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return o.value
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def build_Dict(self, o):
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d = {}
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i = iter(map(self.build, o.getChildren()))
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for el in i:
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d[el] = i.next()
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return d
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def build_Tuple(self, o):
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return tuple(self.build_List(o))
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def build_Name(self, o):
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name = o.name
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if name == 'None':
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return None
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if name == 'True':
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return True
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if name == 'False':
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return False
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# See if the Name is a package or module. If it is, import it.
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try:
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return modules(name)
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except ImportError:
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pass
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# See if the Name is in builtins.
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try:
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import __builtin__
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return getattr(__builtin__, name)
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except AttributeError:
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pass
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raise TypeError("unrepr could not resolve the name %s" % repr(name))
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def build_Add(self, o):
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left, right = map(self.build, o.getChildren())
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return left + right
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def build_Getattr(self, o):
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parent = self.build(o.expr)
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return getattr(parent, o.attrname)
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def build_NoneType(self, o):
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return None
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def build_UnarySub(self, o):
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return -self.build(o.getChildren()[0])
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def build_UnaryAdd(self, o):
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return self.build(o.getChildren()[0])
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def _astnode(s):
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"""Return a Python ast Node compiled from a string."""
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try:
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import compiler
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except ImportError:
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# Fallback to eval when compiler package is not available,
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# e.g. IronPython 1.0.
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return eval(s)
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p = compiler.parse("__tempvalue__ = " + s)
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return p.getChildren()[1].getChildren()[0].getChildren()[1]
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def unrepr(s):
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"""Return a Python object compiled from a string."""
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if not s:
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return s
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obj = _astnode(s)
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return _Builder().build(obj)
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def modules(modulePath):
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"""Load a module and retrieve a reference to that module."""
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try:
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mod = sys.modules[modulePath]
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if mod is None:
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raise KeyError()
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except KeyError:
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# The last [''] is important.
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mod = __import__(modulePath, globals(), locals(), [''])
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return mod
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def attributes(full_attribute_name):
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"""Load a module and retrieve an attribute of that module."""
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# Parse out the path, module, and attribute
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last_dot = full_attribute_name.rfind(".")
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attr_name = full_attribute_name[last_dot + 1:]
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mod_path = full_attribute_name[:last_dot]
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mod = modules(mod_path)
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# Let an AttributeError propagate outward.
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try:
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attr = getattr(mod, attr_name)
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except AttributeError:
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raise AttributeError("'%s' object has no attribute '%s'"
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% (mod_path, attr_name))
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# Return a reference to the attribute.
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return attr
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