| """OpenEmbedded variable typing support |
| |
| Types are defined in the metadata by name, using the 'type' flag on a |
| variable. Other flags may be utilized in the construction of the types. See |
| the arguments of the type's factory for details. |
| """ |
| |
| import inspect |
| import types |
| |
| available_types = {} |
| |
| class MissingFlag(TypeError): |
| """A particular flag is required to construct the type, but has not been |
| provided.""" |
| def __init__(self, flag, type): |
| self.flag = flag |
| self.type = type |
| TypeError.__init__(self) |
| |
| def __str__(self): |
| return "Type '%s' requires flag '%s'" % (self.type, self.flag) |
| |
| def factory(var_type): |
| """Return the factory for a specified type.""" |
| if var_type is None: |
| raise TypeError("No type specified. Valid types: %s" % |
| ', '.join(available_types)) |
| try: |
| return available_types[var_type] |
| except KeyError: |
| raise TypeError("Invalid type '%s':\n Valid types: %s" % |
| (var_type, ', '.join(available_types))) |
| |
| def create(value, var_type, **flags): |
| """Create an object of the specified type, given the specified flags and |
| string value.""" |
| obj = factory(var_type) |
| objflags = {} |
| for flag in obj.flags: |
| if flag not in flags: |
| if flag not in obj.optflags: |
| raise MissingFlag(flag, var_type) |
| else: |
| objflags[flag] = flags[flag] |
| |
| return obj(value, **objflags) |
| |
| def get_callable_args(obj): |
| """Grab all but the first argument of the specified callable, returning |
| the list, as well as a list of which of the arguments have default |
| values.""" |
| if type(obj) is type: |
| obj = obj.__init__ |
| |
| args, varargs, keywords, defaults = inspect.getargspec(obj) |
| flaglist = [] |
| if args: |
| if len(args) > 1 and args[0] == 'self': |
| args = args[1:] |
| flaglist.extend(args) |
| |
| optional = set() |
| if defaults: |
| optional |= set(flaglist[-len(defaults):]) |
| return flaglist, optional |
| |
| def factory_setup(name, obj): |
| """Prepare a factory for use.""" |
| args, optional = get_callable_args(obj) |
| extra_args = args[1:] |
| if extra_args: |
| obj.flags, optional = extra_args, optional |
| obj.optflags = set(optional) |
| else: |
| obj.flags = obj.optflags = () |
| |
| if not hasattr(obj, 'name'): |
| obj.name = name |
| |
| def register(name, factory): |
| """Register a type, given its name and a factory callable. |
| |
| Determines the required and optional flags from the factory's |
| arguments.""" |
| factory_setup(name, factory) |
| available_types[factory.name] = factory |
| |
| |
| # Register all our included types |
| for name in dir(types): |
| if name.startswith('_'): |
| continue |
| |
| obj = getattr(types, name) |
| if not callable(obj): |
| continue |
| |
| register(name, obj) |