1 files changed, 169 insertions, 0 deletions
diff --git a/ipapython/install/util.py b/ipapython/install/util.py
new file mode 100644
index 000000000..58da7bb77
--- /dev/null
+++ b/ipapython/install/util.py
@@ -0,0 +1,169 @@
+#
+# Copyright (C) 2015  FreeIPA Contributors see COPYING for license
+#
+
+"""
+Utilities.
+"""
+
+import sys
+
+
+def raise_exc_info(exc_info):
+    """
+    Raise exception from exception info tuple as returned by `sys.exc_info()`.
+    """
+
+    raise exc_info[0], exc_info[1], exc_info[2]
+
+
+class from_(object):
+    """
+    Wrapper for delegating to a subgenerator.
+
+    See `run_generator_with_yield_from`.
+    """
+    __slots__ = ('obj',)
+
+    def __init__(self, obj):
+        self.obj = obj
+
+
+def run_generator_with_yield_from(gen):
+    """
+    Iterate over a generator object with subgenerator delegation.
+
+    This implements Python 3's ``yield from`` expressions, using Python 2
+    syntax:
+
+    >>> def subgen():
+    ...     yield 'B'
+    ...     yield 'C'
+    ...
+    >>> def gen():
+    ...     yield 'A'
+    ...     yield from_(subgen())
+    ...     yield 'D'
+    ...
+    >>> list(run_generator_with_yield_from(gen()))
+    ['A', 'B', 'C', 'D']
+
+    Returning value from a subgenerator is not supported.
+    """
+
+    exc_info = None
+    value = None
+
+    stack = [gen]
+    while stack:
+        prev_exc_info, exc_info = exc_info, None
+        prev_value, value = value, None
+
+        gen = stack[-1]
+        try:
+            if prev_exc_info is None:
+                value = gen.send(prev_value)
+            else:
+                value = gen.throw(*prev_exc_info)
+        except StopIteration:
+            stack.pop()
+            continue
+        except BaseException:
+            exc_info = sys.exc_info()
+            stack.pop()
+            continue
+        else:
+            if isinstance(value, from_):
+                stack.append(value.obj)
+                value = None
+                continue
+
+        try:
+            value = (yield value)
+        except BaseException:
+            exc_info = sys.exc_info()
+
+    if exc_info is not None:
+        raise_exc_info(exc_info)
+
+
+class InnerClassMeta(type):
+    def __new__(cls, name, bases, class_dict):
+        class_dict.pop('__outer_class__', None)
+        class_dict.pop('__outer_name__', None)
+
+        return super(InnerClassMeta, cls).__new__(cls, name, bases, class_dict)
+
+    def __get__(self, obj, obj_type):
+        outer_class, outer_name = self.__bind(obj_type)
+        if obj is None:
+            return self
+        assert isinstance(obj, outer_class)
+
+        try:
+            return obj.__dict__[outer_name]
+        except KeyError:
+            inner = self(obj)
+            try:
+                getter = inner.__get__
+            except AttributeError:
+                return inner
+            else:
+                return getter(obj, obj_type)
+
+    def __set__(self, obj, value):
+        outer_class, outer_name = self.__bind(obj.__class__)
+        assert isinstance(obj, outer_class)
+
+        inner = self(obj)
+        try:
+            setter = inner.__set__
+        except AttributeError:
+            try:
+                inner.__delete__
+            except AttributeError:
+                obj.__dict__[outer_name] = value
+            else:
+                raise AttributeError('__set__')
+        else:
+            setter(obj, value)
+
+    def __delete__(self, obj):
+        outer_class, outer_name = self.__bind(obj.__class__)
+        assert isinstance(obj, outer_class)
+
+        inner = self(obj)
+        try:
+            deleter = inner.__delete__
+        except AttributeError:
+            try:
+                inner.__set__
+            except AttributeError:
+                try:
+                    del obj.__dict__[outer_name]
+                except KeyError:
+                    raise AttributeError(outer_name)
+            else:
+                raise AttributeError('__delete__')
+        else:
+            deleter(obj)
+
+    def __bind(self, obj_type):
+        try:
+            cls = self.__dict__['__outer_class__']
+            name = self.__dict__['__outer_name__']
+        except KeyError:
+            cls, name, value = None, None, None
+            for cls in obj_type.__mro__:
+                for name, value in cls.__dict__.iteritems():
+                    if value is self:
+                        break
+                if value is self:
+                    break
+            assert value is self
+
+            self.__outer_class__ = cls
+            self.__outer_name__ = name
+            self.__name__ = '.'.join((cls.__name__, name))
+
+        return cls, name