AppPkg/Applications/Python/Python-2.7.10: Initial Checkin part 4/5.

The Lib directory from the cPython 2.7.10 distribution.
These files are unchanged and set the baseline for subsequent commits.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Daryl McDaniel <edk2-lists@mc2research.org>


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18740 6f19259b-4bc3-4df7-8a09-765794883524

AppPkg/Applications/Python/Python-2.7.10/Lib/abc.py

@@ -0,0 +1,185 @@
+# Copyright 2007 Google, Inc. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Abstract Base Classes (ABCs) according to PEP 3119."""
+
+import types
+
+from _weakrefset import WeakSet
+
+# Instance of old-style class
+class _C: pass
+_InstanceType = type(_C())
+
+
+def abstractmethod(funcobj):
+    """A decorator indicating abstract methods.
+
+    Requires that the metaclass is ABCMeta or derived from it.  A
+    class that has a metaclass derived from ABCMeta cannot be
+    instantiated unless all of its abstract methods are overridden.
+    The abstract methods can be called using any of the normal
+    'super' call mechanisms.
+
+    Usage:
+
+        class C:
+            __metaclass__ = ABCMeta
+            @abstractmethod
+            def my_abstract_method(self, ...):
+                ...
+    """
+    funcobj.__isabstractmethod__ = True
+    return funcobj
+
+
+class abstractproperty(property):
+    """A decorator indicating abstract properties.
+
+    Requires that the metaclass is ABCMeta or derived from it.  A
+    class that has a metaclass derived from ABCMeta cannot be
+    instantiated unless all of its abstract properties are overridden.
+    The abstract properties can be called using any of the normal
+    'super' call mechanisms.
+
+    Usage:
+
+        class C:
+            __metaclass__ = ABCMeta
+            @abstractproperty
+            def my_abstract_property(self):
+                ...
+
+    This defines a read-only property; you can also define a read-write
+    abstract property using the 'long' form of property declaration:
+
+        class C:
+            __metaclass__ = ABCMeta
+            def getx(self): ...
+            def setx(self, value): ...
+            x = abstractproperty(getx, setx)
+    """
+    __isabstractmethod__ = True
+
+
+class ABCMeta(type):
+
+    """Metaclass for defining Abstract Base Classes (ABCs).
+
+    Use this metaclass to create an ABC.  An ABC can be subclassed
+    directly, and then acts as a mix-in class.  You can also register
+    unrelated concrete classes (even built-in classes) and unrelated
+    ABCs as 'virtual subclasses' -- these and their descendants will
+    be considered subclasses of the registering ABC by the built-in
+    issubclass() function, but the registering ABC won't show up in
+    their MRO (Method Resolution Order) nor will method
+    implementations defined by the registering ABC be callable (not
+    even via super()).
+
+    """
+
+    # A global counter that is incremented each time a class is
+    # registered as a virtual subclass of anything.  It forces the
+    # negative cache to be cleared before its next use.
+    _abc_invalidation_counter = 0
+
+    def __new__(mcls, name, bases, namespace):
+        cls = super(ABCMeta, mcls).__new__(mcls, name, bases, namespace)
+        # Compute set of abstract method names
+        abstracts = set(name
+                     for name, value in namespace.items()
+                     if getattr(value, "__isabstractmethod__", False))
+        for base in bases:
+            for name in getattr(base, "__abstractmethods__", set()):
+                value = getattr(cls, name, None)
+                if getattr(value, "__isabstractmethod__", False):
+                    abstracts.add(name)
+        cls.__abstractmethods__ = frozenset(abstracts)
+        # Set up inheritance registry
+        cls._abc_registry = WeakSet()
+        cls._abc_cache = WeakSet()
+        cls._abc_negative_cache = WeakSet()
+        cls._abc_negative_cache_version = ABCMeta._abc_invalidation_counter
+        return cls
+
+    def register(cls, subclass):
+        """Register a virtual subclass of an ABC."""
+        if not isinstance(subclass, (type, types.ClassType)):
+            raise TypeError("Can only register classes")
+        if issubclass(subclass, cls):
+            return  # Already a subclass
+        # Subtle: test for cycles *after* testing for "already a subclass";
+        # this means we allow X.register(X) and interpret it as a no-op.
+        if issubclass(cls, subclass):
+            # This would create a cycle, which is bad for the algorithm below
+            raise RuntimeError("Refusing to create an inheritance cycle")
+        cls._abc_registry.add(subclass)
+        ABCMeta._abc_invalidation_counter += 1  # Invalidate negative cache
+
+    def _dump_registry(cls, file=None):
+        """Debug helper to print the ABC registry."""
+        print >> file, "Class: %s.%s" % (cls.__module__, cls.__name__)
+        print >> file, "Inv.counter: %s" % ABCMeta._abc_invalidation_counter
+        for name in sorted(cls.__dict__.keys()):
+            if name.startswith("_abc_"):
+                value = getattr(cls, name)
+                print >> file, "%s: %r" % (name, value)
+
+    def __instancecheck__(cls, instance):
+        """Override for isinstance(instance, cls)."""
+        # Inline the cache checking when it's simple.
+        subclass = getattr(instance, '__class__', None)
+        if subclass is not None and subclass in cls._abc_cache:
+            return True
+        subtype = type(instance)
+        # Old-style instances
+        if subtype is _InstanceType:
+            subtype = subclass
+        if subtype is subclass or subclass is None:
+            if (cls._abc_negative_cache_version ==
+                ABCMeta._abc_invalidation_counter and
+                subtype in cls._abc_negative_cache):
+                return False
+            # Fall back to the subclass check.
+            return cls.__subclasscheck__(subtype)
+        return (cls.__subclasscheck__(subclass) or
+                cls.__subclasscheck__(subtype))
+
+    def __subclasscheck__(cls, subclass):
+        """Override for issubclass(subclass, cls)."""
+        # Check cache
+        if subclass in cls._abc_cache:
+            return True
+        # Check negative cache; may have to invalidate
+        if cls._abc_negative_cache_version < ABCMeta._abc_invalidation_counter:
+            # Invalidate the negative cache
+            cls._abc_negative_cache = WeakSet()
+            cls._abc_negative_cache_version = ABCMeta._abc_invalidation_counter
+        elif subclass in cls._abc_negative_cache:
+            return False
+        # Check the subclass hook
+        ok = cls.__subclasshook__(subclass)
+        if ok is not NotImplemented:
+            assert isinstance(ok, bool)
+            if ok:
+                cls._abc_cache.add(subclass)
+            else:
+                cls._abc_negative_cache.add(subclass)
+            return ok
+        # Check if it's a direct subclass
+        if cls in getattr(subclass, '__mro__', ()):
+            cls._abc_cache.add(subclass)
+            return True
+        # Check if it's a subclass of a registered class (recursive)
+        for rcls in cls._abc_registry:
+            if issubclass(subclass, rcls):
+                cls._abc_cache.add(subclass)
+                return True
+        # Check if it's a subclass of a subclass (recursive)
+        for scls in cls.__subclasses__():
+            if issubclass(subclass, scls):
+                cls._abc_cache.add(subclass)
+                return True
+        # No dice; update negative cache
+        cls._abc_negative_cache.add(subclass)
+        return False