copy: Add pristine from Python-3.3.3 tarball.

Author: pfalcon

copy/copy.py

@@ -0,0 +1,325 @@
+"""Generic (shallow and deep) copying operations.
+
+Interface summary:
+
+        import copy
+
+        x = copy.copy(y)        # make a shallow copy of y
+        x = copy.deepcopy(y)    # make a deep copy of y
+
+For module specific errors, copy.Error is raised.
+
+The difference between shallow and deep copying is only relevant for
+compound objects (objects that contain other objects, like lists or
+class instances).
+
+- A shallow copy constructs a new compound object and then (to the
+  extent possible) inserts *the same objects* into it that the
+  original contains.
+
+- A deep copy constructs a new compound object and then, recursively,
+  inserts *copies* into it of the objects found in the original.
+
+Two problems often exist with deep copy operations that don't exist
+with shallow copy operations:
+
+ a) recursive objects (compound objects that, directly or indirectly,
+    contain a reference to themselves) may cause a recursive loop
+
+ b) because deep copy copies *everything* it may copy too much, e.g.
+    administrative data structures that should be shared even between
+    copies
+
+Python's deep copy operation avoids these problems by:
+
+ a) keeping a table of objects already copied during the current
+    copying pass
+
+ b) letting user-defined classes override the copying operation or the
+    set of components copied
+
+This version does not copy types like module, class, function, method,
+nor stack trace, stack frame, nor file, socket, window, nor array, nor
+any similar types.
+
+Classes can use the same interfaces to control copying that they use
+to control pickling: they can define methods called __getinitargs__(),
+__getstate__() and __setstate__().  See the documentation for module
+"pickle" for information on these methods.
+"""
+
+import types
+import weakref
+from copyreg import dispatch_table
+import builtins
+
+class Error(Exception):
+    pass
+error = Error   # backward compatibility
+
+try:
+    from org.python.core import PyStringMap
+except ImportError:
+    PyStringMap = None
+
+__all__ = ["Error", "copy", "deepcopy"]
+
+def copy(x):
+    """Shallow copy operation on arbitrary Python objects.
+
+    See the module's __doc__ string for more info.
+    """
+
+    cls = type(x)
+
+    copier = _copy_dispatch.get(cls)
+    if copier:
+        return copier(x)
+
+    copier = getattr(cls, "__copy__", None)
+    if copier:
+        return copier(x)
+
+    reductor = dispatch_table.get(cls)
+    if reductor:
+        rv = reductor(x)
+    else:
+        reductor = getattr(x, "__reduce_ex__", None)
+        if reductor:
+            rv = reductor(2)
+        else:
+            reductor = getattr(x, "__reduce__", None)
+            if reductor:
+                rv = reductor()
+            else:
+                raise Error("un(shallow)copyable object of type %s" % cls)
+
+    return _reconstruct(x, rv, 0)
+
+
+_copy_dispatch = d = {}
+
+def _copy_immutable(x):
+    return x
+for t in (type(None), int, float, bool, str, tuple,
+          frozenset, type, range,
+          types.BuiltinFunctionType, type(Ellipsis),
+          types.FunctionType, weakref.ref):
+    d[t] = _copy_immutable
+t = getattr(types, "CodeType", None)
+if t is not None:
+    d[t] = _copy_immutable
+for name in ("complex", "unicode"):
+    t = getattr(builtins, name, None)
+    if t is not None:
+        d[t] = _copy_immutable
+
+def _copy_with_constructor(x):
+    return type(x)(x)
+for t in (list, dict, set):
+    d[t] = _copy_with_constructor
+
+def _copy_with_copy_method(x):
+    return x.copy()
+if PyStringMap is not None:
+    d[PyStringMap] = _copy_with_copy_method
+
+del d
+
+def deepcopy(x, memo=None, _nil=[]):
+    """Deep copy operation on arbitrary Python objects.
+
+    See the module's __doc__ string for more info.
+    """
+
+    if memo is None:
+        memo = {}
+
+    d = id(x)
+    y = memo.get(d, _nil)
+    if y is not _nil:
+        return y
+
+    cls = type(x)
+
+    copier = _deepcopy_dispatch.get(cls)
+    if copier:
+        y = copier(x, memo)
+    else:
+        try:
+            issc = issubclass(cls, type)
+        except TypeError: # cls is not a class (old Boost; see SF #502085)
+            issc = 0
+        if issc:
+            y = _deepcopy_atomic(x, memo)
+        else:
+            copier = getattr(x, "__deepcopy__", None)
+            if copier:
+                y = copier(memo)
+            else:
+                reductor = dispatch_table.get(cls)
+                if reductor:
+                    rv = reductor(x)
+                else:
+                    reductor = getattr(x, "__reduce_ex__", None)
+                    if reductor:
+                        rv = reductor(2)
+                    else:
+                        reductor = getattr(x, "__reduce__", None)
+                        if reductor:
+                            rv = reductor()
+                        else:
+                            raise Error(
+                                "un(deep)copyable object of type %s" % cls)
+                y = _reconstruct(x, rv, 1, memo)
+
+    # If is its own copy, don't memoize.
+    if y is not x:
+        memo[d] = y
+        _keep_alive(x, memo) # Make sure x lives at least as long as d
+    return y
+
+_deepcopy_dispatch = d = {}
+
+def _deepcopy_atomic(x, memo):
+    return x
+d[type(None)] = _deepcopy_atomic
+d[type(Ellipsis)] = _deepcopy_atomic
+d[int] = _deepcopy_atomic
+d[float] = _deepcopy_atomic
+d[bool] = _deepcopy_atomic
+try:
+    d[complex] = _deepcopy_atomic
+except NameError:
+    pass
+d[bytes] = _deepcopy_atomic
+d[str] = _deepcopy_atomic
+try:
+    d[types.CodeType] = _deepcopy_atomic
+except AttributeError:
+    pass
+d[type] = _deepcopy_atomic
+d[range] = _deepcopy_atomic
+d[types.BuiltinFunctionType] = _deepcopy_atomic
+d[types.FunctionType] = _deepcopy_atomic
+d[weakref.ref] = _deepcopy_atomic
+
+def _deepcopy_list(x, memo):
+    y = []
+    memo[id(x)] = y
+    for a in x:
+        y.append(deepcopy(a, memo))
+    return y
+d[list] = _deepcopy_list
+
+def _deepcopy_tuple(x, memo):
+    y = []
+    for a in x:
+        y.append(deepcopy(a, memo))
+    # We're not going to put the tuple in the memo, but it's still important we
+    # check for it, in case the tuple contains recursive mutable structures.
+    try:
+        return memo[id(x)]
+    except KeyError:
+        pass
+    for i in range(len(x)):
+        if x[i] is not y[i]:
+            y = tuple(y)
+            break
+    else:
+        y = x
+    return y
+d[tuple] = _deepcopy_tuple
+
+def _deepcopy_dict(x, memo):
+    y = {}
+    memo[id(x)] = y
+    for key, value in x.items():
+        y[deepcopy(key, memo)] = deepcopy(value, memo)
+    return y
+d[dict] = _deepcopy_dict
+if PyStringMap is not None:
+    d[PyStringMap] = _deepcopy_dict
+
+def _deepcopy_method(x, memo): # Copy instance methods
+    return type(x)(x.__func__, deepcopy(x.__self__, memo))
+_deepcopy_dispatch[types.MethodType] = _deepcopy_method
+
+def _keep_alive(x, memo):
+    """Keeps a reference to the object x in the memo.
+
+    Because we remember objects by their id, we have
+    to assure that possibly temporary objects are kept
+    alive by referencing them.
+    We store a reference at the id of the memo, which should
+    normally not be used unless someone tries to deepcopy
+    the memo itself...
+    """
+    try:
+        memo[id(memo)].append(x)
+    except KeyError:
+        # aha, this is the first one :-)
+        memo[id(memo)]=[x]
+
+def _reconstruct(x, info, deep, memo=None):
+    if isinstance(info, str):
+        return x
+    assert isinstance(info, tuple)
+    if memo is None:
+        memo = {}
+    n = len(info)
+    assert n in (2, 3, 4, 5)
+    callable, args = info[:2]
+    if n > 2:
+        state = info[2]
+    else:
+        state = {}
+    if n > 3:
+        listiter = info[3]
+    else:
+        listiter = None
+    if n > 4:
+        dictiter = info[4]
+    else:
+        dictiter = None
+    if deep:
+        args = deepcopy(args, memo)
+    y = callable(*args)
+    memo[id(x)] = y
+
+    if state:
+        if deep:
+            state = deepcopy(state, memo)
+        if hasattr(y, '__setstate__'):
+            y.__setstate__(state)
+        else:
+            if isinstance(state, tuple) and len(state) == 2:
+                state, slotstate = state
+            else:
+                slotstate = None
+            if state is not None:
+                y.__dict__.update(state)
+            if slotstate is not None:
+                for key, value in slotstate.items():
+                    setattr(y, key, value)
+
+    if listiter is not None:
+        for item in listiter:
+            if deep:
+                item = deepcopy(item, memo)
+            y.append(item)
+    if dictiter is not None:
+        for key, value in dictiter:
+            if deep:
+                key = deepcopy(key, memo)
+                value = deepcopy(value, memo)
+            y[key] = value
+    return y
+
+del d
+
+del types
+
+# Helper for instance creation without calling __init__
+class _EmptyClass:
+    pass