Create _base64 module with wrappers for accelerated functions

If we were strictly following PEP-0399, _base64 would be a C
module for accelerated functions in base64. Due to historical
reasons, those should actually go in binascii instead.

We still want to preserve the existing Python code in base64.
Parting out facilities for accessing the C functions into a
module named _base64 shouldn't risk a naming conflict and
will simplify testing.

Author: kangtastic

Lib/_base64.py

@@ -0,0 +1,33 @@
+"""C accelerator wrappers for originally pure-Python parts of base64."""
+
+from binascii import a2b_ascii85, a2b_base85, b2a_ascii85, b2a_base85
+
+__all__ = ['a85encode', 'a85decode',
+           'b85encode', 'b85decode',
+           'z85encode', 'z85decode']
+
+
+def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False):
+    return b2a_ascii85(b, fold_spaces=foldspaces,
+                       wrap=adobe, width=wrapcol, pad=pad)
+
+
+def a85decode(b, *, foldspaces=False, adobe=False, ignorechars=b' \t\n\r\v'):
+    return a2b_ascii85(b, fold_spaces=foldspaces,
+                       wrap=adobe, ignore=ignorechars)
+
+
+def b85encode(b, pad=False):
+    return b2a_base85(b, pad=pad, newline=False)
+
+
+def b85decode(b):
+    return a2b_base85(b, strict_mode=True)
+
+
+def z85encode(s):
+    return b2a_base85(s, newline=False, z85=True)
+
+
+def z85decode(s):
+    return a2b_base85(s, strict_mode=True, z85=True)

Lib/base64.py

@@ -576,6 +576,13 @@ def decodebytes(s):
     return binascii.a2b_base64(s)
 
 
+# Use accelerated implementations of originally pure-Python parts if possible.
+try:
+    from _base64 import *
+except ImportError:
+    pass
+
+
 # Usable as a script...
 def main():
     """Small main program"""