join_bytes: pass the join() args correctly for py3

[bup.git] / lib / bup / compat.py

diff --git a/lib/bup/compat.py b/lib/bup/compat.py
index 7e362095d9fe8e63bbe48e1111062ab07ca7940f..f713f52253e27e7f792e2ed4f15c0c21eae948c9 100644 (file)
--- a/lib/bup/compat.py
+++ b/lib/bup/compat.py
@@ -1,32 +1,69 @@
 
-from __future__ import print_function
+from __future__ import absolute_import, print_function
+from array import array
 from traceback import print_exception
 import sys
 
+# Please see CODINGSTYLE for important exception handling guidelines
+# and the rationale behind add_ex_tb(), add_ex_ctx(), etc.
+
 py_maj = sys.version_info[0]
 py3 = py_maj >= 3
 
 if py3:
 
+    from shlex import quote
+    range = range
     str_type = str
 
     def add_ex_tb(ex):
-        pass
+        """Do nothing (already handled by Python 3 infrastructure)."""
+        return ex
 
-    def chain_ex(ex, context_ex):
+    def add_ex_ctx(ex, context_ex):
+        """Do nothing (already handled by Python 3 infrastructure)."""
         return ex
 
+    def items(x):
+        return x.items()
+
+    def bytes_from_uint(i):
+        return bytes((i,))
+
+    byte_int = lambda x: x
+
+    def buffer(object, offset=None, size=None):
+        if size:
+            assert offset is not None
+            return memoryview(object)[offset:offset + size]
+        if offset:
+            return memoryview(object)[offset:]
+        return memoryview(object)
+
+    def join_bytes(*items):
+        """Return the concatenated bytes or memoryview arguments as bytes."""
+        return b''.join(items)
+
 else:  # Python 2
 
+    from pipes import quote
+    range = xrange
     str_type = basestring
 
     def add_ex_tb(ex):
+        """Add a traceback to ex if it doesn't already have one.  Return ex.
+
+        """
         if not getattr(ex, '__traceback__', None):
             ex.__traceback__ = sys.exc_info()[2]
+        return ex
+
+    def add_ex_ctx(ex, context_ex):
+        """Make context_ex the __context__ of ex (unless it already has one).
+        Return ex.
 
-    def chain_ex(ex, context_ex):
+        """
         if context_ex:
-            add_ex_tb(context_ex)
             if not getattr(ex, '__context__', None):
                 ex.__context__ = context_ex
         return ex
@@ -47,6 +84,27 @@ else:  # Python 2
             tb = getattr(ex, '__traceback__', None)
             print_exception(type(ex), ex, tb)
 
+    def items(x):
+        return x.iteritems()
+
+    def bytes_from_uint(i):
+        return chr(i)
+
+    byte_int = ord
+
+    buffer = buffer
+
+    def join_bytes(x, y):
+        """Return the concatenated bytes or buffer arguments as bytes."""
+        if type(x) == buffer:
+            assert type(y) in (bytes, buffer)
+            return x + y
+        assert type(x) == bytes
+        if type(y) == bytes:
+            return b''.join((x, y))
+        assert type(y) in (bytes, buffer)
+        return buffer(x) + y
+
 def wrap_main(main):
     """Run main() and raise a SystemExit with the return value if it
     returns, pass along any SystemExit it raises, convert
@@ -67,11 +125,14 @@ def wrap_main(main):
         sys.exit(1)
 
 
-# Excepting wrap_main() in the traceback, these should produce the same output:
+# Excepting wrap_main() in the traceback, these should produce similar output:
 #   python2 lib/bup/compat.py
 #   python3 lib/bup/compat.py
 # i.e.:
 #   diff -u <(python2 lib/bup/compat.py 2>&1) <(python3 lib/bup/compat.py 2>&1)
+#
+# Though the python3 output for 'second' will include a stacktrace
+# starting from wrap_main, rather than from outer().
 
 if __name__ == '__main__':
 
@@ -82,6 +143,10 @@ if __name__ == '__main__':
         try:
             inner()
         except Exception as ex:
-            raise chain_ex(Exception('second'), ex)
+            add_ex_tb(ex)
+            try:
+                raise Exception('second')
+            except Exception as ex2:
+                raise add_ex_ctx(add_ex_tb(ex2), ex)
 
     wrap_main(outer)