Only define helpers.next() if Python's isn't new enough.

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

diff --git a/lib/bup/helpers.py b/lib/bup/helpers.py
index 4943d70ccc6c748a157c871757848e99a478ac01..ef4be682f0152d26c372ca1a8078619a30a5ab49 100644 (file)
--- a/lib/bup/helpers.py
+++ b/lib/bup/helpers.py
@@ -126,6 +126,25 @@ def mkdirp(d, mode=None):
             raise
 
 
+_unspecified_next_default = object()
+
+def _fallback_next(it, default=_unspecified_next_default):
+    """Retrieve the next item from the iterator by calling its
+    next() method. If default is given, it is returned if the
+    iterator is exhausted, otherwise StopIteration is raised."""
+
+    if default is _unspecified_next_default:
+        return it.next()
+    else:
+        try:
+            return it.next()
+        except StopIteration:
+            return default
+
+if sys.version_info < (2, 6):
+    next =  _fallback_next
+
+
 def merge_iter(iters, pfreq, pfunc, pfinal, key=None):
     if key:
         samekey = lambda e, pe: getattr(e, key) == getattr(pe, key, None)