Optionally display listings in raw json

Symlinks have recently added some new keys to container listings.  It's
very convenient to be able to see and reason about the extra information
in container listings.

Allowing raw json output is similar with what the client already does
for the info command, and it's forward compatible with any listing
enhancements added by future middleware development.

Change-Id: I88fb38529342ac4e4198aeccd2f10c69c7396704

1 files changed, 22 insertions, 0 deletions

diff --git a/swiftclient/utils.py b/swiftclient/utils.py
index 2b208b9..9e43237 100644
--- a/swiftclient/utils.py
+++ b/swiftclient/utils.py
@@ -403,3 +403,25 @@ def normalize_manifest_path(path):
     if path.startswith('/'):
         return path[1:]
     return path
+
+
+class JSONableIterable(list):
+    def __init__(self, iterable):
+        self._iterable = iter(iterable)
+        try:
+            self._peeked = next(self._iterable)
+            self._has_items = True
+        except StopIteration:
+            self._peeked = None
+            self._has_items = False
+
+    def __bool__(self):
+        return self._has_items
+
+    __nonzero__ = __bool__
+
+    def __iter__(self):
+        if self._has_items:
+            yield self._peeked
+        for item in self._iterable:
+            yield item