Add 'Bucket.iterator' method.

Exposes additional paramters for narrowing / batching key search.

Fixes #26.

gcloud/storage/bucket.py

@@ -170,6 +170,42 @@ def get_all_keys(self):
         """
         return list(self)
 
+    def iterator(self, prefix=None, delimiter=None, max_results=None,
+                 versions=None):
+        """Return an iterator used to find keys in the bucket.
+
+        :type prefix: string or None
+        :param prefix: optional prefix used to filter keys.
+
+        :type delimiter: string or None
+        :param delimiter: optional delimter, used with ``prefix`` to
+                          emulate hierarchy.
+
+        :type max_results: integer or None
+        :param max_results: maximum number of keys to return.
+
+        :type versions: boolean or None
+        :param versions: whether object versions should be returned as
+                         separate keys.
+
+        :rtype: :class:`_KeyIterator`
+        """
+        extra_params = {}
+
+        if prefix is not None:
+            extra_params['prefix'] = prefix
+
+        if delimiter is not None:
+            extra_params['delimiter'] = delimiter
+
+        if max_results is not None:
+            extra_params['maxResults'] = max_results
+
+        if versions is not None:
+            extra_params['versions'] = versions
+
+        return self._iterator_class(self, extra_params=extra_params)
+
     def new_key(self, key):
         """Given path name (or Key), return a :class:`.storage.key.Key` object.
 

gcloud/storage/test_bucket.py

@@ -170,6 +170,41 @@ def test_get_all_keys_non_empty(self):
         self.assertEqual(kw['path'], '/b/%s/o' % NAME)
         self.assertEqual(kw['query_params'], {})
 
+    def test_iterator_defaults(self):
+        NAME = 'name'
+        connection = _Connection({'items': []})
+        bucket = self._makeOne(connection, NAME)
+        iterator = bucket.iterator()
+        keys = list(iterator)
+        self.assertEqual(keys, [])
+        kw, = connection._requested
+        self.assertEqual(kw['method'], 'GET')
+        self.assertEqual(kw['path'], '/b/%s/o' % NAME)
+        self.assertEqual(kw['query_params'], {})
+
+    def test_iterator_explicit(self):
+        NAME = 'name'
+        EXPECTED = {
+            'prefix': 'subfolder',
+            'delimiter': '/',
+            'maxResults': 10,
+            'versions': True,
+        }
+        connection = _Connection({'items': []})
+        bucket = self._makeOne(connection, NAME)
+        iterator = bucket.iterator(
+            prefix='subfolder',
+            delimiter='/',
+            max_results=10,
+            versions=True,
+        )
+        keys = list(iterator)
+        self.assertEqual(keys, [])
+        kw, = connection._requested
+        self.assertEqual(kw['method'], 'GET')
+        self.assertEqual(kw['path'], '/b/%s/o' % NAME)
+        self.assertEqual(kw['query_params'], EXPECTED)
+
     def test_new_key_existing(self):
         from gcloud.storage.key import Key
         existing = Key()