Support «hosts: groupname[1:]» notation (~= 'the rest of the group')

docsite/rst/intro_patterns.rst

@@ -79,8 +79,9 @@ You can refer to hosts within the group by adding a subscript to the group name:
 
     webservers[0]       # == cobweb
     webservers[-1]      # == weber
-    webservers[0:1]     # == webservers[0]:webservers[1]
-                        # == cobweb:webbing
+    webservers[0:1]     # == webservers[0],webservers[1]
+                        # == cobweb,webbing
+    webservers[1:]      # == webbing,weber
 
 Most people don't specify patterns as regular expressions, but you can.  Just start the pattern with a '~'::
 

lib/ansible/inventory/__init__.py

@@ -342,9 +342,9 @@ class Inventory(object):
             r'''^
                 (.+)                    # A pattern expression ending with...
                 \[(?:                   # A [subscript] expression comprising:
-                    (-?[0-9]+)          # A single positive or negative number
-                    |                   # Or a numeric range
-                    ([0-9]+)([:-])([0-9]+)
+                    (-?[0-9]+)|         # A single positive or negative number
+                    ([0-9]+)([:-])      # Or an x:y or x: range.
+                    ([0-9]*)
                 )\]
                 $
             ''', re.X
@@ -357,6 +357,8 @@ class Inventory(object):
             if idx:
                 subscript = (int(idx), None)
             else:
+                if not end:
+                    end = -1
                 subscript = (int(start), int(end))
                 if sep == '-':
                     display.deprecated("Use [x:y] inclusive subscripts instead of [x-y]", version=2.0, removed=True)
@@ -375,6 +377,8 @@ class Inventory(object):
         (start, end) = subscript
 
         if end:
+            if end == -1:
+                end = len(hosts)-1
             return hosts[start:end+1]
         else:
             return [ hosts[start] ]

test/units/inventory/test_inventory.py

@@ -66,6 +66,9 @@ class TestInventory(unittest.TestCase):
         'a[2:3]': [('a', (2, 3)), ['c', 'd']],
         'a[-1]': [('a', (-1, None)), ['Z']],
         'a[-2]': [('a', (-2, None)), ['Y']],
+        'a[48:]': [('a', (48, -1)), ['W', 'X', 'Y', 'Z']],
+        'a[49:]': [('a', (49, -1)), ['X', 'Y', 'Z']],
+        'a[1:]': [('a', (1, -1)), list(string.ascii_letters[1:])],
     }
 
     def setUp(self):