Merge pull request #12436 from amenonsen/ranges

Support «hosts: foo[1:]» and add tests for split/apply_subscript

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]
+    webservers[0:1]     # == webservers[0],webservers[1]
-                        # == cobweb:webbing
+                        # == 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...
                 \[(?:                   # A [subscript] expression comprising:
-                    (-?[0-9]+)          # A single positive or negative number
+                    (-?[0-9]+)|         # A single positive or negative number
-                    |                   # Or a numeric range
+                    ([0-9]+)([:-])      # Or an x:y or x: range.
-                    ([0-9]+)([:-])([0-9]+)
+                    ([0-9]*)
                 )\]
                 $
             ''', 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

@@ -19,6 +19,8 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
+import string
+
 from ansible.compat.tests import unittest
 from ansible.compat.tests.mock import patch, MagicMock
 
@@ -44,6 +46,7 @@ class TestInventory(unittest.TestCase):
         ' a : b ': ['a', 'b'],
         'foo:bar:baz[1:2]': ['foo', 'bar', 'baz[1:2]'],
     }
+
     pattern_lists = [
         [['a'], ['a']],
         [['a', 'b'], ['a', 'b']],
@@ -52,6 +55,21 @@ class TestInventory(unittest.TestCase):
          ['9a01:7f8:191:7701::9', '9a01:7f8:191:7701::9','foo']]
     ]
 
+    # pattern_string: [ ('base_pattern', (a,b)), ['x','y','z'] ]
+    # a,b are the bounds of the subscript; x..z are the results of the subscript
+    # when applied to string.ascii_letters.
+
+    subscripts = {
+        'a': [('a',None), list(string.ascii_letters)],
+        'a[0]': [('a', (0, None)), ['a']],
+        'a[1]': [('a', (1, None)), ['b']],
+        '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):
         v = VariableManager()
@@ -67,3 +85,16 @@ class TestInventory(unittest.TestCase):
 
         for p, r in self.pattern_lists:
             self.assertEqual(r, self.i._split_pattern(p))
+
+    def test_ranges(self):
+
+        for s in self.subscripts:
+            r = self.subscripts[s]
+            self.assertEqual(r[0], self.i._split_subscript(s))
+            self.assertEqual(
+                r[1],
+                self.i._apply_subscript(
+                    list(string.ascii_letters),
+                    r[0][1]
+                )
+            )