maint: Add Array combinations method

Ruby < 1.8.7 doesn't have this method and we're using it in a test, so
tests won't run on 1.8.6 until this is in place.

It's probably a good thing to use much in implementation since it's
written in pure Ruby when using < 1.8.7 and in C when in > 1.8.7, but
then if you're using older Rubies you're probably not expecting much for
performance anyway.

Reviewed-by: Daniel Pittman <daniel@puppetlabs.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/lib/puppet/util/monkey_patches.rb b/lib/puppet/util/monkey_patches.rb
index a93c66b07..10a268409 100644
--- a/lib/puppet/util/monkey_patches.rb
+++ b/lib/puppet/util/monkey_patches.rb
@@ -90,3 +90,17 @@ if RUBY_VERSION == '1.8.1' || RUBY_VERSION == '1.8.2'
     r
   }
 end
+
+class Array
+  # Ruby < 1.8.7 doesn't have this method but we use it in tests
+  def combination(num)
+    return [] if num < 0 || num > size
+    return [[]] if num == 0
+    return map{|e| [e] } if num == 1
+    tmp = self.dup
+    self[0, size - (num - 1)].inject([]) do |ret, e|
+      tmp.shift
+      ret += tmp.combination(num - 1).map{|a| a.unshift(e) }
+    end
+  end unless method_defined? :combination
+end