First version. Simple shuffle function to use within Puppet DSL.

Signed-off-by: Krzysztof Wilczynski <krzysztof.wilczynski@linux.com>

diff --git a/shuffle.rb b/shuffle.rb
new file mode 100644 (file)
index 0000000..d92a3cd
--- /dev/null
+++ b/shuffle.rb
@@ -0,0 +1,35 @@
+#
+# shuffle.rb
+#
+
+module Puppet::Parser::Functions
+  newfunction(:shuffle, :type => :rvalue, :doc => <<-EOS
+    EOS
+  ) do |arguments|
+
+    raise(Puppet::ParseError, "shuffle(): Wrong number of arguments " +
+      "given (#{arguments.size} for 1)") if arguments.size < 1
+
+    array = arguments[0]
+
+    if not array.is_a?(Array)
+      raise(Puppet::ParseError, 'shuffle(): Requires an array to work with')
+    end
+
+    return []    if array.size == 0
+    return array if array.size <= 1
+
+    list     = array.clone
+    elements = list.size
+
+    # Simple implementation of Fisher–Yates in-place shuffle ...
+    elements.times do |i|
+      j = rand(elements - i) + i
+      list[j], list[i] = list[i], list[j]
+    end
+
+    return list
+  end
+end
+
+# vim: set ts=2 sw=2 et :