[4638] Cleanup of plurals and inheritance relationships in AST

Changed the grammar so that the following "plural" constructs always
parse as an ASTArray:

- funcvalues
- rvalues
- resourceinstances
- anyparams
- params
- caseopts
- casevalues

And the following "singluar" construct never parses as an ASTArray:

- statement

The previous behavior was for these constructs to parse as a scalar
when they represented a single item and an ASTArray when they
contained zero or multiple items.  ("Statement" could sometimes
represent a single item because a single resource declaration could
represent multiple resources).  This complicated other grammar rules
and caused ambiguous handling of nested arrays.

Also made these changes to the AST class hierarchy:

- ResourceInstance no longer derives from ASTArray.  This relationship
  was not meaningful because a ResourceInstance is a (title,
  parameters) pair, not an array, and it produced complications when
  we wanted to represent an array of ResourceInstance objects.

- Resource no longer derives from ResourceReference.  No significant
  functionality was being inherited and the relationship doesn't make
  sense in an AST context.

- ResourceOverride no longer derives from Resource.  No significant
  functionality was being inherited and the relationship doesn't make
  sense in an AST context.

- Resource can now represent a compound resource instance such as
  "notify { foo: ; bar: }".  This saves the parser from having to
  use represent a statement as an array of objects.

- ASTArray's evaluate method never flattens out arrays of arrays.

1 files changed, 3 insertions, 12 deletions

diff --git a/lib/puppet/parser/parser_support.rb b/lib/puppet/parser/parser_support.rb
index 859897a16..1c4947891 100644
--- a/lib/puppet/parser/parser_support.rb
+++ b/lib/puppet/parser/parser_support.rb
@@ -29,18 +29,9 @@ class Puppet::Parser::Parser
     message
   end
 
-  # Create an AST array out of all of the args
-  def aryfy(*args)
-    if args[0].instance_of?(AST::ASTArray)
-      result = args.shift
-      args.each { |arg|
-        result.push arg
-      }
-    else
-      result = ast AST::ASTArray, :children => args
-    end
-
-    result
+  # Create an AST array containing a single element
+  def aryfy(arg)
+    ast AST::ASTArray, :children => [arg]
   end
 
   # Create an AST object, and automatically add the file and line information if