Issue 3638 - Introduce type adblockplus::host

modules/adblockplus/lib/puppet/parser/functions/manifest_exists.rb

+module Puppet::Parser::Functions
+
+  newfunction(:manifest_exists, :type => :rvalue, :doc => <<-'begin') do |args|
+    Determine if a Puppet manifest (*.pp file) exists for the given type name,
+    within the Puppet hierarchy of the (adblockplus) module's parent directory
+  begin
+
+    if args.size != 1
+      message = "Usage: manifest_exists('some::definition::name')"
+      raise Puppet::ParseError, message
+    end
+
+    # 'foo::bar::baz' => 'foo', ['bar', 'baz']
+    module_name, *remainder = args[0].to_s.split('::')
+
+    base_directory = File.expand_path(File.join(
+      File.dirname(__FILE__),
+      '..', # parser
+      '..', # puppet
+      '..', # lib
+      '..', # $module
+      '..' # modules
+    ))
+
+    manifest_path = File.join(
+      base_directory,
+      module_name,
+      'manifests',
+      File.join(*remainder) << '.pp'
+    )
+
+    return File.exists? manifest_path
+
+  end
+end