1 files changed, 32 insertions, 0 deletions
diff --git a/lib/extensions/source_id_validator.rb b/lib/extensions/source_id_validator.rb
new file mode 100644
index 0000000..6e04deb
--- /dev/null
+++ b/lib/extensions/source_id_validator.rb
@@ -0,0 +1,32 @@
+module Nuldoc
+  module Extensions
+    class SourceIdValidator < Asciidoctor::Extensions::TreeProcessor
+      def process(doc)
+        errors = []
+        (doc.find_by(context: :listing) {_1.style == 'source'}).each do |source|
+          errors << validate_section(source)
+        end
+        error_message = errors.compact.join("\n")
+        unless error_message.empty?
+          raise "SourceIdValidator (#{doc.attributes['source-file-path']}):\n#{error_message}"
+        end
+      end
+
+      private
+
+      def validate_section(source)
+        id = source.id
+        unless id
+          return "Each source MUST have an id."
+        end
+        if id.start_with?('source.')
+          return "Source id (##{id}) MUST NOT start with 'source.', which is appended by `nul`."
+        end
+        unless id.match?(/\A[-0-9a-z]+\z/)
+          return "Source id (##{id}) MUST consist of either hypen, digits or lowercases."
+        end
+        nil
+      end
+    end
+  end
+end