Allow interpolation in plain

lib/hamlit/filter_compiler/plain.rb

@@ -1,8 +1,15 @@
+require 'haml/util'
+
 module Hamlit
   class FilterCompiler
     class Plain
       def compile(node)
-        [:static, node.value[:text].rstrip + "\n"]
+        text = node.value[:text].rstrip + "\n"
+        if Haml::Util.contains_interpolation?(text)
+          [:dynamic, Haml::Util.unescape_interpolation(text + "\n")]
+        else
+          [:static, text]
+        end
       end
     end
   end

test/haml-spec/tests.yml

@@ -455,14 +455,14 @@ Ruby-style interpolation:
     optional: true
     locals:
       var: value
-#   interpolation inside filtered content:
-#     haml: |-
-#       :plain
-#         #{var} interpolated: #{var}
-#     html: 'value interpolated: value'
-#     optional: true
-#     locals:
-#       var: value
+  interpolation inside filtered content:
+    haml: |-
+      :plain
+        #{var} interpolated: #{var}
+    html: 'value interpolated: value'
+    optional: true
+    locals:
+      var: value
 # HTML escaping:
 #   code following '&=':
 #     haml: '&= ''<"&>'''