Better meta attributes listing

source/includes/comparison.html.jade

@@ -11,9 +11,9 @@
 	.pick-in
 		table
 			tr
-				th(ng-repeat="(attribute, value) in all[0].meta" ng-if="attribute != 'Active'" ng-bind-html="attribute")
+				th(ng-repeat="attribute in metaKeys" ng-if="attribute != 'Active'" ng-bind-html="attribute")
 			tr(ng-repeat="poem in all" class="switch" ng-class="{disabled: !poem.meta.Active}" ng-click="switchActive(poem)")
-				td(ng-repeat="(attribute, value) in poem.meta" ng-if="attribute != 'Active'" ng-bind-html="value")
+				td(ng-repeat="attribute in metaKeys" ng-if="attribute != 'Active'" ng-bind-html="poem.meta[attribute]")
 
 // verses
 #content

source/scripts/controllers.js.coffee

@@ -41,6 +41,7 @@ angular.module("sideBySide.controllers", [])
 		headingKey = poems.config.heading or "Author"
 		$scope.headings = (version[headingKey] for version in transformed.meta)
 
+		$scope.metaKeys = poems.getMetaKeys()
 		$scope.all = poems.all
 		scroll()
 

source/scripts/services/poems.js.coffee

@@ -23,4 +23,9 @@ angular.module("sideBySide").service "poems", ->
 	@getInactive = ->
 		(poem for poem in @all when poem.meta.Active != true)
 
+	@getMetaKeys = ->
+		@all.reduce (all, one) ->
+			_.uniq all.concat (key for key of one.meta)
+		, []
+
 	@