Handling of multiple extends in a single entry

lib/squib/deck.rb

@@ -109,17 +109,24 @@ module Squib
       end
     end
 
-    # Process the extends
+    # Process the extends recursively
     # :nodoc:
     # @api private
     def recurse_extends(yml, key, visited )
       assert_not_visited(key, visited)
       return yml[key] unless has_extends?(yml, key)
       visited[key] = key
-      parent_key = yml[key]['extends']
+      parent_keys = [yml[key]['extends']].flatten
-      return yml[key].merge(recurse_extends(yml, parent_key, visited)) do |key, child_val, parent_val|
+      h = {}
+      parent_keys.each do |parent_key|
+        from_extends = yml[key].merge(recurse_extends(yml, parent_key, visited)) do |key, child_val, parent_val|
           child_val #child overrides parent when merging 
         end 
+        h = h.merge(from_extends) do |key, older_sibling, younger_sibling|
+          younger_sibling #when two siblings have the same entry, the "younger" (lower one) overrides
+        end
+      end
+      return h
     end
 
     # Does this layout entry have an extends field?
@@ -130,6 +137,9 @@ module Squib
       yml[key].key?('extends')
     end
 
+    # Safeguard against malformed circular extends
+    # :nodoc:
+    # @api private
     def assert_not_visited(key, visited)
       if visited.key? key
         raise "Invalid layout: circular extends with '#{key}'"

spec/data/multi-extends-single-entry.yml

@@ -1,14 +1,14 @@
-base: 
+aunt: 
   a: 101
   b: 102
   c: 103
-frame: 
+uncle: 
   x: 104
   y: 105
   b: 106
-title:
+child:
   extends: 
-    - base
+    - uncle
-    - frame
+    - aunt
   a: 107
   x: 108

spec/deck_spec.rb

@@ -117,28 +117,30 @@ describe Squib::Deck do
           )
     end
 
-    # it "applies multiple extends in a single rule" do
+    it "applies multiple extends in a single rule" do
-    #   d = Squib::Deck.new(layout: test_file('multi-extends-single-entry.yml')) 
+      d = Squib::Deck.new(layout: test_file('multi-extends-single-entry.yml')) 
-    #   expect(d.layout).to \
+      expect(d.layout).to \
-    #     eq({'base' => {
+        eq({'aunt' => {
-    #           'x' => 38, 
+              'a' => 101, 
-    #           'y' => 38, 
+              'b' => 102, 
-    #           },
+              'c' => 103, 
-    #         'frame' => {
+              },
-    #           'extends' => 'frame',
+            'uncle' => {
-    #           'x' => 38, 
+              'x' => 104, 
-    #           'y' => 50, 
+              'y' => 105, 
-    #           'width' => 100,
+              'b' => 106, 
-    #           },
+              },
-    #         'title' => {
+            'child' => {
-    #           'extends' => 'frame',
+              'extends' => ['uncle','aunt'],
-    #           'x' => 75, 
+              'a' => 107, # my own
-    #           'y' => 150, 
+              'b' => 102, # from the younger aunt
-    #           'width' => 150,
+              'c' => 103, # from aunt
-    #           },
+              'x' => 108, # my own
-    #         }
+              'y' => 105, # from uncle
-    #       )
+              },
-    # end
+            }
+          )
+    end
 
     it "applies multi-level extends" do
       d = Squib::Deck.new(layout: test_file('multi-level-extends.yml'))