lib/picky/backends/backend.rb in picky-4.0.0pre1 vs lib/picky/backends/backend.rb in picky-4.0.0pre2

@@ -20,9 +20,46 @@
 
       def extract_lambda_or thing, *args
         thing && (thing.respond_to?(:call) && thing.call(*args) || thing)
       end
 
+      # Returns the total score of the combinations.
+      #
+      # Default implementation. Override to speed up.
+      #
+      def weight combinations
+        combinations.score
+      end
+
+      # Returns the result ids for the allocation.
+      #
+      # Sorts the ids by size and & through them in the following order (sizes):
+      # 0. [100_000, 400, 30, 2]
+      # 1. [2, 30, 400, 100_000]
+      # 2. (100_000 & (400 & (30 & 2))) # => result
+      #
+      # Note: Uses a C-optimized intersection routine (in performant.c)
+      #       for speed and memory efficiency.
+      #
+      # Note: In the memory based version we ignore the amount and
+      # offset hints.
+      # We cannot use the information to speed up the algorithm,
+      # unfortunately.
+      #
+      def ids combinations, _, _
+        # Get the ids for each combination.
+        #
+        id_arrays = combinations.inject([]) do |total, combination|
+          total << combination.ids
+        end
+
+        # Call the optimized C algorithm.
+        #
+        # Note: It orders the passed arrays by size.
+        #
+        Performant::Array.memory_efficient_intersect id_arrays
+      end
+
       #
       #
       def to_s
         self.class.name
       end
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