lib/summaryse.rb in summaryse-1.0.0 vs lib/summaryse.rb in summaryse-1.1.0

@@ -1,3 +1,48 @@
 require "summaryse/version"
 require "summaryse/loader"
+module Summaryse
+
+  # Bypass marker
+  BYPASS = Object.new
+
+  #
+  # Registers a aggregation function under a given name.
+  #
+  # The lambda function is converted as a Proc from the supplied block.
+  # It takes one array argument, on which the aggregation must be done
+  # and returned.
+  #
+  # @param [Symbol] name a aggregation function name
+  # @param [lambda] the function itself
+  # 
+  def self.register(name, &lambda)
+    @aggregators ||= {}
+    @aggregators[name] = lambda
+  end
+
+  #
+  # Returns an aggregator by name, nil if no such aggregator as been
+  # previously registered.
+  #
+  def self.aggregator(name)
+    @aggregators && @aggregators[name]
+  end
+
+  #
+  register(:count)       {|a| a.size                     }
+  register(:sum)         {|a| a.inject(:+)               }
+  register(:avg)         {|a| a.inject(:+)/a.size.to_f   }
+
+  # 
+  register(:first)       {|a| a.first                    }
+  register(:last)        {|a| a.last                     }
+  register(:min)         {|a| a.min                      }
+  register(:max)         {|a| a.max                      }
+
+  #
+  register(:intersection){|a| a.inject(:&)               }
+  register(:union)       {|a| a.inject(:|)               }
+
+end # module Summaryse
 require "summaryse/core_ext/array"
+