lib/datasets/table.rb in red-datasets-0.0.4 vs lib/datasets/table.rb in red-datasets-0.0.5

@@ -1,18 +1,59 @@
 module Datasets
   class Table
+    include Enumerable
+
     def initialize(dataset)
       @dataset = dataset
     end
 
+    def each(&block)
+      columner_data.each(&block)
+    end
+
+    def [](name)
+      columner_data[name.to_sym]
+    end
+
+    def fetch_values(*keys)
+      data = columner_data
+      keys.collect do |key|
+        if data.key?(key)
+          data[key]
+        else
+          raise build_key_error(key) unless block_given?
+          yield(key)
+        end
+      end
+    end
+
     def to_h
       columns = {}
       @dataset.each do |record|
         record.to_h.each do |name, value|
           values = (columns[name] ||= [])
           values << value
         end
       end
       columns
+    end
+
+    private
+    begin
+      KeyError.new("message", receiver: self, key: :key)
+    rescue ArgumentError
+      def build_key_error(key)
+        KeyError.new("key not found: #{key.inspect}")
+      end
+    else
+      def build_key_error(key)
+        KeyError.new("key not found: #{key.inspect}",
+                     receiver: self,
+                     key: key)
+      end
+    end
+
+    def columner_data
+      @columns ||= to_h
     end
   end
 end