Start on Item and ItemSet

lib/imbecile.rb

@@ -8,6 +8,8 @@ require_relative "imbecile/fa/state/transition"
 require_relative "imbecile/lexer"
 require_relative "imbecile/lexer/dfa"
 require_relative "imbecile/parser"
+require_relative "imbecile/parser/item"
+require_relative "imbecile/parser/item_set"
 require_relative "imbecile/regex"
 require_relative "imbecile/regex/nfa"
 require_relative "imbecile/regex/unit"

lib/imbecile/parser.rb

@@ -3,6 +3,12 @@ class Imbecile
   class Parser
 
     def initialize(tokens, rules)
+      start_rules = rules.select {|rule| rule.name == "Start"}
+      start_items = start_rules.map do |rule|
+        Item.new(rule, 0)
+      end
+      start_item_set = ItemSet.new(start_items)
+      start_item_set.close!
     end
 
   end

lib/imbecile/parser/item.rb

@@ -0,0 +1,33 @@
+class Imbecile
+  class Parser
+
+    class Item
+
+      attr_reader :rule
+      attr_reader :position
+
+      def initialize(rule, position)
+        @rule = rule
+        @position = position
+      end
+
+      def next_component
+        @rule.components[@position]
+      end
+
+      def hash
+        [@rule, @position].hash
+      end
+
+      def ==(other)
+        @rule == other.rule && @position == other.position
+      end
+
+      def eql?(other)
+        self == other
+      end
+
+    end
+
+  end
+end

lib/imbecile/parser/item_set.rb

@@ -0,0 +1,26 @@
+class Imbecile
+  class Parser
+
+    class ItemSet
+
+      def initialize(items)
+        @items = Set.new(items)
+      end
+
+      def close!
+        eval_items = @items
+        while eval_items.size > 0
+          this_eval_items = eval_items
+          eval_items = Set.new
+          this_eval_items.each do |item|
+            if item.next_component.is_a?(Rule)
+            end
+          end
+          @items += eval_items
+        end
+      end
+
+    end
+
+  end
+end

spec/imbecile/parser/item_spec.rb

@@ -0,0 +1,19 @@
+class Imbecile
+  class Parser
+
+    describe Item do
+
+      it "operates properly with a set" do
+        rule = Object.new
+        item1 = Item.new(rule, 2)
+        item2 = Item.new(rule, 2)
+        expect(item1).to eq item2
+        expect(item1.eql?(item2)).to be_truthy
+        set = Set.new([item1, item2])
+        expect(set.size).to eq 1
+      end
+
+    end
+
+  end
+end