diff --git a/lib/imbecile.rb b/lib/imbecile.rb
index 87fb486..9524a48 100644
--- a/lib/imbecile.rb
+++ b/lib/imbecile.rb
@@ -1,6 +1,7 @@
 require "erb"
 require "set"
 require_relative "imbecile/cli"
+require_relative "imbecile/code_point_range"
 require_relative "imbecile/grammar"
 require_relative "imbecile/regex"
 require_relative "imbecile/regex/dfa"
diff --git a/lib/imbecile/code_point_range.rb b/lib/imbecile/code_point_range.rb
new file mode 100644
index 0000000..513a6d0
--- /dev/null
+++ b/lib/imbecile/code_point_range.rb
@@ -0,0 +1,82 @@
+module Imbecile
+  class CodePointRange
+
+    MAX_CODE_POINT = 0xFFFFFFFF
+
+    attr_reader :first
+    attr_reader :last
+
+    include Comparable
+
+    # Build a CodePointRange
+    def initialize(first, last = nil)
+      @first = first.ord
+      if last
+        @last = last.ord
+        if @last < @first
+          raise "Invalid CodePointRange: last code point must be > first code point"
+        end
+      else
+        @last = @first
+      end
+    end
+
+    def <=>(other)
+      if self.first != other.first
+        @first <=> other.first
+      else
+        @last <=> other.last
+      end
+    end
+
+    def include?(v)
+      if v.is_a?(CodePointRange)
+        @first <= v.first && v.last <= @last
+      else
+        @first <= v && v <= @last
+      end
+    end
+
+    def size
+      @last - @first + 1
+    end
+
+    class << self
+
+      def invert_ranges(code_point_ranges)
+        new_ranges = []
+        last_cp = -1
+        code_point_ranges.sort.each do |code_point_range|
+          if code_point_range.first > (last_cp + 1)
+            new_ranges << CodePointRange.new(last_cp + 1, code_point_range.first - 1)
+            last_cp = code_point_range.last
+          end
+        end
+        if last_cp < MAX_CODE_POINT
+          new_ranges << CodePointRange.new(last_cp + 1, MAX_CODE_POINT)
+        end
+        new_ranges
+      end
+
+      def first_subrange(code_point_ranges)
+        code_point_ranges.sort.reduce do |result, code_point_range|
+          if code_point_range.include?(result.first)
+            if code_point_range.last < result.last
+              code_point_range
+            else
+              result
+            end
+          else
+            if code_point_range.first <= result.last
+              CodePointRange.new(result.first, code_point_range.first - 1)
+            else
+              result
+            end
+          end
+        end
+      end
+
+    end
+
+  end
+end
diff --git a/lib/imbecile/regex.rb b/lib/imbecile/regex.rb
index f526b3a..999c194 100644
--- a/lib/imbecile/regex.rb
+++ b/lib/imbecile/regex.rb
@@ -83,13 +83,13 @@ module Imbecile
           ccu << parse_backslash
         elsif c == "-" && @pattern[0] != "]"
           begin_cu = ccu.last_unit
-          unless begin_cu.is_a?(CharacterRangeUnit) && begin_cu.range.size == 1
+          unless begin_cu.is_a?(CharacterRangeUnit) && begin_cu.code_point_range.size == 1
             raise Error.new("Character range must be between single characters")
           end
           if @pattern[0] == "\\"
             @pattern.slice!(0)
             end_cu = parse_backslash
-            unless end_cu.is_a?(CharacterRangeUnit) && end_cu.range.size == 1
+            unless end_cu.is_a?(CharacterRangeUnit) && end_cu.code_point_range.size == 1
               raise Error.new("Character range must be between single characters")
             end
             max_code_point = end_cu.code_point
@@ -97,7 +97,7 @@ module Imbecile
             max_code_point = @pattern[0].ord
             @pattern.slice!(0)
           end
-          cru = CharacterRangeUnit.new(begin_cu.min_code_point, max_code_point)
+          cru = CharacterRangeUnit.new(begin_cu.first, max_code_point)
           ccu.replace_last!(cru)
         else
           ccu << CharacterRangeUnit.new(c)
diff --git a/lib/imbecile/regex/nfa.rb b/lib/imbecile/regex/nfa.rb
index 9abf5ec..b7a13ff 100644
--- a/lib/imbecile/regex/nfa.rb
+++ b/lib/imbecile/regex/nfa.rb
@@ -24,12 +24,10 @@ module Imbecile
         def nil_transition_states
           states = Set[self]
           analyze_state = lambda do |state|
-            state.transitions.each do |range, dest_state|
-              if range.nil?
-                unless states.include?(dest_state)
-                  states << dest_state
-                  analyze_state[dest_state]
-                end
+            state.nil_transitions.each do |range, dest_state|
+              unless states.include?(dest_state)
+                states << dest_state
+                analyze_state[dest_state]
               end
             end
           end
@@ -37,6 +35,18 @@ module Imbecile
           states
         end
 
+        def nil_transitions
+          @transitions.select do |code_point, dest_state|
+            code_point.nil?
+          end
+        end
+
+        def cp_transitions
+          @transitions.select do |code_point, dest_state|
+            code_point
+          end
+        end
+
       end
 
       attr_accessor :start_state
@@ -69,13 +79,13 @@ module Imbecile
         visit = lambda do |state|
           accepts_s = state.accepts ? " *" : ""
           rv += "#{state_id[state]}#{accepts_s}:\n"
-          state.transitions.each do |range, dest_state|
-            if range.nil?
+          state.transitions.each do |code_point_range, dest_state|
+            if code_point_range.nil?
               range_s = "nil"
             else
-              range_s = chr[range.first]
-              if range.size > 1
-                range_s += "-" + chr[range.last]
+              range_s = chr[code_point_range.first]
+              if code_point_range.size > 1
+                range_s += "-" + chr[code_point_range.last]
               end
             end
             accepts_s = dest_state.accepts ? " *" : ""
diff --git a/lib/imbecile/regex/unit.rb b/lib/imbecile/regex/unit.rb
index c793234..28c5c70 100644
--- a/lib/imbecile/regex/unit.rb
+++ b/lib/imbecile/regex/unit.rb
@@ -68,18 +68,19 @@ module Imbecile
     end
 
     class CharacterRangeUnit < Unit
-      attr_accessor :min_code_point
-      attr_accessor :max_code_point
+      attr_reader :code_point_range
       def initialize(c1, c2 = nil)
-        @min_code_point = c1.ord
-        @max_code_point = c2 ? c2.ord : @min_code_point
+        @code_point_range = CodePointRange.new(c1, c2)
       end
-      def range
-        @min_code_point..@max_code_point
+      def first
+        @code_point_range.first
+      end
+      def last
+        @code_point_range.last
       end
       def to_nfa
         nfa = NFA.new
-        nfa.start_state.add_transition(range, nfa.end_state)
+        nfa.start_state.add_transition(@code_point_range, nfa.end_state)
         nfa
       end
     end
@@ -108,32 +109,16 @@ module Imbecile
         if @units.empty?
           nfa.start_state.add_transition(nil, nfa.end_state)
         else
-          ranges = @units.map(&:range)
+          code_point_ranges = @units.map(&:code_point_range)
           if @negate
-            ranges = negate_ranges(ranges)
+            code_point_ranges = CodePointRange.invert_ranges(code_point_ranges)
           end
-          ranges.each do |range|
-            nfa.start_state.add_transition(range, nfa.end_state)
+          code_point_ranges.each do |code_point_range|
+            nfa.start_state.add_transition(code_point_range, nfa.end_state)
           end
         end
         nfa
       end
-      private
-      def negate_ranges(ranges)
-        ranges = ranges.sort_by(&:first)
-        new_ranges = []
-        last_cp = -1
-        ranges.each do |range|
-          if range.first > (last_cp + 1)
-            new_ranges << ((last_cp + 1)..(range.first - 1))
-            last_cp = range.last
-          end
-        end
-        if last_cp < 0xFFFFFFFF
-          new_ranges << ((last_cp + 1)..0xFFFFFFFF)
-        end
-        new_ranges
-      end
     end
 
     class MultiplicityUnit < Unit
diff --git a/spec/imbecile/regex_spec.rb b/spec/imbecile/regex_spec.rb
index 3be355e..caeb533 100644
--- a/spec/imbecile/regex_spec.rb
+++ b/spec/imbecile/regex_spec.rb
@@ -114,7 +114,7 @@ module Imbecile
       expect(m_unit.min_count).to eq 5
       expect(m_unit.max_count).to eq 8
       expect(m_unit.unit).to be_a Regex::CharacterRangeUnit
-      expect(m_unit.unit.range.first).to eq "a".ord
+      expect(m_unit.unit.first).to eq "a".ord
     end
 
     it "parses an escaped *" do
@@ -125,9 +125,9 @@ module Imbecile
       seq_unit = regex.unit.alternates[0]
       expect(seq_unit.size).to eq 2
       expect(seq_unit[0]).to be_a Regex::CharacterRangeUnit
-      expect(seq_unit[0].min_code_point).to eq "a".ord
+      expect(seq_unit[0].first).to eq "a".ord
       expect(seq_unit[1]).to be_a Regex::CharacterRangeUnit
-      expect(seq_unit[1].min_code_point).to eq "*".ord
+      expect(seq_unit[1].first).to eq "*".ord
     end
 
     it "parses an escaped +" do
@@ -138,9 +138,9 @@ module Imbecile
       seq_unit = regex.unit.alternates[0]
       expect(seq_unit.size).to eq 2
       expect(seq_unit[0]).to be_a Regex::CharacterRangeUnit
-      expect(seq_unit[0].min_code_point).to eq "a".ord
+      expect(seq_unit[0].first).to eq "a".ord
       expect(seq_unit[1]).to be_a Regex::CharacterRangeUnit
-      expect(seq_unit[1].min_code_point).to eq "+".ord
+      expect(seq_unit[1].first).to eq "+".ord
     end
 
     it "parses an escaped \\" do
@@ -151,9 +151,9 @@ module Imbecile
       seq_unit = regex.unit.alternates[0]
       expect(seq_unit.size).to eq 2
       expect(seq_unit[0]).to be_a Regex::CharacterRangeUnit
-      expect(seq_unit[0].min_code_point).to eq "\\".ord
+      expect(seq_unit[0].first).to eq "\\".ord
       expect(seq_unit[1]).to be_a Regex::CharacterRangeUnit
-      expect(seq_unit[1].min_code_point).to eq "d".ord
+      expect(seq_unit[1].first).to eq "d".ord
     end
 
     it "parses a character class" do
@@ -168,10 +168,10 @@ module Imbecile
       expect(ccu.negate).to be_falsey
       expect(ccu.size).to eq 2
       expect(ccu[0]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[0].min_code_point).to eq "a".ord
-      expect(ccu[0].max_code_point).to eq "z".ord
+      expect(ccu[0].first).to eq "a".ord
+      expect(ccu[0].last).to eq "z".ord
       expect(ccu[1]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[1].min_code_point).to eq "_".ord
+      expect(ccu[1].first).to eq "_".ord
     end
 
     it "parses a negated character class" do
@@ -186,7 +186,7 @@ module Imbecile
       expect(ccu.negate).to be_truthy
       expect(ccu.size).to eq 3
       expect(ccu[0]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[0].min_code_point).to eq "x".ord
+      expect(ccu[0].first).to eq "x".ord
     end
 
     it "parses - as a plain character at beginning of a character class" do
@@ -200,7 +200,7 @@ module Imbecile
       ccu = seq_unit[0]
       expect(ccu.size).to eq 2
       expect(ccu[0]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[0].min_code_point).to eq "-".ord
+      expect(ccu[0].first).to eq "-".ord
     end
 
     it "parses - as a plain character at end of a character class" do
@@ -214,9 +214,9 @@ module Imbecile
       ccu = seq_unit[0]
       expect(ccu.size).to eq 2
       expect(ccu[0]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[0].min_code_point).to eq "0".ord
+      expect(ccu[0].first).to eq "0".ord
       expect(ccu[1]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[1].min_code_point).to eq "-".ord
+      expect(ccu[1].first).to eq "-".ord
     end
 
     it "parses - as a plain character at beginning of a negated character class" do
@@ -231,7 +231,7 @@ module Imbecile
       expect(ccu.negate).to be_truthy
       expect(ccu.size).to eq 2
       expect(ccu[0]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[0].min_code_point).to eq "-".ord
+      expect(ccu[0].first).to eq "-".ord
     end
 
     it "parses . as a plain character in a character class" do
@@ -246,7 +246,7 @@ module Imbecile
       expect(ccu.negate).to be_falsey
       expect(ccu.size).to eq 1
       expect(ccu[0]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[0].min_code_point).to eq ".".ord
+      expect(ccu[0].first).to eq ".".ord
     end
 
     it "parses - as a plain character when escaped in middle of character class" do
@@ -261,11 +261,11 @@ module Imbecile
       expect(ccu.negate).to be_falsey
       expect(ccu.size).to eq 3
       expect(ccu[0]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[0].min_code_point).to eq "0".ord
+      expect(ccu[0].first).to eq "0".ord
       expect(ccu[1]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[1].min_code_point).to eq "-".ord
+      expect(ccu[1].first).to eq "-".ord
       expect(ccu[2]).to be_a Regex::CharacterRangeUnit
-      expect(ccu[2].min_code_point).to eq "9".ord
+      expect(ccu[2].first).to eq "9".ord
     end
 
     it "parses alternates" do
@@ -314,9 +314,9 @@ module Imbecile
       expect(regex.unit.alternates[2]).to be_a Regex::SequenceUnit
       expect(regex.unit.alternates[2].size).to eq 2
       expect(regex.unit.alternates[2][0]).to be_a Regex::CharacterRangeUnit
-      expect(regex.unit.alternates[2][0].min_code_point).to eq "|".ord
+      expect(regex.unit.alternates[2][0].first).to eq "|".ord
       expect(regex.unit.alternates[2][1]).to be_a Regex::CharacterRangeUnit
-      expect(regex.unit.alternates[2][1].min_code_point).to eq "v".ord
+      expect(regex.unit.alternates[2][1].first).to eq "v".ord
       expect(regex.unit.alternates[3]).to be_a Regex::SequenceUnit
       expect(regex.unit.alternates[3].size).to eq 1
       expect(regex.unit.alternates[3][0]).to be_a Regex::MultiplicityUnit
@@ -325,8 +325,8 @@ module Imbecile
       expect(regex.unit.alternates[3][0].unit).to be_a Regex::CharacterClassUnit
       expect(regex.unit.alternates[3][0].unit.size).to eq 1
       expect(regex.unit.alternates[3][0].unit[0]).to be_a Regex::CharacterRangeUnit
-      expect(regex.unit.alternates[3][0].unit[0].min_code_point).to eq "x".ord
-      expect(regex.unit.alternates[3][0].unit[0].max_code_point).to eq "y".ord
+      expect(regex.unit.alternates[3][0].unit[0].first).to eq "x".ord
+      expect(regex.unit.alternates[3][0].unit[0].last).to eq "y".ord
     end
 
   end