From ceb7e9ee32e36c7193f833d7d2d35fc8dcd0bf59 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sun, 29 Aug 2021 11:48:49 -0400
Subject: [PATCH] Add EOF token to Start rule patterns

---
 lib/imbecile/parser.rb | 2 ++
 lib/imbecile/token.rb  | 8 +++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/lib/imbecile/parser.rb b/lib/imbecile/parser.rb
index 2d3c90d..107c3f9 100644
--- a/lib/imbecile/parser.rb
+++ b/lib/imbecile/parser.rb
@@ -3,9 +3,11 @@ class Imbecile
   class Parser
 
     def initialize(tokens, rules)
+      token_eof = Token.new("$", nil, TOKEN_EOF)
       @item_sets = []
       item_sets_set = Set.new
       start_items = rules["Start"].patterns.map do |pattern|
+        pattern.components << token_eof
         Item.new(pattern, 0)
       end
       start_item_set = ItemSet.new(start_items)
diff --git a/lib/imbecile/token.rb b/lib/imbecile/token.rb
index e4283e7..b7607c4 100644
--- a/lib/imbecile/token.rb
+++ b/lib/imbecile/token.rb
@@ -22,9 +22,11 @@ class Imbecile
       @name = name
       @pattern = pattern
       @id = id
-      regex = Regex.new(pattern)
-      regex.nfa.end_state.accepts = self
-      @nfa = regex.nfa
+      unless pattern.nil?
+        regex = Regex.new(pattern)
+        regex.nfa.end_state.accepts = self
+        @nfa = regex.nfa
+      end
     end
 
     def c_name