From 95b3dc6550134630d4b2e973831cf48c9787f4b3 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Thu, 25 Jul 2024 20:33:15 -0400
Subject: [PATCH] Cache ItemSet#next_symbols - #28

---
 lib/propane/parser/item_set.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/propane/parser/item_set.rb b/lib/propane/parser/item_set.rb
index 2fe8403..eedaa34 100644
--- a/lib/propane/parser/item_set.rb
+++ b/lib/propane/parser/item_set.rb
@@ -46,7 +46,7 @@ class Propane
       # @return [Set<Token, RuleSet>]
       #   Set of next symbols for all Items in this ItemSet.
       def next_symbols
-        Set.new(@items.map(&:next_symbol).compact)
+        @_next_symbols ||= Set.new(@items.map(&:next_symbol).compact)
       end
 
       # Build a next ItemSet for the given next symbol.