From 9d16eb3d0580b1fdb78a0283439da1fb79e41e3f Mon Sep 17 00:00:00 2001
From: Tobi Lutke <tobi@shopify.com>
Date: Wed, 11 Mar 2026 08:36:28 -0400
Subject: [PATCH] fast-path simple if truthiness: use byte scanner before
 SIMPLE_CONDITION regex

---
 lib/liquid/tags/if.rb | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/liquid/tags/if.rb b/lib/liquid/tags/if.rb
index b896a1c0..45e85332 100644
--- a/lib/liquid/tags/if.rb
+++ b/lib/liquid/tags/if.rb
@@ -89,6 +89,11 @@ module Liquid
     SIMPLE_CONDITION = /\A\s*(#{QuotedFragment})\s*(?:([=!<>a-z_]+)\s*(#{QuotedFragment}))?\s*\z/o
 
     def lax_parse(markup)
+      # Fastest path: simple identifier truthiness like "product.available" or "forloop.first"
+      if (simple = Variable.simple_variable_markup(markup))
+        return Condition.new(parse_expression(simple))
+      end
+
       # Fast path: simple condition without and/or
       if !markup.include?(' and ') && !markup.include?(' or ') && markup =~ SIMPLE_CONDITION
         return Condition.new(