From 25f9224c856444746c1ffe961e24cc91697da0c6 Mon Sep 17 00:00:00 2001
From: Tobi Lutke <tobi@shopify.com>
Date: Wed, 11 Mar 2026 07:29:47 -0400
Subject: [PATCH] fast-path simple variable parsing: skip Lexer/Parser for
 plain dot-separated lookups

---
 lib/liquid/variable.rb | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/lib/liquid/variable.rb b/lib/liquid/variable.rb
index 21f65582..1088f58b 100644
--- a/lib/liquid/variable.rb
+++ b/lib/liquid/variable.rb
@@ -24,13 +24,37 @@ module Liquid
 
     include ParserSwitching
 
+    # Fast path regex: matches simple "name.lookup.chain" with no filters, no brackets, no quotes
+    # This avoids the full Lexer → Parser → Expression pipeline for the most common case
+    SIMPLE_VARIABLE = /\A\s*([a-zA-Z_][\w-]*(?:\.[a-zA-Z_][\w-]*)*)\s*\z/
+
     def initialize(markup, parse_context)
       @markup        = markup
       @name          = nil
       @parse_context = parse_context
       @line_number   = parse_context.line_number
 
-      strict_parse_with_error_mode_fallback(markup)
+      # Fast path for simple variables like "product.title" (no filters, no brackets)
+      if markup =~ SIMPLE_VARIABLE
+        expr_markup = Regexp.last_match(1)
+        @filters = Const::EMPTY_ARRAY
+        if Expression::LITERALS.key?(expr_markup)
+          @name = Expression::LITERALS[expr_markup]
+        else
+          cache = parse_context.instance_variable_get(:@expression_cache)
+          if cache
+            @name = cache[expr_markup] || (cache[expr_markup] = VariableLookup.parse(
+              expr_markup,
+              parse_context.instance_variable_get(:@string_scanner),
+              cache,
+            ).freeze)
+          else
+            @name = VariableLookup.parse(expr_markup, StringScanner.new(""), nil).freeze
+          end
+        end
+      else
+        strict_parse_with_error_mode_fallback(markup)
+      end
     end
 
     def raw