From 8cd6fc34c4110955b408d21d9898f6fbcdd567fa Mon Sep 17 00:00:00 2001
From: Alex Kocharin <alex@kocharin.ru>
Date: Wed, 25 Nov 2020 16:23:03 +0300
Subject: [PATCH] Fix quadratic compexity on backticks

close https://github.com/markdown-it/markdown-it/issues/736
---
 CHANGELOG.md                  | 2 +-
 lib/rules_inline/backticks.js | 8 +++-----
 test/pathological.js          | 4 ++++
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 45e4e5c03..40200b257 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,7 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `[](url (xxx())` is no longer a valid link.
 - `[](url\ xxx)` is no longer a valid link.
 - Fix performance issues when parsing links, #732, #734.
-- Fix performance issues when parsing backticks, #733.
+- Fix performance issues when parsing backticks, #733, #736.
 - Fix performance issues when parsing emphases, #735.
 
 
diff --git a/lib/rules_inline/backticks.js b/lib/rules_inline/backticks.js
index f7c3d1d0a..b9c9ddb7b 100644
--- a/lib/rules_inline/backticks.js
+++ b/lib/rules_inline/backticks.js
@@ -52,13 +52,11 @@ module.exports = function backtick(state, silent) {
 
     // Some different length found, put it in cache as upper limit of where closer can be found
     state.backticks[closerLength] = matchStart;
-
-    // Scanned through the end, didn't find anything
-    if (matchEnd >= max) {
-      state.backticksScanned = true;
-    }
   }
 
+  // Scanned through the end, didn't find anything
+  state.backticksScanned = true;
+
   if (!silent) state.pending += marker;
   state.pos += openerLength;
   return true;
diff --git a/test/pathological.js b/test/pathological.js
index a905dc551..fbbffddd7 100644
--- a/test/pathological.js
+++ b/test/pathological.js
@@ -122,5 +122,9 @@ describe('Pathological sequences speed', () => {
     it('emphasis **_* pattern', async () => {
       await test_pattern('**_* '.repeat(50000));
     });
+
+    it('backtick ``\\``\\`` pattern', async () => {
+      await test_pattern('``\\'.repeat(50000));
+    });
   });
 });