From e3549eb5bc41b8544f660c0aaffe605808869095 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcel=20M=C3=BCller?= <marcel-mueller@gmx.de>
Date: Tue, 25 Feb 2025 11:04:28 +0100
Subject: [PATCH] perf(escaping): Remove catastrophic backtracking regex for
 code escape
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Marcel Müller <marcel-mueller@gmx.de>
---
 CDMarkdownKitTests/TestCode.swift   | 12 ++++++++++++
 CDMarkdownKitTests/TestSyntax.swift |  8 ++++++++
 Source/CDMarkdownCodeEscaping.swift |  4 ++--
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/CDMarkdownKitTests/TestCode.swift b/CDMarkdownKitTests/TestCode.swift
index 695b25f..2b33fd7 100644
--- a/CDMarkdownKitTests/TestCode.swift
+++ b/CDMarkdownKitTests/TestCode.swift
@@ -44,6 +44,18 @@ final class TestCode: XCTestCase {
         XCTAssertTrue(TestHelpers.isMonospaced(testString: parsed, at: 0))
     }
 
+
+    func testCodeMultiple() throws {
+        let parser = getParser()
+
+        let parsed = parser.parse("`test` abc `test` abc")
+        XCTAssertEqual(parsed.string, "test abc test abc")
+        XCTAssertTrue(TestHelpers.isMonospaced(testString: parsed, at: 2))
+        XCTAssertFalse(TestHelpers.isMonospaced(testString: parsed, at: 6))
+        XCTAssertTrue(TestHelpers.isMonospaced(testString: parsed, at: 11))
+        XCTAssertFalse(TestHelpers.isMonospaced(testString: parsed, at: 15))
+    }
+
     func testCodeSentence() throws {
         let parser = getParser()
 
diff --git a/CDMarkdownKitTests/TestSyntax.swift b/CDMarkdownKitTests/TestSyntax.swift
index 06d1870..1f7eed7 100644
--- a/CDMarkdownKitTests/TestSyntax.swift
+++ b/CDMarkdownKitTests/TestSyntax.swift
@@ -112,4 +112,12 @@ final class TestSyntax: XCTestCase {
         XCTAssertFalse(TestHelpers.anyBold(testString: parsed))
         XCTAssertFalse(TestHelpers.anyItalic(testString: parsed))
     }
+
+    func testSyntaxOnlyStart() throws {
+        let parser = getParser()
+
+        let parsed = parser.parse("```\nsyntax\n")
+        XCTAssertEqual(parsed.string, "```\nsyntax\n")
+        XCTAssertFalse(TestHelpers.isMonospaced(testString: parsed, at: 4))
+    }
 }
diff --git a/Source/CDMarkdownCodeEscaping.swift b/Source/CDMarkdownCodeEscaping.swift
index da0fbdf..2c0cf9c 100644
--- a/Source/CDMarkdownCodeEscaping.swift
+++ b/Source/CDMarkdownCodeEscaping.swift
@@ -33,12 +33,12 @@
 
 open class CDMarkdownCodeEscaping: CDMarkdownElement {
 
-    fileprivate static let regex = ["(?<!\\\\)(?:\\\\\\\\)*+(`+)(.*?[^`].*?)(\\1)(?!`)"]
+    fileprivate static let regex = ["(?<!\\\\)(?:\\\\\\\\)*+(`+(?!`))([\\s\\S]*?)(\\1)"]
     open var enabled: Bool = true
 
     lazy open var regularExpressions: [NSRegularExpression] = {
         // swiftlint:disable:next force_try
-        return try! CDMarkdownCodeEscaping.regex.map { try NSRegularExpression(pattern: $0, options: [.dotMatchesLineSeparators]) }
+        return try! CDMarkdownCodeEscaping.regex.map { try NSRegularExpression(pattern: $0, options: []) }
     }()
 
     open func match(_ match: NSTextCheckingResult,