fix: fix del with escaped tilde (#3517)

* fix: fix del with escaped tilde

* use rules to check for unescaped tilde

* add tests with spaces

src/rules.ts

@@ -301,7 +301,7 @@ const inlineGfm: Record<InlineKeys, RegExp> = {
     .replace('email', /[A-Za-z0-9._+-]+(@)[a-zA-Z0-9-_]+(?:\.[a-zA-Z0-9-_]*[a-zA-Z0-9])+(?![-_])/)
     .getRegex(),
   _backpedal: /(?:[^?!.,:;*_'"~()&]+|\([^)]*\)|&(?![a-zA-Z0-9]+;$)|[?!.,:;*_'"~)]+(?!$))+/,
-  del: /^(~~?)(?=[^\s~])([\s\S]*?[^\s~])\1(?=[^~]|$)/,
+  del: /^(~~?)(?=[^\s~])((?:\\.|[^\\])*?(?:\\.|[^\s~\\]))\1(?=[^~]|$)/,
   text: /^([`~]+|[^`~])(?:(?= {2,}\n)|(?=[a-zA-Z0-9.!#$%&'*+\/=?_`{\|}~-]+@)|[\s\S]*?(?:(?=[\\<!\[`*~_]|\b_|https?:\/\/|ftp:\/\/|www\.|$)|[^ ](?= {2,}\n)|[^a-zA-Z0-9.!#$%&'*+\/=?_`{\|}~-](?=[a-zA-Z0-9.!#$%&'*+\/=?_`{\|}~-]+@)))/,
 };
 

test/specs/new/escape_within_del.html

@@ -0,0 +1,6 @@
+<p><del>\</del></p>
+<p>~\~</p>
+<p><del>~</del></p>
+<p>~\~~</p>
+<p>~~ ~</p>
+<p>~ ~~</p>

test/specs/new/escape_within_del.md

@@ -0,0 +1,11 @@
+~\\~
+
+~\\\~
+
+~\~~
+
+~\\~~
+
+~\~ ~
+
+~ \~~