From 3fc8ac5d8dc4f454b8aa13e7c3c246b9be8875e0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EA=B9=80=EB=8C=80=EC=97=B0?= <daeyeon.kim@nhn.com>
Date: Tue, 5 Jul 2022 14:23:25 +0900
Subject: [PATCH] fix: escape backslash in the middle of sentence (#2588)

* test: add test for escape baskslash

* fix: escape backslash in the middle of sentence
---
 .../editor/src/__test__/unit/convertor.spec.ts | 11 +++++++++++
 apps/editor/src/utils/common.ts                | 18 ++++++++++++------
 2 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/apps/editor/src/__test__/unit/convertor.spec.ts b/apps/editor/src/__test__/unit/convertor.spec.ts
index bef09ec536..6b98f6e0a7 100644
--- a/apps/editor/src/__test__/unit/convertor.spec.ts
+++ b/apps/editor/src/__test__/unit/convertor.spec.ts
@@ -1098,4 +1098,15 @@ describe('Convertor', () => {
 
     expect(result).toBe(`<strong>"test"</strong>a`);
   });
+
+  it('should escape the backslash, which is a plain chracter in the middle of a sentence', () => {
+    const markdown = source`
+      backslash \\in the middle of a sentence
+      `;
+    const expected = source`
+      backslash \\\\in the middle of a sentence
+      `;
+
+    assertConverting(markdown, expected);
+  });
 });
diff --git a/apps/editor/src/utils/common.ts b/apps/editor/src/utils/common.ts
index cd38e93083..3754219237 100644
--- a/apps/editor/src/utils/common.ts
+++ b/apps/editor/src/utils/common.ts
@@ -12,7 +12,8 @@ const reEscapeHTML = /<([a-zA-Z_][a-zA-Z0-9\-._]*)(\s|[^\\>])*\/?>|<(\/)([a-zA-Z
 const reEscapeBackSlash = /\\[!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~\\]/g;
 const reEscapePairedChars = /[*_~`]/g;
 const reMdImageSyntax = /!\[.*\]\(.*\)/g;
-const reEscapedCharInLinkSyntax = /[[\]]/g; //
+const reEscapedCharInLinkSyntax = /[[\]]/g;
+const reEscapeBackSlashInSentence = /(?:^|[^\\])\\(?!\\)/g;
 
 const XMLSPECIAL = '[&<>"]';
 const reXmlSpecial = new RegExp(XMLSPECIAL, 'g');
@@ -118,22 +119,27 @@ export function escapeTextForLink(text: string) {
 }
 
 export function escape(text: string) {
-  const replacer = (matched: string) => `\\${matched}`;
+  const aheadReplacer = (matched: string) => `\\${matched}`;
+  const behindReplacer = (matched: string) => `${matched}\\`;
 
   let escapedText = text.replace(reSpaceMoreThanOne, ' ');
 
   if (reEscapeBackSlash.test(escapedText)) {
-    escapedText = escapedText.replace(reEscapeBackSlash, replacer);
+    escapedText = escapedText.replace(reEscapeBackSlash, aheadReplacer);
   }
 
-  escapedText = escapedText.replace(reEscapePairedChars, replacer);
+  if (reEscapeBackSlashInSentence.test(escapedText)) {
+    escapedText = escapedText.replace(reEscapeBackSlashInSentence, behindReplacer);
+  }
+
+  escapedText = escapedText.replace(reEscapePairedChars, aheadReplacer);
 
   if (reEscapeHTML.test(escapedText)) {
-    escapedText = escapedText.replace(reEscapeHTML, replacer);
+    escapedText = escapedText.replace(reEscapeHTML, aheadReplacer);
   }
 
   if (isNeedEscapeText(escapedText)) {
-    escapedText = escapedText.replace(reEscapeChars, replacer);
+    escapedText = escapedText.replace(reEscapeChars, aheadReplacer);
   }
 
   return escapedText;