From d501ece24776ac85f0ba79252a7f37ac5b6bfbc9 Mon Sep 17 00:00:00 2001
From: Hwang In Tak <sp301415@gmail.com>
Date: Wed, 25 Sep 2024 02:15:53 +0900
Subject: [PATCH] fix: Fix KaTeX corner cases

---
 src/lib/utils/marked/katex-extension.ts | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/lib/utils/marked/katex-extension.ts b/src/lib/utils/marked/katex-extension.ts
index e99fcad31..5bde32c54 100644
--- a/src/lib/utils/marked/katex-extension.ts
+++ b/src/lib/utils/marked/katex-extension.ts
@@ -1,14 +1,13 @@
 import katex from 'katex';
 
 const DELIMITER_LIST = [
-	{ left: '$$\n', right: '\n$$', display: true },
-	{ left: '$$', right: '$$', display: false }, // This should be on top to prevent conflict with $ delimiter
+	{ left: '$$', right: '$$', display: true },
 	{ left: '$', right: '$', display: false },
 	{ left: '\\pu{', right: '}', display: false },
 	{ left: '\\ce{', right: '}', display: false },
 	{ left: '\\(', right: '\\)', display: false },
-	{ left: '\\[\n', right: '\n\\]', display: true },
-	{ left: '\\[', right: '\\]', display: false }
+	{ left: '\\[', right: '\\]', display: true },
+	{ left: '\\begin{equation}', right: '\\end{equation}', display: true }
 ];
 
 // const DELIMITER_LIST = [
@@ -34,14 +33,18 @@ function generateRegexRules(delimiters) {
 		const escapedRight = escapeRegex(right);
 
 		if (!display) {
+			// For inline delimiters, we match everyting
 			inlinePatterns.push(`${escapedLeft}((?:\\\\[^]|[^\\\\])+?)${escapedRight}`);
 		} else {
-			blockPatterns.push(`${escapedLeft}((?:\\\\[^]|[^\\\\])+?)${escapedRight}`);
+			// Block delimiters doubles as inline delimiters when not followed by a newline
+			inlinePatterns.push(`${escapedLeft}(?!\\n)((?:\\\\[^]|[^\\\\])+?)(?!\\n)${escapedRight}`);
+			blockPatterns.push(`${escapedLeft}\\n((?:\\\\[^]|[^\\\\])+?)\\n${escapedRight}`);
 		}
 	});
 
-	const inlineRule = new RegExp(`^(${inlinePatterns.join('|')})(?=[\\s?!.,:？！。，：]|$)`, 'u');
-	const blockRule = new RegExp(`^(${blockPatterns.join('|')})(?=[\\s?!.,:？！。，：]|$)`, 'u');
+	// Math formulas can end in special characters
+	const inlineRule = new RegExp(`^(${inlinePatterns.join('|')})(?=[\\s?。，!-\/:-@[-\`{-~]|$)`, 'u');
+	const blockRule = new RegExp(`^(${blockPatterns.join('|')})(?=[\\s?。，!-\/:-@[-\`{-~]|$)`, 'u');
 
 	return { inlineRule, blockRule };
 }
@@ -51,8 +54,8 @@ const { inlineRule, blockRule } = generateRegexRules(DELIMITER_LIST);
 export default function (options = {}) {
 	return {
 		extensions: [
-			blockKatex(options), // This should be on top to prevent conflict with inline delimiters.
-			inlineKatex(options)
+			inlineKatex(options),
+			blockKatex(options),
 		]
 	};
 }
@@ -86,7 +89,9 @@ function katexStart(src, displayMode: boolean) {
 			return;
 		}
 
-		const f = index === 0 || indexSrc.charAt(index - 1) === ' ';
+		// Check if the delimiter is preceded by a special character.
+		// If it does, then it's potentially a math formula.
+		const f = index === 0 || indexSrc.charAt(index - 1).match(/[\s?。，!-\/:-@[-`{-~]/);
 		if (f) {
 			const possibleKatex = indexSrc.substring(index);