From 88f41f3072458f175e942b3195626232db8c4d57 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Tiago?= <joao.leal.tintas@tecnico.ulisboa.pt>
Date: Sun, 31 Mar 2024 17:01:15 +0100
Subject: [PATCH] Allow math expressions to be preceeded but not suceeded by
 alphanumerical characters
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Signed-off-by: João Tiago <joao.leal.tintas@tecnico.ulisboa.pt>
---
 modules/markup/markdown/markdown_test.go      | 6 +++---
 modules/markup/markdown/math/inline_parser.go | 8 ++++++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/modules/markup/markdown/markdown_test.go b/modules/markup/markdown/markdown_test.go
index 808c7c4e69b57..bfc44728d4fa3 100644
--- a/modules/markup/markdown/markdown_test.go
+++ b/modules/markup/markdown/markdown_test.go
@@ -509,7 +509,7 @@ func TestMathBlock(t *testing.T) {
 		},
 		{
 			`$a a$b b$`,
-			`<p><code class="language-math is-loading">a a</code>b b$</p>` + nl,
+			`<p>$a a<code class="language-math is-loading">b b</code></p>` + nl,
 		},
 		{
 			`a a$b b`,
@@ -517,7 +517,7 @@ func TestMathBlock(t *testing.T) {
 		},
 		{
 			`a$b $a a$b b$`,
-			`<p>a<code class="language-math is-loading">b </code>a a<code class="language-math is-loading">b b</code></p>` + nl,
+			`<p>a$b $a a<code class="language-math is-loading">b b</code></p>` + nl,
 		},
 		{
 			"a$x$",
@@ -525,7 +525,7 @@ func TestMathBlock(t *testing.T) {
 		},
 		{
 			"$x$a",
-			`<p><code class="language-math is-loading">x</code>a</p>` + nl,
+			`<p>$x$a</p>` + nl,
 		},
 		{
 			"$$a$$",
diff --git a/modules/markup/markdown/math/inline_parser.go b/modules/markup/markdown/math/inline_parser.go
index 42c4996668bc5..09fcd45ffdbd1 100644
--- a/modules/markup/markdown/math/inline_parser.go
+++ b/modules/markup/markdown/math/inline_parser.go
@@ -41,6 +41,11 @@ func (parser *inlineParser) Trigger() []byte {
 	return parser.start[0:1]
 }
 
+func isAlphanumeric(b byte) bool {
+	// Github only cares about 0-9A-Za-z
+	return (b >= '0' && b <= '9') || (b >= 'A' && b <= 'Z') || (b >= 'a' && b <= 'z')
+}
+
 // Parse parses the current line and returns a result of parsing.
 func (parser *inlineParser) Parse(parent ast.Node, block text.Reader, pc parser.Context) ast.Node {
 	line, _ := block.PeekLine()
@@ -69,6 +74,9 @@ func (parser *inlineParser) Parse(parent ast.Node, block text.Reader, pc parser.
 		if len(line) <= pos {
 			break
 		}
+		if isAlphanumeric(line[pos]) {
+			return nil
+		}
 		if line[ender-1] != '\\' {
 			break
 		}