format: add EscapeMarkdown

Author: tulir

format/markdown.go

@@ -8,6 +8,7 @@ package format
 
 import (
 	"fmt"
+	"regexp"
 	"strings"
 
 	"github.com/yuin/goldmark"
@@ -39,6 +40,15 @@ func UnwrapSingleParagraph(html string) string {
 	return html
 }
 
+var mdEscapeRegex = regexp.MustCompile("([\\\\`*_[\\]])")
+
+func EscapeMarkdown(text string) string {
+	text = mdEscapeRegex.ReplaceAllString(text, "\\$1")
+	text = strings.ReplaceAll(text, ">", ">")
+	text = strings.ReplaceAll(text, "<", "&lt;")
+	return text
+}
+
 func RenderMarkdownCustom(text string, renderer goldmark.Markdown) event.MessageEventContent {
 	var buf strings.Builder
 	err := renderer.Convert([]byte(text), &buf)