Replace old method with new that is a little overcomplicated

markup/hr.go

@@ -0,0 +1,34 @@
+package markup
+
+import (
+	"unicode"
+)
+
+// MatchesHorizontalLine checks if the string can be interpreted as suitable for rendering as <hr/>.
+//
+// The rule is: if there are more than 4 characters "-" in the string, then make it a horizontal line.
+// Otherwise it is a paragraph (<p>).
+func MatchesHorizontalLine(line string) bool {
+	counter := 0
+
+	// Check initially that the symbol is "-". If it is not a "-", it is most likely a space or another character.
+	// With unicode.IsLetter() we can separate spaces and characters.
+	for _, ch := range line {
+		if ch == '-' {
+			counter++
+			continue
+		}
+		// If we bump into any other character (letter) in the line, it is immediately an incorrect horizontal line.
+		// There is no point in counting further, we end the loop.
+		if unicode.IsLetter(ch) {
+			counter = 0
+			break
+		}
+	}
+
+	if counter >= 4 {
+		return true
+	}
+
+	return false
+}

markup/lexer.go

@@ -235,7 +235,7 @@ normalState:
 	case startsWith("<="):
 		addParagraphIfNeeded()
 		addLine(parseTransclusion(line, state.name))
-	case line[:4] == "----":
+	case MatchesHorizontalLine(line):
 		addParagraphIfNeeded()
 		*ast = append(*ast, Line{id: -1, contents: "<hr/>"})
 	case MatchesImg(line):