refactor: Extract get_max_lineno free function

Author: chengr4

src/renderer/display_list.rs

@@ -72,12 +72,7 @@ impl<'a> fmt::Debug for DisplayList<'a> {
 
 impl<'a> Display for DisplayList<'a> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let max_lineno = self.body.iter().fold(None, |max, set| {
-            set.display_lines.iter().fold(max, |max, line| match line {
-                DisplayLine::Source { lineno, .. } => std::cmp::max(max, *lineno),
-                _ => max,
-            })
-        });
+        let max_lineno = get_max_lineno(&self.body);
         let lineno_width = match max_lineno {
             None => 0,
             Some(_max) if self.anonymized_line_numbers => ANONYMIZED_LINE_NUM.len(),
@@ -149,6 +144,16 @@ impl<'a> DisplayList<'a> {
     }
 }
 
+fn get_max_lineno(body: &[DisplaySet<'_>]) -> Option<usize> {
+    let max_lineno = body.iter().fold(None, |max, set| {
+        set.display_lines.iter().fold(max, |max, line| match line {
+            DisplayLine::Source { lineno, .. } => cmp::max(max, *lineno),
+            _ => max,
+        })
+    });
+    max_lineno
+}
+
 #[derive(Debug, PartialEq)]
 pub(crate) struct DisplaySet<'a> {
     pub(crate) display_lines: Vec<DisplayLine<'a>>,