Refactor MarkupExporter to omit intermediate table result creation and simplify MarkupFormatter emitting

* see: https://github.com/sharkdp/hyperfine/pull/490#pullrequestreview-932424652

src/export/markdown.rs

@@ -37,13 +37,7 @@ impl Exporter for MarkdownExporter {
         }
 
         let formatter = MarkdownFormatter::default();
-        let data_vvs = formatter.results(&entries.unwrap(), unit);
-        let data_vas: Vec<Vec<&str>> = data_vvs
-            .iter()
-            .map(|list| list.iter().map(AsRef::as_ref).collect::<Vec<&str>>())
-            .collect();
-        let data: Vec<&[&str]> = data_vas.iter().map(AsRef::as_ref).collect();
-        let table = formatter.table(&data);
+        let table = formatter.table_results(&entries.unwrap(), unit);
         Ok(table.as_bytes().to_vec())
     }
 }

src/export/markup.rs

@@ -3,45 +3,23 @@ use crate::output::format::format_duration_value;
 use crate::util::units::Unit;
 
 pub trait MarkupFormatter {
-    fn table(&self, data: &[&[&str]]) -> String {
-        let head: &[&str] = data.first().unwrap();
-        let tail = &data[1..];
+    fn table_results(&self, entries: &[BenchmarkResultWithRelativeSpeed], unit: Unit) -> String {
+        // prepare table header strings
+        let notation = format!("[{}]", unit.short_name());
+        let head: [&str; 5] = [
+            "Command",
+            &format!("Mean {}", notation),
+            &format!("Min {}", notation),
+            &format!("Max {}", notation),
+            "Relative",
+        ];
 
         // emit header
-        let table = &mut self.table_data(head);
+        let mut table = self.table_data(&head);
 
         // emit horizontal line
         table.push_str(&self.table_line(head.len()));
 
-        // emit data rows
-        for row in tail {
-            table.push_str(&self.table_data(row))
-        }
-
-        table.to_string()
-    }
-
-    fn table_data(&self, data: &[&str]) -> String;
-
-    fn table_line(&self, size: usize) -> String;
-
-    fn command(&self, size: &str) -> String;
-
-    fn results(
-        &self,
-        entries: &[BenchmarkResultWithRelativeSpeed],
-        unit: Unit,
-    ) -> Vec<Vec<String>> {
-        // prepare table header strings
-        let notation = format!("[{}]", unit.short_name());
-        let mut data: Vec<Vec<_>> = vec![vec![
-            "Command".to_string(),
-            format!("Mean {}", notation),
-            format!("Min {}", notation),
-            format!("Max {}", notation),
-            "Relative".to_string(),
-        ]];
-
         for entry in entries {
             let measurement = &entry.result;
             // prepare data row strings
@@ -63,15 +41,22 @@ pub trait MarkupFormatter {
                 "".into()
             };
             // prepare table row entries
-            data.push(vec![
-                self.command(&cmd_str),
-                format!("{}{}", mean_str, stddev_str),
-                min_str,
-                max_str,
-                format!("{}{}", rel_str, rel_stddev_str),
-            ])
+            let data: [&str; 5] = [
+                &self.command(&cmd_str),
+                &format!("{}{}", mean_str, stddev_str),
+                &min_str,
+                &max_str,
+                &format!("{}{}", rel_str, rel_stddev_str),
+            ];
+            table.push_str(&self.table_data(&data))
         }
 
-        data
+        table
     }
+
+    fn table_data(&self, data: &[&str]) -> String;
+
+    fn table_line(&self, size: usize) -> String;
+
+    fn command(&self, size: &str) -> String;
 }