Implement basic --parameter-list with naive list parsing

src/hyperfine/app.rs

@@ -129,6 +129,21 @@ fn build_app() -> App<'static, 'static> {
                      This performs benchmarks for 'sleep 0.3', 'sleep 0.5' and 'sleep 0.7'.",
                 ),
         )
+        .arg(
+            Arg::with_name("parameter-list")
+                .long("parameter-list")
+                .short("L")
+                .takes_value(true)
+                .allow_hyphen_values(true)
+                .value_names(&["VAR", "VALUES"])
+                .conflicts_with("parameter-scan")
+                .help(
+                    "Perform benchmark runs for each value in the comma-seperated list VALUES. \
+                     Replaces the string '{VAR}' in each command by the current parameter value\
+                     .\n\nExample:  hyperfine -L threads 1,2,4 'make -j {threads}'\n\n\
+                     This performs benchmarks for 'make -j 1', 'make -j 2', and 'make -j 4'.",
+                ),
+        )
         .arg(
             Arg::with_name("style")
                 .long("style")

src/main.rs

@@ -208,6 +208,22 @@ fn build_commands<'a>(matches: &'a ArgMatches<'_>) -> Vec<Command<'a>> {
             Ok(commands) => commands,
             Err(e) => error(e.description()),
         }
+    } else if let Some(mut args) = matches.values_of("parameter-list") {
+        let param_name = args.next().unwrap();
+        let param_list_str = args.next().unwrap();
+
+        let param_list = param_list_str.split(',').collect::<Vec<&str>>();
+        let command_list = command_strings.collect::<Vec<&str>>();
+
+        let mut commands = Vec::with_capacity(param_list.len() * command_list.len());
+
+        for value in param_list {
+            for cmd in &command_list {
+                commands.push(Command::new_parametrized(cmd, param_name, value.to_string()));
+            }
+        }
+
+        commands
     } else {
         command_strings.map(Command::new).collect()
     }