Change design for endianness command line option

src/bin/hexyl.rs

@@ -205,12 +205,15 @@ fn run() -> Result<()> {
                 ),
         )
         .arg(
-            Arg::new("little_endian_dump")
+            Arg::new("endianness")
-                .short('e')
+                .long("endianness")
-                .action(ArgAction::SetTrue)
+                .requires("group_size")
+                .num_args(1)
+                .value_name("ENDIANNESS")
+                .value_parser(["big", "little"])
+                .default_value("big")
                 .help(
-                    "Print out the data in little endian format. Otherwise the data will be shown \
+                    "Whether to print out the data in little endian format or big endian format.",
-                    in big endian format by default.",
                 ),
         );
 
@@ -434,12 +437,10 @@ fn run() -> Result<()> {
         )
     };
 
-    let endianness = match *matches
+    let endianness = match matches.get_one::<String>("endianness").map(String::as_ref) {
-        .get_one::<bool>("little_endian_dump")
+        Some("little") => Endianness::Little,
-        .unwrap_or(&false)
+        Some("big") => Endianness::Big,
-    {
+        _ => unreachable!(),
-        true => Endianness::Little,
-        false => Endianness::Big,
     };
     let stdout = io::stdout();
     let mut stdout_lock = BufWriter::new(stdout.lock());

src/lib.rs

@@ -557,7 +557,7 @@ impl<'a, Writer: Write> Printer<'a, Writer> {
 
         if matches!(self.endianness, Endianness::Little) {
             // reorder the buffer to the little endian format
-            self.reorder_buf_to_le(&mut buf);
+            self.reorder_buf_to_little_endian(&mut buf);
         };
 
         for (i, &b) in buf.iter().enumerate() {

tests/integration_tests.rs

@@ -317,7 +317,7 @@ mod group_and_endianness {
             .arg("ascii")
             .arg("--color=never")
             .arg("--group-size=2")
-            .arg("-e")
+            .arg("--endianness=little")
             .assert()
             .success()
             .stdout(
@@ -348,7 +348,7 @@ mod group_and_endianness {
             .arg("ascii")
             .arg("--color=never")
             .arg("--group-size=4")
-            .arg("-e")
+            .arg("--endianness=little")
             .assert()
             .success()
             .stdout(
@@ -379,7 +379,7 @@ mod group_and_endianness {
             .arg("ascii")
             .arg("--color=never")
             .arg("--group-size=8")
-            .arg("-e")
+            .arg("--endianness=little")
             .assert()
             .success()
             .stdout(