bin: clean up toydump command

src/bin/toydump.rs

@@ -1,38 +1,50 @@
 //! toydump is a debug tool that prints a toyDB BitCask database in
-//! human-readable form. It only prints live BitCask data, not garbage entries.
+//! human-readable form. It can print both the SQL database, and the Raft log
+//! (via --raft). It only outputs live BitCask data, not garbage entries.
+
 #![warn(clippy::all)]
 
 use toydb::encoding::format::{self, Formatter as _};
 use toydb::error::Result;
 use toydb::storage::{BitCask, Engine as _};
 
-fn main() -> Result<()> {
-    let args = clap::command!()
-        .about("Prints toyDB file contents in human-readable form.")
-        .args([
-            clap::Arg::new("raft")
-                .long("raft")
-                .num_args(0)
-                .help("file is a Raft log, not SQL database"),
-            clap::Arg::new("raw").long("raw").num_args(0).help("also show raw key/value"),
-            clap::Arg::new("file").required(true),
-        ])
-        .get_matches();
-    let raft: bool = *args.get_one("raft").unwrap();
-    let raw: bool = *args.get_one("raw").unwrap();
-    let file: &String = args.get_one("file").unwrap();
+use clap::Parser as _;
+
+fn main() {
+    if let Err(error) = Command::parse().run() {
+        eprintln!("Error: {error}")
+    }
+}
+
+/// The toydump command.
+#[derive(clap::Parser)]
+#[command(about = "Prints toyDB file contents.", version, propagate_version = true)]
+struct Command {
+    /// The BitCask file to dump (SQL database unless --raft).
+    file: String,
+    /// The file is a Raft log, not SQL database.
+    #[arg(long)]
+    raft: bool,
+    /// Also show raw key and value.
+    #[arg(long)]
+    raw: bool,
+}
 
-    let mut engine = BitCask::new(file.into())?;
-    let mut scan = engine.scan(..);
-    while let Some((key, value)) = scan.next().transpose()? {
-        let mut string = match raft {
-            true => format::Raft::<format::SQLCommand>::key_value(&key, &value),
-            false => format::MVCC::<format::SQL>::key_value(&key, &value),
-        };
-        if raw {
-            string = format!("{string} [{}]", format::Raw::key_value(&key, &value))
+impl Command {
+    /// Runs the command.
+    fn run(self) -> Result<()> {
+        let mut engine = BitCask::new(self.file.into())?;
+        let mut scan = engine.scan(..);
+        while let Some((key, value)) = scan.next().transpose()? {
+            let mut string = match self.raft {
+                true => format::Raft::<format::SQLCommand>::key_value(&key, &value),
+                false => format::MVCC::<format::SQL>::key_value(&key, &value),
+            };
+            if self.raw {
+                string = format!("{string} [{}]", format::Raw::key_value(&key, &value))
+            }
+            println!("{string}");
         }
-        println!("{string}");
+        Ok(())
     }
-    Ok(())
 }