Use clap-derive to simplify commandline arguments parsing.

This patch is intended to use clap-derive to parse commandline
arguments. This helps improve code readability and make it more
extensible.

Cargo.toml

@@ -7,7 +7,7 @@ build = "build.rs"
 
 [dependencies]
 anyhow = "1.0.94"
-clap = "4.5.23"
+clap = { version = "4.5.23", features = ["derive"] }
 daemonize = "0.5.0"
 log = "0.4.22"
 wayrs-client = "1.1.3"

src/main.rs

@@ -7,7 +7,7 @@ mod clipboard;
 mod protocol;
 
 use anyhow::{Context, Result};
-use clap::{value_parser, Arg, ArgMatches, Command};
+use clap::{Parser, Subcommand};
 use daemonize::Daemonize;
 use std::env;
 use std::fs::File;
@@ -32,73 +32,47 @@ fn choose_backend() -> Backend {
     std::process::exit(1)
 }
 
-fn cli() -> Command {
-    Command::new("richclip")
-        .about("A fictional versioning CLI")
-        .subcommand_required(true)
-        .arg_required_else_help(true)
-        .subcommand(
-            Command::new("copy")
-            .about("Receive and copy data to the clipboard")
-            .arg(
-                    Arg::new("primary")
-                        .long("primary")
-                        .short('p')
-                        .required(false)
-                        .num_args(0)
-                        .help("Use the 'primary' clipboard")
-                )
-            .arg(
-                    Arg::new("foreground")
-                        .long("foreground")
-                        .required(false)
-                        .num_args(0)
-                        .help("Run in foreground")
-                )
-            .arg(
-                    Arg::new("chunk-size")
-                        .long("chunk-size")
-                        .value_parser(value_parser!(usize))
-                        .default_value("0")
-                        .required(false)
-                        .hide(true)
-                        .num_args(1)
-                        .help("For testing X INCR mode")
-                )
-        )
-        .subcommand(
-            Command::new("paste")
-                .about("Paste the data from clipboard to the output")
-                .arg(
-                    Arg::new("list-types")
-                        .long("list-types")
-                        .short('l')
-                        .required(false)
-                        .num_args(0)
-                        .help("List the offered mime-types of the current clipboard only without the contents")
-                )
-                .arg(
-                    Arg::new("type")
-                        .long("type")
-                        .short('t')
-                        .value_name("mime-type")
-                        .required(false)
-                        .num_args(1)
-                        .help("Specify the preferred mime-type to be pasted")
-                )
-                .arg(
-                    Arg::new("primary")
-                        .long("primary")
-                        .short('p')
-                        .required(false)
-                        .num_args(0)
-                        .help("Use the 'primary' clipboard")
-                ),
-        )
-        .subcommand(
-                Command::new("version")
-                .about("Print version info")
-        )
+/// A fictional versioning CLI
+#[derive(Parser)]
+struct Cli {
+    #[command(subcommand)]
+    command: Commands,
+}
+
+#[derive(Subcommand)]
+enum Commands {
+    /// Receive and copy data to the clipboard
+    Copy {
+        /// Use the 'primary' clipboard
+        #[arg(long = "primary", short = 'p', num_args = 0)]
+        primary: bool,
+        /// Run in foreground
+        #[arg(long = "foreground", num_args = 0)]
+        foreground: bool,
+        /// For testing X INCR mode
+        #[arg(
+            long = "chunk-size",
+            hide = true,
+            required = false,
+            num_args = 1,
+            default_value = "0"
+        )]
+        chunk_size: usize,
+    },
+    /// Paste the data from clipboard to the output
+    Paste {
+        /// List the offered mime-types of the current clipboard only without the contents
+        #[arg(long = "list-types", short = 'l', num_args = 0)]
+        list_types: bool,
+        /// Specify the preferred mime-type to be pasted
+        #[arg(long = "type", short = 't', value_name = "mime-type", num_args = 1)]
+        type_: Option<String>,
+        /// Use the 'primary' clipboard
+        #[arg(long = "primary", short = 'p', num_args = 0)]
+        primary: bool,
+    },
+    /// Print version info
+    Version,
 }
 
 fn init_logger() -> Result<()> {
@@ -135,33 +109,34 @@ fn init_logger() -> Result<()> {
 fn main() -> Result<()> {
     init_logger()?;
 
-    let matches = cli().get_matches();
-    match matches.subcommand() {
-        Some(("copy", sub_matches)) => {
-            do_copy(sub_matches)?;
-        }
-        Some(("paste", sub_matches)) => {
-            do_paste(sub_matches)?;
-        }
-        Some(("version", _)) => {
+    let cli = Cli::parse();
+
+    match cli.command {
+        Commands::Copy {
+            primary,
+            foreground,
+            chunk_size,
+        } => do_copy(primary, foreground, chunk_size)?,
+        Commands::Paste {
+            list_types,
+            type_,
+            primary,
+        } => do_paste(&type_.unwrap_or("".to_string()), list_types, primary)?,
+        Commands::Version => {
             let ver = env!("CARGO_PKG_VERSION");
             let git_desc = env!("VERGEN_GIT_DESCRIBE");
             let build_date = env!("VERGEN_BUILD_DATE");
             let target = env!("VERGEN_CARGO_TARGET_TRIPLE");
             println!("richclip {ver} ({git_desc} {target} {build_date})");
         }
-        _ => unreachable!(),
     }
 
     Ok(())
 }
 
-fn do_copy(arg_matches: &ArgMatches) -> Result<()> {
+fn do_copy(primary: bool, foreground: bool, chunk_size: usize) -> Result<()> {
     let stdin = stdin();
     let source_data = protocol::receive_data(&stdin).context("Failed to read data from stdin")?;
-    let foreground = *arg_matches
-        .get_one::<bool>("foreground")
-        .context("`--foreground` option is not specified for the `copy` command")?;
 
     // Move to background. We fork our process and leave the child running in the background, while
     // exiting in the parent. We also replace stdin/stdout with /dev/null so the stdout file
@@ -184,12 +159,8 @@ fn do_copy(arg_matches: &ArgMatches) -> Result<()> {
 
     let copy_config = clipboard::CopyConfig {
         source_data,
-        use_primary: *arg_matches
-            .get_one::<bool>("primary")
-            .context("`--primary` option is not specified for the `copy` command")?,
-        x_chunk_size: *arg_matches
-            .get_one::<usize>("chunk-size")
-            .context("`--chunk-size` option is not specified for the `copy` command")?,
+        use_primary: primary,
+        x_chunk_size: chunk_size,
     };
     match choose_backend() {
         Backend::Wayland => {
@@ -199,20 +170,12 @@ fn do_copy(arg_matches: &ArgMatches) -> Result<()> {
     }
 }
 
-fn do_paste(arg_matches: &ArgMatches) -> Result<()> {
-    let t = match arg_matches.get_one::<String>("type") {
-        Some(t) => t,
-        _ => "",
-    };
+fn do_paste(mime_type: &str, list_types: bool, primary: bool) -> Result<()> {
     let cfg = clipboard::PasteConfig {
-        list_types_only: *arg_matches
-            .get_one::<bool>("list-types")
-            .context("`--list-types` option is not specified for the `paste` command")?,
-        use_primary: *arg_matches
-            .get_one::<bool>("primary")
-            .context("`--primary` option is not specified for the `paste` command")?,
+        list_types_only: list_types,
+        use_primary: primary,
         writter: &mut stdout(),
-        expected_mime_type: t.to_string(),
+        expected_mime_type: mime_type.to_string(),
     };
     match choose_backend() {
         Backend::Wayland => {