cmd: add completion command

Add `bender completion` command that generates completion scripts
for common shells (bash, zsh, fish, ...) using clap's clap_complete
crate.

Cargo.toml

@@ -18,6 +18,7 @@ tokio = { version = "1.27", features = ["full"] }
 async-recursion = "1.0"
 
 clap = { version = "4.0", features = ["derive"] }
+clap_complete = "4.0"
 semver = { version = "1.0", features = ["serde"] }
 blake2 = "0.10"
 typed-arena = "2"

README.md

@@ -445,7 +445,7 @@ Calling update with the `--fetch/-f` flag will force all git dependencies to be
 
 ### `clone` --- Clone dependency to make modifications
 
-The `bender clone <PKG>` command checks out the package `PKG` into a directory (default `working_dir`, can be overridden with `-p / --path <DIR>`). 
+The `bender clone <PKG>` command checks out the package `PKG` into a directory (default `working_dir`, can be overridden with `-p / --path <DIR>`).
 To ensure the package is correctly linked in bender, the `Bender.local` file is modified to include a `path` dependency override, linking to the corresponding package.
 
 This can be used for development of dependent packages within the parent repository, allowing to test uncommitted and committed changes, without the worry that bender would update the dependency.
@@ -535,6 +535,17 @@ This branch can then be rebased and a pull request can be opened from it as usua
 Note: when using mappings in your `vendor_package`, the patches will be relative to the mapped directory.
 Hence, for upstreaming, you might need to use `git am --directory=<mapping.from>` instead of plain `git am`.
 
+### `completion` --- Generate shell completion script
+
+The `bender completion <SHELL>` command prints a completion script for the given shell.
+
+Supported shells:
+- `bash`
+- `elvish`
+- `fish`
+- `powershell`
+- `zsh`
+
 [aur-bender]: https://aur.archlinux.org/packages/bender
 [releases]: https://github.com/pulp-platform/bender/releases
 [rust-installation]: https://doc.rust-lang.org/book/ch01-01-installation.html

src/cli.rs

@@ -77,6 +77,7 @@ pub fn main() -> Result<()> {
         .subcommand(cmd::clone::new())
         .subcommand(cmd::packages::new())
         .subcommand(cmd::sources::new())
+        .subcommand(cmd::completion::new())
         .subcommand(cmd::config::new())
         .subcommand(cmd::script::new())
         .subcommand(cmd::checkout::new())
@@ -99,7 +100,7 @@ pub fn main() -> Result<()> {
     };
 
     // Parse the arguments.
-    let matches = app.get_matches();
+    let matches = app.clone().get_matches();
 
     // Enable debug outputs if needed.
     if matches.contains_id("debug") && matches.get_flag("debug") {
@@ -110,6 +111,11 @@ pub fn main() -> Result<()> {
         return cmd::init::run(matches);
     }
 
+    if let Some(("completion", matches)) = matches.subcommand() {
+        let mut app = app;
+        return cmd::completion::run(matches, &mut app);
+    }
+
     let mut force_fetch = false;
     if let Some(("update", intern_matches)) = matches.subcommand() {
         force_fetch = intern_matches.get_flag("fetch");

src/cmd/completion.rs

@@ -0,0 +1,44 @@
+// Copyright (c) 2017-2024 ETH Zurich
+// Philipp Schilk <[email protected]>
+
+//! The `completion` subcommand.
+
+use std::io;
+
+use crate::error::*;
+use clap::{builder::PossibleValue, Arg, ArgMatches, Command};
+
+/// Assemble the `completion` subcommand.
+pub fn new() -> Command {
+    Command::new("completion")
+        .about("Emit shell completion script")
+        .arg(
+            Arg::new("completion_shell")
+                .help("Shell completion script style")
+                .required(true)
+                .num_args(1)
+                .value_name("SHELL")
+                .value_parser([
+                    PossibleValue::new("bash"),
+                    PossibleValue::new("elvish"),
+                    PossibleValue::new("fish"),
+                    PossibleValue::new("powershell"),
+                    PossibleValue::new("zsh"),
+                ]),
+        )
+}
+
+/// Execute the `completion` subcommand.
+pub fn run(matches: &ArgMatches, app: &mut Command) -> Result<()> {
+    let shell = matches.get_one::<String>("completion_shell").unwrap();
+    let shell = match shell.as_str() {
+        "bash" => clap_complete::Shell::Bash,
+        "elvish" => clap_complete::Shell::Elvish,
+        "fish" => clap_complete::Shell::Fish,
+        "powershell" => clap_complete::Shell::PowerShell,
+        "zsh" => clap_complete::Shell::Zsh,
+        _ => unreachable!(),
+    };
+    clap_complete::generate(shell, app, "bender", &mut io::stdout());
+    Ok(())
+}

src/cmd/mod.rs

@@ -9,6 +9,7 @@
 
 pub mod checkout;
 pub mod clone;
+pub mod completion;
 pub mod config;
 pub mod fusesoc;
 pub mod init;