50 add shell completion

Cargo.toml

@@ -37,3 +37,4 @@ clap = { version = "3.1.9", features = ["derive", "env", "wrap_help"] }
 clap-verbosity-flag = "1.0.0"
 
 clap_mangen = "0.1.3"
+clap_complete = "3.1.1"

build.rs

@@ -11,8 +11,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use crate::cli::Cli;
 use clap::CommandFactory;
-use std::{env, fs, io, path};
+use clap_complete::{generate_to, Shell};
+use clap_mangen::Man;
+use std::path::Path;
+use std::{env, fs, io, path::PathBuf};
 
 #[path = "src/cli.rs"]
 mod cli;
@@ -22,14 +26,34 @@ mod cli;
 fn main() -> io::Result<()> {
     println!("cargo:rerun-if-changed=src/cli.rs");
 
-    let out_dir = path::PathBuf::from(env::var_os("OUT_DIR").ok_or(io::ErrorKind::NotFound)?);
-    let cmd = cli::Cli::command();
+    let out_dir = PathBuf::from(env::var_os("OUT_DIR").ok_or(io::ErrorKind::NotFound)?);
 
-    let man = clap_mangen::Man::new(cmd);
+    generate_man(&out_dir)?;
+    generate_completion(&out_dir)?;
+
+    Ok(())
+}
+
+fn generate_completion(out_dir: &Path) -> io::Result<()> {
+    // We generate Elvish shell completion for anyone who wants to manually install it,
+    // but Homebrew is unable to install Elvish shell completion.
+    let shells = &[Shell::Bash, Shell::Elvish, Shell::Fish, Shell::Zsh];
+
+    for shell in shells {
+        let mut cmd = Cli::command();
+        generate_to(*shell, &mut cmd, "xshe", out_dir)?;
+    }
+    Ok(())
+}
+
+fn generate_man(out_dir: &Path) -> io::Result<()> {
+    let cmd = Cli::command();
+
+    // Generate Man File
+    let man = Man::new(cmd);
     let mut buffer: Vec<u8> = Default::default();
     man.render(&mut buffer)?;
 
     fs::write(out_dir.join("xshe.1"), buffer)?;
-
     Ok(())
 }