Impl generate-completion subcommand

Cargo.toml

@@ -43,6 +43,7 @@ unicode-segmentation = "1.10.1"
 unicode-width = "0.1.10"
 vte = "0.11.0"
 xdg = "2.4.1"
+clap_complete = "4.4.4"
 
 [dependencies.git2]
 version = "0.17.2"

src/cli.rs

@@ -4,6 +4,7 @@ use std::path::{Path, PathBuf};
 
 use bat::assets::HighlightingAssets;
 use clap::{ColorChoice, CommandFactory, FromArgMatches, Parser};
+use clap_complete::Shell;
 use lazy_static::lazy_static;
 use syntect::highlighting::Theme as SyntaxTheme;
 use syntect::parsing::SyntaxSet;
@@ -390,6 +391,10 @@ pub struct Opt {
     /// Sed-style command transforming file paths for display.
     pub file_regex_replacement: Option<String>,
 
+    #[arg(long = "generate-completion")]
+    /// Print completion file for the given shell.
+    pub generate_completion: Option<Shell>,
+
     #[arg(long = "grep-context-line-style", value_name = "STYLE")]
     /// Style string for non-matching lines of grep output.
     ///
@@ -1194,6 +1199,7 @@ impl Opt {
 // pseudo-flag commands such as --list-languages
 lazy_static! {
     static ref IGNORED_OPTION_NAMES: HashSet<&'static str> = vec![
+        "generate-completion",
         "list-languages",
         "list-syntax-themes",
         "show-config",

src/main.rs

@@ -82,7 +82,11 @@ fn run_app() -> std::io::Result<i32> {
         assets,
     );
 
-    let subcommand_result = if opt.list_languages {
+    let subcommand_result = if let Some(shell) = opt.generate_completion {
+        Some(subcommands::generate_completion::generate_completion_file(
+            shell,
+        ))
+    } else if opt.list_languages {
         Some(list_languages())
     } else if opt.list_syntax_themes {
         Some(subcommands::list_syntax_themes::list_syntax_themes())

src/subcommands/generate_completion.rs

@@ -0,0 +1,11 @@
+use clap::CommandFactory;
+use clap_complete::{generate, Shell};
+
+use crate::cli;
+
+pub fn generate_completion_file(shell: Shell) -> std::io::Result<()> {
+    let mut cmd = cli::Opt::command();
+    let bin_name = cmd.get_bin_name().unwrap_or(cmd.get_name()).to_string();
+    generate(shell, &mut cmd, bin_name, &mut std::io::stdout());
+    Ok(())
+}

src/subcommands/mod.rs

@@ -1,4 +1,5 @@
 pub mod diff;
+pub mod generate_completion;
 pub mod list_syntax_themes;
 pub mod parse_ansi;
 mod sample_diff;