Allow user to generate the man page (#108)

Author: RossSmyth

Cargo.lock

@@ -14,3 +14,4 @@ xdg = "2.5.2"
 bitcode = "0.6.6"
 log = "0.4.27"
 env_logger = "0.11.8"
+clap_mangen = "0.2.28"

Cargo.toml

@@ -29,18 +29,22 @@
         pkgs.callPackage (
           {
             callPackage,
-            makeWrapper,
             nix,
             fzy,
             nix-index-unwrapped,
             rustPackages,
+            installShellFiles,
           }:
           let
             naersk-lib = callPackage naersk { };
           in
           naersk-lib.buildPackage {
             pname = "comma";
             src = self;
+
+            nativeBuildInputs = [
+              installShellFiles
+            ];
             overrideMain = _: {
               postPatch = ''
                 substituteInPlace ./src/main.rs \
@@ -67,6 +71,9 @@
                   "$out/etc/nushell/comma-command-not-found.nu" \
                   "$out/etc/fish/functions/comma-command-not-found.fish" \
                   --replace-fail "comma --ask" "$out/bin/comma --ask"
+
+                "$out/bin/comma" --mangen > comma.1
+                installManPage comma.1
               '';
             };
             checkInputs = [ rustPackages.clippy ];

flake.nix

@@ -247,6 +247,17 @@ fn main() -> ExitCode {
         }
     };
 
+    if args.mangen {
+        use clap::CommandFactory;
+        let man = clap_mangen::Man::new(Opt::command());
+
+        if let Err(err) = man.render(&mut std::io::stdout()) {
+            panic!("{}", err)
+        } else {
+            return ExitCode::SUCCESS
+        }
+    }
+
     if args.empty_cache {
         if let Some(ref mut cache) = cache {
             cache.empty();
@@ -373,6 +384,10 @@ fn main() -> ExitCode {
 #[derive(Parser)]
 #[clap(version = crate_version!(), trailing_var_arg = true)]
 struct Opt {
+    /// Generate the man page, then exit
+    #[clap(long, hide = true)]
+    mangen: bool,
+    
     /// Install the derivation containing the executable
     #[clap(short, long)]
     install: bool,
@@ -421,6 +436,6 @@ struct Opt {
     delete_entry: bool,
 
     /// Command to run
-    #[clap(required_unless_present_any = ["empty_cache"], name = "cmd")]
+    #[clap(required_unless_present_any = ["empty_cache", "mangen"], name = "cmd")]
     cmd: Vec<String>,
 }