Implement autocompletion generation

src/completions.rs

@@ -0,0 +1,11 @@
+use std::{io, str::FromStr};
+
+use crate::BoxResult;
+use structopt::clap::{App, Shell};
+
+/// Generates and outputs shell completion script for `rmob` for specific shell: bash, zsh, etc.
+pub(crate) fn generate(app: &mut App, shell: &str) -> BoxResult<()> {
+    let shell = Shell::from_str(shell)?;
+    app.gen_completions_to("rmob", shell, &mut io::stdout());
+    Ok(())
+}

src/lib.rs

@@ -9,6 +9,7 @@ use git2::Repository;
 use structopt::StructOpt;
 
 mod active_copirate;
+mod completions;
 mod copirate;
 mod embark;
 mod prepare_commit_msg;
@@ -64,6 +65,9 @@ enum Command {
         #[structopt(subcommand)]
         cmd: CopirateSubcommand,
     },
+    /// Generates autocompletion config for shell
+    #[structopt(name = "generate-shell-completions")]
+    GenerateShellCompletions { shell: String },
     /// Called from the git hook only
     #[structopt(name = "prepare-commit-msg")]
     PrepareCommitMessage {
@@ -97,6 +101,9 @@ pub fn run() -> BoxResult<()> {
                 }
             };
         }
+        Command::GenerateShellCompletions { ref shell } => {
+            completions::generate(&mut Rmob::clap(), shell)?
+        }
 
         Command::PrepareCommitMessage {
             commit_message_file,