Tab Completion Modules?

[robertdfrench]

How does tab completion work, and can we support it? RipGrep uses clap to automatically generate tab completion files for some shells:

    // Use clap to build completion files.
    let mut app = app::app();
    app.gen_completions("rg", Shell::Bash, &outdir);
    app.gen_completions("rg", Shell::Fish, &outdir);
    app.gen_completions("rg", Shell::PowerShell, &outdir);
    // Note that we do not use clap's support for zsh. Instead, zsh completions
    // are manually maintained in `complete/_rg`.

Zsh-specific

• Completion crash-course for RipGrep devs: https://github.com/BurntSushi/ripgrep/blob/master/complete/_rg#L443
• Official docs: http://zsh.sourceforge.net/Doc/Release/Completion-System.html
• Community style-guide: https://github.com/zsh-users/zsh/blob/master/Etc/completion-style-guide

[robertdfrench]

58 hints at unifying the subcommands into a single binary, which would make clap-generated tab completion much easier.