bash completion for helmsman commands

[rrthomas]

The following code provides bash completion for helmsman commands whose sub-commands are "reasonable" (e.g. use commander):

# Parse helmsman top-level help output
# @param $1  command; if "-", read from stdin and ignore rest of args
# @param $2  command options (default: --help)
#
_parse_helmsman_subcommands ()
{
    eval local cmd=$( quote "$1" )

    local line IFS=''
    LC_ALL=C "$( dequote "$cmd" )" ${2:---help} 2>&1 \
    | while read -r line; do
    [[ $line == @(   )* ]] || continue
    if [[ $line =~ ([A-Za-z][-A-Za-z0-9]*) ]]; then
        printf '%s ' "${BASH_REMATCH[1]}"
    fi
    done
}

# Parse helmsman help output
# Assumes that subcommands accept --help and can be parsed with _parse_help
# @param $1  command; if "-", read from stdin and ignore rest of args
# @param $2  command options (default: --help)
#
_parse_helmsman ()
{
    eval local cmd=$( quote "$1" )
    local cur dashoptions prev i

    COMPREPLY=()
    _get_comp_words_by_ref cur prev

    dashoptions='--help'
    commands=( $(_parse_helmsman_subcommands "$( dequote "$cmd" )") )

    if [[ "$prev" == "$( dequote "$cmd" )" ]]; then
    # Complete subcommand or top-level option
    if [[ "$cur" == -* ]]; then
        COMPREPLY=( $( compgen -W "$dashoptions" -- "$cur" ) )
    else
        COMPREPLY=( $( for command in "${commands[@]}"; do
            [[ ${command:0:${#cur}} == "$cur" ]] && printf '%s\n' $command
            done ) )
    fi
    else # Complete subcommand option or argument
    for command in "${commands[@]}"; do
        if [[ "$command" == "$prev" ]]; then
        COMPREPLY=( $( compgen -W '$( _parse_help "$( dequote "$cmd" )" "$prev --help")' -- "$cur" ) )
        fi
    done
    # If no option found, complete filenames
    [[ ${#COMPREPLY[@]} -eq 0 ]] && _filedir
    fi

    return 0
}

With this in place, one can say, e.g.: complete -F _parse_helmsman foo, where foo is a command written with helmsman, to get completion on subcommand names and options.

I'm not quite sure what the best thing to do with this code is. I just put it in my ~/.bash_completion, but I guess ideally it would go as a file in /usr/share/bash-completion/helpers. It's hard to see how helmsman itself could install that though…You could simply provide it as a file which can be copied (or whose contents can be copied and pasted) at will.