GoLang bash completion

golang_completion.sh

#!/usr/bin/env bash

function _comp_go-subcmd() {
	local cmd=${1:?"cmd is required"}
	local cur=${COMP_WORDS[COMP_CWORD]}

	# try find completion for cmd options
	if _comp_go-subcmd-opts "${cmd}"; then
		return 0
	fi

	# checking empty here make sure that file paths don't bloat when opts wanted to be checked
	if [[ -n ${cur} ]]; then
		_comp_go-subcmd-dirs "${cur}"
		return 0
	fi
}

function _comp_go-subcmd-opts() {
	local cmd=${1:?"cmd is required"}
	local cur=${COMP_WORDS[COMP_CWORD]}
	local prev=${COMP_WORDS[COMP_CWORD - 1]}
	local curRGX=$(CUR="${cur}" perl -e 'print quotemeta($ENV{"CUR"})')

	# option completion
	case ${prev} in
		"-mod")
			COMPREPLY+=($(compgen -W "readonly vendor" -- ${cur}))
			return 0
			;;
		"-count")
			COMPREPLY+=($(compgen -W "1" -- ${cur}))
			return 0
			;;
	esac

	case ${cmd} in
		"test" | "build") COMPREPLY+=($(compgen -W "-mod" -- ${cur})) ;;
	esac

	# option listing
	local opts=$(
		(
			case ${cmd} in
				"test") go doc go/internal/test.HelpTestflag | grep -e '^[[:space:]]*-' ;;
				*) go help "${cmd}" ;;
			esac
		) \
			| perl -n -l -e 'print $1 if /\s+(-\w+)/;' \
			| grep -P -e "^${curRGX}" \
			| sort \
			| uniq
	)

	local opt
	for opt in ${opts[@]}; do
		COMPREPLY+=("${opt}")
	done

	if [[ ${cur} == -* ]]; then
		return 0
	fi

	return 64
}

function _comp_go-subcmd-dirs() {
	local cur=${1:?"current dir path is required"}

	if [[ -d ${cur} ]] && [[ ${cur} == */. ]]; then
		COMPREPLY+=("${cur%/.}/...")
		return 0
	fi

	local -a dirs
	readarray -t dirs < <(compgen -d "${cur}")

	local d
	for d in ${dirs[@]}; do
		COMPREPLY+=("${d}/")
		COMPREPLY+=("${d}/...")
	done
}

function _comp_go-cmds() {
	local cur=${COMP_WORDS[COMP_CWORD]}
	local curRGX=$(CUR="${cur}" perl -e 'print quotemeta($ENV{"CUR"})')

	local kws=$(
		go help \
			| grep -B 128 -F -e 'go help <command>' \
			| perl -n -l -e 'print $1 if /^\t(\w+)/;' \
			| grep -P -e "^${curRGX}"
	)

	local kw
	for kw in ${kws[@]}; do
		COMPREPLY+=("${kw}")
	done
}

function _comp_go() {
	local cur=${COMP_WORDS[COMP_CWORD]}
	local subcmd=${COMP_WORDS[1]}

	# go help [cur]
	if [[ ${subcmd} == "help" ]]; then
		_comp_go-cmds
		return
	fi

	if [[ ${COMP_CWORD} -eq 1 ]]; then
		_comp_go-cmds
		return
	fi

	_comp_go-subcmd "${subcmd}"
}

complete -F _comp_go go

gives auto-completion for

• sub commands
• sub command options
• certain sub command option parameters
• sub command paths
  • directories
  • ...