modd-watch

#!/usr/bin/env bash
dk use: tty

dk.watch() {
	require-any modd dk use: golang
	require-any modd go install github.com/cortesi/modd/cmd/modd@0.8.1  # Need modd for this
	require-any tput  # for pager.watch

	# Trap SIGUSR1 to restart the watch with new configuration
	event quote "$@"
	trap "echo Configuration changed: restarting watch; echo; exec dk watch ""$REPLY" SIGUSR1

	export DEVKIT_PAGER=${DEVKIT_PAGER-pager.watch}     # Use the watch pager by default
	export DEVKIT_ISATTY=1; isatty || export DEVKIT_ISATTY=0   # modd has no pseudo-tty

	# Run modd with our current watch configuration, suppressing "killed" msg
	# via background job + wait
	modd -cf <(event emit modd_conf) "$@" </dev/null & wait $!
}

watch() {
	# Output the command line as part of the reflex config
	on modd_conf __put-watch 'prep +onchange:' "$@"
}
watch+ () {
	# Run the specified command at the start of watch, as well as on changes
	on modd_conf __put-watch 'prep:' "$@"
}

RELOAD_PATTERNS=()
UNWATCH_PATTERNS=()

watch-reload() {
	# Restart watch if given pattern matches
	export WATCH_PID=$$; RELOAD_PATTERNS+=("$@"); on modd_conf __reload-watch
}

unwatch() {
	# Globally exclude the given globs from all watch patterns
	UNWATCH_PATTERNS+=("${@/#/!}")
}

__reload-watch() {
	__put-watch 'prep +onchange:' "${RELOAD_PATTERNS[@]}" \
		-- bash -c 'kill -SIGUSR1 '$WATCH_PID'; kill -9 $PPID'
}

__put-watch() {
	# Output a reflex with global exclusion(s) added
	local m="$1" patterns command

	doubledash-split patterns command "${@:2}"
	! ((${#UNWATCH_PATTERNS[@]})) || patterns+=("${UNWATCH_PATTERNS[@]}")

	! ((${#patterns[@]})) || { pattern-quote "${patterns[@]}"; pattern=$REPLY; }
	! ((${#command[@]}))  || { event quote   "${command[@]}";  command=$REPLY; }

	printf '%s {\n\t%s %s\n}\n\n' "${pattern-}" "$m" "${command-}"
}

doubledash-split() {
	local __hd=$1 __tl=$2; shift 2; eval "$__hd=(); $__tl=()"
	while (($#)) && [[ $1 != -- ]]; do
		eval "$__hd"'+=("$1")'; shift
	done
	! (($#)) || shift
	eval "$__tl"'=("$@")'
}

pattern-quote() {
	# Quote patterns in such a way that modd will read them correctly
	local bs=\\ q='"' qq=\\'"'
	set -- "${@//$bs/$bs$bs}"  # double backslashes
	set -- "${@//$q/$qq}"      # backslash quotes
	set -- "${@/#/$q}"         # enclose in quotes
	set -- "${@/%/$q}"
	set -- "${@/#$q!/!$q}"     # Move pattern negation outside quotes
	REPLY="$*"
}

# automatically re-run watch if configuration changes
watch-reload .dkrc