zsh-autosuggestions/src/async.zsh

#--------------------------------------------------------------------#
# Async                                                              #
#--------------------------------------------------------------------#

_zsh_autosuggest_async_fetch_suggestion() {
	# Send the prefix to the pty to fetch a suggestion
	zpty -w -n $ZSH_AUTOSUGGEST_PTY_NAME $1 $'\0'
}

# Pty is spawned running this function
_zsh_autosuggest_async_suggestion_server() {
	emulate -R zsh

	while read -d $'\0' prefix; do
		# Kill last bg process
		kill -KILL %1 &>/dev/null

		# Run suggestion search in the background
		echo -n -E "$(_zsh_autosuggest_strategy_default "$prefix")"$'\0' &
	done
}

# Called when new data is ready to be read from the pty
# First arg will be fd ready for reading
# Second arg will be passed in case of error
_zsh_autosuggest_async_suggestion_ready() {
	local suggestion

	zpty -rt $ZSH_AUTOSUGGEST_PTY_NAME suggestion '*'$'\0' 2>/dev/null
	zle _autosuggest-show-suggestion "${suggestion%$'\0'}"
}

# Recreate the pty to get a fresh list of history events
_zsh_autosuggest_async_recreate_pty() {
	typeset -g _ZSH_AUTOSUGGEST_PTY_FD

	# Kill the old pty
	if [ -n "$_ZSH_AUTOSUGGEST_PTY_FD" ]; then
		# Remove the input handler
		zle -F $_ZSH_AUTOSUGGEST_PTY_FD

		# Destroy the pty
		zpty -d $ZSH_AUTOSUGGEST_PTY_NAME &>/dev/null
	fi

	# REPLY stores the fd to read from
	typeset -h REPLY

	# Start a new pty running the server function
	zpty -b $ZSH_AUTOSUGGEST_PTY_NAME _zsh_autosuggest_async_suggestion_server

	# Store the fd so we can destroy this pty later
	_ZSH_AUTOSUGGEST_PTY_FD=$REPLY

	# Set up input handler from the pty
	zle -F $_ZSH_AUTOSUGGEST_PTY_FD _zsh_autosuggest_async_suggestion_ready
}

add-zsh-hook precmd _zsh_autosuggest_async_recreate_pty