zsh-autosuggestions/src/strategies/default.zsh

#--------------------------------------------------------------------#
# Default Suggestion Strategy                                        #
#--------------------------------------------------------------------#
# Suggests the most recent history item that matches the given
# prefix.
#

_zsh_autosuggest_strategy_default() {
	setopt localoptions EXTENDED_GLOB

	local prefix="${1//(#m)[\\()\[\]|*?~]/\\$MATCH}"

	# Get the keys of the history items that match
	local -a histkeys
	histkeys=(${(k)history[(r)$prefix*]})

	# Give back the value of the first key
	suggestion="${history[$histkeys[1]]}"
}