Helper functions for variables.

variables.sh

var_empty(){
# var_empty "_varname"
# var_empty "_array[index]"
# var_empty "_dict[key]"
# Returns 0 if a variable is set to an empty string
	[[ -z ${!1-unset} ]] && return 0 || return 1
}

var_gettype(){
# var_gettype "_varname"
# Returns the type of variable
	local var=$( declare -p $1 2>/dev/null)
    local reg='^declare -n [^=]+=\"([^\"]+)\"$'
    while [[ $var =~ $reg ]]; do
            var=$( declare -p ${BASH_REMATCH[1]} )
    done

    case "${var#declare -}" in
    a*)
            echo "ARRAY"
            ;;
    A*)
            echo "DICT"
            ;;
    i*)
            echo "INT"
            ;;
    x*)
            echo "EXPORT"
            ;;
    *)
            echo "OTHER"
            ;;
    esac
}

var_is_array(){
# var_is_array "_arrayname"
# Returns 0 if value is an array. Returns 1 otherwise.
	[[ "$(declare -p -- "$1" 2>/dev/null)" == "declare -a "* ]] && return 0 || return 1
}

var_is_dict(){
# var_is_dict "_dictname"
# Returns 0 if value is a dictionary. Returns 1 otherwise.
	[[ "$(declare -p -- "$1" 2>/dev/null)" == "declare -A "* ]] && return 0 || return 1
}

var_is_ref(){
# var_is_ref "_refname"
# Returns 0 if the variable is a reference. Returns 1 otherwise
	[[ "$(declare -p -- "$1" 2>/dev/null)" == "declare -n "* ]] && return 0 || return 1
}

var_is_unset(){
# var_is_unset "_varname"
# var_is_unset "_arr[index]"
# var_is_unset "_dict[key]"
# Returns 0 if <variable,index,or key> is unset. Returns 1 otherwise.
	[[ -z "${!1+set}" ]] && return 0 || return 1
}

var_is_unset_or_empty(){
    # var_is_unset_or_empty "_varname"
    # var_is_unset_or_empty "_arr[index]"
    # var_is_unset_or_empty "_dict[key]"
    # Returns 0 if <variable,index,or key> is unset or empty. Returns 1 otherwise.
    [[ -z "${!1}" ]] && return 0 || return 1
}

var_isset(){
# var_is_unset "_varname"
# var_is_unset "_arr[index]"
# var_is_unset "_dict[key]"
# Returns 0 if <variable> has been declared and has any value other than empty. Returns 1 otherwise.
	[[ -n ${!1} ]] && return 0 || return 1
}