recursive & iterative string split functions in Lua

string-split.lua

-- example:
--    split("a", "/")       --=> {"a"}
--    split("a/b/", "/")    --=> {"a", "b", ""}
-- 3rd argument in split_r should be omitted by caller
function split_r(str, delim, parts)
    if not parts then
        parts = {}
    end
    local pos = str:find(delim)
    if not pos then
        table.insert(parts, str)
        return parts
    else
        table.insert(parts, str:sub(1, pos - 1))
        return split(str:sub(pos + 1), delim, parts)
    end
end

function split_i(str, delim)
    local parts = {}
    local start = 1
    local find = 1

    while find do
        find = str:find(delim, start)
        if find then
            table.insert(parts, str:sub(start, find - 1))
            start = find + 1
        else
            table.insert(parts, str:sub(start))
        end
    end
    return parts
end