scan.lua

require('lfs')

local function filtered_dir(d) 
    local f, s_, v_ = lfs.dir(d)
    local function g(s, v)
        while true do
            local vn=f(s, v)
            if vn~='.' and vn~='..' then
                return vn
            end
        end
    end
    return g, s_, v_
end


function scan(d)
    local h={}
    for f in filtered_dir(d) do
        local n=d..'/'..f
        local a=lfs.attributes(n)
        if a.mode=='directory' then
            local nh=scan(n)
            h[n]=nh
        elseif a.mode=='file' then
            h[n]=true
        end
    end
    return h
end

function hfold(h, a, f, g)
    for n, c in pairs(h) do
        if type(c)=='table' then
            hfold(c, f(a, n), f, g)
        else
            g(a, n)
        end
    end
end