if not modules then modules = { } end modules ['pack-rul'] = {
    version   = 1.001,
    comment   = "companion to pack-rul.mkiv",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

--[[ldx--
<p>An explanation is given in the history document <t>mk</t>.</p>
--ldx]]--

local hpack           = node.hpack
local free            = node.free
local copy            = node.copy_list
local traverse_id     = node.traverse_id
local node_dimensions = node.dimensions

local hlist_code      = nodes.nodecodes.hlist
local vlist_code      = nodes.nodecodes.vlist
local box_code        = nodes.listcodes.box

local texsetdimen     = tex.setdimen
local texsetcount     = tex.setcount
local texgetbox       = tex.getbox

function commands.doreshapeframedbox(n)
    local box            = texgetbox(n)
    local noflines       = 0
    local firstheight    = nil
    local lastdepth      = nil
    local lastlinelength = 0
    local minwidth       = 0
    local maxwidth       = 0
    local totalwidth     = 0
    local averagewidth   = 0
    local boxwidth       = box.width
    if boxwidth ~= 0 then -- and h.subtype == vlist_code
        local list = box.list
        if list then
            local function check(n,usewidth)
                if not firstheight then
                    firstheight = n.height
                end
                lastdepth = n.depth
                noflines = noflines + 1
                local l = n.list
                if l then
                    if usewidth or n.subtype == box_code then -- maybe more
                        lastlinelength = n.width
                    else
                        lastlinelength = node_dimensions(l) -- used to be: hpack(copy(l)).width
                    end
                    if lastlinelength > maxwidth then
                        maxwidth = lastlinelength
                    end
                    if lastlinelength < minwidth or minwidth == 0 then
                        minwidth = lastlinelength
                    end
                    totalwidth = totalwidth + lastlinelength
                end
            end
            local hdone = false
         -- local vdone = false
            for h in traverse_id(hlist_code,list) do -- no dir etc needed
                check(h)
                hdone = true
            end
            for v in traverse_id(vlist_code,list) do -- no dir etc needed
                check(v)
             -- vdone = true
            end
            if firstheight then
                if maxwidth ~= 0 then
                    if hdone then
                        for h in traverse_id(hlist_code,list) do
                            local l = h.list
                            if l then
                                if h.subtype == box_code then
                                    -- explicit box, no 'line'
                                else
                                 -- if h.width ~= maxwidth then -- else no display math handling (uses shift)
                                     -- challenge: adapt glue_set
                                     -- h.glue_set = h.glue_set * h.width/maxwidth -- interesting ... doesn't matter much
                                     -- h.width = maxwidth
                                        h.list = hpack(l,maxwidth,'exactly',h.dir)
                                        h.shift = 0 -- needed for display math
                                        h.width = maxwidth
                                 -- end
                                end
                            end
                        end
                    end
                    box.width    = maxwidth -- moved
                    averagewidth = noflines > 0 and totalwidth/noflines or 0
                end
            end
        end
    end
    texsetcount("global","framednoflines",noflines)
    texsetdimen("global","framedfirstheight",firstheight or 0) -- also signal
    texsetdimen("global","framedlastdepth",lastdepth or 0)
    texsetdimen("global","framedminwidth",minwidth)
    texsetdimen("global","framedmaxwidth",maxwidth)
    texsetdimen("global","framedaveragewidth",averagewidth)
end

function commands.doanalyzeframedbox(n)
    local box         = texgetbox(n)
    local noflines    = 0
    local firstheight = nil
    local lastdepth   = nil
    if box.width ~= 0 then
        local list = box.list
        if list then
            local function check(n)
                if not firstheight then
                    firstheight = n.height
                end
                lastdepth = n.depth
                noflines = noflines + 1
            end
            for h in traverse_id(hlist_code,list) do
                check(h)
            end
            for v in traverse_id(vlist_code,list) do
                check(v)
            end
        end
    end
    texsetcount("global","framednoflines",noflines)
    texsetdimen("global","framedfirstheight",firstheight or 0)
    texsetdimen("global","framedlastdepth",lastdepth or 0)
end