path: root/Master/texmf-dist/tex/context/base/mkiv/node-nut.lua

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

-- Here starts some more experimental code that Luigi and I use in a next stage of
-- exploring and testing potential speedups in the engines. This code is not meant
-- for users and can change (or be removed) any moment. During the experiments I'll
-- do my best to keep the code as fast as possible by using two codebases. See
-- about-fast.pdf for some more info about impacts. Although key based access has
-- more charm, function based is somewhat faster and has more potential for future
-- speedups.

-- This next iteration is flagged direct because we avoid user data which has a price
-- in allocation and metatable tagging. Although in this stage we pass numbers around
-- future versions might use light user data, so never depend on what direct function
-- return. Using the direct approach had some speed advantages but you loose the key
-- based access. The speed gain is only measurable in cases with lots of access. For
-- instance when typesettign arabic with advanced fonts, we're talking of many millions
-- of function calls and there we can get a 30\% or more speedup. On average complex
-- \CONTEXT\ runs the gain can be 10\% to 15\% percent. Because mixing the two models
-- (here we call then nodes and nuts) is not possible you need to cast either way which
-- has a penalty. Also, error messages in nuts mode are less clear and \LUATEX\ will
-- often simply abort when you make mistakes of mix the models. So, development (at least
-- in \CONTEXT) can be done in node mode and not in nuts mode. Only robust code will
-- be turned nuts afterwards and quite likely not all code. The official \LUATEX\ api
-- to nodes is userdata!
--
-- Listening to 'lunatic soul' at the same time helped wrapping my mind around the mixed
-- usage of both models. Just for the record: the potential of the direct approach only
-- became clear after experimenting for weeks and partly adapting code. It is one of those
-- (sub)projects where you afterwards wonder if it was worth the trouble, but users that
-- rely on lots of complex functionality and font support will probably notice the speedup.
--
--                                luatex                    luajittex
-- -------------    -----    --------------------     ---------------------------------
-- name             pages     old   new       pct      old         new              pct
-- -------------    -----    --------------------     ---------------------------------
-- fonts-mkiv         166     9.3   7.7/7.4  17.2      7.4 (37.5)  5.9/5.7 (55.6)  20.3
-- about               60     3.3   2.7/2.6  20.4      2.5 (39.5)  2.1     (57.0)  23.4
-- arabic-001          61    25.3  15.8      18.2     15.3 (46.7)  6.8     (54.7)  16.0
-- torture-001        300    21.4  11.4      24.2     13.9 (35.0)  6.3     (44.7)  22.2
--
-- so:
--
-- - we run around 20% faster on documents of average complexity and gain more when
--   dealing with scripts like arabic and such
-- - luajittex benefits a bit more so a luajittex job can (in principle) now be much
--   faster
-- - if we reason backwards, and take luajittex as norm we get 1:2:3 on some jobs for
--   luajittex direct:luatex direct:luatex normal i.e. we can be 3 times faster
-- - keep in mind that these are tex/lua runs so the real gain at the lua end is much
--   larger
--
-- Because we can fake direct mode a little bit by using the fast getfield and setfield
-- at the cost of wrapped getid and alike, we still are running quite ok. As we could gain
-- some 5% with fast mode, we can sacrifice some on wrappers when we use a few fast core
-- functions. This means that simulated direct mode runs font-mkiv in 9.1 seconds (we could
-- get down to 8.7 seconds in fast mode) and that we can migrate slowely to direct mode.
--
-- The following measurements are from 2013-07-05 after adapting some 47 files to nuts. Keep
-- in mind that the old binary can fake a fast getfield and setfield but that the other
-- getters are wrapped functions. The more we have, the slower it gets.
--
--                                           fonts   about   arabic
-- old mingw, indexed plus some functions :   8.9     3.2     20.3
-- old mingw, fake functions              :   9.9     3.5     27.4
-- new mingw, node functions              :   9.0     3.1     20.8
-- new mingw, indexed plus some functions :   8.6     3.1     19.6
-- new mingw, direct functions            :   7.5     2.6     14.4
--
-- \starttext \dorecurse{1000}{test\page} \stoptext :
--
-- luatex    560 pps
-- luajittex 600 pps
--
-- \setupbodyfont[pagella]
--
-- \edef\zapf{\cldcontext{context(io.loaddata(resolvers.findfile("zapf.tex")))}}
--
-- \starttext \dorecurse{1000}{\zapf\par} \stoptext
--
-- luatex    3.9 sec / 54 pps
-- luajittex 2.3 sec / 93 pps

local type, rawget = type, rawget

local nodes               = nodes
local direct              = node.direct

local fastcopy            = table.fastcopy

local nodecodes           = nodes.nodecodes
local hlist_code          = nodecodes.hlist
local vlist_code          = nodecodes.vlist

local nuts                = nodes.nuts or { }
nodes.nuts                = nuts

nodes.is_node             = direct.is_node   or function() return true  end
nodes.is_direct           = direct.is_direct or function() return false end
nodes.is_nut              = nodes.is_direct

-- casters

local tonode              = direct.tonode   or function(n) return n end
local tonut               = direct.todirect or function(n) return n end

nuts.tonode               = tonode
nuts.tonut                = tonut

nodes.tonode              = tonode
nodes.tonut               = tonut

-- -- some tracing:
--
-- local hash = table.setmetatableindex("number")
-- local ga = direct.get_attribute
-- function direct.get_attribute(n,a)
--     hash[a] = hash[a] + 1
--     return ga(n,a)
-- end
-- function nuts.reportattr()
--     inspect(hash)
-- end
--
-- local function track(name)
--     local n = 0
--     local f = nuts[name]
--     function nuts[name](...)
--         n = n + 1
--         if n % 1000 == 0 then
--             print(name,n)
--         end
--         return f(...)
--     end
-- end
--
-- track("getfield")

-- helpers

if not direct.getfam then -- LUATEXVERSION < 1.070

    local getfield = direct.getfield
    local setfield = direct.setfield

    direct.getfam = function(n)   return getfield(n,"small_fam")   end
    direct.setfam = function(n,f)        setfield(n,"small_fam",f) end

end

if not direct.getdirection then

    local getdir = direct.getdir
    local setdir = direct.setdir

    direct.getdirection = function(n)
        local d = getdir(n)
        if d ==  "TLT" then return 0        end
        if d == "+TLT" then return 0, false end
        if d == "-TLT" then return 0, true  end
        if d ==  "TRT" then return 1        end
        if d == "+TRT" then return 1, false end
        if d == "-TRT" then return 1, true  end
        if d ==  "LTL" then return 2        end
        if d == "+LTL" then return 2, false end
        if d == "-LTL" then return 2, true  end
        if d ==  "RTT" then return 3        end
        if d == "+RTT" then return 3, false end
        if d == "-RTT" then return 3, true  end
    end

    direct.setdirection = function(n,d,c)
            if d == 0 then if c == true then setdir(n,"-TLT") elseif c == false then setdir(n,"+TLT") else setdir(n,"TLT") end
        elseif d == 1 then if c == true then setdir(n,"-TRT") elseif c == false then setdir(n,"+TRT") else setdir(n,"TRT") end
        elseif d == 2 then if c == true then setdir(n,"-LTL") elseif c == false then setdir(n,"+LTL") else setdir(n,"LTL") end
        elseif d == 3 then if c == true then setdir(n,"-RTT") elseif c == false then setdir(n,"+RTT") else setdir(n,"RTT") end
        else               if c == true then setdir(n,"-TLT") elseif c == false then setdir(n,"+TLT") else setdir(n,"TLT") end end
    end

end

local nuts                 = nodes.nuts

nuts.tostring              = direct.tostring
nuts.copy                  = direct.copy
nuts.copy_node             = direct.copy
nuts.copy_list             = direct.copy_list
nuts.delete                = direct.delete
nuts.dimensions            = direct.dimensions
nuts.rangedimensions       = direct.rangedimensions
nuts.end_of_math           = direct.end_of_math
nuts.flush                 = direct.flush_node
nuts.flush_node            = direct.flush_node
nuts.flush_list            = direct.flush_list
nuts.free                  = direct.free
nuts.insert_after          = direct.insert_after
nuts.insert_before         = direct.insert_before
nuts.hpack                 = direct.hpack
nuts.new                   = direct.new
nuts.tail                  = direct.tail
nuts.traverse              = direct.traverse
nuts.traverse_id           = direct.traverse_id
nuts.traverse_char         = direct.traverse_char
nuts.slide                 = direct.slide
nuts.writable_spec         = direct.writable_spec
nuts.vpack                 = direct.vpack
nuts.is_node               = direct.is_node
nuts.is_direct             = direct.is_direct
nuts.is_nut                = direct.is_direct
nuts.first_glyph           = direct.first_glyph
nuts.has_glyph             = direct.has_glyph or direct.first_glyph
nuts.count                 = direct.count
nuts.length                = direct.length
nuts.find_attribute        = direct.find_attribute
nuts.unset_attribute       = direct.unset_attribute

nuts.current_attr          = direct.current_attr
nuts.has_field             = direct.has_field
nuts.last_node             = direct.last_node
nuts.usedlist              = direct.usedlist
nuts.protrusion_skippable  = direct.protrusion_skippable
nuts.check_discretionaries = direct.check_discretionaries
nuts.write                 = direct.write

nuts.has_attribute         = direct.has_attribute
nuts.set_attribute         = direct.set_attribute
nuts.unset_attribute       = direct.unset_attribute

nuts.protect_glyph         = direct.protect_glyph
nuts.protect_glyphs        = direct.protect_glyphs
nuts.unprotect_glyph       = direct.unprotect_glyph
nuts.unprotect_glyphs      = direct.unprotect_glyphs
nuts.ligaturing            = direct.ligaturing
nuts.kerning               = direct.kerning

if not direct.mlist_to_hlist then -- needed

    local n_mlist_to_hlist = node.mlist_to_hlist

    function nuts.mlist_to_hlist(head)
        return tonode(n_mlist_to_hlist(tonut(head)))
    end

end

nuts.getfield              = direct.getfield
nuts.setfield              = direct.setfield

nuts.getnext               = direct.getnext
nuts.setnext               = direct.setnext

nuts.getid                 = direct.getid

nuts.getprev               = direct.getprev
nuts.setprev               = direct.setprev

nuts.getattr               = direct.get_attribute
nuts.setattr               = direct.set_attribute
nuts.takeattr              = direct.unset_attribute -- ?

nuts.is_zero_glue          = direct.is_zero_glue
nuts.effective_glue        = direct.effective_glue

nuts.getglue               = direct.getglue
nuts.setglue               = direct.setglue
nuts.getboxglue            = direct.getglue
nuts.setboxglue            = direct.setglue

nuts.getdisc               = direct.getdisc
nuts.setdisc               = direct.setdisc
nuts.getdiscretionary      = direct.getdisc
nuts.setdiscretionary      = direct.setdisc

nuts.getwhd                = direct.getwhd
nuts.setwhd                = direct.setwhd
nuts.getwidth              = direct.getwidth
nuts.setwidth              = direct.setwidth
nuts.getheight             = direct.getheight
nuts.setheight             = direct.setheight
nuts.getdepth              = direct.getdepth
nuts.setdepth              = direct.setdepth
nuts.getshift              = direct.getshift
nuts.setshift              = direct.setshift

nuts.getnucleus            = direct.getnucleus
nuts.setnucleus            = direct.setnucleus
nuts.getsup                = direct.getsup
nuts.setsup                = direct.setsup
nuts.getsub                = direct.getsub
nuts.setsub                = direct.setsub

nuts.getchar               = direct.getchar
nuts.setchar               = direct.setchar
nuts.getfont               = direct.getfont
nuts.setfont               = direct.setfont
nuts.getfam                = direct.getfam
nuts.setfam                = direct.setfam

nuts.getboth               = direct.getboth
nuts.setboth               = direct.setboth
nuts.setlink               = direct.setlink
nuts.setsplit              = direct.setsplit

nuts.getlist               = direct.getlist -- only hlist and vlist !
nuts.setlist               = direct.setlist
nuts.getleader             = direct.getleader
nuts.setleader             = direct.setleader
nuts.getcomponents         = direct.getcomponents
nuts.setcomponents         = direct.setcomponents

nuts.getsubtype            = direct.getsubtype
nuts.setsubtype            = direct.setsubtype

nuts.getlang               = direct.getlang
nuts.setlang               = direct.setlang
nuts.getlanguage           = direct.getlang
nuts.setlanguage           = direct.setlang

nuts.getattrlist           = direct.getattributelist
nuts.setattrlist           = direct.setattributelist
nuts.getattributelist      = direct.getattributelist
nuts.setattributelist      = direct.setattributelist

nuts.getoffsets            = direct.getoffsets
nuts.setoffsets            = direct.setoffsets

nuts.getkern               = direct.getkern
nuts.setkern               = direct.setkern

nuts.getdir                = direct.getdir
nuts.setdir                = direct.setdir

nuts.getdirection          = direct.getdirection
nuts.setdirection          = direct.setdirection

nuts.getpenalty            = direct.getpenalty
nuts.setpenalty            = direct.setpenalty

nuts.getbox                = direct.getbox
nuts.setbox                = direct.setbox

nuts.is_char               = direct.is_char
nuts.ischar                = direct.is_char
nuts.is_glyph              = direct.is_glyph
nuts.isglyph               = direct.is_glyph

local d_remove_node        = direct.remove
local d_flush_node         = direct.flush_node
local d_getnext            = direct.getnext
local d_getprev            = direct.getprev
local d_getid              = direct.getid
local d_getlist            = direct.getlist
local d_find_tail          = direct.tail
local d_insert_after       = direct.insert_after
local d_insert_before      = direct.insert_before
local d_slide              = direct.slide
----- d_copy_node          = direct.copy
local d_traverse           = direct.traverse
local d_setlink            = direct.setlink
local d_setboth            = direct.setboth
local d_getboth            = direct.getboth

local function remove(head,current,free_too)
    if current then
        local h, c = d_remove_node(head,current)
        if free_too then
            d_flush_node(current)
            return h, c
        else
            d_setboth(current)
            return h, c, current
        end
    end
    return head, current
end

-- alias

nuts.getsurround = nuts.getkern
nuts.setsurround = nuts.setkern

-- bad: we can have prev's being glue_spec

nuts.remove = remove

function nuts.delete(head,current)
    return remove(head,current,true)
end

function nuts.replace(head,current,new) -- no head returned if false
    if not new then
        head, current, new = false, head, current
    end
    local prev, next = d_getboth(current)
    if prev or next then
        d_setlink(prev,new,next)
    end
    if head then
        if head == current then
            head = new
        end
        d_flush_node(current)
        return head, new
    else
        d_flush_node(current)
        return new
    end
end

local function countall(stack,flat)
    local n = 0
    while stack do
        local id = d_getid(stack)
        if not flat and id == hlist_code or id == vlist_code then
            local list = d_getlist(stack)
            if list then
                n = n + 1 + countall(list) -- self counts too
            else
                n = n + 1
            end
        else
            n = n + 1
        end
        stack = d_getnext(stack)
    end
    return n
end

nuts.countall = countall

function nodes.countall(stack,flat)
    return countall(tonut(stack),flat)
end

function nuts.append(head,current,...)
    for i=1,select("#",...) do
        head, current = d_insert_after(head,current,(select(i,...)))
    end
    return head, current
end

function nuts.prepend(head,current,...)
    for i=1,select("#",...) do
        head, current = d_insert_before(head,current,(select(i,...)))
    end
    return head, current
end

function nuts.linked(...) -- slides !
    local head, last
    for i=1,select("#",...) do
        local next = select(i,...)
        if next then
            if head then
                d_setlink(last,next)
            else
                head = next
            end
            last = d_find_tail(next) -- we could skip the last one
        end
    end
    return head
end

function nuts.concat(list) -- consider tail instead of slide
    local head, tail
    for i=1,#list do
        local li = list[i]
        if li then
            if head then
                d_setlink(tail,li)
            else
                head = li
            end
            tail = d_slide(li)
        end
    end
    return head, tail
end

function nuts.reference(n)
    return n or "<none>"
end

-- quick and dirty tracing of nuts

-- for k, v in next, nuts do
--     if string.find(k,"box") then
--         nuts[k] = function(...) print(k,...) return v(...) end
--     end
-- end

function nodes.vianuts (f) return function(n,...) return tonode(f(tonut (n),...)) end end
function nodes.vianodes(f) return function(n,...) return tonut (f(tonode(n),...)) end end

nuts.vianuts  = nodes.vianuts
nuts.vianodes = nodes.vianodes

-- function nodes.insert_before(h,c,n)
--     if c then
--         if c == h then
--             n_setfield(n,"next",h)
--             n_setfield(n,"prev",nil)
--             n_setfield(h,"prev",n)
--         else
--             local cp = n_getprev(c)
--             n_setfield(n,"next",c)
--             n_setfield(n,"prev",cp)
--             if cp then
--                 n_setfield(cp,"next",n)
--             end
--             n_setfield(c,"prev",n)
--             return h, n
--         end
--     end
--     return n, n
-- end

-- function nodes.insert_after(h,c,n)
--     if c then
--         local cn = n_getnext(c)
--         if cn then
--             n_setfield(n,"next",cn)
--             n_setfield(cn,"prev",n)
--         else
--             n_setfield(n,"next",nil)
--         end
--         n_setfield(c,"next",n)
--         n_setfield(n,"prev",c)
--         return h, n
--     end
--     return n, n
-- end

function nodes.insert_list_after(h,c,n)
    local t = n_tail(n)
    if c then
        local cn = n_getnext(c)
        if cn then
            -- no setboth here yet
            n_setfield(t,"next",cn)
            n_setfield(cn,"prev",t)
        else
            n_setfield(t,"next",nil)
        end
        n_setfield(c,"next",n)
        n_setfield(n,"prev",c)
        return h, n
    end
    return n, t
end

-- function nuts.insert_before(h,c,n)
--     if c then
--         if c == h then
--             d_setnext(n,h)
--             d_setprev(n)
--             d_setprev(h,n)
--         else
--             local cp = d_getprev(c)
--             d_setnext(n,c)
--             d_setprev(n,cp)
--             if cp then
--                 d_setnext(cp,n)
--             end
--             d_setprev(c,n)
--             return h, n
--         end
--     end
--     return n, n
-- end

-- function nuts.insert_after(h,c,n)
--     if c then
--         local cn = d_getnext(c)
--         if cn then
--             d_setlink(n,cn)
--         else
--             d_setnext(n,nil)
--         end
--         d_setlink(c,n)
--         return h, n
--     end
--     return n, n
-- end

function nuts.insert_list_after(h,c,n)
    local t = d_tail(n)
    if c then
        local cn = d_getnext(c)
        if cn then
            d_setlink(t,cn)
        else
            d_setnext(t)
        end
        d_setlink(c,n)
        return h, n
    end
    return n, t
end

-- test code only

-- collectranges and mix

local report = logs.reporter("sliding")

local function message(detail,head,current,previous)
    report("error: %s, current: %s:%s, previous: %s:%s, list: %s, text: %s",
        detail,
        nodecodes[d_getid(current)],
        current,
        nodecodes[d_getid(previous)],
        previous,
        nodes.idstostring(head),
        nodes.listtoutf(head)
    )
    utilities.debugger.showtraceback(report)
end

local function warn()
    report()
    report("warning: the slide tracer is enabled")
    report()
    warn = false
end

local function tracedslide(head)
    if head then
        if warn then
            warn()
        end
        local next = d_getnext(head)
        if next then
            local prev = head
            for n in d_traverse(next) do
                local p = d_getprev(n)
                if not p then
                    message("unset",head,n,prev)
                 -- break
                elseif p ~= prev then
                    message("wrong",head,n,prev)
                 -- break
                end
                prev = n
            end
        end
        return d_slide(head)
    end
end

local function nestedtracedslide(head,level) -- no sliding !
    if head then
        if warn then
            warn()
        end
        local id = d_getid(head)
        local next = d_getnext(head)
        if next then
            report("%whead:%s",level or 0,nodecodes[id])
            local prev = head
            for n in d_traverse(next) do
                local p = d_getprev(n)
                if not p then
                    message("unset",head,n,prev)
                 -- break
                elseif p ~= prev then
                    message("wrong",head,n,prev)
                 -- break
                end
                prev = n
                local id = d_getid(n)
                if id == hlist_code or id == vlist_code then
                    nestedtracedslide(d_getlist(n),(level or 0) + 1)
                end
            end
        elseif id == hlist_code or id == vlist_code then
            report("%wlist:%s",level or 0,nodecodes[id])
            nestedtracedslide(d_getlist(head),(level or 0) + 1)
        end
     -- return d_slide(head)
    end
end

local function untracedslide(head)
    if head then
        if warn then
            warn()
        end
        local next = d_getnext(head)
        if next then
            local prev = head
            for n in d_traverse(next) do
                local p = d_getprev(n)
                if not p then
                    return "unset", d_getid(n)
                elseif p ~= prev then
                    return "wrong", d_getid(n)
                end
                prev = n
            end
        end
        return d_slide(head)
    end
end

nuts.tracedslide       = tracedslide
nuts.untracedslide     = untracedslide
nuts.nestedtracedslide = nestedtracedslide

-- nuts.slide          = tracedslide

-- this might move

local propertydata = direct.get_properties_table and direct.get_properties_table()

local getattr = nuts.getattr
local setattr = nuts.setattr

nodes.properties = {
    data = propertydata,
}

------.set_properties_mode(true,false) -- shallow copy ... problem: in fonts we then affect the originals too
direct.set_properties_mode(true,true)  -- create metatable, slower but needed for font-otj.lua (unless we use an intermediate table)

-- todo:
--
-- function direct.set_properties_mode()
--     -- we really need the set modes
-- end

-- experimental code with respect to copying attributes has been removed
-- as it doesn't pay of (most attributes are only accessed once anyway)

nuts.getprop = function(n,k)
    local p = propertydata[n]
    if p then
        return p[k]
    end
end

nuts.rawprop = function(n,k)
    local p = rawget(propertydata,n)
    if p then
        return p[k]
    end
end

nuts.setprop = function(n,k,v)
    local p = propertydata[n]
    if p then
        p[k] = v
    else
        propertydata[n] = { [k] = v }
    end
end

nuts.theprop = function(n)
    local p = propertydata[n]
    if not p then
        p = { }
        propertydata[n] = p
    end
    return p
end

nodes.setprop = nodes.setproperty
nodes.getprop = nodes.getproperty

function nuts.copy_properties(source,target,what)
    local newprops = propertydata[source]
    if not newprops then
        -- nothing to copy
        return
    end
    if what then
        -- copy one category
        newprops = rawget(source,what)
        if newprops then
            newprops = fastcopy(newprops)
            local p = rawget(propertydata,target)
            if p then
                p[what] = newprops
            else
                propertydata[target] = {
                    [what] = newprops,
                }
            end
        end
    else
        -- copy all properties
        newprops = fastcopy(newprops)
        propertydata[target] = newprops
    end
    return newprops -- for checking
end

-- here:

nuts.get_synctex_fields = direct.get_synctex_fields
nuts.set_synctex_fields = direct.set_synctex_fields

-- for now

nodes.uses_font = nodes.uses_font
nuts.uses_font  = direct.uses_font

if not nuts.uses_font then

    local glyph_code  = nodecodes.glyph
    local getdisc     = nuts.getdisc
    local getfont     = nuts.getfont
    local traverse_id = nuts.traverse_id
    local tonut       = nodes.tonut

    function nuts.uses_font(n,font)
        local pre, post, replace = getdisc(n)
        if pre then
            -- traverse_char
            for n in traverse_id(glyph_code,pre) do
                if getfont(n) == font then
                    return true
                end
            end
        end
        if post then
            for n in traverse_id(glyph_code,post) do
                if getfont(n) == font then
                    return true
                end
            end
        end
        if replace then
            for n in traverse_id(glyph_code,replace) do
                if getfont(n) == font then
                    return true
                end
            end
        end
        return false
    end

    function nodes.uses_font(n,font)
        return nuts.uses_font(tonut(n),font)
    end

end

-- for the moment (pre 6380)

if not nuts.unprotect_glyph then

    local protect_glyph    = nuts.protect_glyph
    local protect_glyphs   = nuts.protect_glyphs
    local unprotect_glyph  = nuts.unprotect_glyph
    local unprotect_glyphs = nuts.unprotect_glyphs

    local getnext          = nuts.getnext
    local setnext          = nuts.setnext

    function nuts.protectglyphs(first,last)
        if first == last then
            return protect_glyph(first)
        elseif last then
            local nxt = getnext(last)
            setnext(last)
            local f, b = protect_glyphs(first)
            setnext(last,nxt)
            return f, b
        else
            return protect_glyphs(first)
        end
    end

    function nuts.unprotectglyphs(first,last)
        if first == last then
            return unprotect_glyph(first)
        elseif last then
            local nxt = getnext(last)
            setnext(last)
            local f, b = unprotect_glyphs(first)
            setnext(last,nxt)
            return f, b
        else
            return unprotect_glyphs(first)
        end
    end

end

if LUATEXFUNCTIONALITY < 6384 then -- LUATEXVERSION < 1.070

    local getfield = nuts.getfield
    local setfield = nuts.setfield

    function nuts.getboxglue(n,glue_set,glue_order,glue_sign)
        return
            getfield(n,"glue_set"),
            getfield(n,"glue_order"),
            getfield(n,"glue_sign")
    end

    function nuts.setboxglue(n,glue_set,glue_order,glue_sign)
        setfield(n,"glue_set",  glue_set   or 0)
        setfield(n,"glue_order",glue_order or 0)
        setfield(n,"glue_sign", glue_sign  or 0)
    end

end