X-Git-Url: http://git.osdn.net/view?a=blobdiff_plain;f=src%2Fltj-ruby.lua;h=060b3226ad3a6051e66b377ba178da00ee3306d3;hb=35f327cea38d7ac9d6933227c72310f3a02ef7bf;hp=2368b42388e8dcb1efd306b5b512573b3b1ff13a;hpb=76c2f061a5f0d85e7c0e4a6bf433f0279e908fd7;p=luatex-ja%2Fluatexja.git diff --git a/src/ltj-ruby.lua b/src/ltj-ruby.lua index 2368b42..060b322 100644 --- a/src/ltj-ruby.lua +++ b/src/ltj-ruby.lua @@ -3,34 +3,31 @@ -- luatexbase.provides_module({ name = 'luatexja.ruby', - date = '2014/03/19', - description = 'Ruby', + date = '2018/09/29', + description = 'Ruby annotation', }) -module('luatexja.ruby', package.seeall) -local err, warn, info, log = luatexbase.errwarinf(_NAME) - +luatexja.ruby = {} luatexja.load_module('stack'); local ltjs = luatexja.stack - -local Dnode = node.direct or node - -local nullfunc = function(n) return n end -local to_node = (Dnode ~= node) and Dnode.tonode or nullfunc -local to_direct = (Dnode ~= node) and Dnode.todirect or nullfunc - -local setfield = (Dnode ~= node) and Dnode.setfield or function(n, i, c) n[i] = c end -local getfield = (Dnode ~= node) and Dnode.getfield or function(n, i) return n[i] end -local getid = (Dnode ~= node) and Dnode.getid or function(n) return n.id end -local getfont = (Dnode ~= node) and Dnode.getfont or function(n) return n.font end -local getlist = (Dnode ~= node) and Dnode.getlist or function(n) return n.head end -local getchar = (Dnode ~= node) and Dnode.getchar or function(n) return n.char end -local getsubtype = (Dnode ~= node) and Dnode.getsubtype or function(n) return n.subtype end - -local node_new = Dnode.new -local node_remove = luatexja.Dnode_remove -- Dnode.remove -local node_next = (Dnode ~= node) and Dnode.getnext or node.next -local node_copy, node_free, node_tail = Dnode.copy, Dnode.free, Dnode.tail -local has_attr, set_attr = Dnode.has_attribute, Dnode.set_attribute -local insert_before, insert_after = Dnode.insert_before, Dnode.insert_after +luatexja.load_module('base'); local ltjb = luatexja.base + +local to_node = node.direct.tonode +local to_direct = node.direct.todirect + +local setfield = node.direct.setfield +local setglue = luatexja.setglue +local getfield = node.direct.getfield +local getid = node.direct.getid +local getfont = node.direct.getfont +local getlist = node.direct.getlist +local getchar = node.direct.getchar +local getsubtype = node.direct.getsubtype + +local node_new = node.direct.new +local node_remove = node.direct.remove +local node_next = node.direct.getnext +local node_copy, node_free, node_tail = node.direct.copy, node.direct.free, node.direct.tail +local has_attr, set_attr = node.direct.has_attribute, node.direct.set_attribute +local insert_before, insert_after = node.direct.insert_before, node.direct.insert_after local id_hlist = node.id('hlist') local id_vlist = node.id('vlist') @@ -39,7 +36,6 @@ local id_whatsit = node.id('whatsit') local id_glue = node.id('glue') local id_kern = node.id('kern') local id_penalty = node.id('penalty') -local id_glue_spec = node.id('glue_spec') local sid_user = node.subtype('user_defined') local ltjs_get_stack_table = luatexja.stack.get_stack_table local id_pbox_w = 258 -- cluster which consists of a whatsit @@ -71,17 +67,16 @@ luatexja.userid_table.RUBY_PRE = luatexbase.newuserwhatsitid('ruby_pre', 'luate luatexja.userid_table.RUBY_POST = luatexbase.newuserwhatsitid('ruby_post', 'luatexja') local RUBY_PRE = luatexja.userid_table.RUBY_PRE local RUBY_POST = luatexja.userid_table.RUBY_POST +local PROCESSED_BEGIN_FLAG = luatexja.icflag_table.PROCESSED_BEGIN_FLAG ---------------------------------------------------------------- -- TeX interface 0 ---------------------------------------------------------------- -if Dnode ~= node then - function cpbox() return node_copy(Dnode.getbox(0)) end -else - function cpbox() return node.copy(tex.box[0]) end +do + local getbox = node.direct.getbox + function luatexja.ruby.cpbox() return node_copy(getbox(0)) end end - ---------------------------------------------------------------- -- 補助関数群 1 ---------------------------------------------------------------- @@ -91,27 +86,50 @@ local function gauss(coef) local deg = #coef for i = 1, deg do if coef[i][i]==0 then - for j = i+1, deg do + for j = i+1, deg do if coef[j][i]~=0 then coef[i], coef[j] = coef[j], coef[i]; break end end end - for j = 1,deg do + for j = 1,deg do local d = coef[i][i]; if j~=i then local e = coef[j][i] for k = 1, deg+1 do coef[j][k] = coef[j][k] - e*coef[i][k]/d end - else + else for k = 1, deg+1 do coef[i][k] = coef[i][k]/d end end end end end +local function solve_1(coef) + local a, b, c = coef[1][4], coef[2][4], coef[3][4] + coef[1][4], coef[2][4], coef[3][4] = c-b, a+b-c, c-a + return coef +end + +local function solve_2(coef) + local a, b, c, d, e = coef[1][6], coef[2][6], coef[3][6], coef[4][6], coef[5][6] + coef[1][6], coef[2][6], coef[3][6], coef[4][6], coef[5][6] + = e-c, a+c-e, e-a-d, b+d-e, e-b + return coef +end + + -- 実行回数 + ルビ中身 から uniq_id を作る関数 --- 未実装.これを使えば 2 回目以降の組版に 1 回目の情報が使える -old_break_info = {} -- public, 前 run 時の分割情報 +luatexja.ruby.old_break_info = {} -- public, 前 run 時の分割情報 +local old_break_info = luatexja.ruby.old_break_info +local cache_handle +function luatexja.ruby.read_old_break_info() + if tex.jobname then + local fname = tex.jobname .. '.ltjruby' + local real_file = kpse.find_file(fname) + if real_file then dofile(real_file) end + cache_handle = io.open(fname, 'w') + end +end local make_uniq_id do local exec_count = 0 @@ -124,29 +142,42 @@ end -- concatenation of boxes: reusing nodes -- ルビ組版が行われている段落/hboxでの設定が使われる. -- ルビ文字を格納しているボックスでの設定ではない! -local function concat(f, b) - if f then - if b then - local h = getlist(f) - setfield(node_tail(h), 'next', getlist(b)) - setfield(f, 'head', nil); node_free(f) - setfield(b, 'head', nil); node_free(b) - return Dnode.hpack(luatexja.jfmglue.main(h,false)) - else - return f +local concat +do + local node_prev = node.direct.getprev + local function get_attr_icflag(p) + return (has_attr(p, attr_icflag) or 0) % PROCESSED_BEGIN_FLAG + end + function concat(f, b) + if f then + if b then + local h, nh = getlist(f), getlist(b) + if getid(nh)==id_whatsit and getsubtype(nh)==sid_user then + nh=node_next(nh); node_free(node_prev(nh)) + end + set_attr(nh, attr_icflag, + get_attr_icflag(nh) + PROCESSED_BEGIN_FLAG) + setfield(node_tail(h), 'next', nh) + setfield(f, 'head', nil); node_free(f) + setfield(b, 'head', nil); node_free(b) + local g = luatexja.jfmglue.main(h,false) + return node.direct.hpack(g) + else + return f + end + elseif b then + return b + else + local h = node_new(id_hlist) + setfield(h, 'subtype', 0) + setfield(h, 'width', 0) + setfield(h, 'height', 0) + setfield(h, 'depth', 0) + setfield(h, 'glue_set', 0) + setfield(h, 'glue_order', 0) + setfield(h, 'head', nil) + return h end - elseif b then - return b - else - local h = node_new(id_hlist) - setfield(h, 'subtype', 0) - setfield(h, 'width', 0) - setfield(h, 'height', 0) - setfield(h, 'depth', 0) - setfield(h, 'glue_set', 0) - setfield(h, 'glue_order', 0) - setfield(h, 'head', nil) - return h end end @@ -173,58 +204,40 @@ do enlarge = function (box, new_width, pre, middle, post, prenw, postnw) -- pre, middle, post: 伸縮比率 -- prenw, postnw: 前後の自然長 (sp) - local h = getlist(box); + local h = getlist(box); local hh, hd = getfield(box, 'height'), getfield(box, 'depth') local hx = h while hx do - local hic = has_attr(hx, attr_icflag) + local hic = has_attr(hx, attr_icflag) or 0 if (hic == KANJI_SKIP) or (hic == KANJI_SKIP_JFM) or (hic == XKANJI_SKIP) or (hic == XKANJI_SKIP_JFM) - or ((hic<=FROM_JFM+2) and (hic>=FROM_JFM-2)) then + or ((hic<=FROM_JFM+63) and (hic>=FROM_JFM)) then -- この 5 種類の空白をのばす if getid(hx) == id_kern then local k = node_new(id_glue) - local ks = node_new(id_glue_spec) - setfield(ks, 'width', getfield(hx, 'kern')) - setfield(ks, 'stretch_order', 2) - setfield(ks, 'stretch', round(middle*65536)) - setfield(ks, 'shrink_order', 0); setfield(ks, 'shrink', 0) - setfield(k, 'subtype', 0); setfield(k, 'spec', ks) + setglue(k, getfield(hx, 'kern'), round(middle*65536), 0, + 2, 0) + setfield(k, 'subtype', 0); h = insert_after(h, hx, k); h = node_remove(h, hx); node_free(hx); hx = k else -- glue - local old_spec = getfield(hx, 'spec') - local ks = node_copy(old_spec) - setfield(ks, 'stretch_order', 2) - setfield(ks, 'stretch', round(middle*65536)) - setfield(ks, 'shrink_order', 0); setfield(ks, 'shrink', 0) - setfield(hx, 'spec', ks) - -- decrease old_spec's reference count - local b = node_new(id_glue) - setfield(b, 'spec', old_spec); node_free(b) + setglue(hx, getfield(hx, 'width'), round(middle*65536), 0, + 2, 0) end end hx = node_next(hx) end -- 先頭の空白を挿入 local k = node_new(id_glue); - local ks = node_new(id_glue_spec) - setfield(ks, 'width', prenw) - setfield(ks, 'stretch_order', 2); setfield(ks, 'stretch', round(pre*65536)) - setfield(ks, 'shrink_order', 0); setfield(ks, 'shrink', 0) - setfield(k, 'subtype', 0); setfield(k, 'spec', ks) + setglue(k, prenw, round(pre*65536), 0, 2, 0) h = insert_before(h, h, k); -- 末尾の空白を挿入 local k = node_new(id_glue); - local ks = node_new(id_glue_spec); - setfield(ks, 'width', postnw) - setfield(ks, 'stretch_order', 2); setfield(ks, 'stretch', round(post*65536)) - setfield(ks, 'shrink_order', 0); setfield(ks, 'shrink', 0) - setfield(k, 'subtype', 0);setfield(k, 'spec', ks) + setglue(k, postnw, round(post*65536), 0, 2, 0) insert_after(h, node_tail(h), k); -- hpack setfield(box, 'head', nil); node_free(box) - box = Dnode.hpack(h, new_width, 'exactly') + box = node.direct.hpack(h, new_width, 'exactly') setfield(box, 'height', hh) setfield(box, 'depth', hd) return box @@ -245,6 +258,7 @@ local function texiface_low(rst, rtlr, rtlp) setfield(w, 'value', to_node(wv)) setfield(wv, 'type', 100) setfield(wv, 'value', floor(#rtlr)) + setfield(wv, 'user_id', RUBY_PRE) -- dummy set_attr(wv, attr_ruby, rst.rubyzw) set_attr(wv, attr_ruby_maxmargin, rst.maxmargin) set_attr(wv, attr_ruby_maxprep, rst.pre) @@ -258,15 +272,15 @@ local function texiface_low(rst, rtlr, rtlp) _, n = insert_after(wv, n, rtlp[i]) end -- w.value: (whatsit) .. r1 .. p1 .. r2 .. p2 - Dnode.write(w); return w,wv + node.direct.write(w); return w,wv end -- rst: table -function texiface(rst, rtlr, rtlp) +function luatexja.ruby.texiface(rst, rtlr, rtlp) if #rtlr ~= #rtlp then for i=1, #rtlr do node_free(rtlr[i]) end for i=1, #rtlp do node_free(rtlp[i]) end - luatexja.base.package_error('luatexja-ruby', + ltjb.package_error('luatexja-ruby', 'Group count mismatch between the ruby and\n' .. 'the body (' .. #rtlr .. ' != ' .. #rtlp .. ').', '') @@ -301,17 +315,17 @@ local function enlarge_parent(r, p, ppre, pmid, ppost, mapre, mapost, intmode) local sumprot = rwidth - getfield(p, 'width') -- >0 local pre_intrusion, post_intrusion if intmode == 0 then -- とりあえず組んでから決める - p = enlarge(p, rwidth, ppre, pmid, ppost, 0, 0) + p = enlarge(p, rwidth, ppre, pmid, ppost, 0, 0) pre_intrusion = min(mapre, round(ppre*getfield(p, 'glue_set')*65536)) post_intrusion = min(mapost, round(ppost*getfield(p, 'glue_set')*65536)) elseif intmode == 1 then - pre_intrusion = min(mapre, sumprot); + pre_intrusion = min(mapre, sumprot); post_intrusion = min(mapost, max(sumprot-pre_intrusion, 0)) p = enlarge(p, rwidth, ppre, pmid, ppost, pre_intrusion, post_intrusion) elseif intmode == 2 then - post_intrusion = min(mapost, sumprot); + post_intrusion = min(mapost, sumprot); pre_intrusion = min(mapre, max(sumprot-post_intrusion, 0)) - p = enlarge(p, rwidth, ppre, pmid, ppost, pre_intrusion, post_intrusion) + p = enlarge(p, rwidth, ppre, pmid, ppost, pre_intrusion, post_intrusion) else -- intmode == 3 local n = min(mapre, mapost)*2 if n < sumprot then @@ -319,7 +333,7 @@ local function enlarge_parent(r, p, ppre, pmid, ppost, mapre, mapost, intmode) else pre_intrusion = floor(sumprot/2); post_intrusion = sumprot - pre_intrusion end - p = enlarge(p, rwidth, ppre, pmid, ppost, pre_intrusion, post_intrusion) + p = enlarge(p, rwidth, ppre, pmid, ppost, pre_intrusion, post_intrusion) pre_intrusion = min(mapre, pre_intrusion + round(ppre*getfield(p, 'glue_set')*65536)) post_intrusion = min(mapost, post_intrusion + round(ppost*getfield(p, 'glue_set')*65536)) end @@ -327,7 +341,7 @@ local function enlarge_parent(r, p, ppre, pmid, ppost, mapre, mapost, intmode) local rwidth = rwidth - pre_intrusion - post_intrusion setfield(r, 'width', rwidth) setfield(p, 'width', rwidth) - local ps = getfield(getlist(p), 'spec') + local ps = getlist(p) setfield(ps, 'width', getfield(ps, 'width') - pre_intrusion) return r, p, post_intrusion end @@ -335,7 +349,7 @@ end -- ルビボックスの生成(単一グループ) -- returned value: , , local max_margin -local function new_ruby_box(r, p, ppre, pmid, ppost, +local function new_ruby_box(r, p, ppre, pmid, ppost, mapre, mapost, imode, rgap) local post_intrusion = 0 local intmode = imode%4 @@ -347,35 +361,35 @@ local function new_ruby_box(r, p, ppre, pmid, ppost, if getfield(r, 'width') > getfield(p, 'width') then -- change the width of p r, p, post_intrusion = enlarge_parent(r, p, ppre, pmid, ppost, mapre, mapost, intmode) elseif getfield(r, 'width') < getfield(p, 'width') then -- change the width of r - r = enlarge(r, getfield(p, 'width'), rpre, rmid, rpost, 0, 0) + r = enlarge(r, getfield(p, 'width'), rpre, rmid, rpost, 0, 0) post_intrusion = 0 local need_repack = false -- margin が大きくなりすぎた時の処理 if round(rpre*getfield(r, 'glue_set')*65536) > max_margin then - local ps = getfield(getlist(r), 'spec'); need_repack = true + local ps = getlist(r); need_repack = true setfield(ps, 'width', max_margin) setfield(ps, 'stretch', 1) -- 全く伸縮しないのも困る end if round(rpost*getfield(r, 'glue_set')*65536) > max_margin then - local ps = getfield(node_tail(getlist(r)), 'spec'); need_repack = true + local ps = node_tail(getlist(r)); need_repack = true setfield(ps, 'width', max_margin) setfield(ps, 'stretch', 1) -- 全く伸縮しないのも困る end if need_repack then local rt = r - r = Dnode.hpack(getlist(r), getfield(r, 'width'), 'exactly') + r = node.direct.hpack(getlist(r), getfield(r, 'width'), 'exactly') setfield(rt, 'head', nil); node_free(rt); end end - local a, k = node_new(id_rule), node_new(id_kern) + local a, k = node_new(id_rule), node_new(id_kern, 1) setfield(a, 'width', 0); setfield(a, 'height', 0) setfield(a, 'depth', 0); setfield(k, 'kern', rgap) insert_after(r, r, a); insert_after(r, a, k); insert_after(r, k, p); setfield(p, 'next', nil) - a = Dnode.vpack(r); setfield(a, 'shift', 0) + a = node.direct.vpack(r); setfield(a, 'shift', 0) set_attr(a, attr_ruby, post_intrusion) if rsmash or getfield(a, 'height')0 then - tex.sprint(cat_lp, - '\\write\\@mainaux{\\string\\directlua{luatexja.ruby.old_break_info[' - .. tostring(id) .. ']=' .. num - .. '}}') + if id>0 and cache_handle then + cache_handle:write( + 'luatexja.ruby.old_break_info[' + .. tostring(id) .. ']=' .. num + .. '\n') end end @@ -551,35 +570,35 @@ do local hn = has_attr(rs[1], attr_ruby) local fn = has_attr(rs[#rs], attr_ruby) local wv = getfield(rw, 'value') - if hn==1 then + if hn==1 then if fn==2*cmp+2 then local hn = node_tail(wv) node_remove(wv, hn) - insert_after(ch, rs[#rs], hn) + insert_after(ch, rs[1], hn) set_attr(hn, attr_icflag, PROCESSED) write_aux(wv, has_attr(hn, attr_ruby))-- 行中形 else local deg, hn = (fn-1)/2, wv - for i = 1, deg do hn = node_next(hn) end; + for i = 1, deg do hn = node_next(hn) end; node_remove(wv, hn) setfield(hn, 'next', nil) - insert_after(ch, rs[#rs], hn) + insert_after(ch, rs[1], hn) set_attr(hn, attr_icflag, PROCESSED) write_aux(wv, has_attr(hn, attr_ruby)) end else - local deg, hn = max((hn-1)/2,2), wv + local deg, hn = max((hn-1)/2,2), wv for i = 1, cmp+deg-1 do hn = node_next(hn) end - -- -1 is needed except the case hn = 3, + -- -1 is needed except the case hn = 3, -- because a ending-line form is removed already from the list node_remove(wv, hn); setfield(hn, 'next', nil) - insert_after(ch, rs[#rs], hn) + insert_after(ch, rs[1], hn) set_attr(hn, attr_icflag, PROCESSED) if fn == 2*cmp-1 then write_aux(wv, has_attr(hn, attr_ruby)) end end - for i = 1,#rs do + for i = 1,#rs do local ri = rs[i] ch = node_remove(ch, ri); node_free(ri); end @@ -590,63 +609,63 @@ do end local function post_high_break(head) - local rs = {} -- rs: sequence of ruby_nodes, + local rs = {} -- rs: sequence of ruby_nodes, local rw = nil -- rw: main whatsit local cmp = -2 -- dummy - for h in Dnode.traverse_id(id_hlist, to_direct(head)) do + for h in node.direct.traverse_id(id_hlist, to_direct(head)) do for i = 1, #rs do rs[i] = nil end local ha = getlist(h) while ha do local hai = getid(ha) - local i = (((hai == id_glue and getsubtype(ha)==0) - or (hai == id_rule and getsubtype(ha)==0) - or (hai == id_whatsit and getsubtype(ha)==sid_user - and getfield(ha, 'user_id')==RUBY_POST)) - and has_attr(ha, attr_ruby)) or 0 - if i==1 then + local i = ((hai == id_glue and getsubtype(ha)==0) + or (hai == id_rule and getsubtype(ha)==0) + or (hai == id_whatsit and getsubtype(ha)==sid_user + and getfield(ha, 'user_id', RUBY_POST))) + and has_attr(ha, attr_ruby) or 0 + if i==0 then + ha = node_next(ha) + elseif i==1 then setfield(h, 'head', post_lown(rs, rw, cmp, getlist(h))) for i = 2, #rs do rs[i] = nil end -- rs[1] is set by the next statement rs[1], rw = ha, nil; ha = node_next(ha) - elseif i>=3 then - rs[#rs+1] = ha; ha = node_next(ha) - elseif i==2 then + elseif i==2 then rw = ha cmp = getfield(getfield(rw, 'value'), 'value') local hb, hc = node_remove(getlist(h), rw) setfield(h, 'head', hb); ha = hc - else - ha = node_next(ha) + else -- i>=3 + rs[#rs+1] = ha; ha = node_next(ha) end end setfield(h, 'head', post_lown(rs, rw, cmp, getlist(h))) end return head -end +end local function post_high_hbox(ahead) local ha = to_direct(ahead); local head = ha - local rs = {}; -- rs: sequence of ruby_nodes, + local rs = {}; -- rs: sequence of ruby_nodes, local rw = nil; -- rw: main whatsit local cmp while ha do local hai = getid(ha) - local i = (((hai == id_glue and getsubtype(ha)==0) - or (hai == id_rule and getsubtype(ha)==0) - or (hai == id_whatsit and getsubtype(ha)==sid_user - and getfield(ha, 'user_id', RUBY_POST))) - and has_attr(ha, attr_ruby)) or 0 - if i==1 then + local i = ((hai == id_glue and getsubtype(ha)==0) + or (hai == id_rule and getsubtype(ha)==0) + or (hai == id_whatsit and getsubtype(ha)==sid_user + and getfield(ha, 'user_id', RUBY_POST))) + and has_attr(ha, attr_ruby) or 0 + if i==0 then + ha = node_next(ha) + elseif i==1 then head = post_lown(rs, rw, cmp, head) for i = 2, #rs do rs[i] = nil end -- rs[1] is set by the next statement rs[1], rw = ha, nil; ha = node_next(ha) - elseif i>=3 then - rs[#rs+1] = ha; ha = node_next(ha) - elseif i==2 then + elseif i==2 then rw = ha cmp = getfield(getfield(rw, 'value'), 'value') head, ha = node_remove(head, rw) - else - ha = node_next(ha) + else -- i >= 3 + rs[#rs+1] = ha; ha = node_next(ha) end end return to_node(post_lown(rs, rw, cmp, head)) @@ -661,9 +680,9 @@ luatexbase.add_to_callback('hpack_filter', post_high_hbox, 'ltj.ruby.post_hbox', ---------------------------------------------------------------- do local RIPRE = luatexja.stack_table_index.RIPRE - local function whatsit_callback(Np, lp, Nq, bsl) - if Np.nuc then return Np - elseif getfield(lp, 'user_id') == RUBY_PRE then + local function whatsit_callback(Np, lp, Nq) + if Np.nuc then return Np + elseif getfield(lp, 'user_id') == RUBY_PRE then Np.first, Np.nuc, Np.last = lp, lp, lp local lpv = getfield(lp, 'value') local x = node_next(node_next(lpv)) @@ -699,6 +718,8 @@ do set_attr(lpv, attr_ruby_maxprep, 0) end return Np + else + return Np end end luatexbase.add_to_callback("luatexja.jfmglue.whatsit_getinfo", whatsit_callback, @@ -707,8 +728,15 @@ end do local RIPOST = luatexja.stack_table_index.RIPOST - local function whatsit_after_callback(s, Nq, Np, bsl) + local function whatsit_after_callback(s, Nq, Np) if not s and getfield(Nq.nuc, 'user_id') == RUBY_PRE then + if Np then + local last_glue = node_new(id_glue) + set_attr(last_glue, attr_icflag, 0) + insert_before(Nq.nuc, Np.first, last_glue) + Np.first = last_glue + next_cluster_array[Nq.nuc] = last_glue -- ルビ処理用のグルー + end local nqnv = getfield(Nq.nuc, 'value') local x = node_next(node_next(nqnv)) for i = 2, getfield(nqnv, 'value') do x = node_next(node_next(x)) end