X-Git-Url: http://git.osdn.jp/view?a=blobdiff_plain;f=src%2Fltj-adjust.lua;h=7131bbc7b773d564050baebff2210d78db27e278;hb=d177010c46e52e722b4752eded1ae4a6807953df;hp=49a4334498f70d33db43fbf3f850dc3b12c0fcee;hpb=ae77474c1513fdada9dde1a239c0c11fc9c112c0;p=luatex-ja%2Fluatexja.git

diff --git a/src/ltj-adjust.lua b/src/ltj-adjust.lua
index 49a4334..7131bbc 100644
--- a/src/ltj-adjust.lua
+++ b/src/ltj-adjust.lua
@@ -5,6 +5,7 @@ luatexja.load_module('jfont');     local ltjf = luatexja.jfont
 luatexja.load_module('jfmglue');   local ltjj = luatexja.jfmglue
 luatexja.load_module('stack');     local ltjs = luatexja.stack
 luatexja.load_module('direction'); local ltjd = luatexja.direction
+luatexja.adjust = luatexja.adjust or {}
 
 local to_node = node.direct.tonode
 local to_direct = node.direct.todirect
@@ -12,7 +13,6 @@ local to_direct = node.direct.todirect
 local setfield = node.direct.setfield
 local setglue = luatexja.setglue
 local getfield = node.direct.getfield
-local is_zero_glue = node.direct.is_zero_glue
 local getlist = node.direct.getlist
 local getid = node.direct.getid
 local getfont = node.direct.getfont
@@ -20,8 +20,6 @@ local getsubtype = node.direct.getsubtype
 
 local node_traverse_id = node.direct.traverse_id
 local node_new = node.direct.new
-local node_copy = node.direct.copy
-local node_hpack = node.direct.hpack
 local node_next = node.direct.getnext
 local node_free = node.direct.free
 local node_prev = node.direct.getprev
@@ -35,30 +33,22 @@ local id_kern = node.id('kern')
 local id_hlist = node.id('hlist')
 local id_glue  = node.id('glue')
 local id_whatsit = node.id('whatsit')
+local id_penalty = node.id('penalty')
 local attr_icflag = luatexbase.attributes['ltj@icflag']
 local attr_jchar_class = luatexbase.attributes['ltj@charclass']
 local lang_ja = luatexja.lang_ja
 
 local ltjf_font_metric_table = ltjf.font_metric_table
-local round, pairs = tex.round, pairs
+local ipairs, pairs = ipairs, pairs
 
 local PACKED       = luatexja.icflag_table.PACKED
+local LINEEND      = luatexja.icflag_table.LINEEND
 local FROM_JFM     = luatexja.icflag_table.FROM_JFM
 local KANJI_SKIP   = luatexja.icflag_table.KANJI_SKIP
 local KANJI_SKIP_JFM = luatexja.icflag_table.KANJI_SKIP_JFM
 local XKANJI_SKIP  = luatexja.icflag_table.XKANJI_SKIP
 local XKANJI_SKIP_JFM  = luatexja.icflag_table.XKANJI_SKIP_JFM
 
-local priority_table = {
-   FROM_JFM + 2,
-   FROM_JFM + 1,
-   FROM_JFM,
-   FROM_JFM - 1,
-   FROM_JFM - 2,
-   XKANJI_SKIP,
-   KANJI_SKIP
-}
-
 local get_attr_icflag
 do
    local PROCESSED_BEGIN_FLAG = luatexja.icflag_table.PROCESSED_BEGIN_FLAG
@@ -67,88 +57,98 @@ do
    end
 end
 
+local priority_num = { 0, 0 }
+local at2pr = { {}, {} }
+local at2pr_st, at2pr_sh = at2pr[1], at2pr[2]
+do
+   local priority_table = {{},{}}
+   luatexja.adjust.priority_table = priority_table
+   local tmp = {}
+   local function cmp(a,b) return a[1]>b[1] end -- 大きいほうが先！
+   local function make_priority_table(glue_sign)
+      for i,_ in pairs(tmp) do tmp[i]=nil end
+      if glue_sign==2 then -- shrink
+	 for i=0,63 do tmp[#tmp+1] = { (i%8)-4, FROM_JFM+i } end
+      else -- stretch
+	 for i=0,63 do tmp[#tmp+1] = { math.floor(i/8)-4, FROM_JFM+i } end
+      end    
+      local pt = priority_table[glue_sign]
+      tmp[#tmp+1] = { pt[2]/10, XKANJI_SKIP }
+      tmp[#tmp+1] = { pt[2]/10, XKANJI_SKIP_JFM }
+      tmp[#tmp+1] = { pt[1]/10, KANJI_SKIP }
+      tmp[#tmp+1] = { pt[1]/10, KANJI_SKIP_JFM }
+      tmp[#tmp+1] = { pt[3]/10, -1 }
+      table.sort(tmp, cmp)
+      local a, m, n = at2pr[glue_sign], 10000000, 0
+      for i=1,#tmp do
+	 if tmp[i][1]<m then n,m = n+1,tmp[i][1] end
+	 a[tmp[i][2]] = n
+      end
+      local o = a[-1]
+      priority_num[glue_sign] = n
+      setmetatable(a, {__index = function () return o end })
+   end
+   luatexja.adjust.make_priority_table = make_priority_table
+end
+
 -- box 内で伸縮された glue の合計値を計算
 
 local total_stsh = {{},{}}
 local total_st, total_sh = total_stsh[1], total_stsh[2]
-local function get_total_stretched(p, line)
+local get_total_stretched
+do
+local dimensions = node.direct.dimensions
+function get_total_stretched(p)
 -- return value: <補正値(sp)>
-   local go, gf, gs
-     = getfield(p, 'glue_order'), getfield(p, 'glue_set'), getfield(p, 'glue_sign')
+   local ph = getlist(p)
+   if not ph then return 0 end
    for i,_ in pairs(total_st) do total_st[i]=nil; total_sh[i]=nil end
-   for i=1,#priority_table do 
-      total_st[priority_table[i]]=0; total_sh[priority_table[i]]=0; 
-   end
+   for i=1,priority_num[1] do total_st[i]=0 end
+   for i=1,priority_num[2] do total_sh[i]=0 end
    for i=0,4 do total_st[i*65536]=0; total_sh[i*65536]=0 end
-   total_st[-1]=0; total_sh[-1]=0;
-   for q in node_traverse_id(id_glue, getlist(p)) do
-       local a = getfield(q, 'stretch_order')
-      if a>0 then a=a*65536 else 
-         total_st[0] = total_st[0]+getfield(q, 'stretch')
-         a = get_attr_icflag(q)
-         if a == KANJI_SKIP_JFM  then a = KANJI_SKIP
-	 elseif a == XKANJI_SKIP_JFM  then a = XKANJI_SKIP
-	 elseif type(total_st[a])~='number' then a = -1 end
+   for q in node_traverse_id(id_glue, ph) do
+      local a = getfield(q, 'stretch_order')
+      if a==0 then
+	 local b = at2pr_st[get_attr_icflag(q)]; 
+	 total_st[b] = total_st[b]+getfield(q, 'stretch')
       end
-      total_st[a] = total_st[a]+getfield(q, 'stretch')
+      total_st[a*65536] = total_st[a]+getfield(q, 'stretch')
       local a = getfield(q, 'shrink_order')
-      if a>0 then a=a*65536 else 
-         total_sh[0] = total_sh[0]+getfield(q, 'shrink')
-         a = get_attr_icflag(q)
-         if a == KANJI_SKIP_JFM  then a = KANJI_SKIP
-         elseif a == XKANJI_SKIP_JFM  then a = XKANJI_SKIP
-	 elseif type(total_sh[a])~='number' then a = -1 end
+      if a==0 then
+	 local b = at2pr_sh[get_attr_icflag(q)]; 
+	 total_sh[b] = total_sh[b]+getfield(q, 'shrink')
       end
-      total_sh[a] = total_sh[a]+getfield(q, 'shrink')
+      total_sh[a*65536] = total_sh[a]+getfield(q, 'shrink')
    end
-   for i=4,0,-1 do if total_st[i*65536]~=0 then total_st.order=i; break end; end
-   for i=4,0,-1 do if total_sh[i*65536]~=0 then total_sh.order=i; break end; end
-   if gs==0 then
-      return 0, gf
-   else 
-      return round((3-2*gs)*total_stsh[gs][go*65536]*gf), gf
+   for i=4,1,-1 do if total_st[i*65536]~=0 then total_st.order=i; break end; end
+   if not total_st.order then
+       total_st.order, total_st[-65536] = -1,0.1 -- dummy
    end
-end
-
-local function clear_stretch(p, ic, name)
-   for q in node_traverse_id(id_glue, getlist(p)) do
-      local f = get_attr_icflag(q)
-      if (f == ic) or ((ic ==KANJI_SKIP) and (f == KANJI_SKIP_JFM))
-	   or ((ic ==XKANJI_SKIP) and (f == XKANJI_SKIP_JFM)) then
-         setfield(q, name..'_order', 0)
-         setfield(q, name, 0)
-      end
+   for i=4,1,-1 do if total_sh[i*65536]~=0 then total_sh.order=i; break end; end
+   if not total_sh.order then
+       total_sh.order, total_sh[-65536] = -1,0.1 -- dummy
    end
+   return getfield(p,'width') - dimensions(ph)
 end
-
-local function set_stretch(p, after, before, ic, name)
-   if before > 0 then
-      local ratio = after/before
-      for q in node_traverse_id(id_glue, getlist(p)) do
-	 local f = get_attr_icflag(q)
-         if (f == ic) or ((ic ==KANJI_SKIP) and (f == KANJI_SKIP_JFM))
-	   or ((ic ==XKANJI_SKIP) and (f == XKANJI_SKIP_JFM)) then
-            if getfield(q, name..'_order')==0 then
-               setfield(q, name, getfield(q, name)*ratio)
-            end
-         end
-      end
-   end
 end
 
 -- step 1: 行末に kern を挿入（句読点，中点用）
 local abs = math.abs
 local ltjd_glyph_from_packed = ltjd.glyph_from_packed
-local function aw_step1(p, total, ntr)
+local function aw_step1(p, total)
    local head = getlist(p)
    local x = node_tail(head); if not x then return total, false end
    -- x: \rightskip
    x = node_prev(x); if not x then return total, false end
    local xi, xc = getid(x)
-   if xi == id_glue and getsubtype(x) == 15 then
-      -- 段落最終行のときは，\penalty10000 \parfillskip が入るので，
-      -- その前の node が本来の末尾文字となる
-      x = node_prev(node_prev(x)); xi = getid(x)
+   -- x may be penalty
+   while xi==id_penalty do
+      x = node_prev(x); if not x then return total, false end
+      xi = getid(x)
+   end
+   if (total>0 and total_st.order>0) or (total<0 and total_sh.order>0) then
+       -- 無限大のグルーで処理が行われているときは処理中止．
+       return total, false
    end
    if xi == id_glyph and getfield(x, 'lang')==lang_ja then
       -- 和文文字
@@ -182,10 +182,9 @@ local function aw_step1(p, total, ntr)
        end
        return a[4]<b[4]
    end)
-   --print('min', eadt[eadt_ratio[1][1]], eadt_ratio[1][3])
    if eadt[eadt_ratio[1][1]]~=0 then
-      local kn = node_new(id_kern)
-      setfield(kn, 'kern', eadt[eadt_ratio[1][1]]); set_attr(kn, attr_icflag, FROM_JFM)
+      local kn = node_new(id_kern, 1)
+      setfield(kn, 'kern', eadt[eadt_ratio[1][1]]); set_attr(kn, attr_icflag, LINEEND)
       insert_after(head, x, kn)
       return eadt_ratio[1][3], true
    else
@@ -193,94 +192,246 @@ local function aw_step1(p, total, ntr)
    end
 end
 
+-- step 1 最終行用
+local min, max = math.min, math.max
+local function aw_step1_last(p, total)
+   local head = getlist(p)
+   local x = node_tail(head); if not x then return total, false end
+   -- x: \rightskip
+   pf = node_prev(x); if not x then return total, false end
+   if getid(pf) ~= id_glue or getsubtype(pf) ~= 15 then return total, false end
+   x = node_prev(node_prev(pf)); xi = getid(x)
+   local xi, xc = getid(x)
+   if xi == id_glyph and getfield(x, 'lang')==lang_ja then
+      -- 和文文字
+      xc = x
+   elseif xi == id_hlist and get_attr_icflag(x) == PACKED then
+      -- packed JAchar
+      xc = ltjd_glyph_from_packed(x)
+      while getid(xc) == id_whatsit do xc = node_next(xc) end -- これはなんのために？
+   else
+      return total, false-- それ以外は対象外．
+   end
+   -- 続行条件1：無限の伸縮度を持つグルーは \parfillskipのみ
+   if total>0 and total_st.order>0 then
+      if total_st.order ~= getfield(pf, 'stretch_order') then return total, false end
+      if total_st[total_st.order*65536] ~= getfield(pf, 'stretch') then return total, false end
+      for i=total_st.order-1, 1, -1 do
+	 if total_st[i*65536] ~= 0 then return total, false end
+      end
+   end
+   if total<0 and total_sh.order>0 then
+      if total_sh.order ~= getfield(pf, 'shrink_order') then return total, false end
+      if total_sh[total_sh.order*65536] ~= getfield(pf, 'shrink') then return total, false end
+      for i=total_sh.order-1, 1, -1 do
+	 if total_sh[i*65536] ~= 0 then return total, false end
+      end
+   end
+   local eadt = ltjf_font_metric_table[getfont(xc)]
+      .char_type[has_attr(xc, attr_jchar_class) or 0].end_adjust
+   if not eadt then 
+      return total, false
+   end
+   -- 続行条件2: min(eadt[1], 0)<= \parfillskip <= max(eadt[#eadt], 0)
+   local pfw = getfield(pf, 'width') 
+     + (total>0 and getfield(pf, 'stretch') or -getfield(pf, 'shrink')) *getfield(p, 'glue_set') 
+   if pfw<min(0,eadt[1]) or max(0,eadt[#eadt])<pfw then return total, false end
+   -- \parfillskip を 0 にする
+   total = total + getfield(pf, 'width') 
+   total_st.order, total_sh.order = 0, 0
+   if getfield(pf, 'stretch_order')==0 then 
+      local i = at2pr_st[-1] 
+      total_st[0] = total_st[0] - getfield(pf, 'stretch') 
+      total_st[i] = total_st[i] - getfield(pf, 'stretch') 
+      total_st.order = (total_st[0]==0) and -1 or 0
+   end
+   if getfield(pf, 'shrink_order')==0 then 
+      local i = at2pr_sh[-1] 
+      total_sh[0] = total_sh[0] - getfield(pf, 'shrink') 
+      total_sh[i] = total_sh[i] - getfield(pf, 'shrink') 
+      total_sh.order = (total_sh[0]==0) and -1 or 0
+   end
+   setfield(pf, 'subtype', 1); setglue(pf)
+   local eadt_ratio = {}
+   for i, v in ipairs(eadt) do
+      local t = total - v
+      if t>0 then
+	 eadt_ratio[i] = {i, t/total_st[65536*total_st.order], t, v}
+      else
+	 eadt_ratio[i] = {i, t/total_sh[65536*total_sh.order], t, v}
+      end
+   end
+   table.sort(eadt_ratio, 
+   function (a,b) 
+       for i=2,4 do
+	   local at, bt = abs(a[i]), abs(b[i])
+	   if at~=bt then return at<bt end
+       end
+       return a[4]<b[4]
+   end)
+   if eadt[eadt_ratio[1][1]]~=0 then
+      local kn = node_new(id_kern, 1)
+      setfield(kn, 'kern', eadt[eadt_ratio[1][1]]); set_attr(kn, attr_icflag, LINEEND)
+      insert_after(head, x, kn)
+      return eadt_ratio[1][3], true
+   else
+      return total, false
+   end
+end
+
+
 -- step 2: 行中の glue を変える
-local function aw_step2_dummy(p, _, added_flag)
-   if added_flag then -- 行末に kern 追加したので，それによる補正
-      local f = node_hpack(getlist(p), getfield(p, 'width'), 'exactly')
-      setfield(f, 'head', nil)
-      setfield(p, 'glue_set', getfield(f, 'glue_set'))
-      setfield(p, 'glue_order', getfield(f, 'glue_order'))
-      setfield(p, 'glue_sign', getfield(f, 'glue_sign'))
-      node_free(f)
-      return
+local aw_step2, aw_step2_dummy
+do
+local node_hpack = node.direct.hpack
+local function repack(p)
+   local f = node_hpack(getlist(p), getfield(p, 'width'), 'exactly')
+   setfield(f, 'head', nil)
+   setfield(p, 'glue_set', getfield(f, 'glue_set'))
+   setfield(p, 'glue_order', getfield(f, 'glue_order'))
+   setfield(p, 'glue_sign', getfield(f, 'glue_sign'))
+   node_free(f)
+   return
+end
+function aw_step2_dummy(p, _, added_flag)
+   if added_flag then return repack(p) end
+end
+
+local function clear_stretch(p, ind, ap, name)
+   for q in node_traverse_id(id_glue, getlist(p)) do
+      local f = ap[get_attr_icflag(q)]
+      if f == ind then
+         setfield(q, name..'_order', 0)
+         setfield(q, name, 0)
+      end
+   end
+end
+
+local function set_stretch(p, after, before, ind, ap, name)
+   if before > 0 then
+      local ratio = after/before
+      for q in node_traverse_id(id_glue, getlist(p)) do
+	 local f = ap[get_attr_icflag(q)]
+         if (f==ind) and getfield(q, name..'_order')==0 then
+            setfield(q, name, getfield(q, name)*ratio)
+         end
+      end
    end
 end
-local function aw_step2(p, total, added_flag)
+
+function aw_step2(p, total, added_flag)
    local name = (total>0) and 'stretch' or 'shrink'
-   local res = total_stsh[(total>0) and 1 or 2]
+   local id =  (total>0) and 1 or 2
+   local res = total_stsh[id]
+   local pnum = priority_num[id]
    if total==0 or res.order > 0 then 
       -- もともと伸縮の必要なしか，残りの伸縮量は無限大
-      if added_flag then -- 行末に kern 追加したので，それによる補正
-	 local f = node_hpack(getlist(p), getfield(p, 'width'), 'exactly')
-	 setfield(f, 'head', nil)
-	 setfield(p, 'glue_set', getfield(f, 'glue_set'))
-	 setfield(p, 'glue_order', getfield(f, 'glue_order'))
-	 setfield(p, 'glue_sign', getfield(f, 'glue_sign'))
-	 node_free(f)
-	 return
-      end
+      if added_flag then return repack(p) end
    end
-   total = math.abs(total)
-   if total <= res[-1] then -- 和文処理グルー以外で足りる
-      for _,v in pairs(priority_table) do clear_stretch(p, v, name) end
-      local f = node_hpack(getlist(p), getfield(p, 'width'), 'exactly')
-      setfield(f, 'head', nil)
-      setfield(p, 'glue_set', getfield(f, 'glue_set'))
-      setfield(p, 'glue_order', getfield(f, 'glue_order'))
-      setfield(p, 'glue_sign', getfield(f, 'glue_sign'))
-      node_free(f)
-   else
-      total = total - res[-1];
-      for i = 1, #priority_table do
-	 local v = priority_table[i]
-         if total <= res[v] then
-            for j = i+1,#priority_table do
-               clear_stretch(p, priority_table[j], name)
-            end
-            set_stretch(p, total, res[v], v, name); break
+   total = abs(total)
+   for i = 1, pnum do
+      if total <= res[i] then
+	 local a = at2pr[id]  
+         for j = i+1,pnum do
+            clear_stretch(p, j, a, name)
          end
-         total = total - res[v]
+         set_stretch(p, total, res[i], i, a, name); break
       end
-      local f = node_hpack(getlist(p), getfield(p, 'width'), 'exactly')
-      setfield(f, 'head', nil)
-      setfield(p, 'glue_set', getfield(f, 'glue_set'))
-      setfield(p, 'glue_order', getfield(f, 'glue_order'))
-      setfield(p, 'glue_sign', getfield(f, 'glue_sign'))
-      node_free(f)
+      total = total - res[i]
    end
+   return repack(p)
+end
 end
 
+-- step 1': lineend=extended の場合（行分割時に考慮））
+local insert_lineend_kern
+do
+   local insert_before = node.direct.insert_before
+   local KINSOKU      = luatexja.icflag_table.KINSOKU
+   function insert_lineend_kern(head, nq, np, Bp)
+      if nq.met then 
+         local eadt = nq.met.char_type[nq.class].end_adjust
+	 if not eadt then return end
+	 if eadt[1]~=0 then
+	    local x = node_new(id_kern, 1)
+	    setfield(x, 'kern', eadt[1]); set_attr(x, attr_icflag, LINEEND)
+	    insert_before(head, np.first, x)
+	 end
+	 local eadt_num = #eadt
+	 for i=2,eadt_num do
+	    local x = node_new(id_penalty)
+	    setfield(x, 'penalty', 0); set_attr(x, attr_icflag, KINSOKU)
+	    insert_before(head, np.first, x); Bp[#Bp+1] = x
+	    local x = node_new(id_kern, 1)
+	    setfield(x, 'kern', eadt[i]-eadt[i-1]); set_attr(x, attr_icflag, LINEEND)
+	    insert_before(head, np.first, x)
+	 end
+         if eadt_num>1 or eadt[1]~=0 then
+	    local x = node_new(id_penalty)
+	    setfield(x, 'penalty', 0); set_attr(x, attr_icflag, KINSOKU)
+	    insert_before(head, np.first, x); Bp[#Bp+1] = x
+	    local x = node_new(id_kern, 1)
+	    setfield(x, 'kern', -eadt[eadt_num]); set_attr(x, attr_icflag, LINEEND)
+	    insert_before(head, np.first, x)
+	    local x = node_new(id_penalty)
+	    setfield(x, 'penalty', 10000); set_attr(x, attr_icflag, KINSOKU)
+	    insert_before(head, np.first, x); Bp[#Bp+1] = x
+	 end
+      end
+   end
+end
 
+local adjust_width
 do
-   local myaw_atep1, myaw_step2
+   local myaw_atep1, myaw_step2, myaw_step1_last
    local dummy =  function(p,t,n) return t, false end
    local ltjs_fast_get_stack_skip = ltjs.fast_get_stack_skip
-   local function adjust_width(head)
+   function adjust_width(head)
       if not head then return head end
-      local line = 1
+      local last_p
       for p in node_traverse_id(id_hlist, to_direct(head)) do
-         line = line + 1
-         myaw_step2(p, myaw_step1(p, get_total_stretched(p, line)))
+	 if last_p then
+	    myaw_step2(last_p, myaw_step1(last_p, get_total_stretched(last_p)))
+	 end
+         last_p = p
+      end
+      if last_p then
+         myaw_step2(last_p, myaw_step1_last(last_p, get_total_stretched(last_p)))
       end
       return to_node(head)
    end
    local is_reg = false
-   function enable_cb(status)
-      if status>0 and (not is_reg) then
+   function enable_cb(status_le, status_pr)
+      if (status_le>0 or status_pr>0) and (not is_reg) then
 	 luatexbase.add_to_callback('post_linebreak_filter',
 				    adjust_width, 'Adjust width', 100)
 	 is_reg = true
-      elseif is_reg and status==0 then
+      elseif is_reg and (status_le==0 and status_pr==0) then
 	 luatexbase.remove_from_callback('post_linebreak_filter', 'Adjust width')
 	 is_reg = false
       end
-      myaw_step1 = (status%2>0) and aw_step1 or dummy
-      myaw_step2 = (status>=2) and aw_step2 or aw_step2_dummy
+      if status_le==2 then
+	 if not luatexbase.in_callback('luatexja.adjust_jfmglue', 'luatexja.adjust') then
+	    luatexbase.add_to_callback('luatexja.adjust_jfmglue', insert_lineend_kern, 'luatexja.adjust')
+	 end
+         myaw_step1, myaw_step1_last = dummy, aw_step1_last
+      else
+         if status_le==0 then
+            myaw_step1, myaw_step1_last = dummy, dummy
+         else
+            myaw_step1, myaw_step1_last = aw_step1, aw_step1_last
+         end
+         if luatexbase.in_callback('luatexja.adjust_jfmglue', 'luatexja.adjust') then
+   	    luatexbase.remove_from_callback('luatexja.adjust_jfmglue', 'luatexja.adjust')
+         end
+      end
+      myaw_step2 = (status_pr>0) and aw_step2 or aw_step2_dummy
    end
    function disable_cb() -- only for compatibility
        enable_cs(0)
    end
-   luatexja.adjust = luatexja.adjust or {enable_cb=enable_cb, disable_cb=disable_cb}  
+   luatexja.adjust.enable_cb=enable_cb
+   luatexja.adjust.disable_cb=disable_cb
 end
 
 luatexja.unary_pars.adjust = function(t)