Added luatexja.node_remove and luatexja.Dnode_remove ("safe node.remove")

[luatex-ja/luatexja.git] / src / luatexja.lua

diff --git a/src/luatexja.lua b/src/luatexja.lua
index b205460..d935235 100644 (file)
--- a/src/luatexja.lua
+++ b/src/luatexja.lua
@@ -57,6 +57,44 @@ userid_table.IHB  = luatexbase.newuserwhatsitid('inhibitglue',  'luatexja') -- \
 userid_table.STCK = luatexbase.newuserwhatsitid('stack_marker', 'luatexja') -- スタック管理
 userid_table.BPAR = luatexbase.newuserwhatsitid('begin_par',    'luatexja') -- 「段落始め」
 
+do
+   local node_remove, node_next, node_prev = node.remove, node.next, node.prev
+   function luatexja.node_remove (head, current)
+      if head==current then
+        local q, r = node_next(current), node_prev(current)
+        current.next = nil
+        if q then q.prev = r end
+        if r and node_next(r)==current then
+           -- r is "real prev"
+           r.next = q
+        end
+        return q, node_next(q)
+      else
+        return node_remove(head, current)
+      end
+   end
+
+   local Dnode = node.direct or node
+   local Dnode_remove, Dnode_next, Dnode_prev = Dnode.remove, Dnode.getnext, Dnode.getprev
+   local getfield = (Dnode ~= node) and Dnode.getfield or function(n, i) return n[i] end
+   local setfield = (Dnode ~= node) and Dnode.setfield or function(n, i, c) n[i] = c end
+   function luatexja.Dnode_remove (head, current)
+      if head==current then
+        local q, r = Dnode_next(current), Dnode_prev(current)
+        setfield(current, 'next', nil)
+        if q then setfield(q, 'prev', r) end
+        if r and Dnode_next(r) == current then
+           -- r is "real prev"
+           setfield(r, 'next', q)
+        end
+        return q, Dnode_next(q)
+      else
+        return Dnode_remove(head, current)
+      end
+   end
+
+end
+
 --- 定義終わり
 
 local load_module = luatexja.load_module