new Lua library for persistent maps of arbitrary degree.

library/lua/persist-table.lua

@@ -0,0 +1,121 @@
+
+local _ENV = mkmodule('persist-table')
+
+symbols = symbols or {}
+symbolCount = symbolCount or {}
+
+function ensure(name)
+ return dfhack.persistent.save({key=name})
+end
+
+function gensym(prefix)
+ if not symbols[prefix] then
+  symbols[prefix] = {}
+ end
+ local sym = symbols[prefix] or {}
+ local i = 0
+ while true do
+  if not sym[i] then
+   symbols[prefix][i] = true
+   symbolCount[prefix] = math.max(symbolCount[prefix] or 0,i)
+   return prefix .. '&' .. tostring(i)
+  end
+  i = i+1
+ end
+end
+
+function releasesym(prefix, symb)
+ local sym = symbols[prefix] or {}
+ local i = 0
+ while true do
+  if prefix .. '&' .. tostring(i) == symb then
+   symbols[prefix][i] = nil
+   --symbolCount[prefix] = -1 + symbolCount[prefix]
+  end
+  i = i+1
+  if i > symbolCount[prefix] then
+   return
+  end
+ end
+end
+
+function accessTable(prefix,...)
+ local args = {...}
+ local name = '__master_table'
+ local previousName = nil
+ local child
+ for n,arg in ipairs(args) do
+  child = ensure(name .. '$$' .. arg)
+  local old = child.value
+  if old == '' then
+   child.value = gensym(prefix)
+   local size = ensure(name .. '$size')
+   size.value = tostring(1+(tonumber(size.value) or 0))
+   size:save()
+   if previousName then
+    --local size = ensure(previousName .. '$size')
+    --size.value = tostring(1+(tonumber(size.value) or 0))
+    --size:save()
+    local prev = ensure(name .. '$previous')
+    prev.value = previousName
+    prev:save()
+   end
+   child:save()
+   --new child
+   dfhack.persistent.save({key=name, value=arg}, true)
+  end
+  --print(n,arg,previousName,child.key,child.value)
+  previousName = name
+  name = child.value
+ end
+ return child
+end
+
+function deleteTable(prefix,name)
+ if not name then
+  do return end
+ end
+ local previous = ensure(name .. '$previous').value
+ local children = dfhack.persistent.get_all(name) or {}
+ for _,child in ipairs(children) do
+  --print('delete: ', name, previous, child)
+  local ptr = ensure(name .. '$$' .. child.value)
+  releasesym(prefix,ptr.value)
+  deleteTable(prefix,ptr.value)
+  ptr:delete()
+  child:delete()
+ end
+ ensure(name .. '$previous'):delete()
+ ensure(name .. '$size'):delete()
+ if previous ~= '' then
+  local size = ensure(previous .. '$size')
+  size.value = tostring(-1 + tonumber(size.value))
+  size:save()
+  local children = dfhack.persistent.get_all(previous) or {}
+  for _,sibling in ipairs(children) do
+   --print(sibling.value, name, previous .. '$$' .. sibling.value)
+   local ptr = ensure(previous .. '$$' .. sibling.value)
+   if ptr.value == name then
+    ptr:delete()
+    sibling:delete()
+   end
+  end
+ end
+ releasesym(prefix,name)
+end
+
+function setTable(prefix,...)
+ local args = {...}
+ local last = args[#args]
+ table.remove(args,#args)
+ --table.setn(args, #args-1)
+ local entry = accessTable(prefix,table.unpack(args))
+ local old = entry.value
+ deleteTable(prefix,old)
+ releasesym(prefix,old)
+ entry.value = last
+ entry:save()
+ return old
+end
+
+return _ENV