lib/table_io.lua

--[[
  Save Table to File
  Load Table from File
  v 1.0

  Lua 5.2 compatible

  Only Saves Tables, Numbers and Strings
  Insides Table References are saved
  Does not save Userdata, Metatables, Functions and indices of these
  ----------------------------------------------------
  table.save( table , filename )

  on failure: returns an error msg

  ----------------------------------------------------
  table.load( filename or stringtable )

  Loads a table that has been saved via the table.save function

  on success: returns a previously saved table
  on failure: returns as second argument an error msg
  ----------------------------------------------------

  Licensed under the same terms as Lua itself.

  http://lua-users.org/wiki/SaveTableToFile
]]--
do
  -- declare local variables
  --// exportstring( string )
  --// returns a "Lua" portable version of the string
  local function exportstring( s )
    return string.format("%q", s)
  end

  --// The Save Function
  function table.save(  tbl,filename )
    local charS,charE = "   ","\n"
    local file,err = io.open( filename, "wb" )
    if err then return err end

    -- initiate variables for save procedure
    local tables,lookup = { tbl },{ [tbl] = 1 }
    file:write( "return {"..charE )

    for idx,t in ipairs( tables ) do
      file:write( "-- Table: {"..idx.."}"..charE )
      file:write( "{"..charE )
      local thandled = {}

      for i,v in ipairs( t ) do
        thandled[i] = true
        local stype = type( v )
        -- only handle value
        if stype == "table" then
          if not lookup[v] then
            table.insert( tables, v )
            lookup[v] = #tables
          end
          file:write( charS.."{"..lookup[v].."},"..charE )
        elseif stype == "string" then
          file:write(  charS..exportstring( v )..","..charE )
        elseif stype == "number" then
          file:write(  charS..tostring( v )..","..charE )
        end
      end

      for i,v in pairs( t ) do
        -- escape handled values
        if (not thandled[i]) then

          local str = ""
          local stype = type( i )
          -- handle index
          if stype == "table" then
            if not lookup[i] then
              table.insert( tables,i )
              lookup[i] = #tables
            end
            str = charS.."[{"..lookup[i].."}]="
          elseif stype == "string" then
            str = charS.."["..exportstring( i ).."]="
          elseif stype == "number" then
            str = charS.."["..tostring( i ).."]="
          end

          if str ~= "" then
            stype = type( v )
            -- handle value
            if stype == "table" then
              if not lookup[v] then
                table.insert( tables,v )
                lookup[v] = #tables
              end
              file:write( str.."{"..lookup[v].."},"..charE )
            elseif stype == "string" then
              file:write( str..exportstring( v )..","..charE )
            elseif stype == "number" then
              file:write( str..tostring( v )..","..charE )
            end
          end
        end
      end
      file:write( "},"..charE )
    end
    file:write( "}" )
    file:close()
  end

  --// The Load Function
  function table.load( sfile )
    local ftables,err = loadfile( sfile )
    if err then return _,err end
    local tables = ftables()
    for idx = 1,#tables do
      local tolinki = {}
      for i,v in pairs( tables[idx] ) do
        if type( v ) == "table" then
          tables[idx][i] = tables[v[1]]
        end
        if type( i ) == "table" and tables[i[1]] then
          table.insert( tolinki,{ i,tables[i[1]] } )
        end
      end
      -- link indices
      for _,v in ipairs( tolinki ) do
        tables[idx][v[2]],tables[idx][v[1]] =  tables[idx][v[1]],nil
      end
    end
    return tables[1]
  end
-- close do
end

-- ChillCode