One thing I find useful is to store state from a table. I found this gem but I am not sure who it's credited to. The header file has no author. It allows you to save and load a lua table to a file.
Code: Select all
--[[
Save Table to File/Stringtable
Load Table from File/Stringtable
v 0.94
Lua 5.1 compatible
Userdata and indices of these are not saved
Functions are saved via string.dump, so make sure it has no upvalues
References are saved
----------------------------------------------------
table.save( table [, filename] )
Saves a table so it can be called via the table.load function again
table must a object of type 'table'
filename is optional, and may be a string representing a filename or true/1
table.save( table )
on success: returns a string representing the table (stringtable)
(uses a string as buffer, ideal for smaller tables)
table.save( table, true or 1 )
on success: returns a string representing the table (stringtable)
(uses io.tmpfile() as buffer, ideal for bigger tables)
table.save( table, "filename" )
on success: returns 1
(saves the table to file "filename")
on failure: returns as second argument 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
----------------------------------------------------
chillcode, http://lua-users.org/wiki/SaveTableToFile
Licensed under the same terms as Lua itself.
]]--
do
-- declare local variables
--// exportstring( string )
--// returns a "Lua" portable version of the string
local function exportstring( s )
s = string.format( "%q",s )
-- to replace
s = string.gsub( s,"\\\n","\\n" )
s = string.gsub( s,"\r","\\r" )
s = string.gsub( s,string.char(26),"\"..string.char(26)..\"" )
return s
end
--// The Save Function
function table.save( tbl,filename )
local charS,charE = " ","\n"
local file,err
-- create a pseudo file that writes to a string and return the string
if not filename then
file = { write = function( self,newstr ) self.str = self.str..newstr end, str = "" }
charS,charE = "",""
-- write table to tmpfile
elseif filename == true or filename == 1 then
charS,charE,file = "","",io.tmpfile()
-- write table to file
-- use io.open here rather than io.output, since in windows when clicking on a file opened with io.output will create an error
else
file,err = io.open( filename, "w" )
if err then return _,err end
end
-- initiate variables for save procedure
local tables,lookup = { tbl },{ [tbl] = 1 }
file:write( "return {"..charE )
for idx,t in ipairs( tables ) do
if filename and filename ~= true and filename ~= 1 then
file:write( "-- Table: {"..idx.."}"..charE )
end
file:write( "{"..charE )
local thandled = {}
for i,v in ipairs( t ) do
thandled[i] = true
-- escape functions and userdata
if type( v ) ~= "userdata" then
-- only handle value
if type( v ) == "table" then
if not lookup[v] then
table.insert( tables, v )
lookup[v] = #tables
end
file:write( charS.."{"..lookup[v].."},"..charE )
elseif type( v ) == "function" then
file:write( charS.."loadstring("..exportstring(string.dump( v )).."),"..charE )
else
local value = ( type( v ) == "string" and exportstring( v ) ) or tostring( v )
file:write( charS..value..","..charE )
end
end
end
for i,v in pairs( t ) do
-- escape functions and userdata
if (not thandled[i]) and type( v ) ~= "userdata" then
-- handle index
if type( i ) == "table" then
if not lookup[i] then
table.insert( tables,i )
lookup[i] = #tables
end
file:write( charS.."[{"..lookup[i].."}]=" )
else
local index = ( type( i ) == "string" and "["..exportstring( i ).."]" ) or string.format( "[%d]",i )
file:write( charS..index.."=" )
end
-- handle value
if type( v ) == "table" then
if not lookup[v] then
table.insert( tables,v )
lookup[v] = #tables
end
file:write( "{"..lookup[v].."},"..charE )
elseif type( v ) == "function" then
file:write( "loadstring("..exportstring(string.dump( v )).."),"..charE )
else
local value = ( type( v ) == "string" and exportstring( v ) ) or tostring( v )
file:write( value..","..charE )
end
end
end
file:write( "},"..charE )
end
file:write( "}" )
-- Return Values
-- return stringtable from string
if not filename then
-- set marker for stringtable
return file.str.."--|"
-- return stringttable from file
elseif filename == true or filename == 1 then
file:seek ( "set" )
-- no need to close file, it gets closed and removed automatically
-- set marker for stringtable
return file:read( "*a" ).."--|"
-- close file and return 1
else
file:close()
return 1
end
end
--// The Load Function
function table.load( sfile )
-- catch marker for stringtable
if string.sub( sfile,-3,-1 ) == "--|" then
tables,err = loadstring( sfile )
else
tables,err = loadfile( sfile )
end
if err then return _,err
end
tables = tables()
for idx = 1,#tables do
local tolinkv,tolinki = {},{}
for i,v in pairs( tables[idx] ) do
if type( v ) == "table" and tables[v[1]] then
table.insert( tolinkv,{ i,tables[v[1]] } )
end
if type( i ) == "table" and tables[i[1]] then
table.insert( tolinki,{ i,tables[i[1]] } )
end
end
-- link values, first due to possible changes of indices
for _,v in ipairs( tolinkv ) do
tables[idx][v[1]] = v[2]
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
Code: Select all
function table.contains(table, element)
for _, value in pairs(table) do
if value == element then
return true
end
end
return false
end
Finaly for debug purposes, this is a gem too. It will print the table to the stdout.
Code: Select all
--
-- tprint.lua
--[[
For debugging what tables have in them, prints recursively
See forum thread: http://www.gammon.com.au/forum/?id=4903
eg.
require "tprint"
tprint (GetStyleInfo (20))
--]]
function tprint (t, indent, done)
-- in case we run it standalone
local Note = Note or print
local Tell = Tell or io.write
-- show strings differently to distinguish them from numbers
local function show (val)
if type (val) == "string" then
return '"' .. val .. '"'
else
return tostring (val)
end -- if
end -- show
-- entry point here
done = done or {}
indent = indent or 0
for key, value in pairs (t) do
Tell (string.rep (" ", indent)) -- indent it
if type (value) == "table" and not done [value] then
done [value] = true
Note (show (key), ":");
tprint (value, indent + 2, done)
else
Tell (show (key), "=")
print (show (value))
end
end
end
return tprint
