lsave 0.5

-- lsave v0.5
-- (C) 2012 User 'Advert' at http://www.computercraft.info/forums2/
-- X11/mit licence (use/modify at your will, but please, leave credit where due)

-- This is from a project I'm working on, and I think it'd be useful for others, so I'm making it a snippet.
-- All functions return success, result/error message.
--
-- Currently only saves the following data types:
-- string, number, boolean
--
-- Functions:
-- local sucess, error = lsave.save(filename, table with data) -- does not return anything other than if it succeeded
-- WARNING: lsave.save WILL OVERWRITE YOUR FILE.
-- local sucess, result = lsave.load(filename) -- if success is true, then result should be a table with your data.
--
-- HOW 2 USE 4 DUMMIES
--
-- save as "lsave" on your computer/floppy, keep note of where it's saved.
--
-- To include it in your program, do this:
-- local loadFunc, err = loadfile("path/to/lsave")
-- if type(loadFunc) == "function" then
--  lsave = loadFunc()
-- else
--  -- We has error! file not exist or whatever.
--  error(err)
-- end
--
--


local lsave = {} -- will carry the public functions; loadfile does not like globals :/
do

    function lsave.load(sFile) -- This function will check that lsave saved the file in the future.
        if not fs.exists(sFile) then return false, "nofile" end -- We can't load a file that doesn't exist.
        local hHandle = io.open(sFile, "r")
        local err, res = pcall(function() return setfenv(loadfile(sFile),getfenv())() end)
        if not err then
            return false, res
        end
        return true, res
    end

    -- Saving helper format strings/functions
    lsave.types = {}
    lsave.types.boolean = "data[%q] = %s"
    lsave.types.string = "data[%q] = %q"
    lsave.types.number = "data[%q] = %d"

    -- Saving function
    function lsave.save(sFile, data)
        if type(sFile) ~= "string" or type(data) ~= "table" then
            return false, "Invalid arguments"
        end
        local sData = "local data = {} -- This file, generated by lsave 0.5. Edit at your own risk.\n\n"
        for k, v in pairs(data) do
            local sDataType = type(v)
            local saveHelper = lsave.types[sDataType]
            if not saveHelper then
                -- We have problem, let's just print it, and continue without saving it.
                print("Warning: (saveToFile) unknown data type (ignoring), in key: " .. k)
            else
                -- No errors, save it.
                if type(saveHelper) == "string" then
                    sData = sData .. string.format(saveHelper, k, tostring(v)) .. "\n"
                elseif type(saveHelper) == "function" then -- For the future, and custom stuff.
                    sData = sData .. saveHelper(k, v) .. "\n"
                end
            end
        end
        sData = sData .. "\nreturn data" -- We need to return the config in order to retrieve it.
        -- Delete and save.
        local hHandle, err = io.open(sFile, "w")
        if not hHandle then
            return false, err
        end
        hHandle:write(sData)
        hHandle:close()
        return true
    end
end

return lsave -- This, so you can do "lsave = loadfile("lsave")()"
-- Remove the line if you want to just paste it in your program, instead.
-- I think you should be able to convert this to an API, if you remove lsave. from function names (and lsave.types), and remove lsave = {}.


-- Testing code (you will need to use interpreter to fill the fridge):
-- in 'lua':
-- lsave = loadfile("lsave")() -- not checking for errors since interpreter will spew
-- fridge = {}
-- fridge.stuff = 42
-- fridge.otherstuff = false
-- --etc.
-- -- then, call
-- lsave.save("fridge-data", fridge)
-- -- you should then see "true" printed.
-- exit() -- out of interpreter, then use fridge-test:
-- then, load this program (call it fridge-test, or whatever.):

--[[
local loadFunc, err = loadfile("lsave")

if type(loadFunc) == "function" then
 lsave = loadFunc()
else
 error(err)
end

local empty = false
local suc, fridge = lsave.load("fridge-data")
if not suc then
    if fridge == "nofile" then
        print("Fridge is empty :(")
        empty = true
    else
        error("Error:" .. tostring(fridge))
    end
end
if not empty then

    print("Fridge Contents: ")
    for k, v in pairs(fridge) do
        print(k .. ": " .. tostring(v))
    end
end


--]]