Censoring words in lua

Question

(repost: https://stackoverflow.com/questions/59665338/censoring-words-in-lua#comment105491094_59665338, as advised)

Im currently making a discord censor bot for my friend, and I was wondering if anyone with experience could help me, or if theres an easier way to complete my code.

local BadWords = {
    ['poop']=true,
}

client:on('messageCreate', function(msg)
    Msg = msg.content
    local msgs = string.split(Msg,' ')
    for i,v in pairs(msgs) do
        if BadWords[v:lower()] then
            msg:reply({
                embed = {
                    fields = {
                    {name = "Bad Word",value=v,inline = true},
                    },
                    color = discordia.Color.fromRGB(114, 137, 218).value,

                    --footer = os.time(),
                }
            })
            --msg:reply(('Blacklisted word: %s'):format(v))
        end
    end
    --[[table.foreach(msgs,function(i,v)
        if BadWords[i] or BadWords[v] then
            msg:reply(('Blacklisted word: %s'):format(v))
        end
    end)--]]
end)
client:run(Settings.Token)

There's nothing wrong with it, nor is it complete but my idea was to split, or concatenate all the words they send respectively, mutate into all versions of the word (i.e. farm, f4rm, type shit) and then checking the BadWord list.

Mostly what I was wondering was if there's a more efficient way to do this, or if I just gotta do what I gotta do

Answer 1

If you care about performance, you should have a look at LPeg. It makes it way easier to handle large numbers of string matching and substitution rules.

For example, you could define patterns and their substitution values like this:

local lpeg = require 'lpeg'

local p = lpeg.P
local bad_word = 
   p"bad" / "good" +
   (p"dumb" + p"stupid") / "$#&*"

local sanitize = lpeg.Cs( (bad_word + p(1))^1 )

print(sanitize:match("this is a bad word"))
print(sanitize:match("python is dumb!"))

Which makes it much easier both to add new entries and to eventually move them into a table or even a separate file.