Brainfuck

brainfuck = {}

brainfuck.errorC = {
    [1] = "Closing brackets are missed!",
    [2] = "Openin brackets are missed!",
    [3] = "No source!",
    [4] = "Unknown error"
}

brainfuck.verify = function(s)
    local error,l = 0,0
    for i = 1,#s,1 do
        if s:byte(i) == 91 then
            l = l + 1
        elseif s:byte(i) == 93 then
            l = l - 1
            if l < 0 then
                return 2
            end
        end
    end
    if l > 0 then
        return 1
    elseif l < 0 then
        return 2
    else
        return 0
    end
end

brainfuck.error = function(x)
    error(brainfuck.errorC[x or 4])
end

brainfuck.token = function(s)
    local size,max,m,p,l = 3e4,255,{},0,0,0
    local toReturn = {}
    for i = 0,size,1 do
        m[i] = 0
    end
    i = 0
    while i <= #s do
        i = i + 1
        if s:byte(i) == 43 then
            if m[p] < max then
                m[p] = m[p] + 1
            end
        elseif s:byte(i) == 45 then
            if m[p] > 0 then
                m[p] = m[p] - 1
            end
        elseif s:byte(i) == 44 then
            local copy = s:match("(.-)\n")
            m[p] = copy:byte(1)
        elseif s:byte(i) == 46 then
            table.insert(toReturn,tostring(m[p]):char())
        elseif s:byte(i) == 60 then
            p = p - 1
            if p < 0 then
                p = 0
            end
        elseif s:byte(i) == 62 then
            p = p + 1
            if p > size then
                p = size
            end
        elseif s:byte(i) == 91 then
            if m[p] == 0 then
                while s:byte(i)~=93 or l>0 do
                    i = i + 1
                    if s:byte(i) == 91 then
                        l = l + 1
                    end
                    if s:byte(i) == 93 then
                        l = l - 1
                    end
                end
            end
        elseif s:byte(i) == 93 then
            if m[p] ~= 0 then
                while s:byte(i)~=91 or l>0 do
                    i = i - 1
                    if s:byte(i) == 91 then
                        l = l - 1
                    end
                    if s:byte(i) == 93 then
                        l = l + 1
                    end
                end
            end
        end
    end
    return table.concat(toReturn,nil,1,#toReturn-1)
end

brainfuck.compile = function(s)
    local error = brainfuck.verify(s)
    if error == 0 then
        return brainfuck.token(s)
    else
        brainfuck.error(error)
    end
end