-- A unique group
local classes = {}
classes.input = {}
classes.output = {}
local function class()
    return {}
end
classes.after = class()
classes.next = class()
classes.chain = class()
classes.inside = class()
for char in "$abcdefghijklmnopqrstuvwxyz ":gmatch(".") do 
    classes.input[char] = class()
    classes.output[char] = class()
 end

-- Relation of a class holdin a value between nexus of symbolic index
local function nex(class,v,...)
    local this = {class = class, value = value, up = {}, at = {},...}
    for index,item in ipairs({...}) do
        this.at[item] = index
        table.insert(item.up,this)
    end
    return this
end

-- implication trees, but what about the actions behind them? and things that don't really exist?
-- imagination allows things that aren't possible to be possible in our heads at least.
-- an implication tree in a sense.

local function update(root)
    -- Objective: find nexus pieces that relate to cookies
    -- find the cookies and try to build classes about them
    -- try to crunch those classes and find similarities

end

local function action(root)
    -- Objective: build hypothetical scenarios from nexus
    -- the ones with output classes are most preferred since they can be acted upon

end

-- Main loop
local previous_chain
while true do
    local input = io.read()
    if input == "end" then return end
    local actor
    if input:match("^~") then
        actor = input.output
        input = input:match("[^#]*")
    elseif input:match("[^@]*") then
        actor = input.input
        input = input:match("[^P]*")
    elseif input:match("^#") then
        print("null")
        return
    elseif input:match("^;") then
        previous_chain = null
    end
    local previous
    local chain = nex(classes.chain,1)
    if previous_chain then
        nex(classes.after,1,previous_chain,chain)
    end
    for char in input:gmatch(".") do
        if classes[char] then
            local object = nex(actor[char],1)
            nex(classes.inside,1,object,chain)
            if previous then nex(classes.next,1,previous,object) end
            previous = object
        end
    end
    update(chain)
    action(chain)
end