Monoidally-managed Minetest state modifications
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player_monoids/init.lua

120 lines
2.5 KiB

-- Copyright (c) raymoo 2016
-- Licensed under Apache 2.0 license. See COPYING for details.
-- Any documentation here are internal details, please avoid using them in your
-- mod.
local modpath = minetest.get_modpath(minetest.get_current_modname()) .. "/"
player_monoids = {}
local mon_meta = {}
mon_meta.__index = mon_meta
local nop = function() end
-- A monoid object is a table with the following fields:
-- def: The monoid definition
-- player_map: A map from player names to their effect tables. Effect tables
-- are maps from effect IDs to values.
-- value_cache: A map from player names to the cached value for the monoid.
-- next_id: The next unique ID to assign an effect.
local function monoid(def)
local mon = {}
local actual_def = {}
for k, v in pairs(def) do
actual_def[k] = v
end
if not actual_def.apply then
actual_def.apply = nop
end
if not actual_def.on_change then
actual_def.on_change = nop
end
mon.def = actual_def
local p_map = {}
mon.player_map = p_map
mon.next_id = 1
local v_cache = {}
mon.value_cache = v_cache
setmetatable(mon, mon_meta)
minetest.register_on_leaveplayer(function(player)
local p_name = player:get_player_name()
p_map[p_name] = nil
v_cache[p_name] = nil
end)
return mon
end
player_monoids.make_monoid = monoid
function mon_meta:add_change(player, value, id)
local p_name = player:get_player_name()
local def = self.def
local p_effects = self.player_map[p_name]
if p_effects == nil then
p_effects = {}
self.player_map[p_name] = p_effects
end
local actual_id
if id then
actual_id = id
else
actual_id = self.next_id
self.next_id = actual_id + 1
end
local old_total = self.value_cache[p_name]
p_effects[actual_id] = value
local new_total = def.fold(p_effects)
self.value_cache[p_name] = new_total
def.apply(new_total, player)
def.on_change(old_total, new_total, player)
return actual_id
end
function mon_meta:del_change(player, id)
local p_name = player:get_player_name()
local def = self.def
local p_effects = self.player_map[p_name]
if p_effects == nil then return end
local old_total = self.value_cache[p_name]
p_effects[id] = nil
local new_total = def.fold(p_effects)
self.value_cache[p_name] = new_total
def.apply(new_total, player)
def.on_change(old_total, new_total, player)
end
function mon_meta:value(player)
local p_name = player:get_player_name()
return self.value_cache[p_name] or self.def.identity
end
dofile(modpath .. "standard_monoids.lua")
dofile(modpath .. "test.lua")
minetest.log("action", "[player_monoids] loaded.")