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https://github.com/mod-playerbots/mod-playerbots.git
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<!-- > [!WARNING] > **This is a DRAFT PR.** > The structure is not definitive. The code might not be optimised yet. It might not even start nor compile yet. > **Don't panic. ✋ It's going to be ok. 👌 We can make modifications, we can fix things.** 😁 --> # Description This PR aims to refactor the NextAction declaration to achieve two goals: ## Eliminate C-style sentinel arrays Currently, a double pointer (`NextAction**`) approach is being used. This an old pre-C++11 (< 2011) trick before `std::vector<>` became a thing. This approach is painful for developers because they constantly need to declare their `NextAction` arrays as: ```cpp NextAction::array(0, new NextAction("foo", 1.0f), nullptr) ``` Instead of: ```cpp { new NextAction("foo", 1.0f) } ``` The first argument of `NextAction::array` is actually a hack. It is used to have a named argument so `va_args` can find the remaining arguments. It is set to 0 everywhere but in fact does nothing. This is very confusing to people unfamiliar with this antiquated syntax. The last argument `nullptr` is what we call a sentinel. It's a `nullptr` because `va_args` is looking for a `nullptr` to stop iterating. It's also a hack and also leads to confusion. ## Eliminate unnecessary pointers for `NextAction` Pointers can be used for several reasons, to cite a few: - Indicate strong, absolute identity. - Provide strong but transferable ownership (unlike references). - When a null value is acceptable (`nullptr`). - When copy is expensive. `NextAction` meets none of these criteria: - It has no identity because it is purely behavioural. - It is never owned by anything as it is passed around and never fetched from a registry. - The only situations where it can be `nullptr` are errors that should in fact throw an `std::invalid_argument` instead. - They are extremely small objects that embark a single `std::string` and a single `float`. Pointers should be avoided when not strictly necessary because they can quickly lead to undefined behaviour due to unhandled `nullptr` situations. They also make the syntax heavier due to the necessity to constantly check for `nullptr`. Finally, they aren't even good for performance in that situation because shifting a pointer so many times is likely more expensive than copying such a trivial object. # End goal The end goal is to declare `NextAction` arrays this way: ```cpp { NextAction("foo", 1.0f) } ``` > [!NOTE] > Additional note: `NextAction` is nothing but a hacky proxy to an `Action` constructor. This should eventually be reworked to use handles instead of strings. This would make copying `NextAction` even cheaper and remove the need for the extremely heavy stringly typed current approach. Stringly typed entities are a known anti-pattern so we need to move on from those.
146 lines
3.5 KiB
C++
146 lines
3.5 KiB
C++
/*
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* Copyright (C) 2016+ AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license, you may redistribute it
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* and/or modify it under version 3 of the License, or (at your option), any later version.
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*/
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#include "Strategy.h"
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#include "Playerbots.h"
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class ActionNodeFactoryInternal : public NamedObjectFactory<ActionNode>
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{
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public:
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ActionNodeFactoryInternal()
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{
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creators["melee"] = &melee;
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creators["healthstone"] = &healthstone;
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creators["be near"] = &follow_master_random;
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creators["attack anything"] = &attack_anything;
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creators["move random"] = &move_random;
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creators["move to loot"] = &move_to_loot;
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creators["food"] = &food;
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creators["drink"] = &drink;
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creators["mana potion"] = &mana_potion;
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creators["healing potion"] = &healing_potion;
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creators["flee"] = &flee;
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}
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private:
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static ActionNode* melee([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"melee",
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/*P*/ {},
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/*A*/ {},
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/*C*/ {}
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);
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}
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static ActionNode* healthstone([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"healthstone",
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/*P*/ {},
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/*A*/ { NextAction("healing potion") },
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/*C*/ {}
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);
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}
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static ActionNode* follow_master_random([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"be near",
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/*P*/ {},
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/*A*/ { NextAction("follow") },
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/*C*/ {}
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);
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}
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static ActionNode* attack_anything([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"attack anything",
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/*P*/ {},
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/*A*/ {},
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/*C*/ {}
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);
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}
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static ActionNode* move_random([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"move random",
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/*P*/ {},
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/*A*/ { NextAction("stay line") },
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/*C*/ {}
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);
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}
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static ActionNode* move_to_loot([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"move to loot",
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/*P*/ {},
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/*A*/ {},
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/*C*/ {}
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);
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}
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static ActionNode* food([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"food",
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/*P*/ {},
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/*A*/ {},
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/*C*/ {}
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);
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}
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static ActionNode* drink([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"drink",
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/*P*/ {},
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/*A*/ {},
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/*C*/ {}
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);
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}
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static ActionNode* mana_potion([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"mana potion",
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/*P*/ {},
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/*A*/ {},
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/*C*/ {}
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);
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}
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static ActionNode* healing_potion([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"healing potion",
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/*P*/ {},
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/*A*/ { NextAction("food") },
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/*C*/ {}
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);
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}
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static ActionNode* flee([[maybe_unused]] PlayerbotAI* botAI)
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{
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return new ActionNode(
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"flee",
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/*P*/ {},
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/*A*/ {},
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/*C*/ {}
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);
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}
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};
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Strategy::Strategy(PlayerbotAI* botAI) : PlayerbotAIAware(botAI)
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{
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actionNodeFactories.Add(new ActionNodeFactoryInternal());
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}
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ActionNode* Strategy::GetAction(std::string const name) { return actionNodeFactories.GetContextObject(name, botAI); }
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