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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.
148 lines
4.1 KiB
C++
148 lines
4.1 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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#pragma once
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#include "AiObject.h"
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#include "Common.h"
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#include "Event.h"
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#include "Value.h"
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class PlayerbotAI;
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class Unit;
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class NextAction
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{
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public:
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NextAction(std::string const name, float relevance = 0.0f)
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: relevance(relevance), name(name) {} // name after relevance - whipowill
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NextAction(NextAction const& o) : relevance(o.relevance), name(o.name) {} // name after relevance - whipowill
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std::string const getName() { return name; }
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float getRelevance() { return relevance; }
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static std::vector<NextAction> merge(std::vector<NextAction> const& what, std::vector<NextAction> const& with)
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{
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std::vector<NextAction> result = {};
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for (NextAction const& action : what)
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{
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result.push_back(action);
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}
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for (NextAction const& action : with)
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{
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result.push_back(action);
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}
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return result;
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};
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private:
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float relevance;
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std::string name;
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};
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class Action : public AiNamedObject
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{
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public:
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enum class ActionThreatType
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{
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None = 0,
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Single = 1,
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Aoe = 2
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};
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Action(PlayerbotAI* botAI, std::string const name = "action")
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: AiNamedObject(botAI, name), verbose(false) {} // verbose after ainamedobject - whipowill
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virtual ~Action(void) {}
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virtual bool Execute([[maybe_unused]] Event event) { return true; }
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virtual bool isPossible() { return true; }
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virtual bool isUseful() { return true; }
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virtual std::vector<NextAction> getPrerequisites() { return {}; }
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virtual std::vector<NextAction> getAlternatives() { return {}; }
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virtual std::vector<NextAction> getContinuers() { return {}; }
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virtual ActionThreatType getThreatType() { return ActionThreatType::None; }
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void Update() {}
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void Reset() {}
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virtual Unit* GetTarget();
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virtual Value<Unit*>* GetTargetValue();
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virtual std::string const GetTargetName() { return "self target"; }
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void MakeVerbose() { verbose = true; }
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void setRelevance(uint32 relevance1) { relevance = relevance1; };
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virtual float getRelevance() { return relevance; }
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protected:
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bool verbose;
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float relevance = 0;
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};
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class ActionNode
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{
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public:
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ActionNode(
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std::string name,
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std::vector<NextAction> prerequisites = {},
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std::vector<NextAction> alternatives = {},
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std::vector<NextAction> continuers = {}
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) :
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name(std::move(name)),
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action(nullptr),
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continuers(continuers),
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alternatives(alternatives),
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prerequisites(prerequisites)
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{}
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virtual ~ActionNode() = default;
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Action* getAction() { return action; }
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void setAction(Action* action) { this->action = action; }
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const std::string getName() { return name; }
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std::vector<NextAction> getContinuers()
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{
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return NextAction::merge(this->continuers, action->getContinuers());
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}
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std::vector<NextAction> getAlternatives()
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{
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return NextAction::merge(this->alternatives, action->getAlternatives());
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}
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std::vector<NextAction> getPrerequisites()
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{
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return NextAction::merge(this->prerequisites, action->getPrerequisites());
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}
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private:
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const std::string name;
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Action* action;
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std::vector<NextAction> continuers;
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std::vector<NextAction> alternatives;
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std::vector<NextAction> prerequisites;
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};
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class ActionBasket
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{
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public:
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ActionBasket(ActionNode* action, float relevance, bool skipPrerequisites, Event event);
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virtual ~ActionBasket(void) {}
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float getRelevance() { return relevance; }
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ActionNode* getAction() { return action; }
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Event getEvent() { return event; }
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bool isSkipPrerequisites() { return skipPrerequisites; }
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void AmendRelevance(float k) { relevance *= k; }
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void setRelevance(float relevance) { this->relevance = relevance; }
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bool isExpired(uint32_t msecs);
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private:
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ActionNode* action;
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float relevance;
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bool skipPrerequisites;
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Event event;
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uint32_t created;
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};
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