cs_Component.h

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/*
 * Author: Crownstone Team
 * Copyright: Crownstone (https://crownstone.rocks)
 * Date: Aug 18, 2021
 * License: LGPLv3+, Apache License 2.0, and/or MIT (triple-licensed)
 */
 
#pragma once
 
#include <logging/cs_Logger.h>
#include <protocol/cs_ErrorCodes.h>
#include <protocol/cs_Typedefs.h>
 
#include <vector>
 
class Component {
public:
    template <class T>
    T* getComponent(Component* requester = nullptr);
 
    // ============== life cycle events ===============
 
    virtual cs_ret_code_t init() { return ERR_SUCCESS; }
 
    void parentAllChildren();
 
    // ================== Con-/destructors ==================
 
    virtual ~Component() = default;
 
protected:
    // ================== Getters ==================
 
    virtual std::vector<Component*> getChildren() { return {}; }
 
    // ============== parenting ==============
 
    cs_ret_code_t initChildren();
 
    void setParent(Component* p);
 
 
private:
    Component* _parent = nullptr;
};
 
// -------------------- Template implementation details -------------------
 
template <class T>
T* Component::getComponent(Component* requester) {
    // jump up in hierarchy to parent.
    if (requester == nullptr) {
        if (_parent != nullptr) {
            // request from the parent to find a sibling.
            // keeping track of the original requester.
            return _parent->getComponent<T>(this);
        }
        else {
            // no parent means no siblings.
            // use get subcomponents if you want that.
            return nullptr;
        }
    }
 
    // traverse children
    for (auto c : getChildren()) {
        if (c == requester) {
            // skip original requester to avoid infinite recursions.
            continue;
        }
 
        T* t = dynamic_cast<T*>(c);
        if (t != nullptr) {
            return t;
        }
    }
 
    // jump up in hierarchy one stack frame deeper
    if (_parent != nullptr) {
        return _parent->getComponent<T>(this);
    }
 
    return nullptr;
}