feat: add Variants type for creating instances

CMakeLists.txt

@@ -25,6 +25,7 @@ qt_standard_project_setup(REQUIRES 6.6)
 qt_add_executable(qtshell
 	src/cpp/main.cpp
 	src/cpp/shell.cpp
+	src/cpp/variants.cpp
 )
 
 qt_add_qml_module(qtshell URI QtShell)

src/cpp/variants.cpp

@@ -0,0 +1,94 @@
+#include "variants.hpp"
+#include <algorithm>
+#include <utility>
+
+#include <qcontainerfwd.h>
+#include <qlogging.h>
+
+void Variants::setVariants(QVariantList variants) {
+	this->mVariants = std::move(variants);
+	qDebug() << "configurations updated:" << this->mVariants;
+
+	this->updateVariants();
+}
+
+void Variants::componentComplete() {
+	qDebug() << "configure ready";
+
+	this->updateVariants();
+}
+
+void Variants::updateVariants() {
+	if (this->mComponent == nullptr) {
+		qWarning() << "Variants instance does not have a component specified";
+		return;
+	}
+
+	// clean up removed entries
+	for (auto iter = this->instances.values.begin(); iter < this->instances.values.end();) {
+		if (this->mVariants.contains(iter->first)) {
+			iter++;
+		} else {
+			iter->second->deleteLater();
+			iter = this->instances.values.erase(iter);
+		}
+	}
+
+	for (auto iter = this->mVariants.begin(); iter < this->mVariants.end(); iter++) {
+		auto& variantObj = *iter;
+		if (!variantObj.canConvert<QVariantMap>()) {
+			qWarning() << "value passed to Variants is not an object and will be ignored:" << variantObj;
+		} else {
+			auto variant = variantObj.value<QVariantMap>();
+
+			for (auto iter2 = this->mVariants.begin(); iter2 < iter; iter2++) {
+				if (*iter2 == variantObj) {
+					qWarning() << "same value specified twice in Variants, duplicates will be ignored:"
+					           << variantObj;
+					goto outer;
+				}
+			}
+
+			if (this->instances.contains(variant)) {
+				continue; // we dont need to recreate this one
+			}
+
+			auto* instance = this->mComponent->createWithInitialProperties(variant, nullptr);
+
+			if (instance == nullptr) {
+				qWarning() << "failed to create variant with object" << variant;
+				continue;
+			}
+
+			instance->setParent(this);
+			this->instances.insert(variant, instance);
+		}
+
+	outer:;
+	}
+}
+
+template <typename K, typename V>
+bool AwfulMap<K, V>::contains(const K& key) const {
+	return std::ranges::any_of(this->values, [&](const QPair<K, V>& pair) {
+		return pair.first == key;
+	});
+}
+
+template <typename K, typename V>
+void AwfulMap<K, V>::insert(K key, V value) {
+	this->values.push_back(QPair<K, V>(key, value));
+}
+
+template <typename K, typename V>
+bool AwfulMap<K, V>::remove(const K& key) {
+	for (auto iter = this->values.begin(); iter < this->values.end(); iter++) {
+		if (iter->first == key) {
+			this->values.erase(iter);
+
+			return true;
+		}
+	}
+
+	return false;
+}

src/cpp/variants.hpp

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <qcontainerfwd.h>
+#include <qlist.h>
+#include <qmap.h>
+#include <qobject.h>
+#include <qqmlcomponent.h>
+#include <qqmlparserstatus.h>
+
+// extremely inefficient map
+template <typename K, typename V>
+class AwfulMap {
+public:
+	[[nodiscard]] bool contains(const K& key) const;
+	void insert(K key, V value); // assumes no duplicates
+	bool remove(const K& key);   // returns true if anything was removed
+	QList<QPair<K, V>> values;
+};
+
+class Variants: public QObject, public QQmlParserStatus {
+	Q_OBJECT;
+	Q_PROPERTY(QQmlComponent* component MEMBER mComponent);
+	Q_PROPERTY(QVariantList variants MEMBER mVariants WRITE setVariants);
+	Q_CLASSINFO("DefaultProperty", "component");
+	QML_ELEMENT;
+
+public:
+	explicit Variants(QObject* parent = nullptr): QObject(parent) {}
+
+	void classBegin() override {};
+	void componentComplete() override;
+
+private:
+	void setVariants(QVariantList variants);
+	void updateVariants();
+
+	QQmlComponent* mComponent = nullptr;
+	QVariantList mVariants;
+	AwfulMap<QVariantMap, QObject*> instances;
+};