From ca22b4438f88daab4f6f221004a3449bbc785d1e Mon Sep 17 00:00:00 2001
From: maelstrom <maelstrom@maelstrom.dev>
Date: Sun, 12 Jan 2025 17:18:03 +0100
Subject: [PATCH] infra: Base Instance classes

---
 src/objects/base.h            |  4 ++++
 src/objects/base/instance.cpp | 37 +++++++++++++++++++++++++++++++++++
 src/objects/base/instance.h   | 30 ++++++++++++++++++++++++++++
 src/objects/base/metadata.h   |  3 ++-
 4 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 src/objects/base.h
 create mode 100644 src/objects/base/instance.cpp
 create mode 100644 src/objects/base/instance.h

diff --git a/src/objects/base.h b/src/objects/base.h
new file mode 100644
index 0000000..8e9856d
--- /dev/null
+++ b/src/objects/base.h
@@ -0,0 +1,4 @@
+#pragma once
+
+#include "base/metadata.h"
+#include "base/instance.h"
\ No newline at end of file
diff --git a/src/objects/base/instance.cpp b/src/objects/base/instance.cpp
new file mode 100644
index 0000000..28a2aa6
--- /dev/null
+++ b/src/objects/base/instance.cpp
@@ -0,0 +1,37 @@
+#include "instance.h"
+#include <algorithm>
+#include <memory>
+#include <optional>
+
+// Static so that this variable name is "local" to this source file
+static InstanceType TYPE_ {
+    .super = NULL,
+    .className = "Instance",
+    .constructor = NULL, // Instance is abstract and therefore not creatable
+};
+
+InstanceType* Instance::TYPE = &TYPE_;
+
+InstanceType* GetClass() {
+    return &TYPE_;
+}
+
+void Instance::SetParent(std::optional<std::shared_ptr<Instance>> newParent) {
+    // If we currently have a parent, remove ourselves from it before adding ourselves to the new one
+    if (this->parent.has_value() && !this->parent.value().expired()) {
+        auto oldParent = this->parent.value().lock();
+        oldParent->children.erase(std::find(oldParent->children.begin(), oldParent->children.end(), this->shared_from_this()));
+    }
+    // Add ourselves to the new parent
+    if (newParent.has_value()) {
+        newParent.value()->children.push_back(this->shared_from_this());
+    }
+    this->parent = newParent;
+    // TODO: Add code for sending signals for parent updates
+}
+
+std::optional<std::shared_ptr<Instance>> Instance::GetParent() {
+    if (!parent.has_value()) return std::nullopt;
+    if (parent.value().expired()) return std::nullopt;
+    return parent.value().lock();
+}
\ No newline at end of file
diff --git a/src/objects/base/instance.h b/src/objects/base/instance.h
new file mode 100644
index 0000000..614951e
--- /dev/null
+++ b/src/objects/base/instance.h
@@ -0,0 +1,30 @@
+#pragma once
+
+#include "metadata.h"
+#include <memory>
+#include <string>
+
+// Struct describing information about an instance
+struct InstanceType {
+    InstanceType* super; // May be null
+    std::string className;
+    InstanceConstructor constructor;
+};
+
+// Base class for all instances in the data model
+class Instance : std::enable_shared_from_this<Instance> {
+private:
+    std::optional<std::weak_ptr<Instance>> parent;
+    std::vector<std::shared_ptr<Instance>> children;
+public:
+    static InstanceType* TYPE;
+    std::string name;
+
+    InstanceType* GetClass();
+    void SetParent(std::optional<std::shared_ptr<Instance>> newParent);
+    std::optional<std::shared_ptr<Instance>> GetParent();
+    inline const std::vector<std::shared_ptr<Instance>> GetChildren() { return children; }
+};
+
+typedef std::shared_ptr<Instance> InstanceRef;
+typedef std::weak_ptr<Instance> InstanceRefWeak;
\ No newline at end of file
diff --git a/src/objects/base/metadata.h b/src/objects/base/metadata.h
index 3bff353..83b2416 100644
--- a/src/objects/base/metadata.h
+++ b/src/objects/base/metadata.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <memory>
 #include <optional>
 #include <string>
 #include <variant>
@@ -9,7 +10,7 @@
 #include "../../datatype.h"
 
 class Instance;
-typedef Instance(*InstanceConstructor)();
+typedef std::shared_ptr<Instance>(*InstanceConstructor)();
 
 const uint INST_NOT_CREATABLE = 1;
 // const uint INST_SINGLETON = 2;