Refactor Object metadata

* API kept the same (Although functions could be renamed to set_metadata/get_metadata in a later PR), so not much should change.
* Metadata now exposed as individual properties.
* Properties are editable in inspector (unless metadata name begins with _) under the metadata/ namespace.
* Added the ability to Add/Remove metadata properties to the inspector.

This is a functionality that was requested very often, that makes metadata work a bit more similar to custom properties in Blender.

2 files changed, 52 insertions, 22 deletions

diff --git a/core/object/object.cpp b/core/object/object.cpp
index 096edd4e60..226d3ef0b8 100644
--- a/core/object/object.cpp
+++ b/core/object/object.cpp
@@ -416,12 +416,22 @@ void Object::set(const StringName &p_name, const Variant &p_value, bool *r_valid
 		}
 		return;
 
-	} else if (p_name == CoreStringNames::get_singleton()->_meta) {
-		metadata = p_value.duplicate();
-		if (r_valid) {
-			*r_valid = true;
+	} else {
+		OrderedHashMap<StringName, Variant>::Element *E = metadata_properties.getptr(p_name);
+		if (E) {
+			E->get() = p_value;
+			if (r_valid) {
+				*r_valid = true;
+			}
+			return;
+		} else if (p_name.operator String().begins_with("metadata/")) {
+			// Must exist, otherwise duplicate() will not work.
+			set_meta(p_name.operator String().replace_first("metadata/", ""), p_value);
+			if (r_valid) {
+				*r_valid = true;
+			}
+			return;
 		}
-		return;
 	}
 
 	// Something inside the object... :|
@@ -496,9 +506,12 @@ Variant Object::get(const StringName &p_name, bool *r_valid) const {
 			*r_valid = true;
 		}
 		return ret;
+	}
+
+	const OrderedHashMap<StringName, Variant>::Element *E = metadata_properties.getptr(p_name);
 
-	} else if (p_name == CoreStringNames::get_singleton()->_meta) {
-		ret = metadata;
+	if (E) {
+		ret = E->get();
 		if (r_valid) {
 			*r_valid = true;
 		}
@@ -648,13 +661,20 @@ void Object::get_property_list(List<PropertyInfo> *p_list, bool p_reversed) cons
 	if (!is_class("Script")) { // can still be set, but this is for user-friendliness
 		p_list->push_back(PropertyInfo(Variant::OBJECT, "script", PROPERTY_HINT_RESOURCE_TYPE, "Script", PROPERTY_USAGE_DEFAULT));
 	}
-	if (!metadata.is_empty()) {
-		p_list->push_back(PropertyInfo(Variant::DICTIONARY, "__meta__", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_NO_EDITOR | PROPERTY_USAGE_INTERNAL));
-	}
+
 	if (script_instance && !p_reversed) {
 		p_list->push_back(PropertyInfo(Variant::NIL, "Script Variables", PROPERTY_HINT_NONE, String(), PROPERTY_USAGE_CATEGORY));
 		script_instance->get_property_list(p_list);
 	}
+
+	for (OrderedHashMap<StringName, Variant>::ConstElement K = metadata.front(); K; K = K.next()) {
+		PropertyInfo pi = PropertyInfo(K.value().get_type(), "metadata/" + K.key().operator String());
+		if (K.value().get_type() == Variant::OBJECT) {
+			pi.hint = PROPERTY_HINT_RESOURCE_TYPE;
+			pi.hint_string = "Resource";
+		}
+		p_list->push_back(pi);
+	}
 }
 
 void Object::_validate_property(PropertyInfo &property) const {
@@ -915,11 +935,23 @@ bool Object::has_meta(const StringName &p_name) const {
 
 void Object::set_meta(const StringName &p_name, const Variant &p_value) {
 	if (p_value.get_type() == Variant::NIL) {
-		metadata.erase(p_name);
+		if (metadata.has(p_name)) {
+			metadata.erase(p_name);
+			metadata_properties.erase("metadata/" + p_name.operator String());
+			notify_property_list_changed();
+		}
 		return;
 	}
 
-	metadata[p_name] = p_value;
+	OrderedHashMap<StringName, Variant>::Element E = metadata.find(p_name);
+	if (E) {
+		E.value() = p_value;
+	} else {
+		ERR_FAIL_COND(!p_name.operator String().is_valid_identifier());
+		E = metadata.insert(p_name, p_value);
+		metadata_properties["metadata/" + p_name.operator String()] = E;
+		notify_property_list_changed();
+	}
 }
 
 Variant Object::get_meta(const StringName &p_name) const {
@@ -928,7 +960,7 @@ Variant Object::get_meta(const StringName &p_name) const {
 }
 
 void Object::remove_meta(const StringName &p_name) {
-	metadata.erase(p_name);
+	set_meta(p_name, Variant());
 }
 
 Array Object::_get_property_list_bind() const {
@@ -954,20 +986,16 @@ Array Object::_get_method_list_bind() const {
 Vector<StringName> Object::_get_meta_list_bind() const {
 	Vector<StringName> _metaret;
 
-	List<Variant> keys;
-	metadata.get_key_list(&keys);
-	for (const Variant &E : keys) {
-		_metaret.push_back(E);
+	for (OrderedHashMap<StringName, Variant>::ConstElement K = metadata.front(); K; K = K.next()) {
+		_metaret.push_back(K.key());
 	}
 
 	return _metaret;
 }
 
 void Object::get_meta_list(List<StringName> *p_list) const {
-	List<Variant> keys;
-	metadata.get_key_list(&keys);
-	for (const Variant &E : keys) {
-		p_list->push_back(E);
+	for (OrderedHashMap<StringName, Variant>::ConstElement K = metadata.front(); K; K = K.next()) {
+		p_list->push_back(K.key());
 	}
 }
 
diff --git a/core/object/object.h b/core/object/object.h
index 6b4f1c81e6..41365cfe51 100644
--- a/core/object/object.h
+++ b/core/object/object.h
@@ -39,6 +39,7 @@
 #include "core/templates/hash_map.h"
 #include "core/templates/list.h"
 #include "core/templates/map.h"
+#include "core/templates/ordered_hash_map.h"
 #include "core/templates/safe_refcount.h"
 #include "core/templates/set.h"
 #include "core/templates/vmap.h"
@@ -530,7 +531,8 @@ private:
 #endif
 	ScriptInstance *script_instance = nullptr;
 	Variant script; // Reference does not exist yet, store it in a Variant.
-	Dictionary metadata;
+	OrderedHashMap<StringName, Variant> metadata;
+	HashMap<StringName, OrderedHashMap<StringName, Variant>::Element> metadata_properties;
 	mutable StringName _class_name;
 	mutable const StringName *_class_ptr = nullptr;