Reduce unnecessary COW on Vector by make writing explicit

This commit makes operator[] on Vector const and adds a write proxy to it.  From
now on writes to Vectors need to happen through the .write proxy. So for
instance:

Vector<int> vec;
vec.push_back(10);
std::cout << vec[0] << std::endl;
vec.write[0] = 20;

Failing to use the .write proxy will cause a compilation error.

In addition COWable datatypes can now embed a CowData pointer to their data.
This means that String, CharString, and VMap no longer use or derive from
Vector.

_ALWAYS_INLINE_ and _FORCE_INLINE_ are now equivalent for debug and non-debug
builds. This is a lot faster for Vector in the editor and while running tests.
The reason why this difference used to exist is because force-inlined methods
used to give a bad debugging experience. After extensive testing with modern
compilers this is no longer the case.

1 files changed, 2 insertions, 2 deletions

diff --git a/editor/editor_resource_preview.cpp b/editor/editor_resource_preview.cpp
index aa67ea03d7..a9eaad47b7 100644
--- a/editor/editor_resource_preview.cpp
+++ b/editor/editor_resource_preview.cpp
@@ -46,7 +46,7 @@ bool EditorResourcePreviewGenerator::handles(const String &p_type) const {
 	ERR_EXPLAIN("EditorResourcePreviewGenerator::handles needs to be overridden");
 	ERR_FAIL_V(false);
 }
-Ref<Texture> EditorResourcePreviewGenerator::generate(const RES &p_from) {
+Ref<Texture> EditorResourcePreviewGenerator::generate(const RES &p_from) const {
 
 	if (get_script_instance() && get_script_instance()->has_method("generate")) {
 		return get_script_instance()->call("generate", p_from);
@@ -55,7 +55,7 @@ Ref<Texture> EditorResourcePreviewGenerator::generate(const RES &p_from) {
 	ERR_FAIL_V(Ref<Texture>());
 }
 
-Ref<Texture> EditorResourcePreviewGenerator::generate_from_path(const String &p_path) {
+Ref<Texture> EditorResourcePreviewGenerator::generate_from_path(const String &p_path) const {
 
 	if (get_script_instance() && get_script_instance()->has_method("generate_from_path")) {
 		return get_script_instance()->call("generate_from_path", p_path);