Add support for scene/resource customization in export plugins

EditorExportPlugin adds a set of callbacks to allow customizing scenes, resources or subresources in all files exported:
* Can take scene files, resource files and subresources in all of them.
* Uses a cache for the converted files if nothing changes, so this work only happens if a file is modified.
* Uses hashing to differentiate export configuration caches.
* Removed the previous conversion code to binary, as this one uses existing stuff.

This API is useful in several scenarios:
* Needed by the "server" export platform to get rid of textures, meshes, audio, etc.
* Needed by text to binary converters.
* Needed by eventual optimizations such as shader precompiling on export, mesh merging and optimization, etc.

This is a draft, feedback is very welcome.

2 files changed, 28 insertions, 0 deletions

diff --git a/core/io/config_file.cpp b/core/io/config_file.cpp
index ae421654ca..f84a95347a 100644
--- a/core/io/config_file.cpp
+++ b/core/io/config_file.cpp
@@ -32,6 +32,7 @@
 
 #include "core/io/file_access_encrypted.h"
 #include "core/os/keyboard.h"
+#include "core/string/string_builder.h"
 #include "core/variant/variant_parser.h"
 
 PackedStringArray ConfigFile::_get_sections() const {
@@ -130,6 +131,28 @@ void ConfigFile::erase_section_key(const String &p_section, const String &p_key)
 	}
 }
 
+String ConfigFile::encode_to_text() const {
+	StringBuilder sb;
+	bool first = true;
+	for (const KeyValue<String, HashMap<String, Variant>> &E : values) {
+		if (first) {
+			first = false;
+		} else {
+			sb.append("\n");
+		}
+		if (!E.key.is_empty()) {
+			sb.append("[" + E.key + "]\n\n");
+		}
+
+		for (const KeyValue<String, Variant> &F : E.value) {
+			String vstr;
+			VariantWriter::write_to_string(F.value, vstr);
+			sb.append(F.key.property_name_encode() + "=" + vstr + "\n");
+		}
+	}
+	return sb.as_string();
+}
+
 Error ConfigFile::save(const String &p_path) {
 	Error err;
 	Ref<FileAccess> file = FileAccess::open(p_path, FileAccess::WRITE, &err);
@@ -295,6 +318,7 @@ Error ConfigFile::_parse(const String &p_path, VariantParser::Stream *p_stream)
 void ConfigFile::clear() {
 	values.clear();
 }
+
 void ConfigFile::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_value", "section", "key", "value"), &ConfigFile::set_value);
 	ClassDB::bind_method(D_METHOD("get_value", "section", "key", "default"), &ConfigFile::get_value, DEFVAL(Variant()));
@@ -312,6 +336,8 @@ void ConfigFile::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("parse", "data"), &ConfigFile::parse);
 	ClassDB::bind_method(D_METHOD("save", "path"), &ConfigFile::save);
 
+	ClassDB::bind_method(D_METHOD("encode_to_text"), &ConfigFile::encode_to_text);
+
 	BIND_METHOD_ERR_RETURN_DOC("load", ERR_FILE_CANT_OPEN);
 
 	ClassDB::bind_method(D_METHOD("load_encrypted", "path", "key"), &ConfigFile::load_encrypted);
diff --git a/core/io/config_file.h b/core/io/config_file.h
index 3b07ec52f5..f6209492b7 100644
--- a/core/io/config_file.h
+++ b/core/io/config_file.h
@@ -68,6 +68,8 @@ public:
 	Error load(const String &p_path);
 	Error parse(const String &p_data);
 
+	String encode_to_text() const; // used by exporter
+
 	void clear();
 
 	Error load_encrypted(const String &p_path, const Vector<uint8_t> &p_key);