Add feature to generate list of preloaded assets

Author: SomeRanDev

src/gdcompiler/GDCompiler.hx

@@ -99,6 +99,13 @@ class GDCompiler extends reflaxe.DirectToStringCompiler {
 	**/
 	var compilingInConstructor: Bool = false;
 
+	#if generate_resource_export_list
+	/**
+		A list of resources preloaded by the code.
+	**/
+	var usedResources: Array<String> = [];
+	#end
+
 	public function new() {
 		super();
 
@@ -141,6 +148,11 @@ class GDCompiler extends reflaxe.DirectToStringCompiler {
 		if(Context.defined(Define.GenerateGodotPlugin)) {
 			generatePlugin();
 		}
+		#if generate_resource_export_list
+		if(Context.defined(Define.GenerateResourceExportList)) {
+			setExtraFile("resource_export_list.txt", usedResources.join(", "));
+		}
+		#end
 	}
 
 	/**
@@ -390,7 +402,11 @@ ${exitTreeLines.length > 0 ? exitTreeLines.join("\n").tab() : "\tpass"}
 
 				switch(field.meta.extractExpressionsFromFirstMeta(Meta.Const)) {
 					case [macro preload = $expr]: {
-						overrideExpression = "preload(\"" + expr.getConstString() + "\");";
+						final path = expr.getConstString();
+						#if generate_resource_export_list
+						usedResources.push(path);
+						#end
+						overrideExpression = "preload(\"" + path + "\");";
 					}
 					case []: {
 						// No arguments is allowed but doesn't do anything...

src/gdcompiler/config/Define.hx

@@ -64,4 +64,13 @@ enum abstract Define(String) from String to String {
 		`-D gdscript_output_dirs` is defined.
 	**/
 	var GDScriptAlwaysUsePackagesInOutputFilenames = "gdscript_always_packages_in_output_filenames";
+
+	/**
+		-D generate_resource_export_list
+
+		If defined, a `.txt` file contained a comma separated list of preloaded
+		paths will be generated. These will be taken from uses of `@:const(preload = "path")`
+		and do not account for normal calls to `preload` at the moment.
+	**/
+	var GenerateResourceExportList = "generate_resource_export_list";
 }