NativeScript/packages/webpack/transformers/ns-transform-native-classes.ts

import * as ts from 'typescript';

export default function (ctx: ts.TransformationContext) {
	function isNativeClassExtension(node: ts.ClassDeclaration) {
		return (
			node.decorators &&
			node.decorators.filter((d) => {
				const fullText = d.getFullText().trim();
				return fullText.indexOf('@NativeClass') > -1;
			}).length > 0
		);
	}
	function visitNode(node: ts.Node): ts.Node {
		if (ts.isClassDeclaration(node) && isNativeClassExtension(node)) {
			return createHelper(node);
		}
		return ts.visitEachChild(node, visitNode, ctx);
	}

	function createHelper(node: ts.Node) {
		// we remove the decorator for now!
		return ts.createIdentifier(
			ts.transpileModule(node.getText().replace(/@NativeClass(\((.|\n)*?\))?/gm, ''), {
				compilerOptions: { noEmitHelpers: true, module: ts.ModuleKind.CommonJS, target: ts.ScriptTarget.ES5 },
			}).outputText
		);
	}

	return (source: ts.SourceFile) => ts.updateSourceFileNode(source, ts.visitNodes(source.statements, visitNode));
}