Function before

tools/transformers/native-class.js:3–121

(_options, program)

const ts = require('typescript');

function before(_options, program) {
	const compilerOptions = program?.getCompilerOptions?.() ?? {};

	return (context) => {
		const factory = context.factory ?? ts.factory;

		return (sourceFile) => {
			let mutated = false;

			// Always preserve original top-level import declarations in final output
			const originalImportStatements = sourceFile.statements.filter((s) => ts.isImportDeclaration(s));

			const transformStatements = (statements, isTopLevel) => {
				let changed = false;
				const result = [];

				for (const statement of statements) {
					if (ts.isClassDeclaration(statement) && hasNativeClassDecorator(statement)) {
						mutated = true;
						changed = true;
						result.push(...emitDownleveledClass(statement));
						continue;
					}

					if (ts.isExpressionStatement(statement)) {
						const updated = removeNativeClassFromDecorate(factory, statement);
						if (updated === undefined) {
							mutated = true;
							changed = true;
							continue;
						}
						const visited = ts.visitEachChild(updated, visitNode, context);
						if (updated !== statement || visited !== statement) {
							mutated = true;
							changed = true;
						}
						result.push(visited);
						continue;
					}

					if (isTopLevel && ts.isImportDeclaration(statement)) {
						// Safety: Do not alter import declarations here. Earlier versions attempted to
						// remove `NativeClass` from named imports, but this proved too risky and could
						// accidentally elide unrelated imports in certain TS versions/configs. We keep
						// imports intact and rely on bundlers/TS to tree-shake if needed.
						result.push(statement);
						continue;
					}

					const visited = ts.visitEachChild(statement, visitNode, context);
					if (visited !== statement) {
						mutated = true;
						changed = true;
					}
					result.push(visited);
				}

				return [changed ? factory.createNodeArray(result) : statements, changed];