examples - refactor to load transformer from separate file

example/src/transforms/index.ts

@@ -0,0 +1,8 @@
+import SwapExpression from "./swap-expression";
+import { TransformModuleExport } from "src/types";
+
+export type ModuleNames = "swap-expression";
+
+export const moduleMap: { [key in ModuleNames]: TransformModuleExport } = {
+  "swap-expression": SwapExpression
+};

example/src/transforms/swap-expression.ts

@@ -0,0 +1,30 @@
+import * as ts from "typescript";
+import { TransformModuleExport } from "../types";
+
+const sourceCodeString = `x = y; a = b + c`;
+
+const transformer: ts.TransformerFactory<ts.SourceFile> = context => {
+  return sourceFile => {
+    const visitor = (node: ts.Node): ts.Node => {
+      if (
+        ts.isBinaryExpression(node) &&
+        node.operatorToken.kind === ts.SyntaxKind.EqualsToken &&
+        ts.isIdentifier(node.left) &&
+        ts.isIdentifier(node.right)
+      ) {
+        return ts.updateBinary(node, node.right, node.left);
+      }
+
+      return ts.visitEachChild(node, visitor, context);
+    };
+
+    return ts.visitNode(sourceFile, visitor);
+  };
+};
+
+const toExport: TransformModuleExport = {
+  sourceCodeString,
+  transformer
+};
+
+export default toExport;