chore(core): embedded export for cfn-parse (#19773)

This PR moves `cfn-parse.ts` under a folder within `@aws-cdk/core/lib`, where it is "secretly" exported. You can access the API of `cfn-parse` by importing `import * as cfn_parse from '@aws-cdk/core/lib/cfn-parse';`.

The motivation behind this change is to stabilize the code generated by `cfn2ts`. `cfn2ts` imports `cfn_parse` but until now, this was not possible in v2 since `aws-cdk-lib` is export-restricted. This change should allow cdk v2 users the ability to generate L1 code via `cfn2ts`.

Closes #18037. 

----

### All Submissions:

* [x] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/master/CONTRIBUTING.md)

### Adding new Unconventional Dependencies:

* [ ] This PR adds new unconventional dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/master/CONTRIBUTING.md/#adding-new-unconventional-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/master/INTEGRATION_TESTS.md)?
	* [ ] Did you use `cdk-integ` to deploy the infrastructure and generate the snapshot (i.e. `cdk-integ` without `--dry-run`)?

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/cloudformation-include/lib/cfn-include.ts

@@ -1,5 +1,5 @@
 import * as core from '@aws-cdk/core';
-import * as cfn_parse from '@aws-cdk/core/lib/cfn-parse';
+import * as cfn_parse from '@aws-cdk/core/lib/helpers-internal';
 import { Construct } from 'constructs';
 import * as cfn_type_to_l1_mapping from './cfn-type-to-l1-mapping';
 import * as futils from './file-utils';

packages/@aws-cdk/core/lib/cfn-codedeploy-blue-green-hook.ts

@@ -1,7 +1,7 @@
 import { Construct } from 'constructs';
 import { CfnHook } from './cfn-hook';
-import { FromCloudFormationOptions } from './cfn-parse';
 import { CfnResource } from './cfn-resource';
+import { FromCloudFormationOptions } from './helpers-internal';
 import { undefinedIfAllValuesAreEmpty } from './util';
 
 /**

packages/@aws-cdk/core/lib/cfn-parse.ts → packages/@aws-cdk/core/lib/helpers-internal/cfn-parse.ts

@@ -1,20 +1,20 @@
-import { CfnCondition } from './cfn-condition';
-import { CfnElement } from './cfn-element';
-import { Fn } from './cfn-fn';
-import { CfnMapping } from './cfn-mapping';
-import { Aws } from './cfn-pseudo';
-import { CfnResource } from './cfn-resource';
+import { CfnCondition } from '../cfn-condition';
+import { CfnElement } from '../cfn-element';
+import { Fn } from '../cfn-fn';
+import { CfnMapping } from '../cfn-mapping';
+import { Aws } from '../cfn-pseudo';
+import { CfnResource } from '../cfn-resource';
 import {
   CfnAutoScalingReplacingUpdate, CfnAutoScalingRollingUpdate, CfnAutoScalingScheduledAction, CfnCodeDeployLambdaAliasUpdate,
   CfnCreationPolicy, CfnDeletionPolicy, CfnResourceAutoScalingCreationPolicy, CfnResourceSignal, CfnUpdatePolicy,
-} from './cfn-resource-policy';
-import { CfnTag } from './cfn-tag';
-import { Lazy } from './lazy';
-import { CfnReference, ReferenceRendering } from './private/cfn-reference';
-import { IResolvable } from './resolvable';
-import { Validator } from './runtime';
-import { isResolvableObject, Token } from './token';
-import { undefinedIfAllValuesAreEmpty } from './util';
+} from '../cfn-resource-policy';
+import { CfnTag } from '../cfn-tag';
+import { Lazy } from '../lazy';
+import { CfnReference, ReferenceRendering } from '../private/cfn-reference';
+import { IResolvable } from '../resolvable';
+import { Validator } from '../runtime';
+import { isResolvableObject, Token } from '../token';
+import { undefinedIfAllValuesAreEmpty } from '../util';
 
 /**
  * The class used as the intermediate result from the generated L1 methods

packages/@aws-cdk/core/lib/helpers-internal/index.ts

@@ -0,0 +1 @@
+export * from './cfn-parse';

packages/@aws-cdk/core/package.json

@@ -162,6 +162,11 @@
     "lines": 55,
     "branches": 35
   },
+  "ubergen": {
+    "exports": {
+      "./lib/helpers-internal": "./lib/helpers-internal/index.js"
+    }
+  },
   "keywords": [
     "aws",
     "cdk",

tools/@aws-cdk/cfn2ts/lib/codegen.ts

@@ -58,8 +58,8 @@ export default class CodeGenerator {
     this.code.line('/* eslint-disable max-len */ // This is generated code - line lengths are difficult to control');
     this.code.line();
     this.code.line(`import * as ${CORE} from '${coreImport}';`);
-    // explicitly import the cfn-parse.ts file from @core, which is not part of the public API of the module
-    this.code.line(`import * as ${CFN_PARSE} from '${coreImport}/${coreImport === '.' ? '' : 'lib/'}cfn-parse';`);
+    // import cfn-parse from an embedded folder inside @core, since it is not part of the public API of the module
+    this.code.line(`import * as ${CFN_PARSE} from '${coreImport}/${coreImport === '.' ? '' : 'lib/'}helpers-internal';`);
   }
 
   public emitCode(): void {

tools/@aws-cdk/ubergen/bin/ubergen.ts

@@ -97,6 +97,11 @@ interface PackageJson {
      * @default true
      */
     readonly explicitExports?: boolean;
+
+    /**
+     * An exports section that should be ignored for v1 but included for ubergen
+     */
+    readonly exports?: Record<string, string>;
   };
   exports?: Record<string, string>;
 }
@@ -305,8 +310,11 @@ async function prepareSourceFiles(libraries: readonly LibraryReference[], packag
 function copySubmoduleExports(targetExports: Record<string, string>, library: LibraryReference, subdirectory: string) {
   const visibleName = library.shortName;
 
-  for (const [relPath, relSource] of Object.entries(library.packageJson.exports ?? {})) {
-    targetExports[`./${unixPath(path.join(visibleName, relPath))}`] = `./${unixPath(path.join(subdirectory, relSource))}`;
+  // Do both REAL "exports" section, as well as virtual, ubergen-only "exports" section
+  for (const exportSet of [library.packageJson.exports, library.packageJson.ubergen?.exports]) {
+    for (const [relPath, relSource] of Object.entries(exportSet ?? {})) {
+      targetExports[`./${unixPath(path.join(visibleName, relPath))}`] = `./${unixPath(path.join(subdirectory, relSource))}`;
+    }
   }
 
   // If there was an export for '.' in the original submodule, this assignment will overwrite it,