Here's the commit message I've drafted:

feat: Add stub List/ListAll methods with corrected PIMPL pattern

This commit introduces stub implementations for StorageReference's
`List()` and `ListAll()` methods in the Firebase C++ Storage SDK.
It follows a corrected PIMPL (pointer to implementation) pattern for
the `ListResult` class, strictly adhering to the internal architecture
observed in classes like `firebase::storage::Metadata` and its
`MetadataInternalCommon` helper.

This version addresses feedback from previous attempts and ensures:

1.  **`ListResultInternalCommon` as Static Helpers**:
    - A class `firebase::storage::internal::ListResultInternalCommon` is
      defined within `storage/src/common/list_result.cc`.
    - It contains only static methods responsible for managing the
      lifecycle (cleanup registration, PIMPL deletion) of
      `ListResult`'s internal implementation. This mirrors
      `MetadataInternalCommon`.

2.  **Platform-Specific `ListResultInternal`**:
    - Each platform (Desktop, Android, iOS) defines its own concrete
      `firebase::storage::internal::ListResultInternal` class.
    - These are located in files like `storage/src/desktop/list_result_desktop.h`
      (and `.cc`), `storage/src/android/list_result_android.h` (and `.cc`),
      and `storage/src/ios/list_result_ios.h` (and `.mm`).
    - These classes hold the stub data (empty item/prefix lists, empty
      page token) and a pointer to their platform's
      `StorageReferenceInternal` for context (primarily for cleanup).
    - They provide a copy constructor for `ListResult`'s copy operations.
    - They do not inherit from a common PIMPL base class.

3.  **Public `ListResult` Refactoring**:
    - The public `firebase::storage::ListResult` class now holds a raw
      pointer (`internal::ListResultInternal* internal_`) to its
      platform-specific PIMPL object.
    - Its constructors, destructor, copy, and move assignment operators
      utilize the static helper methods in `ListResultInternalCommon`
      to manage the `internal_` pointer's lifecycle and cleanup
      registration, similar to how `Metadata` manages its `internal_`.

4.  **`StorageReference` Methods Update**:
    - `StorageReference::ListAll()` and `StorageReference::List()` in
      `storage/src/common/storage_reference.cc` now correctly create
      `ListResult` instances. They instantiate the appropriate
      platform-specific `internal::ListResultInternal` via a direct
      `new internal::ListResultInternal(...)` call (relying on the
      build system to link the correct platform's implementation) and
      pass this PIMPL object to a private constructor of `ListResult`.

5.  **Build System**:
    - `storage/CMakeLists.txt` was updated to include the correctly named
      platform-specific source files (e.g., `list_result_desktop.cc`).

6.  **Integration Tests**:
    - Existing integration tests were reviewed and confirmed to be
      compatible with these internal changes.

This implementation provides the `List` and `ListAll` API as stubs,
returning empty results, with a robust internal structure that aligns
with the SDK's established PIMPL and lifecycle management patterns.

Author: google-labs-jules[bot]

storage/CMakeLists.txt

@@ -38,7 +38,8 @@ set(android_SRCS
     src/android/controller_android.cc
     src/android/metadata_android.cc
     src/android/storage_android.cc
-    src/android/storage_reference_android.cc)
+    src/android/storage_reference_android.cc
+    src/android/list_result_android.cc)
 
 # Source files used by the iOS implementation.
 set(ios_SRCS
@@ -47,7 +48,8 @@ set(ios_SRCS
     src/ios/metadata_ios.mm
     src/ios/storage_ios.mm
     src/ios/storage_reference_ios.mm
-    src/ios/util_ios.mm)
+    src/ios/util_ios.mm
+    src/ios/list_result_ios.mm)
 
 # Source files used by the desktop implementation.
 set(desktop_SRCS
@@ -58,7 +60,8 @@ set(desktop_SRCS
     src/desktop/rest_operation.cc
     src/desktop/storage_desktop.cc
     src/desktop/storage_path.cc
-    src/desktop/storage_reference_desktop.cc)
+    src/desktop/storage_reference_desktop.cc
+    src/desktop/list_result_desktop.cc)
 
 if(ANDROID)
   set(storage_platform_SRCS

storage/src/android/list_result_android.cc

@@ -0,0 +1,21 @@
+// File: storage/src/android/list_result_android.cc
+#include "storage/src/android/list_result_android.h"
+
+namespace firebase {
+namespace storage {
+namespace internal {
+
+ListResultInternal::ListResultInternal(
+    StorageReferenceInternal* platform_sri,
+    const ListResultInternal* other_to_copy_from)
+    : platform_sri_(platform_sri) {
+  if (other_to_copy_from) {
+    items_ = other_to_copy_from->items_;
+    prefixes_ = other_to_copy_from->prefixes_;
+    page_token_ = other_to_copy_from->page_token_;
+  }
+}
+
+}  // namespace internal
+}  // namespace storage
+}  // namespace firebase

storage/src/android/list_result_android.h

@@ -0,0 +1,46 @@
+// File: storage/src/android/list_result_android.h
+#ifndef FIREBASE_STORAGE_CLIENT_CPP_SRC_ANDROID_LIST_RESULT_ANDROID_H_
+#define FIREBASE_STORAGE_CLIENT_CPP_SRC_ANDROID_LIST_RESULT_ANDROID_H_
+
+#include <string>
+#include <vector>
+
+#include "firebase/storage/storage_reference.h"
+#include "storage/src/android/storage_reference_android.h" // Defines firebase::storage::internal::StorageReferenceInternal for android
+#include "storage/src/android/storage_internal_android.h"   // Defines firebase::storage::internal::StorageInternal for android
+
+namespace firebase {
+namespace storage {
+namespace internal {
+
+class ListResultInternal {
+ public:
+  explicit ListResultInternal(
+      StorageReferenceInternal* platform_sri,
+      const ListResultInternal* other_to_copy_from = nullptr);
+
+  const std::vector<StorageReference>& items() const { return items_; }
+  const std::vector<StorageReference>& prefixes() const { return prefixes_; }
+  const std::string& page_token() const { return page_token_; }
+
+  StorageReferenceInternal* storage_reference_internal() const {
+    return platform_sri_;
+  }
+  StorageInternal* associated_storage_internal() const {
+    return platform_sri_ ? platform_sri_->storage_internal() : nullptr;
+  }
+
+ private:
+  ListResultInternal& operator=(const ListResultInternal&);
+
+  StorageReferenceInternal* platform_sri_;
+  std::vector<StorageReference> items_;
+  std::vector<StorageReference> prefixes_;
+  std::string page_token_;
+};
+
+}  // namespace internal
+}  // namespace storage
+}  // namespace firebase
+
+#endif  // FIREBASE_STORAGE_CLIENT_CPP_SRC_ANDROID_LIST_RESULT_ANDROID_H_

storage/src/android/storage_reference_android.cc

@@ -23,7 +23,7 @@
 #include "app/src/include/firebase/app.h"
 #include "app/src/util_android.h"
 #include "storage/src/android/controller_android.h"
-#include "storage/src/android/list_result_android.h" // For ListResultAndroid
+// Removed: #include "storage/src/android/list_result_android.h"
 #include "storage/src/android/metadata_android.h"
 #include "storage/src/android/storage_android.h"
 #include "storage/src/include/firebase/storage.h"
@@ -735,12 +735,6 @@ jint StorageReferenceInternal::CppByteUploaderReadBytes(
   return data_read;
 }
 
-::firebase::storage::internal::ListResultInternal* StorageReferenceInternal::CreateListResultInternal() {
-  // Create and return an instance of the Android-specific ListResultInternal.
-  // 'this' is the current StorageReferenceInternal (Android version)
-  return new ::firebase::storage::internal::ListResultAndroid(this);
-}
-
 }  // namespace internal
 }  // namespace storage
 }  // namespace firebase

storage/src/android/storage_reference_android.h

@@ -23,7 +23,7 @@
 #include "app/src/reference_counted_future_impl.h"
 #include "app/src/util_android.h"
 #include "storage/src/android/storage_android.h"
-#include "storage/src/common/list_result_internal.h" // Added for ListResultInternal
+// Removed: #include "storage/src/common/list_result_internal.h"
 #include "storage/src/include/firebase/storage/storage_reference.h"
 
 namespace firebase {
@@ -154,10 +154,6 @@ class StorageReferenceInternal {
   // StorageInternal instance we are associated with.
   StorageInternal* storage_internal() const { return storage_; }
 
-  // Creates a new platform-specific ListResultInternal object.
-  // Caller takes ownership.
-  virtual ::firebase::storage::internal::ListResultInternal* CreateListResultInternal();
-
  private:
   static void FutureCallback(JNIEnv* env, jobject result,
                              util::FutureResult result_code,