Firestore/pipelines

[demolaf]

No description provided.

[gemini-code-assist]

Code Review

This pull request implements the Firestore Pipelines API, introducing a framework for complex, multi-stage data transformations and aggregations. The changes include a comprehensive set of new classes for expressions, aggregate functions, and pipeline stages, as well as integration into the Transaction API and a new usage example. Feedback from the review identifies an unnecessary empty file that should be removed and suggests adding a validation check to the rawStage method to prevent potential runtime errors when handling empty input data.

[gemini-code-assist]

This file is empty and appears to be unnecessary. Please remove it.

[gemini-code-assist]

The rawStage method does not validate that the data map is non-empty. Passing an empty map will cause a StateError in _stageToProto when accessing data.keys.first. Please add a validation check.

Suggested change

	Pipeline rawStage(Map<String, dynamic> data) {
	return Pipeline._(
	firestore: firestore,
	stages: [..._stages, _RawStage(data)],
	);
	}
	Pipeline rawStage(Map<String, dynamic> data) {
	if (data.isEmpty) {
	throw ArgumentError('Raw stage data cannot be empty');
	}
	return Pipeline._(
	firestore: firestore,
	stages: [..._stages, _RawStage(data)],
	);
	}