Swift routines for chunking a collection (eg. Data, Array) into an array of chunks

Collection+chunk.swift

extension Collection {
	/// Perform a block on each chunk of `size` elements in this collection
	/// - Parameters:
	///   - size: The maximum size of the chunk
	///   - block: The block to call with the chunk. Set `stop = true` to stop processing
	func chunking(into size: Int, _ block: (SubSequence, inout Bool) -> Void) {
		var stop = false
		var index = 0
		while index < self.count {
			let offset = index + Swift.min(size, count - index)
			let start = self.index(self.startIndex, offsetBy: index)
			let end = self.index(self.startIndex, offsetBy: offset)
			block(self[start ..< end], &stop)
			if stop { return }
			index = offset
		}
	}

	/// Perform a block on each chunk of `size` elements in this collection
	/// - Parameters:
	///   - size: The maximum size of the chunk
	///   - block: The block to call with the chunk.
	func chunking(into size: Int, _ block: (SubSequence) -> Void) {
		let bl: (SubSequence, inout Bool) -> Void = { collection, stop in
			block(collection)
		}
		self.chunking(into: size, bl)
	}

	/// Chunk the contents of the collection into 'size' based chunks
	/// - Parameter size: The size
	/// - Returns: An array of subsequence chunks
	func chunked(into size: Int) -> [SubSequence] {
		var result = [SubSequence]()
		result.reserveCapacity((self.count / size) + 1)
		self.chunking(into: size) { chunk, stop in result.append(chunk) }
		return result
	}
}