How do you implement custom collection types?

Implementing custom collection types requires conforming to specific protocols with careful consideration of performance.\n\n• **Basic Collection Protocol:**\n\nstruct RingBuffer: Collection {\n var buffer: [Element?]\n var head = 0\n var tail = 0\n let capacity: Int\n \n init(capacity: Int) {\n self.capacity = capacity\n self.buffer = Array(repeating: nil, count: capacity)\n }\n \n // Collection requirements\n var startIndex: Int { return head }\n var endIndex: Int { return tail }\n \n func index(after i: Int) -> Int {\n return (i + 1) % capacity\n }\n \n subscript(position: Int) -> Element {\n return buffer[position]!\n }\n}\n\n\n• **Mutable Collection:**\n\nextension RingBuffer: MutableCollection {\n subscript(position: Int) -> Element {\n get { return buffer[position]! }\n set { buffer[position] = newValue }\n }\n}\n\n\n• **Range Replaceable Collection:**\n\nextension RingBuffer: RangeReplaceableCollection {\n init() {\n self.init(capacity: 16)\n }\n \n func replaceSubrange(_ subrange: Range, with newElements: C) where C: Collection, Element == C.Element {\n // Implementation for replacing elements\n }\n}\n\n\n• **Performance Considerations:**\n\n// Lazy collections for performance\nstruct LazyFilterCollection {\n let base: Base\n let predicate: (Base.Element) -> Bool\n \n func makeIterator() -> LazyFilterIterator {\n return LazyFilterIterator(base: base.makeIterator(), predicate: predicate)\n }\n}\n\n\n• **Copy-on-Write Implementation:**\n\nstruct COWArray {\n var storage: ArrayStorage\n \n func append(_ element: Element) {\n if !isKnownUniquelyReferenced(&storage) {\n storage = storage.copy()\n }\n storage.append(element)\n }\n}\n