//===--- ArrayType.swift - Protocol for Array-like types ------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See http://swift.org/LICENSE.txt for license information
// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

public // @testable
protocol _ArrayProtocol
  : RangeReplaceableCollection,
    ExpressibleByArrayLiteral
{
  //===--- public interface -----------------------------------------------===//
  /// The number of elements the Array stores.
  var count: Int { get }

  /// The number of elements the Array can store without reallocation.
  var capacity: Int { get }

  /// `true` if and only if the Array is empty.
  var isEmpty: Bool { get }

  /// An object that guarantees the lifetime of this array's elements.
  var _owner: AnyObject? { get }

  /// If the elements are stored contiguously, a pointer to the first
  /// element. Otherwise, `nil`.
  var _baseAddressIfContiguous: UnsafeMutablePointer<Element>? { get }

  subscript(index: Int) -> Iterator.Element { get set }

  //===--- basic mutations ------------------------------------------------===//

  /// Reserve enough space to store minimumCapacity elements.
  ///
  /// - Postcondition: `capacity >= minimumCapacity` and the array has
  ///   mutable contiguous storage.
  ///
  /// - Complexity: O(`self.count`).
  mutating func reserveCapacity(_ minimumCapacity: Int)

  /// Operator form of `append(contentsOf:)`.
  static func += <S : Sequence>(lhs: inout Self, rhs: S)
    where S.Iterator.Element == Iterator.Element

  /// Insert `newElement` at index `i`.
  ///
  /// Invalidates all indices with respect to `self`.
  ///
  /// - Complexity: O(`self.count`).
  ///
  /// - Precondition: `startIndex <= i`, `i <= endIndex`.
  mutating func insert(_ newElement: Iterator.Element, at i: Int)

  /// Remove and return the element at the given index.
  ///
  /// - returns: The removed element.
  ///
  /// - Complexity: Worst case O(N).
  ///
  /// - Precondition: `count > index`.
  @discardableResult
  mutating func remove(at index: Int) -> Iterator.Element

  //===--- implementation detail  -----------------------------------------===//

  associatedtype _Buffer : _ArrayBufferProtocol
  init(_ buffer: _Buffer)

  // For testing.
  var _buffer: _Buffer { get }
}