test/stdlib/NewStringAppending.swift

// RUN: %target-run-stdlib-swift | %FileCheck %s
// REQUIRES: executable_test
//
// Parts of this test depend on memory allocator specifics.  The test
// should be rewritten soon so it doesn't expose legacy components
// like OpaqueString anyway, so we can just disable the failing
// configuration
//
// Memory allocator specifics also vary across platforms.
// REQUIRES: CPU=x86_64, OS=macosx

import Foundation
import Swift

func hexAddrVal<T>(_ x: T) -> String {
  return "@0x" + String(UInt64(unsafeBitCast(x, to: Int.self)), radix: 16)
}

func hexAddr(_ x: AnyObject?) -> String {
  if let owner = x {
    if let y = owner as? _SwiftRawStringStorage {
      return ".native\(hexAddrVal(y))"
    }
    if let y = owner as? NSString {
      return ".cocoa\(hexAddrVal(y))"
    }
    else {
      return "?Uknown?\(hexAddrVal(owner))"
    }
  }
  return "nil"
}

func repr(_ x: NSString) -> String {
  return "\(NSStringFromClass(object_getClass(x)))\(hexAddr(x)) = \"\(x)\""
}

func repr(_ x: _StringGuts) -> String {
  if x._isNative {
    return "Native("
      + "owner: \(hexAddrVal(x._owner)), "
      + "count: \(x.count), "
      + "capacity: \(x.capacity))"
  } else if x._isCocoa {
    return "Cocoa("
      + "owner: \(hexAddrVal(x._owner)), "
      + "count: \(x.count))"
  } else if x._isSmall {
    return "Cocoa("
      + "owner: <tagged>, "
      + "count: \(x.count))"
  } else if x._isUnmanaged {
    return "Unmanaged("
      + "count: \(x.count))"
  }
  return "?????"
}

func repr(_ x: String) -> String {
  return "String(\(repr(x._guts))) = \"\(x)\""
}

// ===------- Appending -------===

// CHECK: --- Appending ---
print("--- Appending ---")

var s = "⓪" // start non-empty

// To make this test independent of the memory allocator implementation,
// explicitly request initial capacity.
s.reserveCapacity(16)

// CHECK-NEXT: String(Native(owner: @[[storage0:[x0-9a-f]+]], count: 1, capacity: 16)) = "⓪"
print("\(repr(s))")

// CHECK-NEXT: String(Native(owner: @[[storage0]], count: 2, capacity: 16)) = "⓪1"
s += "1"
print("\(repr(s))")

// CHECK-NEXT: String(Native(owner: @[[storage0]], count: 8, capacity: 16)) = "⓪1234567"
s += "234567"
print("\(repr(s))")

// CHECK-NEXT: String(Native(owner: @[[storage0:[x0-9a-f]+]], count: 9, capacity: 16)) = "⓪12345678"
// CHECK-NOT: @[[storage0]],
s += "8"
print("\(repr(s))")

// CHECK-NEXT: String(Native(owner: @[[storage0]], count: 16, capacity: 16)) = "⓪123456789012345"
s += "9012345"
print("\(repr(s))")

// -- expect a reallocation here

// Appending more than the next level of capacity only takes as much
// as required.  I'm not sure whether this is a great idea, but the
// point is to prevent huge amounts of fragmentation when a long
// string is appended to a short one.  The question, of course, is
// whether more appends are coming, in which case we should give it
// more capacity.  It might be better to always grow to a multiple of
// the current capacity when the capacity is exceeded.

// CHECK-NEXT: String(Native(owner: @[[storage2:[x0-9a-f]+]], count: 48, capacity: 48))
// CHECK-NOT: @[[storage1]],
s += s + s
print("\(repr(s))")

// -- expect a reallocation here

// CHECK-NEXT: String(Native(owner: @[[storage3:[x0-9a-f]+]], count: 49, capacity: 96))
// CHECK-NOT: @[[storage2]],
s += "C"
print("\(repr(s))")

var s1 = s

// CHECK-NEXT: String(Native(owner: @[[storage3]], count: 49, capacity: 96))
print("\(repr(s1))")

/// The use of later buffer capacity by another string forces
/// reallocation; however, the original capacity is kept by intact

// CHECK-NEXT: String(Native(owner: @[[storage4:[x0-9a-f]+]], count: 50, capacity: 96)) = "{{.*}}X"
// CHECK-NOT: @[[storage3]],
s1 += "X"
print("\(repr(s1))")

/// The original copy is left unchanged

// CHECK-NEXT: String(Native(owner: @[[storage3]], count: 49, capacity: 96))
print("\(repr(s))")

/// Appending to an empty string re-uses the RHS

// CHECK-NEXT: @[[storage3]],
var s2 = String()
s2 += s
print("\(repr(s2))")