//===--- StringNormalization.swift ----------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

import SwiftShims

internal enum _Normalization {

  // ICU's NFC unorm2 instance
  //
  // TODO(String performance): Should we cache one on TLS? Is this an expensive
  // call?
  internal static var _nfcNormalizer: OpaquePointer = {
    var err = __swift_stdlib_U_ZERO_ERROR
    let normalizer = __swift_stdlib_unorm2_getNFCInstance(&err)
    guard err.isSuccess else {
      // This shouldn't be possible unless some deep (unrecoverable) system
      // invariants are violated
      fatalError("Unable to talk to ICU")
    }
    return normalizer
  }()

  // When normalized in NFC, some segments may expand in size (e.g. some non-BMP
  // musical notes). This expansion is capped by the maximum expansion factor of
  // the normal form. For NFC, that is 3x.
  internal static let _maxNFCExpansionFactor = 3
}