mfbt/EnumeratedArray.h
author Geoff Brown <gbrown@mozilla.com>
Fri, 12 May 2017 15:18:38 -0600
changeset 406366 f0f6bd0a45434bcd6159ae9f7c4f558367332fe7
parent 362517 42d33a2ab63bb176c1e0f4f692d17288654d9519
child 414454 8069471cda21110700b5a451641f3e2faed95418
permissions -rw-r--r--
Bug 1361732 - Mozharness support for a second virtualenv using python3; r=aki Currently Mozharness creates a Python 2.7 virtualenvironment with all the packages needed for Mozharness to run plus any applications that need to execute within it. For Talos, we now need a second Python virtual environment for mitmproxy, however, this package is for Python 3 and not for Python 2 (perhaps it could have worked). In any case, having the ability to support create Python 3 virtual environments will be handy. Specially since the approach of creating virtual environments is not by using 'virtualenv /path/to/venv' but by calling the venv module like 'python3 -m venv /path/to/venv'. The initial implementation only supports a list of modules. The following iteration will support requirement files and other parameters needed for pip and internal pypi hosts. Originally authored by armenzg.

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* EnumeratedArray is like Array, but indexed by a typed enum. */

#ifndef mozilla_EnumeratedArray_h
#define mozilla_EnumeratedArray_h

#include "mozilla/Array.h"
#include "mozilla/Move.h"

namespace mozilla {

/**
 * EnumeratedArray is a fixed-size array container for use when an
 * array is indexed by a specific enum class.
 *
 * This provides type safety by guarding at compile time against accidentally
 * indexing such arrays with unrelated values. This also removes the need
 * for manual casting when using a typed enum value to index arrays.
 *
 * Aside from the typing of indices, EnumeratedArray is similar to Array.
 *
 * Example:
 *
 *   enum class AnimalSpecies {
 *     Cow,
 *     Sheep,
 *     Count
 *   };
 *
 *   EnumeratedArray<AnimalSpecies, AnimalSpecies::Count, int> headCount;
 *
 *   headCount[AnimalSpecies::Cow] = 17;
 *   headCount[AnimalSpecies::Sheep] = 30;
 *
 */
template<typename IndexType,
         IndexType SizeAsEnumValue,
         typename ValueType>
class EnumeratedArray
{
public:
  static const size_t kSize = size_t(SizeAsEnumValue);

private:
  typedef Array<ValueType, kSize> ArrayType;

  ArrayType mArray;

public:
  EnumeratedArray() {}

  template <typename... Args>
  MOZ_IMPLICIT EnumeratedArray(Args&&... aArgs)
    : mArray{mozilla::Forward<Args>(aArgs)...}
  {}

  explicit EnumeratedArray(const EnumeratedArray& aOther)
  {
    for (size_t i = 0; i < kSize; i++) {
      mArray[i] = aOther.mArray[i];
    }
  }

  EnumeratedArray(EnumeratedArray&& aOther)
  {
    for (size_t i = 0; i < kSize; i++) {
      mArray[i] = Move(aOther.mArray[i]);
    }
  }

  ValueType& operator[](IndexType aIndex)
  {
    return mArray[size_t(aIndex)];
  }

  const ValueType& operator[](IndexType aIndex) const
  {
    return mArray[size_t(aIndex)];
  }

  typedef typename ArrayType::iterator               iterator;
  typedef typename ArrayType::const_iterator         const_iterator;
  typedef typename ArrayType::reverse_iterator       reverse_iterator;
  typedef typename ArrayType::const_reverse_iterator const_reverse_iterator;

  // Methods for range-based for loops.
  iterator begin() { return mArray.begin(); }
  const_iterator begin() const { return mArray.begin(); }
  const_iterator cbegin() const { return mArray.cbegin(); }
  iterator end() { return mArray.end(); }
  const_iterator end() const { return mArray.end(); }
  const_iterator cend() const { return mArray.cend(); }

  // Methods for reverse iterating.
  reverse_iterator rbegin() { return mArray.rbegin(); }
  const_reverse_iterator rbegin() const { return mArray.rbegin(); }
  const_reverse_iterator crbegin() const { return mArray.crbegin(); }
  reverse_iterator rend() { return mArray.rend(); }
  const_reverse_iterator rend() const { return mArray.rend(); }
  const_reverse_iterator crend() const { return mArray.crend(); }
};

} // namespace mozilla

#endif // mozilla_EnumeratedArray_h