mfbt/IntegerRange.h
author Narcis Beleuzu <nbeleuzu@mozilla.com>
Thu, 21 Jun 2018 16:51:55 +0300
changeset 477502 59322b179c0fdb4423d42b624da7bf64ee5a2327
parent 373368 2a0ce9941af5823ae45d7dcd6af03fb00f6c3948
child 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Backed out 4 changesets (bug 1268889) for Windows GTest failures. CLOSED TREE Backed out changeset da427a67372e (bug 1268889) Backed out changeset 97528847b7b7 (bug 1268889) Backed out changeset b2320061fbcb (bug 1268889) Backed out changeset dd3b7047ea6f (bug 1268889)

/* -*- 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/. */

/* Iterator over ranges of integers */

#ifndef mozilla_IntegerRange_h
#define mozilla_IntegerRange_h

#include "mozilla/Assertions.h"
#include "mozilla/ReverseIterator.h"
#include "mozilla/TypeTraits.h"

namespace mozilla {

namespace detail {

template<typename IntTypeT>
class IntegerIterator
{
public:
  template<typename IntType>
  explicit IntegerIterator(IntType aCurrent)
    : mCurrent(aCurrent) { }

  template<typename IntType>
  explicit IntegerIterator(const IntegerIterator<IntType>& aOther)
    : mCurrent(aOther.mCurrent) { }

  IntTypeT operator*() const { return mCurrent; }

  /* Increment and decrement operators */

  IntegerIterator& operator++() { ++mCurrent; return *this; }
  IntegerIterator& operator--() { --mCurrent; return *this; }
  IntegerIterator operator++(int) { auto ret = *this; ++mCurrent; return ret; }
  IntegerIterator operator--(int) { auto ret = *this; --mCurrent; return ret; }

  /* Comparison operators */

  template<typename IntType1, typename IntType2>
  friend bool operator==(const IntegerIterator<IntType1>& aIter1,
                         const IntegerIterator<IntType2>& aIter2);
  template<typename IntType1, typename IntType2>
  friend bool operator!=(const IntegerIterator<IntType1>& aIter1,
                         const IntegerIterator<IntType2>& aIter2);
  template<typename IntType1, typename IntType2>
  friend bool operator<(const IntegerIterator<IntType1>& aIter1,
                        const IntegerIterator<IntType2>& aIter2);
  template<typename IntType1, typename IntType2>
  friend bool operator<=(const IntegerIterator<IntType1>& aIter1,
                         const IntegerIterator<IntType2>& aIter2);
  template<typename IntType1, typename IntType2>
  friend bool operator>(const IntegerIterator<IntType1>& aIter1,
                        const IntegerIterator<IntType2>& aIter2);
  template<typename IntType1, typename IntType2>
  friend bool operator>=(const IntegerIterator<IntType1>& aIter1,
                         const IntegerIterator<IntType2>& aIter2);

private:
  IntTypeT mCurrent;
};

template<typename IntType1, typename IntType2>
bool operator==(const IntegerIterator<IntType1>& aIter1,
                const IntegerIterator<IntType2>& aIter2)
{
  return aIter1.mCurrent == aIter2.mCurrent;
}

template<typename IntType1, typename IntType2>
bool operator!=(const IntegerIterator<IntType1>& aIter1,
                const IntegerIterator<IntType2>& aIter2)
{
  return aIter1.mCurrent != aIter2.mCurrent;
}

template<typename IntType1, typename IntType2>
bool operator<(const IntegerIterator<IntType1>& aIter1,
               const IntegerIterator<IntType2>& aIter2)
{
  return aIter1.mCurrent < aIter2.mCurrent;
}

template<typename IntType1, typename IntType2>
bool operator<=(const IntegerIterator<IntType1>& aIter1,
                const IntegerIterator<IntType2>& aIter2)
{
  return aIter1.mCurrent <= aIter2.mCurrent;
}

template<typename IntType1, typename IntType2>
bool operator>(const IntegerIterator<IntType1>& aIter1,
               const IntegerIterator<IntType2>& aIter2)
{
  return aIter1.mCurrent > aIter2.mCurrent;
}

template<typename IntType1, typename IntType2>
bool operator>=(const IntegerIterator<IntType1>& aIter1,
                const IntegerIterator<IntType2>& aIter2)
{
  return aIter1.mCurrent >= aIter2.mCurrent;
}

template<typename IntTypeT>
class IntegerRange
{
public:
  typedef IntegerIterator<IntTypeT> iterator;
  typedef IntegerIterator<IntTypeT> const_iterator;
  typedef ReverseIterator<IntegerIterator<IntTypeT>> reverse_iterator;
  typedef ReverseIterator<IntegerIterator<IntTypeT>> const_reverse_iterator;

  template<typename IntType>
  explicit IntegerRange(IntType aEnd)
    : mBegin(0), mEnd(aEnd) { }

  template<typename IntType1, typename IntType2>
  IntegerRange(IntType1 aBegin, IntType2 aEnd)
    : mBegin(aBegin), mEnd(aEnd) { }

  iterator begin() const { return iterator(mBegin); }
  const_iterator cbegin() const { return begin(); }
  iterator end() const { return iterator(mEnd); }
  const_iterator cend() const { return end(); }
  reverse_iterator rbegin() const { return reverse_iterator(mEnd); }
  const_reverse_iterator crbegin() const { return rbegin(); }
  reverse_iterator rend() const { return reverse_iterator(mBegin); }
  const_reverse_iterator crend() const { return rend(); }

private:
  IntTypeT mBegin;
  IntTypeT mEnd;
};

template<typename T, bool = IsUnsigned<T>::value>
struct GeqZero
{
  static bool check(T t) {
    return t >= 0;
  }
};

template<typename T>
struct GeqZero<T, true>
{
  static bool check(T t) {
    return true;
  }
};

} // namespace detail

template<typename IntType>
detail::IntegerRange<IntType>
IntegerRange(IntType aEnd)
{
  static_assert(IsIntegral<IntType>::value, "value must be integral");
  MOZ_ASSERT(detail::GeqZero<IntType>::check(aEnd),
             "Should never have negative value here");
  return detail::IntegerRange<IntType>(aEnd);
}

template<typename IntType1, typename IntType2>
detail::IntegerRange<IntType2>
IntegerRange(IntType1 aBegin, IntType2 aEnd)
{
  static_assert(IsIntegral<IntType1>::value && IsIntegral<IntType2>::value,
                "values must both be integral");
  static_assert(IsSigned<IntType1>::value == IsSigned<IntType2>::value,
                "signed/unsigned mismatch");
  MOZ_ASSERT(aEnd >= aBegin, "End value should be larger than begin value");
  return detail::IntegerRange<IntType2>(aBegin, aEnd);
}

} // namespace mozilla

#endif // mozilla_IntegerRange_h