mfbt/IntegerRange.h
author Ryan VanderMeulen <ryanvm@gmail.com>
Thu, 24 May 2018 14:12:20 -0400
changeset 473436 0f95c023462e4de617ebdd77cbe90ec523efad10
parent 375652 2a0ce9941af5823ae45d7dcd6af03fb00f6c3948
child 508163 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Backed out 5 changesets (bug 1462497) for causing widespread test failures. Backed out changeset f89eb2186154 (bug 1462497) Backed out changeset e8836b424826 (bug 1462497) Backed out changeset 3dcce8353e13 (bug 1462497) Backed out changeset 21f67c8e36fb (bug 1462497) Backed out changeset b14f835411db (bug 1462497)

/* -*- 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