Quelle IntegerRange.h Sprache: C

/* -*- 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 <iterator>
#include <type_traits>

namespace mozilla {

namespace detail {

template <typename IntTypeT>
class IntegerIterator {
public:
  // It is disputable whether these type definitions are correct, since
  // operator* doesn't return a reference at all. Also, the iterator_category
  // can be at most std::input_iterator_tag (rather than
  // std::bidrectional_iterator_tag, as it might seem), because it is a stashing
  // iterator. See also, e.g.,
  // https://stackoverflow.com/questions/50909701/what-should-be-iterator-category-for-a-stashing-iterator
  using value_type = const IntTypeT;
  using pointer = const value_type*;
  using reference = const value_type&;
  using difference_type = std::make_signed_t<IntTypeT>;
  using iterator_category = std::input_iterator_tag;

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

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

  // This intentionally returns a value rather than a reference, to make
  // mozilla::ReverseIterator work with it. Still, std::reverse_iterator cannot
  // be used with IntegerIterator because it still is a "stashing iterator". See
  // Bug 1175485.
  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(iterator(mEnd)); }
  const_reverse_iterator crbegin() const { return rbegin(); }
  reverse_iterator rend() const { return reverse_iterator(iterator(mBegin)); }
  const_reverse_iterator crend() const { return rend(); }

private:
  IntTypeT mBegin;
  IntTypeT mEnd;
};

template <typename T, bool = std::is_unsigned_v<T>>
struct GeqZero {
  static bool isNonNegative(T t) { return t >= 0; }
};

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

}  // namespace detail

template <typename IntType>
detail::IntegerRange<IntType> IntegerRange(IntType aEnd) {
  static_assert(std::is_integral_v<IntType>, "value must be integral");
  MOZ_ASSERT(detail::GeqZero<IntType>::isNonNegative(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(std::is_integral_v<IntType1> && std::is_integral_v<IntType2>,
                "values must both be integral");
  static_assert(std::is_signed_v<IntType1> == std::is_signed_v<IntType2>,
                "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

quality89%

¤ Dauer der Verarbeitung: 0.28 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.