mfbt/Saturate.h
author Morten Stenshorne <mstensho@chromium.org>
Tue, 09 Oct 2018 04:14:13 +0000
changeset 495959 13844f50ee32e17f513b7c1013c2348200e21b8c
parent 475080 b54db66223586b4e04f5cb926fccdacf8a176b91
child 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1496274 [wpt PR 13345] - [LayoutNG] Correct clip-path reference box calculation., a=testonly Automatic update from web-platform-tests[LayoutNG] Correct clip-path reference box calculation. We used coordinates relatively to the line box, while we were expected by the caller to be relative to the containing block. Flipping for writing mode was bogus for NG (but needed by legacy), since NG uses truly physical coordinates. Hardened tests to contain a leading line and padding, and leading content on the first line of the clipped child. Bug: 641907 Change-Id: I2b1b9ff4ea92a6405fcdffcf139842458b46442f Cq-Include-Trybots: luci.chromium.try​:linux_layout_tests_layout_ng Reviewed-on: https://chromium-review.googlesource.com/c/1257913 Reviewed-by: Koji Ishii <kojii@chromium.org> Reviewed-by: Fredrik Söderquist <fs@opera.com> Commit-Queue: Morten Stenshorne <mstensho@chromium.org> Cr-Commit-Position: refs/heads/master@{#596554} -- wpt-commits: e9a0828c85819340f721f121aac19ab8eefa3439 wpt-pr: 13345

/* -*- 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/. */

/* Provides saturation arithmetics for scalar types. */

#ifndef mozilla_Saturate_h
#define mozilla_Saturate_h

#include "mozilla/Attributes.h"
#include "mozilla/Move.h"
#include "mozilla/TypeTraits.h"

#include <limits>

namespace mozilla {
namespace detail {

/**
 * |SaturateOp<T>| wraps scalar values for saturation arithmetics. Usage:
 *
 *    uint32_t value = 1;
 *
 *    ++SaturateOp<uint32_t>(value); // value is 2
 *    --SaturateOp<uint32_t>(value); // value is 1
 *    --SaturateOp<uint32_t>(value); // value is 0
 *    --SaturateOp<uint32_t>(value); // value is still 0
 *
 * Please add new operators when required.
 *
 * |SaturateOp<T>| will saturate at the minimum and maximum values of
 * type T. If you need other bounds, implement a clamped-type class and
 * specialize the type traits accordingly.
 */
template <typename T>
class SaturateOp
{
public:
  explicit SaturateOp(T& aValue)
    : mValue(aValue)
  {
    // We should actually check for |std::is_scalar<T>::value| to be
    // true, but this type trait is not available everywhere. Relax
    // this assertion if you want to use floating point values as well.
    static_assert(IsIntegral<T>::value,
                  "Integral type required in instantiation");
  }

  // Add and subtract operators

  T operator+(const T& aRhs) const
  {
    return T(mValue) += aRhs;
  }

  T operator-(const T& aRhs) const
  {
    return T(mValue) -= aRhs;
  }

  // Compound operators

  const T& operator+=(const T& aRhs) const
  {
    const T min = std::numeric_limits<T>::min();
    const T max = std::numeric_limits<T>::max();

    if (aRhs > static_cast<T>(0)) {
      mValue = (max - aRhs) < mValue ? max : mValue + aRhs;
    } else {
      mValue = (min - aRhs) > mValue ? min : mValue + aRhs;
    }
    return mValue;
  }

  const T& operator-=(const T& aRhs) const
  {
    const T min = std::numeric_limits<T>::min();
    const T max = std::numeric_limits<T>::max();

    if (aRhs > static_cast<T>(0)) {
      mValue = (min + aRhs) > mValue ? min : mValue - aRhs;
    } else {
      mValue = (max + aRhs) < mValue ? max : mValue - aRhs;
    }
    return mValue;
  }

  // Increment and decrement operators

  const T& operator++() const // prefix
  {
    return operator+=(static_cast<T>(1));
  }

  T operator++(int) const // postfix
  {
    const T value(mValue);
    operator++();
    return value;
  }

  const T& operator--() const // prefix
  {
    return operator-=(static_cast<T>(1));
  }

  T operator--(int) const // postfix
  {
    const T value(mValue);
    operator--();
    return value;
  }

private:
  SaturateOp(const SaturateOp<T>&) = delete;
  SaturateOp(SaturateOp<T>&&) = delete;
  SaturateOp& operator=(const SaturateOp<T>&) = delete;
  SaturateOp& operator=(SaturateOp<T>&&) = delete;

  T& mValue;
};

/**
 * |Saturate<T>| is a value type for saturation arithmetics. It's
 * build on top of |SaturateOp<T>|.
 */
template <typename T>
class Saturate
{
public:
  Saturate() = default;
  MOZ_IMPLICIT Saturate(const Saturate<T>&) = default;

  MOZ_IMPLICIT Saturate(Saturate<T>&& aValue)
  {
    mValue = std::move(aValue.mValue);
  }

  explicit Saturate(const T& aValue)
    : mValue(aValue)
  { }

  const T& value() const
  {
    return mValue;
  }

  // Compare operators

  bool operator==(const Saturate<T>& aRhs) const
  {
    return mValue == aRhs.mValue;
  }

  bool operator!=(const Saturate<T>& aRhs) const
  {
    return !operator==(aRhs);
  }

  bool operator==(const T& aRhs) const
  {
    return mValue == aRhs;
  }

  bool operator!=(const T& aRhs) const
  {
    return !operator==(aRhs);
  }

  // Assignment operators

  Saturate<T>& operator=(const Saturate<T>&) = default;

  Saturate<T>& operator=(Saturate<T>&& aRhs)
  {
    mValue = std::move(aRhs.mValue);
    return *this;
  }

  // Add and subtract operators

  Saturate<T> operator+(const Saturate<T>& aRhs) const
  {
    Saturate<T> lhs(mValue);
    return lhs += aRhs.mValue;
  }

  Saturate<T> operator+(const T& aRhs) const
  {
    Saturate<T> lhs(mValue);
    return lhs += aRhs;
  }

  Saturate<T> operator-(const Saturate<T>& aRhs) const
  {
    Saturate<T> lhs(mValue);
    return lhs -= aRhs.mValue;
  }

  Saturate<T> operator-(const T& aRhs) const
  {
    Saturate<T> lhs(mValue);
    return lhs -= aRhs;
  }

  // Compound operators

  Saturate<T>& operator+=(const Saturate<T>& aRhs)
  {
    SaturateOp<T>(mValue) += aRhs.mValue;
    return *this;
  }

  Saturate<T>& operator+=(const T& aRhs)
  {
    SaturateOp<T>(mValue) += aRhs;
    return *this;
  }

  Saturate<T>& operator-=(const Saturate<T>& aRhs)
  {
    SaturateOp<T>(mValue) -= aRhs.mValue;
    return *this;
  }

  Saturate<T>& operator-=(const T& aRhs)
  {
    SaturateOp<T>(mValue) -= aRhs;
    return *this;
  }

  // Increment and decrement operators

  Saturate<T>& operator++() // prefix
  {
    ++SaturateOp<T>(mValue);
    return *this;
  }

  Saturate<T> operator++(int) // postfix
  {
    return Saturate<T>(SaturateOp<T>(mValue)++);
  }

  Saturate<T>& operator--() // prefix
  {
    --SaturateOp<T>(mValue);
    return *this;
  }

  Saturate<T> operator--(int) // postfix
  {
    return Saturate<T>(SaturateOp<T>(mValue)--);
  }

private:
  T mValue;
};

} // namespace detail

typedef detail::Saturate<int8_t> SaturateInt8;
typedef detail::Saturate<int16_t> SaturateInt16;
typedef detail::Saturate<int32_t> SaturateInt32;
typedef detail::Saturate<uint8_t> SaturateUint8;
typedef detail::Saturate<uint16_t> SaturateUint16;
typedef detail::Saturate<uint32_t> SaturateUint32;

} // namespace mozilla

template<typename LhsT, typename RhsT>
bool
operator==(LhsT aLhs, const mozilla::detail::Saturate<RhsT>& aRhs)
{
  return aRhs.operator==(static_cast<RhsT>(aLhs));
}

template<typename LhsT, typename RhsT>
bool
operator!=(LhsT aLhs, const mozilla::detail::Saturate<RhsT>& aRhs)
{
  return !(aLhs == aRhs);
}

#endif // mozilla_Saturate_h