tor-browser

nsCSSPropertyIDSet.h (9446B)

---

/* 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/. */

/* bit vectors for sets of CSS properties */

#ifndef nsCSSPropertyIDSet_h__
#define nsCSSPropertyIDSet_h__

#include <limits.h>  // for CHAR_BIT

#include <initializer_list>
#include <ostream>

#include "mozilla/ArrayUtils.h"
// For COMPOSITOR_ANIMATABLE_PROPERTY_LIST and
// COMPOSITOR_ANIMATABLE_PROPERTY_LIST_LENGTH
#include "NonCustomCSSPropertyId.h"
#include "mozilla/CSSPropertyId.h"
#include "mozilla/CompositorAnimatableProperties.h"
#include "nsCSSProps.h"  // For operator<< for NonCustomCSSPropertyId

/**
* nsCSSPropertyIDSet maintains a set of non-shorthand CSS properties.  In
* other words, for each longhand CSS property we support, it has a bit
* for whether that property is in the set.
*/
class nsCSSPropertyIDSet {
public:
 constexpr nsCSSPropertyIDSet() : mProperties{0} {}
 // auto-generated copy-constructor OK

 explicit constexpr nsCSSPropertyIDSet(
     std::initializer_list<NonCustomCSSPropertyId> aProperties)
     : mProperties{0} {
   for (auto property : aProperties) {
     size_t p = property;
     mProperties[p / kBitsInChunk] |= property_set_type(1)
                                      << (p % kBitsInChunk);
   }
 }

 void AssertInSetRange(NonCustomCSSPropertyId aProperty) const {
   MOZ_DIAGNOSTIC_ASSERT(aProperty != eCSSProperty_UNKNOWN &&
                             aProperty < eCSSProperty_COUNT_no_shorthands,
                         "out of bounds");
 }

 // Conversion of aProperty to |size_t| after AssertInSetRange
 // lets the compiler generate significantly tighter code.

 void AddProperty(NonCustomCSSPropertyId aProperty) {
   AssertInSetRange(aProperty);
   size_t p = aProperty;
   mProperties[p / kBitsInChunk] |= property_set_type(1) << (p % kBitsInChunk);
 }

 void RemoveProperty(NonCustomCSSPropertyId aProperty) {
   AssertInSetRange(aProperty);
   size_t p = aProperty;
   mProperties[p / kBitsInChunk] &=
       ~(property_set_type(1) << (p % kBitsInChunk));
 }

 bool HasProperty(const mozilla::CSSPropertyId& aProperty) const {
   return !aProperty.IsCustom() && HasProperty(aProperty.mId);
 }

 bool HasProperty(NonCustomCSSPropertyId aProperty) const {
   AssertInSetRange(aProperty);
   size_t p = aProperty;
   return (mProperties[p / kBitsInChunk] &
           (property_set_type(1) << (p % kBitsInChunk))) != 0;
 }

 // Returns an nsCSSPropertyIDSet including all properties that can be run
 // on the compositor.
 static constexpr nsCSSPropertyIDSet CompositorAnimatables() {
   return nsCSSPropertyIDSet(COMPOSITOR_ANIMATABLE_PROPERTY_LIST);
 }

 static constexpr size_t CompositorAnimatableCount() {
   return COMPOSITOR_ANIMATABLE_PROPERTY_LIST_LENGTH;
 }

 static constexpr size_t CompositorAnimatableDisplayItemCount() {
   // We have 3 individual transforms and 5 motion path properties, and they
   // also use DisplayItemType::TYPE_TRANSFORM.
   return COMPOSITOR_ANIMATABLE_PROPERTY_LIST_LENGTH - 8;
 }

 static constexpr nsCSSPropertyIDSet CSSTransformProperties() {
   return nsCSSPropertyIDSet{eCSSProperty_transform, eCSSProperty_translate,
                             eCSSProperty_rotate, eCSSProperty_scale};
 }

 static constexpr nsCSSPropertyIDSet MotionPathProperties() {
   return nsCSSPropertyIDSet{
       eCSSProperty_offset_path, eCSSProperty_offset_distance,
       eCSSProperty_offset_rotate, eCSSProperty_offset_anchor,
       eCSSProperty_offset_position};
 }

 static constexpr nsCSSPropertyIDSet TransformLikeProperties() {
   return nsCSSPropertyIDSet{
       eCSSProperty_transform,      eCSSProperty_translate,
       eCSSProperty_rotate,         eCSSProperty_scale,
       eCSSProperty_offset_path,    eCSSProperty_offset_distance,
       eCSSProperty_offset_rotate,  eCSSProperty_offset_anchor,
       eCSSProperty_offset_position};
 }

 static constexpr nsCSSPropertyIDSet OpacityProperties() {
   return nsCSSPropertyIDSet{eCSSProperty_opacity};
 }

 bool Intersects(const nsCSSPropertyIDSet& aOther) const {
   for (size_t i = 0; i < std::size(mProperties); ++i) {
     if (mProperties[i] & aOther.mProperties[i]) {
       return true;
     }
   }
   return false;
 }

 void Empty() { memset(mProperties, 0, sizeof(mProperties)); }

 void AssertIsEmpty(const char* aText) const {
   for (size_t i = 0; i < std::size(mProperties); ++i) {
     NS_ASSERTION(mProperties[i] == 0, aText);
   }
 }

 bool Equals(const nsCSSPropertyIDSet& aOther) const {
   return mozilla::ArrayEqual(mProperties, aOther.mProperties);
 }

 bool IsEmpty() const {
   for (size_t i = 0; i < std::size(mProperties); ++i) {
     if (mProperties[i] != 0) {
       return false;
     }
   }
   return true;
 }

 bool IsSubsetOf(const nsCSSPropertyIDSet& aOther) const {
   return this->Intersect(aOther).Equals(*this);
 }

 // Returns a new nsCSSPropertyIDSet with all properties that are both in
 // this set and |aOther|.
 nsCSSPropertyIDSet Intersect(const nsCSSPropertyIDSet& aOther) const {
   nsCSSPropertyIDSet result;
   for (size_t i = 0; i < std::size(mProperties); ++i) {
     result.mProperties[i] = mProperties[i] & aOther.mProperties[i];
   }
   return result;
 }

 // Returns a new nsCSSPropertyIDSet with all properties that are in either
 // this set or |aOther| but not both.
 nsCSSPropertyIDSet Xor(const nsCSSPropertyIDSet& aOther) const {
   nsCSSPropertyIDSet result;
   for (size_t i = 0; i < std::size(mProperties); ++i) {
     result.mProperties[i] = mProperties[i] ^ aOther.mProperties[i];
   }
   return result;
 }

 nsCSSPropertyIDSet& operator|=(const nsCSSPropertyIDSet& aOther) {
   for (size_t i = 0; i < std::size(mProperties); ++i) {
     mProperties[i] |= aOther.mProperties[i];
   }
   return *this;
 }

private:
 typedef unsigned long property_set_type;

public:
 // number of bits in |property_set_type|.
 static const size_t kBitsInChunk = sizeof(property_set_type) * CHAR_BIT;
 // number of |property_set_type|s in the set
 static const size_t kChunkCount =
     (eCSSProperty_COUNT_no_shorthands + kBitsInChunk - 1) / kBitsInChunk;

 /*
  * For fast enumeration of all the bits that are set, callers can
  * check each chunk against zero (since in normal cases few bits are
  * likely to be set).
  */
 bool HasPropertyInChunk(size_t aChunk) const {
   return mProperties[aChunk] != 0;
 }
 bool HasPropertyAt(size_t aChunk, size_t aBit) const {
   return (mProperties[aChunk] & (property_set_type(1) << aBit)) != 0;
 }
 static NonCustomCSSPropertyId CSSPropertyAt(size_t aChunk, size_t aBit) {
   return NonCustomCSSPropertyId(aChunk * kBitsInChunk + aBit);
 }

 // Iterator for use in range-based for loops
 class Iterator {
  public:
   Iterator(Iterator&& aOther)
       : mPropertySet(aOther.mPropertySet),
         mChunk(aOther.mChunk),
         mBit(aOther.mBit) {}

   static Iterator BeginIterator(const nsCSSPropertyIDSet& aPropertySet) {
     Iterator result(aPropertySet);

     // Search for the first property.
     // Unsigned integer overflow is defined so the following is safe.
     result.mBit = -1;
     ++result;

     return result;
   }

   static Iterator EndIterator(const nsCSSPropertyIDSet& aPropertySet) {
     Iterator result(aPropertySet);
     result.mChunk = kChunkCount;
     result.mBit = 0;
     return result;
   }

   bool operator!=(const Iterator& aOther) const {
     return mChunk != aOther.mChunk || mBit != aOther.mBit;
   }

   Iterator& operator++() {
     MOZ_ASSERT(mChunk < kChunkCount, "Should not iterate beyond end");

     do {
       mBit++;
     } while (mBit < kBitsInChunk &&
              !mPropertySet.HasPropertyAt(mChunk, mBit));
     if (mBit != kBitsInChunk) {
       return *this;
     }

     do {
       mChunk++;
     } while (mChunk < kChunkCount &&
              !mPropertySet.HasPropertyInChunk(mChunk));
     mBit = 0;
     if (mChunk != kChunkCount) {
       while (mBit < kBitsInChunk &&
              !mPropertySet.HasPropertyAt(mChunk, mBit)) {
         mBit++;
       }
     }

     return *this;
   }

   NonCustomCSSPropertyId operator*() {
     MOZ_ASSERT(mChunk < kChunkCount, "Should not dereference beyond end");
     return nsCSSPropertyIDSet::CSSPropertyAt(mChunk, mBit);
   }

  private:
   explicit Iterator(const nsCSSPropertyIDSet& aPropertySet)
       : mPropertySet(aPropertySet) {}

   Iterator() = delete;
   Iterator(const Iterator&) = delete;
   Iterator& operator=(const Iterator&) = delete;
   Iterator& operator=(const Iterator&&) = delete;

   const nsCSSPropertyIDSet& mPropertySet;
   size_t mChunk = 0;
   size_t mBit = 0;
 };

 Iterator begin() const { return Iterator::BeginIterator(*this); }
 Iterator end() const { return Iterator::EndIterator(*this); }

private:
 property_set_type mProperties[kChunkCount];
};

// MOZ_DBG support

inline std::ostream& operator<<(std::ostream& aOut,
                               const nsCSSPropertyIDSet& aPropertySet) {
 AutoTArray<NonCustomCSSPropertyId, 16> properties;
 for (NonCustomCSSPropertyId property : aPropertySet) {
   properties.AppendElement(property);
 }
 return aOut << properties;
}

#endif /* !defined(nsCSSPropertyIDSet_h__) */