layout/style/nsCSSPropertyIDSet.h

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 /* bit vectors for sets of CSS properties */
   6
   7 #ifndef nsCSSPropertyIDSet_h__
   8 #define nsCSSPropertyIDSet_h__
   9
  10 #include <initializer_list>
  11 #include <limits.h>  // for CHAR_BIT
  12 #include <ostream>
  13
  14 #include "mozilla/ArrayUtils.h"
  15 // For COMPOSITOR_ANIMATABLE_PROPERTY_LIST and
  16 // COMPOSITOR_ANIMATABLE_PROPERTY_LIST_LENGTH
  17 #include "mozilla/CompositorAnimatableProperties.h"
  18 #include "nsCSSProps.h"  // For operator<< for nsCSSPropertyID
  19 #include "nsCSSPropertyID.h"
  20
  21 /**
  22  * nsCSSPropertyIDSet maintains a set of non-shorthand CSS properties.  In
  23  * other words, for each longhand CSS property we support, it has a bit
  24  * for whether that property is in the set.
  25  */
  26 class nsCSSPropertyIDSet {
  27  public:
  28   nsCSSPropertyIDSet() { Empty(); }
  29   // auto-generated copy-constructor OK
  30
  31   explicit constexpr nsCSSPropertyIDSet(
  32       std::initializer_list<nsCSSPropertyID> aProperties)
  33       : mProperties{0} {
  34     for (auto property : aProperties) {
  35       size_t p = property;
  36       mProperties[p / kBitsInChunk] |= property_set_type(1)
  37                                        << (p % kBitsInChunk);
  38     }
  39   }
  40
  41   void AssertInSetRange(nsCSSPropertyID aProperty) const {
  42     NS_ASSERTION(0 <= aProperty && aProperty < eCSSProperty_COUNT_no_shorthands,
  43                  "out of bounds");
  44   }
  45
  46   // Conversion of aProperty to |size_t| after AssertInSetRange
  47   // lets the compiler generate significantly tighter code.
  48
  49   void AddProperty(nsCSSPropertyID aProperty) {
  50     AssertInSetRange(aProperty);
  51     size_t p = aProperty;
  52     mProperties[p / kBitsInChunk] |= property_set_type(1) << (p % kBitsInChunk);
  53   }
  54
  55   void RemoveProperty(nsCSSPropertyID aProperty) {
  56     AssertInSetRange(aProperty);
  57     size_t p = aProperty;
  58     mProperties[p / kBitsInChunk] &=
  59         ~(property_set_type(1) << (p % kBitsInChunk));
  60   }
  61
  62   bool HasProperty(nsCSSPropertyID aProperty) const {
  63     AssertInSetRange(aProperty);
  64     size_t p = aProperty;
  65     return (mProperties[p / kBitsInChunk] &
  66             (property_set_type(1) << (p % kBitsInChunk))) != 0;
  67   }
  68
  69   // Returns an nsCSSPropertyIDSet including all properties that can be run
  70   // on the compositor.
  71   static constexpr nsCSSPropertyIDSet CompositorAnimatables() {
  72     return nsCSSPropertyIDSet(COMPOSITOR_ANIMATABLE_PROPERTY_LIST);
  73   }
  74
  75   static constexpr size_t CompositorAnimatableCount() {
  76     return COMPOSITOR_ANIMATABLE_PROPERTY_LIST_LENGTH;
  77   }
  78
  79   static constexpr size_t CompositorAnimatableDisplayItemCount() {
  80     // We have 3 individual transforms and 5 motion path properties, and they
  81     // also use DisplayItemType::TYPE_TRANSFORM.
  82     return COMPOSITOR_ANIMATABLE_PROPERTY_LIST_LENGTH - 8;
  83   }
  84
  85   static constexpr nsCSSPropertyIDSet CSSTransformProperties() {
  86     return nsCSSPropertyIDSet{eCSSProperty_transform, eCSSProperty_translate,
  87                               eCSSProperty_rotate, eCSSProperty_scale};
  88   }
  89
  90   static constexpr nsCSSPropertyIDSet MotionPathProperties() {
  91     return nsCSSPropertyIDSet{
  92         eCSSProperty_offset_path, eCSSProperty_offset_distance,
  93         eCSSProperty_offset_rotate, eCSSProperty_offset_anchor,
  94         eCSSProperty_offset_position};
  95   }
  96
  97   static constexpr nsCSSPropertyIDSet TransformLikeProperties() {
  98     return nsCSSPropertyIDSet{
  99         eCSSProperty_transform,      eCSSProperty_translate,
 100         eCSSProperty_rotate,         eCSSProperty_scale,
 101         eCSSProperty_offset_path,    eCSSProperty_offset_distance,
 102         eCSSProperty_offset_rotate,  eCSSProperty_offset_anchor,
 103         eCSSProperty_offset_position};
 104   }
 105
 106   static constexpr nsCSSPropertyIDSet OpacityProperties() {
 107     return nsCSSPropertyIDSet{eCSSProperty_opacity};
 108   }
 109
 110   bool Intersects(const nsCSSPropertyIDSet& aOther) const {
 111     for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
 112       if (mProperties[i] & aOther.mProperties[i]) {
 113         return true;
 114       }
 115     }
 116     return false;
 117   }
 118
 119   void Empty() { memset(mProperties, 0, sizeof(mProperties)); }
 120
 121   void AssertIsEmpty(const char* aText) const {
 122     for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
 123       NS_ASSERTION(mProperties[i] == 0, aText);
 124     }
 125   }
 126
 127   bool Equals(const nsCSSPropertyIDSet& aOther) const {
 128     return mozilla::ArrayEqual(mProperties, aOther.mProperties);
 129   }
 130
 131   bool IsEmpty() const {
 132     for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
 133       if (mProperties[i] != 0) {
 134         return false;
 135       }
 136     }
 137     return true;
 138   }
 139
 140   bool IsSubsetOf(const nsCSSPropertyIDSet& aOther) const {
 141     return this->Intersect(aOther).Equals(*this);
 142   }
 143
 144   // Return a new nsCSSPropertyIDSet which is the inverse of this set.
 145   nsCSSPropertyIDSet Inverse() const {
 146     nsCSSPropertyIDSet result;
 147     for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
 148       result.mProperties[i] = ~mProperties[i];
 149     }
 150     return result;
 151   }
 152
 153   // Returns a new nsCSSPropertyIDSet with all properties that are both in
 154   // this set and |aOther|.
 155   nsCSSPropertyIDSet Intersect(const nsCSSPropertyIDSet& aOther) const {
 156     nsCSSPropertyIDSet result;
 157     for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
 158       result.mProperties[i] = mProperties[i] & aOther.mProperties[i];
 159     }
 160     return result;
 161   }
 162
 163   // Return a new nsCSSPropertyIDSet with all properties that are in either
 164   // this set or |aOther| but not both.
 165   nsCSSPropertyIDSet Xor(const nsCSSPropertyIDSet& aOther) const {
 166     nsCSSPropertyIDSet result;
 167     for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
 168       result.mProperties[i] = mProperties[i] ^ aOther.mProperties[i];
 169     }
 170     return result;
 171   }
 172
 173   nsCSSPropertyIDSet& operator|=(const nsCSSPropertyIDSet& aOther) {
 174     for (size_t i = 0; i < mozilla::ArrayLength(mProperties); ++i) {
 175       mProperties[i] |= aOther.mProperties[i];
 176     }
 177     return *this;
 178   }
 179
 180  private:
 181   typedef unsigned long property_set_type;
 182
 183  public:
 184   // number of bits in |property_set_type|.
 185   static const size_t kBitsInChunk = sizeof(property_set_type) * CHAR_BIT;
 186   // number of |property_set_type|s in the set
 187   static const size_t kChunkCount =
 188       (eCSSProperty_COUNT_no_shorthands + kBitsInChunk - 1) / kBitsInChunk;
 189
 190   /*
 191    * For fast enumeration of all the bits that are set, callers can
 192    * check each chunk against zero (since in normal cases few bits are
 193    * likely to be set).
 194    */
 195   bool HasPropertyInChunk(size_t aChunk) const {
 196     return mProperties[aChunk] != 0;
 197   }
 198   bool HasPropertyAt(size_t aChunk, size_t aBit) const {
 199     return (mProperties[aChunk] & (property_set_type(1) << aBit)) != 0;
 200   }
 201   static nsCSSPropertyID CSSPropertyAt(size_t aChunk, size_t aBit) {
 202     return nsCSSPropertyID(aChunk * kBitsInChunk + aBit);
 203   }
 204
 205   // Iterator for use in range-based for loops
 206   class Iterator {
 207    public:
 208     Iterator(Iterator&& aOther)
 209         : mPropertySet(aOther.mPropertySet),
 210           mChunk(aOther.mChunk),
 211           mBit(aOther.mBit) {}
 212
 213     static Iterator BeginIterator(const nsCSSPropertyIDSet& aPropertySet) {
 214       Iterator result(aPropertySet);
 215
 216       // Search for the first property.
 217       // Unsigned integer overflow is defined so the following is safe.
 218       result.mBit = -1;
 219       ++result;
 220
 221       return result;
 222     }
 223
 224     static Iterator EndIterator(const nsCSSPropertyIDSet& aPropertySet) {
 225       Iterator result(aPropertySet);
 226       result.mChunk = kChunkCount;
 227       result.mBit = 0;
 228       return result;
 229     }
 230
 231     bool operator!=(const Iterator& aOther) const {
 232       return mChunk != aOther.mChunk || mBit != aOther.mBit;
 233     }
 234
 235     Iterator& operator++() {
 236       MOZ_ASSERT(mChunk < kChunkCount, "Should not iterate beyond end");
 237
 238       do {
 239         mBit++;
 240       } while (mBit < kBitsInChunk &&
 241                !mPropertySet.HasPropertyAt(mChunk, mBit));
 242       if (mBit != kBitsInChunk) {
 243         return *this;
 244       }
 245
 246       do {
 247         mChunk++;
 248       } while (mChunk < kChunkCount &&
 249                !mPropertySet.HasPropertyInChunk(mChunk));
 250       mBit = 0;
 251       if (mChunk != kChunkCount) {
 252         while (mBit < kBitsInChunk &&
 253                !mPropertySet.HasPropertyAt(mChunk, mBit)) {
 254           mBit++;
 255         }
 256       }
 257
 258       return *this;
 259     }
 260
 261     nsCSSPropertyID operator*() {
 262       MOZ_ASSERT(mChunk < kChunkCount, "Should not dereference beyond end");
 263       return nsCSSPropertyIDSet::CSSPropertyAt(mChunk, mBit);
 264     }
 265
 266    private:
 267     explicit Iterator(const nsCSSPropertyIDSet& aPropertySet)
 268         : mPropertySet(aPropertySet) {}
 269
 270     Iterator() = delete;
 271     Iterator(const Iterator&) = delete;
 272     Iterator& operator=(const Iterator&) = delete;
 273     Iterator& operator=(const Iterator&&) = delete;
 274
 275     const nsCSSPropertyIDSet& mPropertySet;
 276     size_t mChunk = 0;
 277     size_t mBit = 0;
 278   };
 279
 280   Iterator begin() const { return Iterator::BeginIterator(*this); }
 281   Iterator end() const { return Iterator::EndIterator(*this); }
 282
 283  private:
 284   property_set_type mProperties[kChunkCount];
 285 };
 286
 287 // MOZ_DBG support
 288
 289 inline std::ostream& operator<<(std::ostream& aOut,
 290                                 const nsCSSPropertyIDSet& aPropertySet) {
 291   AutoTArray<nsCSSPropertyID, 16> properties;
 292   for (nsCSSPropertyID property : aPropertySet) {
 293     properties.AppendElement(property);
 294   }
 295   return aOut << properties;
 296 }
 297
 298 #endif /* !defined(nsCSSPropertyIDSet_h__) */