dom/base/AttrArray.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * Storage of the attributes of a DOM node.
   9  */
  10
  11 #ifndef AttrArray_h___
  12 #define AttrArray_h___
  13
  14 #include "mozilla/Attributes.h"
  15 #include "mozilla/MemoryReporting.h"
  16 #include "mozilla/UniquePtr.h"
  17 #include "mozilla/Span.h"
  18 #include "mozilla/dom/BorrowedAttrInfo.h"
  19
  20 #include "nscore.h"
  21 #include "nsAttrName.h"
  22 #include "nsAttrValue.h"
  23 #include "nsCaseTreatment.h"
  24
  25 namespace mozilla {
  26 class AttributeStyles;
  27 struct StyleLockedDeclarationBlock;
  28 }  // namespace mozilla
  29
  30 class AttrArray {
  31   using BorrowedAttrInfo = mozilla::dom::BorrowedAttrInfo;
  32
  33  public:
  34   AttrArray() = default;
  35   ~AttrArray() = default;
  36
  37   bool HasAttrs() const { return !!AttrCount(); }
  38
  39   uint32_t AttrCount() const { return mImpl ? mImpl->mAttrCount : 0; }
  40
  41   const nsAttrValue* GetAttr(const nsAtom* aLocalName) const;
  42
  43   const nsAttrValue* GetAttr(const nsAtom* aLocalName,
  44                              int32_t aNamespaceID) const;
  45   // As above but using a string attr name and always using
  46   // kNameSpaceID_None.  This is always case-sensitive.
  47   const nsAttrValue* GetAttr(const nsAString& aName) const;
  48   // Get an nsAttrValue by qualified name.  Can optionally do
  49   // ASCII-case-insensitive name matching.
  50   const nsAttrValue* GetAttr(const nsAString& aName,
  51                              nsCaseTreatment aCaseSensitive) const;
  52   const nsAttrValue* AttrAt(uint32_t aPos) const;
  53   // SetAndSwapAttr swaps the current attribute value with aValue.
  54   // If the attribute was unset, an empty value will be swapped into aValue
  55   // and aHadValue will be set to false. Otherwise, aHadValue will be set to
  56   // true.
  57   nsresult SetAndSwapAttr(nsAtom* aLocalName, nsAttrValue& aValue,
  58                           bool* aHadValue);
  59   nsresult SetAndSwapAttr(mozilla::dom::NodeInfo* aName, nsAttrValue& aValue,
  60                           bool* aHadValue);
  61
  62   // This stores the argument and clears the pending mapped attribute evaluation
  63   // bit, so after calling this IsPendingMappedAttributeEvaluation() is
  64   // guaranteed to return false.
  65   void SetMappedDeclarationBlock(
  66       already_AddRefed<mozilla::StyleLockedDeclarationBlock>);
  67
  68   bool IsPendingMappedAttributeEvaluation() const {
  69     return mImpl && mImpl->mMappedAttributeBits & 1;
  70   }
  71
  72   mozilla::StyleLockedDeclarationBlock* GetMappedDeclarationBlock() const {
  73     return mImpl ? mImpl->GetMappedDeclarationBlock() : nullptr;
  74   }
  75
  76   // Remove the attr at position aPos.  The value of the attr is placed in
  77   // aValue; any value that was already in aValue is destroyed.
  78   nsresult RemoveAttrAt(uint32_t aPos, nsAttrValue& aValue);
  79
  80   // Returns attribute name at given position, *not* out-of-bounds safe
  81   const nsAttrName* AttrNameAt(uint32_t aPos) const;
  82
  83   // Returns the attribute info at a given position, *not* out-of-bounds safe
  84   BorrowedAttrInfo AttrInfoAt(uint32_t aPos) const;
  85
  86   // Returns attribute name at given position or null if aPos is out-of-bounds
  87   const nsAttrName* GetSafeAttrNameAt(uint32_t aPos) const;
  88
  89   const nsAttrName* GetExistingAttrNameFromQName(const nsAString& aName) const;
  90   int32_t IndexOfAttr(const nsAtom* aLocalName) const;
  91   int32_t IndexOfAttr(const nsAtom* aLocalName, int32_t aNamespaceID) const;
  92
  93   void Compact();
  94
  95   size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
  96
  97   // Mark the element as pending mapped attribute evaluation. This should be
  98   // called when a mapped attribute is changed (regardless of connectedness).
  99   bool MarkAsPendingPresAttributeEvaluation() {
 100     // It'd be great to be able to assert that mImpl is non-null or we're the
 101     // <body> or <svg> elements.
 102     if (MOZ_UNLIKELY(!mImpl) && !GrowBy(1)) {
 103       return false;
 104     }
 105     InfallibleMarkAsPendingPresAttributeEvaluation();
 106     return true;
 107   }
 108
 109   // See above.
 110   void InfallibleMarkAsPendingPresAttributeEvaluation() {
 111     MOZ_ASSERT(mImpl);
 112     mImpl->mMappedAttributeBits |= 1;
 113   }
 114
 115   // Clear the servo declaration block on the mapped attributes, if any
 116   // Will assert off main thread
 117   void ClearMappedServoStyle();
 118
 119   // Increases capacity (if necessary) to have enough space to accomodate the
 120   // unmapped attributes of |aOther|.
 121   nsresult EnsureCapacityToClone(const AttrArray& aOther);
 122
 123   enum AttrValuesState { ATTR_MISSING = -1, ATTR_VALUE_NO_MATCH = -2 };
 124   using AttrValuesArray = nsStaticAtom* const;
 125   int32_t FindAttrValueIn(int32_t aNameSpaceID, const nsAtom* aName,
 126                           AttrValuesArray* aValues,
 127                           nsCaseTreatment aCaseSensitive) const;
 128
 129   inline bool GetAttr(int32_t aNameSpaceID, const nsAtom* aName,
 130                       nsAString& aResult) const {
 131     MOZ_ASSERT(aResult.IsEmpty(), "Should have empty string coming in");
 132     const nsAttrValue* val = GetAttr(aName, aNameSpaceID);
 133     if (!val) {
 134       return false;
 135     }
 136     val->ToString(aResult);
 137     return true;
 138   }
 139
 140   inline bool GetAttr(const nsAtom* aName, nsAString& aResult) const {
 141     MOZ_ASSERT(aResult.IsEmpty(), "Should have empty string coming in");
 142     const nsAttrValue* val = GetAttr(aName);
 143     if (!val) {
 144       return false;
 145     }
 146     val->ToString(aResult);
 147     return true;
 148   }
 149
 150   inline bool HasAttr(const nsAtom* aName) const { return !!GetAttr(aName); }
 151
 152   inline bool HasAttr(int32_t aNameSpaceID, const nsAtom* aName) const {
 153     return !!GetAttr(aName, aNameSpaceID);
 154   }
 155
 156   inline bool AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
 157                           const nsAString& aValue,
 158                           nsCaseTreatment aCaseSensitive) const {
 159     NS_ASSERTION(aName, "Must have attr name");
 160     NS_ASSERTION(aNameSpaceID != kNameSpaceID_Unknown, "Must have namespace");
 161     const nsAttrValue* val = GetAttr(aName, aNameSpaceID);
 162     return val && val->Equals(aValue, aCaseSensitive);
 163   }
 164
 165   inline bool AttrValueIs(int32_t aNameSpaceID, const nsAtom* aName,
 166                           const nsAtom* aValue,
 167                           nsCaseTreatment aCaseSensitive) const {
 168     NS_ASSERTION(aName, "Must have attr name");
 169     NS_ASSERTION(aNameSpaceID != kNameSpaceID_Unknown, "Must have namespace");
 170     NS_ASSERTION(aValue, "Null value atom");
 171
 172     const nsAttrValue* val = GetAttr(aName, aNameSpaceID);
 173     return val && val->Equals(aValue, aCaseSensitive);
 174   }
 175
 176   struct InternalAttr {
 177     nsAttrName mName;
 178     nsAttrValue mValue;
 179   };
 180
 181   AttrArray(const AttrArray& aOther) = delete;
 182   AttrArray& operator=(const AttrArray& aOther) = delete;
 183
 184   bool GrowBy(uint32_t aGrowSize);
 185   bool GrowTo(uint32_t aCapacity);
 186
 187   void Clear() { mImpl = nullptr; }
 188
 189  private:
 190   // Tries to create an attribute, growing the buffer if needed, with the given
 191   // name and value.
 192   //
 193   // The value is moved from the argument.
 194   //
 195   // `Name` can be anything you construct a `nsAttrName` with (either an atom or
 196   // a NodeInfo pointer).
 197   template <typename Name>
 198   nsresult AddNewAttribute(Name*, nsAttrValue&);
 199
 200   class Impl {
 201    public:
 202     constexpr static size_t AllocationSizeForAttributes(uint32_t aAttrCount) {
 203       return sizeof(Impl) + aAttrCount * sizeof(InternalAttr);
 204     }
 205
 206     mozilla::StyleLockedDeclarationBlock* GetMappedDeclarationBlock() const {
 207       return reinterpret_cast<mozilla::StyleLockedDeclarationBlock*>(
 208           mMappedAttributeBits & ~uintptr_t(1));
 209     }
 210
 211     auto Attrs() const {
 212       return mozilla::Span<const InternalAttr>{mBuffer, mAttrCount};
 213     }
 214
 215     auto Attrs() { return mozilla::Span<InternalAttr>{mBuffer, mAttrCount}; }
 216
 217     Impl(const Impl&) = delete;
 218     Impl(Impl&&) = delete;
 219     ~Impl();
 220
 221     uint32_t mAttrCount;
 222     uint32_t mCapacity;  // In number of InternalAttrs
 223
 224     // mMappedAttributeBits is a tagged pointer of a
 225     // StyleLockedDeclarationBlock, which holds the style information that our
 226     // attributes map to.
 227     //
 228     // If the lower bit is set, then our mapped attributes are dirty. This just
 229     // means that we might have mapped attributes (or used to and no longer
 230     // have), and are pending an update to recompute our declaration.
 231     uintptr_t mMappedAttributeBits = 0;
 232
 233     // Allocated in the same buffer as `Impl`.
 234     InternalAttr mBuffer[0];
 235   };
 236
 237   mozilla::Span<InternalAttr> Attrs() {
 238     return mImpl ? mImpl->Attrs() : mozilla::Span<InternalAttr>();
 239   }
 240
 241   mozilla::Span<const InternalAttr> Attrs() const {
 242     return mImpl ? mImpl->Attrs() : mozilla::Span<const InternalAttr>();
 243   }
 244
 245   mozilla::UniquePtr<Impl> mImpl;
 246 };
 247
 248 #endif