layout/style/ServoComputedData.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 #ifndef mozilla_ServoComputedData_h
   8 #define mozilla_ServoComputedData_h
   9
  10 class nsWindowSizes;
  11
  12 #include "mozilla/ServoStyleConsts.h"
  13
  14 /*
  15  * ServoComputedData and its related types.
  16  */
  17
  18 namespace mozilla {
  19
  20 struct ServoWritingMode {
  21   uint8_t mBits;
  22 };
  23
  24 struct ServoCustomPropertiesMap {
  25   uintptr_t mPtr;
  26 };
  27
  28 struct ServoRuleNode {
  29   uintptr_t mPtr;
  30 };
  31
  32 class ComputedStyle;
  33
  34 }  // namespace mozilla
  35
  36 #define STYLE_STRUCT(name_) struct nsStyle##name_;
  37 #include "nsStyleStructList.h"
  38 #undef STYLE_STRUCT
  39
  40 class ServoComputedData;
  41
  42 struct ServoComputedDataForgotten {
  43   // Make sure you manually mem::forget the backing ServoComputedData
  44   // after calling this
  45   explicit ServoComputedDataForgotten(const ServoComputedData* aValue)
  46       : mPtr(aValue) {}
  47   const ServoComputedData* mPtr;
  48 };
  49
  50 /**
  51  * We want C++ to be able to read the style struct fields of ComputedValues
  52  * so we define this type on the C++ side and use the bindgenned version
  53  * on the Rust side.
  54  */
  55 class ServoComputedData {
  56   friend class mozilla::ComputedStyle;
  57
  58  public:
  59   // Constructs via memcpy.  Will not move out of aValue.
  60   explicit ServoComputedData(const ServoComputedDataForgotten aValue);
  61
  62 #define STYLE_STRUCT(name_)                                       \
  63   const nsStyle##name_* name_;                                    \
  64   const nsStyle##name_* Style##name_() const MOZ_NONNULL_RETURN { \
  65     return name_;                                                 \
  66   }
  67 #include "nsStyleStructList.h"
  68 #undef STYLE_STRUCT
  69
  70   void AddSizeOfExcludingThis(nsWindowSizes& aSizes) const;
  71
  72   mozilla::ServoWritingMode WritingMode() const { return writing_mode; }
  73
  74  private:
  75   mozilla::ServoCustomPropertiesMap custom_properties;
  76   mozilla::ServoWritingMode writing_mode;
  77   mozilla::StyleComputedValueFlags flags;
  78   /// The rule node representing the ordered list of rules matched for this
  79   /// node.  Can be None for default values and text nodes.  This is
  80   /// essentially an optimization to avoid referencing the root rule node.
  81   mozilla::ServoRuleNode rules;
  82   /// The element's computed values if visited, only computed if there's a
  83   /// relevant link for this element. A element's "relevant link" is the
  84   /// element being matched if it is a link or the nearest ancestor link.
  85   const mozilla::ComputedStyle* visited_style;
  86
  87   // C++ just sees this struct as a bucket of bits, and will
  88   // do the wrong thing if we let it use the default copy ctor/assignment
  89   // operator. Remove them so that there is no footgun.
  90   //
  91   // We remove the move ctor/assignment operator as well, because
  92   // moves in C++ don't prevent destructors from being called,
  93   // which will lead to double frees.
  94   ServoComputedData& operator=(const ServoComputedData&) = delete;
  95   ServoComputedData(const ServoComputedData&) = delete;
  96   ServoComputedData&& operator=(const ServoComputedData&&) = delete;
  97   ServoComputedData(const ServoComputedData&&) = delete;
  98 };
  99
 100 #endif  // mozilla_ServoComputedData_h