1 files changed, 111 insertions, 0 deletions
diff --git a/layout/style/ServoComputedData.h b/layout/style/ServoComputedData.h
new file mode 100644
index 0000000000..9da716263b
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+++ b/layout/style/ServoComputedData.h
@@ -0,0 +1,111 @@
+/* -*- 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/. */
+
+#ifndef mozilla_ServoComputedData_h
+#define mozilla_ServoComputedData_h
+
+class nsWindowSizes;
+
+#include "mozilla/ServoStyleConsts.h"
+
+/*
+ * ServoComputedData and its related types.
+ */
+
+namespace mozilla {
+
+struct ServoWritingMode {
+  uint8_t mBits;
+};
+
+struct ServoComputedCustomProperties {
+  uintptr_t mInherited;
+  uintptr_t mNonInherited;
+};
+
+struct ServoRuleNode {
+  uintptr_t mPtr;
+};
+
+class ComputedStyle;
+
+}  // namespace mozilla
+
+#define STYLE_STRUCT(name_) struct nsStyle##name_;
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT
+
+class ServoComputedData;
+
+struct ServoComputedDataForgotten {
+  // Make sure you manually mem::forget the backing ServoComputedData
+  // after calling this
+  explicit ServoComputedDataForgotten(const ServoComputedData* aValue)
+      : mPtr(aValue) {}
+  const ServoComputedData* mPtr;
+};
+
+/**
+ * We want C++ to be able to read the style struct fields of ComputedValues
+ * so we define this type on the C++ side and use the bindgenned version
+ * on the Rust side.
+ */
+class ServoComputedData {
+  friend class mozilla::ComputedStyle;
+
+ public:
+  // Constructs via memcpy.  Will not move out of aValue.
+  explicit ServoComputedData(const ServoComputedDataForgotten aValue);
+
+#define STYLE_STRUCT(name_)                                       \
+  const nsStyle##name_* name_;                                    \
+  const nsStyle##name_* Style##name_() const MOZ_NONNULL_RETURN { \
+    return name_;                                                 \
+  }
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT
+
+  void AddSizeOfExcludingThis(nsWindowSizes& aSizes) const;
+
+  mozilla::ServoWritingMode WritingMode() const { return writing_mode; }
+
+ private:
+  mozilla::ServoComputedCustomProperties custom_properties;
+  mozilla::ServoWritingMode writing_mode;
+  /// The effective zoom (as in, the CSS zoom property) of this style.
+  ///
+  /// zoom is a non-inherited property, yet changes to it propagate through in
+  /// an inherited fashion, and all length resolution code need to access it.
+  /// This could, in theory, be stored in any other inherited struct, but it's
+  /// weird to have an inherited struct field depend on a non inherited
+  /// property.
+  ///
+  /// So the style object itself is probably a reasonable place to store it.
+  mozilla::StyleZoom effective_zoom;
+  mozilla::StyleComputedValueFlags flags;
+  /// The rule node representing the ordered list of rules matched for this
+  /// node.  Can be None for default values and text nodes.  This is
+  /// essentially an optimization to avoid referencing the root rule node.
+  mozilla::ServoRuleNode rules;
+  /// The element's computed values if visited, only computed if there's a
+  /// relevant link for this element. A element's "relevant link" is the
+  /// element being matched if it is a link or the nearest ancestor link.
+  const mozilla::ComputedStyle* visited_style;
+
+  // C++ just sees this struct as a bucket of bits, and will
+  // do the wrong thing if we let it use the default copy ctor/assignment
+  // operator. Remove them so that there is no footgun.
+  //
+  // We remove the move ctor/assignment operator as well, because
+  // moves in C++ don't prevent destructors from being called,
+  // which will lead to double frees.
+  ServoComputedData& operator=(const ServoComputedData&) = delete;
+  ServoComputedData(const ServoComputedData&) = delete;
+  ServoComputedData&& operator=(const ServoComputedData&&) = delete;
+  ServoComputedData(const ServoComputedData&&) = delete;
+};
+
+#endif  // mozilla_ServoComputedData_h