diff -r 000000000000 -r 6474c204b198 layout/style/Rule.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/style/Rule.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,133 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/* base class for all rule types in a CSS style sheet */
+
+#ifndef mozilla_css_Rule_h___
+#define mozilla_css_Rule_h___
+
+#include "mozilla/MemoryReporting.h"
+#include "nsIStyleRule.h"
+#include "nsIDOMCSSRule.h"
+#include "nsCSSStyleSheet.h"
+
+class nsIStyleSheet;
+class nsIDocument;
+struct nsRuleData;
+template<class T> struct already_AddRefed;
+class nsHTMLCSSStyleSheet;
+
+namespace mozilla {
+namespace css {
+class GroupRule;
+
+#define DECL_STYLE_RULE_INHERIT_NO_DOMRULE  \
+virtual void MapRuleInfoInto(nsRuleData* aRuleData);
+
+#define DECL_STYLE_RULE_INHERIT                   \
+  DECL_STYLE_RULE_INHERIT_NO_DOMRULE              \
+  virtual nsIDOMCSSRule* GetDOMRule();            \
+  virtual nsIDOMCSSRule* GetExistingDOMRule();
+
+class Rule : public nsIStyleRule {
+protected:
+  Rule()
+    : mSheet(0),
+      mParentRule(nullptr)
+  {
+  }
+
+  Rule(const Rule& aCopy)
+    : mSheet(aCopy.mSheet),
+      mParentRule(aCopy.mParentRule)
+  {
+  }
+
+  virtual ~Rule() {}
+
+public:
+
+  // The constants in this list must maintain the following invariants:
+  //   If a rule of type N must appear before a rule of type M in stylesheets
+  //   then N < M
+  // Note that nsCSSStyleSheet::RebuildChildList assumes that no other kinds of
+  // rules can come between two rules of type IMPORT_RULE.
+  enum {
+    UNKNOWN_RULE = 0,
+    CHARSET_RULE,
+    IMPORT_RULE,
+    NAMESPACE_RULE,
+    STYLE_RULE,
+    MEDIA_RULE,
+    FONT_FACE_RULE,
+    PAGE_RULE,
+    KEYFRAME_RULE,
+    KEYFRAMES_RULE,
+    DOCUMENT_RULE,
+    SUPPORTS_RULE,
+    FONT_FEATURE_VALUES_RULE
+  };
+
+  virtual int32_t GetType() const = 0;
+
+  nsCSSStyleSheet* GetStyleSheet() const;
+  nsHTMLCSSStyleSheet* GetHTMLCSSStyleSheet() const;
+
+  // Return the document the rule lives in, if any
+  nsIDocument* GetDocument() const
+  {
+    nsCSSStyleSheet* sheet = GetStyleSheet();
+    return sheet ? sheet->GetDocument() : nullptr;
+  }
+
+  virtual void SetStyleSheet(nsCSSStyleSheet* aSheet);
+  // This does not need to be virtual, because GroupRule and MediaRule are not
+  // used for inline style.
+  void SetHTMLCSSStyleSheet(nsHTMLCSSStyleSheet* aSheet);
+
+  void SetParentRule(GroupRule* aRule) {
+    // We don't reference count this up reference. The group rule
+    // will tell us when it's going away or when we're detached from
+    // it.
+    mParentRule = aRule;
+  }
+
+  /**
+   * Clones |this|. Never returns nullptr.
+   */
+  virtual already_AddRefed<Rule> Clone() const = 0;
+
+  // Note that this returns null for inline style rules since they aren't
+  // supposed to have a DOM rule representation (and our code wouldn't work).
+  virtual nsIDOMCSSRule* GetDOMRule() = 0;
+
+  // Like GetDOMRule(), but won't create one if we don't have one yet
+  virtual nsIDOMCSSRule* GetExistingDOMRule() = 0;
+
+  // to implement methods on nsIDOMCSSRule
+  nsresult GetParentRule(nsIDOMCSSRule** aParentRule);
+  nsresult GetParentStyleSheet(nsIDOMCSSStyleSheet** aSheet);
+
+  // This is pure virtual because all of Rule's data members are non-owning and
+  // thus measured elsewhere.
+  virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf)
+    const MOZ_MUST_OVERRIDE = 0;
+
+  // This is used to measure nsCOMArray<Rule>s.
+  static size_t SizeOfCOMArrayElementIncludingThis(css::Rule* aElement,
+                                                   mozilla::MallocSizeOf aMallocSizeOf,
+                                                   void* aData);
+
+protected:
+  // This is either an nsCSSStyleSheet* or a nsHTMLStyleSheet*.  The former
+  // if the low bit is 0, the latter if the low bit is 1.
+  uintptr_t         mSheet;
+  GroupRule*        mParentRule;
+};
+
+} // namespace css
+} // namespace mozilla
+
+#endif /* mozilla_css_Rule_h___ */