зеркало из https://github.com/mozilla/gecko-dev.git
439 строки
18 KiB
C++
439 строки
18 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* the interface (to internal code) for retrieving computed style data */
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#ifndef _nsStyleContext_h_
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#define _nsStyleContext_h_
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#include "nsRuleNode.h"
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#include "nsIAtom.h"
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#include "nsCSSPseudoElements.h"
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class nsPresContext;
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/**
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* An nsStyleContext represents the computed style data for an element.
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* The computed style data are stored in a set of structs (see
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* nsStyleStruct.h) that are cached either on the style context or in
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* the rule tree (see nsRuleNode.h for a description of this caching and
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* how the cached structs are shared).
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*
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* Since the data in |nsIStyleRule|s and |nsRuleNode|s are immutable
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* (with a few exceptions, like system color changes), the data in an
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* nsStyleContext are also immutable (with the additional exception of
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* GetUniqueStyleData). When style data change,
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* nsFrameManager::ReResolveStyleContext creates a new style context.
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*
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* Style contexts are reference counted. References are generally held
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* by:
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* 1. the |nsIFrame|s that are using the style context and
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* 2. any *child* style contexts (this might be the reverse of
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* expectation, but it makes sense in this case)
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* Style contexts participate in the mark phase of rule node garbage
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* collection.
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*/
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class nsStyleContext
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{
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public:
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/**
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* Create a new style context.
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* @param aParent The parent of a style context is used for CSS
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* inheritance. When the element or pseudo-element
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* this style context represents the style data of
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* inherits a CSS property, the value comes from the
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* parent style context. This means style context
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* parentage must match the definitions of inheritance
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* in the CSS specification.
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* @param aPseudoTag The pseudo-element or anonymous box for which
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* this style context represents style. Null if
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* this style context is for a normal DOM element.
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* @param aPseudoType Must match aPseudoTag.
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* @param aRuleNode A rule node representing the ordered sequence of
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* rules that any element, pseudo-element, or
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* anonymous box that this style context is for
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* matches. See |nsRuleNode| and |nsIStyleRule|.
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*/
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nsStyleContext(nsStyleContext* aParent, nsIAtom* aPseudoTag,
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nsCSSPseudoElements::Type aPseudoType,
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nsRuleNode* aRuleNode);
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~nsStyleContext();
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void* operator new(size_t sz, nsPresContext* aPresContext) CPP_THROW_NEW;
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void Destroy();
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nsrefcnt AddRef() {
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if (mRefCnt == UINT32_MAX) {
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NS_WARNING("refcount overflow, leaking object");
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return mRefCnt;
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}
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++mRefCnt;
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NS_LOG_ADDREF(this, mRefCnt, "nsStyleContext", sizeof(nsStyleContext));
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return mRefCnt;
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}
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nsrefcnt Release() {
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if (mRefCnt == UINT32_MAX) {
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NS_WARNING("refcount overflow, leaking object");
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return mRefCnt;
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}
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--mRefCnt;
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NS_LOG_RELEASE(this, mRefCnt, "nsStyleContext");
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if (mRefCnt == 0) {
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Destroy();
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return 0;
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}
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return mRefCnt;
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}
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nsPresContext* PresContext() const { return mRuleNode->GetPresContext(); }
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nsStyleContext* GetParent() const { return mParent; }
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nsIAtom* GetPseudo() const { return mPseudoTag; }
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nsCSSPseudoElements::Type GetPseudoType() const {
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return static_cast<nsCSSPseudoElements::Type>(mBits >>
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NS_STYLE_CONTEXT_TYPE_SHIFT);
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}
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// Find, if it already exists *and is easily findable* (i.e., near the
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// start of the child list), a style context whose:
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// * GetPseudo() matches aPseudoTag
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// * GetRuleNode() matches aRules
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// * !GetStyleIfVisited() == !aRulesIfVisited, and, if they're
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// non-null, GetStyleIfVisited()->GetRuleNode() == aRulesIfVisited
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// * RelevantLinkVisited() == aRelevantLinkVisited
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already_AddRefed<nsStyleContext>
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FindChildWithRules(const nsIAtom* aPseudoTag, nsRuleNode* aRules,
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nsRuleNode* aRulesIfVisited,
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bool aRelevantLinkVisited);
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// Does this style context or any of its ancestors have text
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// decoration lines?
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bool HasTextDecorationLines() const
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{ return !!(mBits & NS_STYLE_HAS_TEXT_DECORATION_LINES); }
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// Does this style context represent the style for a pseudo-element or
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// inherit data from such a style context? Whether this returns true
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// is equivalent to whether it or any of its ancestors returns
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// non-null for GetPseudo.
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bool HasPseudoElementData() const
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{ return !!(mBits & NS_STYLE_HAS_PSEUDO_ELEMENT_DATA); }
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// Is the only link whose visitedness is allowed to influence the
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// style of the node this style context is for (which is that element
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// or its nearest ancestor that is a link) visited?
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bool RelevantLinkVisited() const
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{ return !!(mBits & NS_STYLE_RELEVANT_LINK_VISITED); }
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// Is this a style context for a link?
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bool IsLinkContext() const {
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return
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GetStyleIfVisited() && GetStyleIfVisited()->GetParent() == GetParent();
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}
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// Is this style context the GetStyleIfVisited() for some other style
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// context?
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bool IsStyleIfVisited() const
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{ return !!(mBits & NS_STYLE_IS_STYLE_IF_VISITED); }
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// Tells this style context that it should return true from
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// IsStyleIfVisited.
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void SetIsStyleIfVisited()
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{ mBits |= NS_STYLE_IS_STYLE_IF_VISITED; }
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// Return the style context whose style data should be used for the R,
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// G, and B components of color, background-color, and border-*-color
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// if RelevantLinkIsVisited().
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//
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// GetPseudo() and GetPseudoType() on this style context return the
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// same as on |this|, and its depth in the tree (number of GetParent()
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// calls until null is returned) is the same as |this|, since its
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// parent is either |this|'s parent or |this|'s parent's
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// style-if-visited.
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//
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// Structs on this context should never be examined without also
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// examining the corresponding struct on |this|. Doing so will likely
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// both (1) lead to a privacy leak and (2) lead to dynamic change bugs
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// related to the Peek code in nsStyleContext::CalcStyleDifference.
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nsStyleContext* GetStyleIfVisited() const
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{ return mStyleIfVisited; }
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// To be called only from nsStyleSet.
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void SetStyleIfVisited(already_AddRefed<nsStyleContext> aStyleIfVisited)
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{
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NS_ABORT_IF_FALSE(!IsStyleIfVisited(), "this context is not visited data");
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NS_ABORT_IF_FALSE(aStyleIfVisited.get()->IsStyleIfVisited(),
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"other context is visited data");
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NS_ABORT_IF_FALSE(!aStyleIfVisited.get()->GetStyleIfVisited(),
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"other context does not have visited data");
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NS_ASSERTION(!mStyleIfVisited, "should only be set once");
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mStyleIfVisited = aStyleIfVisited;
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NS_ASSERTION(GetStyleIfVisited()->GetPseudo() == GetPseudo(),
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"pseudo tag mismatch");
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if (GetParent() && GetParent()->GetStyleIfVisited()) {
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NS_ASSERTION(GetStyleIfVisited()->GetParent() ==
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GetParent()->GetStyleIfVisited() ||
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GetStyleIfVisited()->GetParent() == GetParent(),
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"parent mismatch");
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} else {
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NS_ASSERTION(GetStyleIfVisited()->GetParent() == GetParent(),
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"parent mismatch");
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}
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}
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// Tell this style context to cache aStruct as the struct for aSID
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void SetStyle(nsStyleStructID aSID, void* aStruct);
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// Setters for inherit structs only, since rulenode only sets those eagerly.
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#define STYLE_STRUCT_INHERITED(name_, checkdata_cb_, ctor_args_) \
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void SetStyle##name_ (nsStyle##name_ * aStruct) { \
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void *& slot = \
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mCachedInheritedData.mStyleStructs[eStyleStruct_##name_]; \
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NS_ASSERTION(!slot || \
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(mBits & \
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nsCachedStyleData::GetBitForSID(eStyleStruct_##name_)), \
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"Going to leak styledata"); \
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slot = aStruct; \
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}
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#define STYLE_STRUCT_RESET(name_, checkdata_cb_, ctor_args_) /* nothing */
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT_RESET
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#undef STYLE_STRUCT_INHERITED
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nsRuleNode* GetRuleNode() { return mRuleNode; }
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void AddStyleBit(const uint32_t& aBit) { mBits |= aBit; }
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/*
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* Mark this style context's rule node (and its ancestors) to prevent
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* it from being garbage collected.
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*/
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void Mark();
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/*
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* Get the style data for a style struct. This is the most important
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* member function of nsIStyleContext. It fills in a const pointer
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* to a style data struct that is appropriate for the style context's
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* frame. This struct may be shared with other contexts (either in
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* the rule tree or the style context tree), so it should not be
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* modified.
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*
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* This function will NOT return null (even when out of memory) when
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* given a valid style struct ID, so the result does not need to be
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* null-checked.
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*
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* The typesafe functions below are preferred to the use of this
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* function, both because they're easier to read and because they're
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* faster.
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*/
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const void* NS_FASTCALL GetStyleData(nsStyleStructID aSID);
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/**
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* Define typesafe getter functions for each style struct by
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* preprocessing the list of style structs. These functions are the
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* preferred way to get style data. The macro creates functions like:
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* const nsStyleBorder* GetStyleBorder();
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* const nsStyleColor* GetStyleColor();
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*/
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#define STYLE_STRUCT(name_, checkdata_cb_, ctor_args_) \
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const nsStyle##name_ * GetStyle##name_() { \
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return DoGetStyle##name_(true); \
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}
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT
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/**
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* PeekStyle* is like GetStyle* but doesn't trigger style
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* computation if the data is not cached on either the style context
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* or the rule node.
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*
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* Perhaps this shouldn't be a public nsStyleContext API.
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*/
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#define STYLE_STRUCT(name_, checkdata_cb_, ctor_args_) \
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const nsStyle##name_ * PeekStyle##name_() { \
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return DoGetStyle##name_(false); \
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}
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT
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void* GetUniqueStyleData(const nsStyleStructID& aSID);
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/**
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* Compute the style changes needed during restyling when this style
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* context is being replaced by aOther. (This is nonsymmetric since
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* we optimize by skipping comparison for styles that have never been
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* requested.)
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*
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* This method returns a change hint (see nsChangeHint.h). All change
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* hints apply to the frame and its later continuations or special
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* siblings. Most (all of those except the "NotHandledForDescendants"
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* hints) also apply to all descendants. The caller must pass in any
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* non-inherited hints that resulted from the parent style context's
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* style change. The caller *may* pass more hints than needed, but
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* must not pass less than needed; therefore if the caller doesn't
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* know, the caller should pass
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* nsChangeHint_Hints_NotHandledForDescendants.
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*/
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nsChangeHint CalcStyleDifference(nsStyleContext* aOther,
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nsChangeHint aParentHintsNotHandledForDescendants);
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/**
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* Get a color that depends on link-visitedness using this and
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* this->GetStyleIfVisited().
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*
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* aProperty must be a color-valued property that nsStyleAnimation
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* knows how to extract. It must also be a property that we know to
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* do change handling for in nsStyleContext::CalcDifference.
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*
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* Note that if aProperty is eCSSProperty_border_*_color, this
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* function handles -moz-use-text-color.
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*/
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nscolor GetVisitedDependentColor(nsCSSProperty aProperty);
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/**
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* aColors should be a two element array of nscolor in which the first
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* color is the unvisited color and the second is the visited color.
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*
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* Combine the R, G, and B components of whichever of aColors should
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* be used based on aLinkIsVisited with the A component of aColors[0].
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*/
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static nscolor CombineVisitedColors(nscolor *aColors,
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bool aLinkIsVisited);
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/**
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* Allocate a chunk of memory that is scoped to the lifetime of this
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* style context, i.e., memory that will automatically be freed when
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* this style context is destroyed. This is intended for allocations
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* that are stored on this style context or its style structs. (Use
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* on style structs is fine since any style context to which this
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* context's style structs are shared will be a descendant of this
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* style context and thus keep it alive.)
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*
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* This currently allocates the memory out of the pres shell arena.
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*
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* It would be relatively straightforward to write a Free method
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* for the underlying implementation, but we don't need it (or the
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* overhead of making a doubly-linked list or other structure to
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* support it).
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*
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* WARNING: Memory allocated using this method cannot be stored in the
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* rule tree, since rule nodes may outlive the style context.
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*/
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void* Alloc(size_t aSize);
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/**
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* Start the background image loads for this style context.
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*/
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void StartBackgroundImageLoads() {
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// Just get our background struct; that should do the trick
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GetStyleBackground();
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}
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#ifdef DEBUG
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void List(FILE* out, int32_t aIndent);
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#endif
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protected:
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void AddChild(nsStyleContext* aChild);
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void RemoveChild(nsStyleContext* aChild);
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void ApplyStyleFixups();
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void FreeAllocations(nsPresContext* aPresContext);
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// Helper function that GetStyleData and GetUniqueStyleData use. Only
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// returns the structs we cache ourselves; never consults the ruletree.
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inline const void* GetCachedStyleData(nsStyleStructID aSID);
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// Helper functions for GetStyle* and PeekStyle*
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#define STYLE_STRUCT_INHERITED(name_, checkdata_cb_, ctor_args_) \
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const nsStyle##name_ * DoGetStyle##name_(bool aComputeData) { \
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const nsStyle##name_ * cachedData = \
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static_cast<nsStyle##name_*>( \
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mCachedInheritedData.mStyleStructs[eStyleStruct_##name_]); \
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if (cachedData) /* Have it cached already, yay */ \
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return cachedData; \
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/* Have the rulenode deal */ \
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return mRuleNode->GetStyle##name_(this, aComputeData); \
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}
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#define STYLE_STRUCT_RESET(name_, checkdata_cb_, ctor_args_) \
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const nsStyle##name_ * DoGetStyle##name_(bool aComputeData) { \
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const nsStyle##name_ * cachedData = mCachedResetData \
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? static_cast<nsStyle##name_*>( \
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mCachedResetData->mStyleStructs[eStyleStruct_##name_]) \
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: nullptr; \
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if (cachedData) /* Have it cached already, yay */ \
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return cachedData; \
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/* Have the rulenode deal */ \
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return mRuleNode->GetStyle##name_(this, aComputeData); \
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}
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#include "nsStyleStructList.h"
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#undef STYLE_STRUCT_RESET
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#undef STYLE_STRUCT_INHERITED
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nsStyleContext* const mParent; // STRONG
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// Children are kept in two circularly-linked lists. The list anchor
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// is not part of the list (null for empty), and we point to the first
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// child.
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// mEmptyChild for children whose rule node is the root rule node, and
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// mChild for other children. The order of children is not
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// meaningful.
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nsStyleContext* mChild;
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nsStyleContext* mEmptyChild;
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nsStyleContext* mPrevSibling;
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nsStyleContext* mNextSibling;
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// Style to be used instead for the R, G, and B components of color,
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// background-color, and border-*-color if the nearest ancestor link
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// element is visited (see RelevantLinkVisited()).
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nsRefPtr<nsStyleContext> mStyleIfVisited;
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// If this style context is for a pseudo-element or anonymous box,
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// the relevant atom.
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nsCOMPtr<nsIAtom> mPseudoTag;
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// The rule node is the node in the lexicographic tree of rule nodes
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// (the "rule tree") that indicates which style rules are used to
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// compute the style data, and in what cascading order. The least
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// specific rule matched is the one whose rule node is a child of the
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// root of the rule tree, and the most specific rule matched is the
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// |mRule| member of |mRuleNode|.
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nsRuleNode* const mRuleNode;
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// Private to nsStyleContext::Alloc and FreeAllocations.
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struct AllocationHeader {
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AllocationHeader* mNext;
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size_t mSize;
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void* mStorageStart; // ensure the storage is at least pointer-aligned
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};
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AllocationHeader* mAllocations;
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// mCachedInheritedData and mCachedResetData point to both structs that
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// are owned by this style context and structs that are owned by one of
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// this style context's ancestors (which are indirectly owned since this
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// style context owns a reference to its parent). If the bit in |mBits|
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// is set for a struct, that means that the pointer for that struct is
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// owned by an ancestor or by mRuleNode rather than by this style context.
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// Since style contexts typically have some inherited data but only sometimes
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// have reset data, we always allocate the mCachedInheritedData, but only
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// sometimes allocate the mCachedResetData.
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nsResetStyleData* mCachedResetData; // Cached reset style data.
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nsInheritedStyleData mCachedInheritedData; // Cached inherited style data
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uint32_t mBits; // Which structs are inherited from the
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// parent context or owned by mRuleNode.
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uint32_t mRefCnt;
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};
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already_AddRefed<nsStyleContext>
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NS_NewStyleContext(nsStyleContext* aParentContext,
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nsIAtom* aPseudoTag,
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nsCSSPseudoElements::Type aPseudoType,
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nsRuleNode* aRuleNode);
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#endif
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