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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ai:sw=4:ts=4:et:
/* 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 */
/* implementation of CSS counters (for numbering things) */
#ifndef nsCounterManager_h_
#define nsCounterManager_h_
#include "mozilla/Attributes.h"
#include "nsGenConList.h"
#include "nsClassHashtable.h"
#include "mozilla/Likely.h"
#include "CounterStyleManager.h"
class nsCounterList;
struct nsCounterUseNode;
struct nsCounterChangeNode;
namespace mozilla {
class ContainStyleScope;
} // namespace mozilla
struct nsCounterNode : public nsGenConNode {
enum Type {
RESET, // a "counter number" pair in 'counter-reset'
INCREMENT, // a "counter number" pair in 'counter-increment'
SET, // a "counter number" pair in 'counter-set'
USE // counter() or counters() in 'content'
Type mType;
// Counter value after this node
int32_t mValueAfter = 0;
// mScopeStart points to the node (usually a RESET, but not in the
// case of an implied 'counter-reset') that created the scope for
// this element (for a RESET, its outer scope, i.e., the one it is
// inside rather than the one it creates).
// May be null for all types, but only when mScopePrev is also null.
// Being null for a non-RESET means that it is an implied
// 'counter-reset'. Being null for a RESET means it has no outer
// scope.
nsCounterNode* mScopeStart = nullptr;
// mScopePrev points to the previous node that is in the same scope,
// or for a RESET, the previous node in the scope outside of the
// reset.
// May be null for all types, but only when mScopeStart is also
// null. Following the mScopePrev links will eventually lead to
// mScopeStart. Being null for a non-RESET means that it is an
// implied 'counter-reset'. Being null for a RESET means it has no
// outer scope.
nsCounterNode* mScopePrev = nullptr;
// Whether or not this node's scope crosses `contain: style` boundaries.
// This can happen for USE nodes that come before any other types of
// nodes in a `contain: style` boundary's list.
bool mCrossesContainStyleBoundaries = false;
inline nsCounterUseNode* UseNode();
inline nsCounterChangeNode* ChangeNode();
// For RESET, INCREMENT and SET nodes, aPseudoFrame need not be a
// pseudo-element, and aContentIndex represents the index within the
// 'counter-reset', 'counter-increment' or 'counter-set' property
// instead of within the 'content' property but offset to ensure
// that (reset, increment, set, use) sort in that order.
// It is zero for legacy bullet USE counter nodes.
// (This slight weirdness allows sharing a lot of code with 'quotes'.)
nsCounterNode(int32_t aContentIndex, Type aType)
: nsGenConNode(aContentIndex), mType(aType) {}
// to avoid virtual function calls in the common case
inline void Calc(nsCounterList* aList, bool aNotify);
// Is this a RESET node for a content-based (i.e. without a start value)
// reversed() counter?
inline bool IsContentBasedReset();
// Is this a RESET node for a reversed() counter?
inline bool IsReversed();
// Is this an INCREMENT node that needs to be initialized to -1 or 1
// depending on if our scope is reversed() or not?
inline bool IsUnitializedIncrementNode();
struct nsCounterUseNode : public nsCounterNode {
mozilla::CounterStylePtr mCounterStyle;
nsString mSeparator;
// false for counter(), true for counters()
bool mAllCounters = false;
bool mForLegacyBullet = false;
enum ForLegacyBullet { ForLegacyBullet };
nsCounterUseNode(enum ForLegacyBullet, mozilla::CounterStylePtr aCounterStyle)
: nsCounterNode(0, USE),
mForLegacyBullet(true) {}
// args go directly to member variables here and of nsGenConNode
nsCounterUseNode(mozilla::CounterStylePtr aCounterStyle, nsString aSeparator,
uint32_t aContentIndex, bool aAllCounters)
: nsCounterNode(aContentIndex, USE),
mAllCounters(aAllCounters) {
NS_ASSERTION(aContentIndex <= INT32_MAX, "out of range");
bool InitTextFrame(nsGenConList* aList, nsIFrame* aPseudoFrame,
nsIFrame* aTextFrame) override;
// assign the correct |mValueAfter| value to a node that has been inserted,
// and update the value of the text node, notifying if `aNotify` is true.
// Should be called immediately after calling |Insert|.
void Calc(nsCounterList* aList, bool aNotify);
// The text that should be displayed for this counter.
void GetText(nsString& aResult);
void GetText(mozilla::WritingMode aWM, mozilla::CounterStyle* aStyle,
nsString& aResult);
struct nsCounterChangeNode : public nsCounterNode {
// |aPseudoFrame| is not necessarily a pseudo-element's frame, but
// since it is for every other subclass of nsGenConNode, we follow
// the naming convention here.
// |aPropIndex| is the index of the value within the list in the
// 'counter-increment', 'counter-reset' or 'counter-set' property.
nsCounterChangeNode(nsIFrame* aPseudoFrame, nsCounterNode::Type aChangeType,
int32_t aChangeValue, int32_t aPropIndex,
bool aIsReversed)
: nsCounterNode( // Fake a content index for resets, increments and sets
// that comes before all the real content, with
// the resets first, in order, and then the increments
// and then the sets.
aPropIndex + (aChangeType == RESET ? (INT32_MIN)
: (aChangeType == INCREMENT
? ((INT32_MIN / 3) * 2)
: INT32_MIN / 3)),
mSeenSetNode(false) {
NS_ASSERTION(aPropIndex >= 0, "out of range");
aChangeType == INCREMENT || aChangeType == SET || aChangeType == RESET,
"bad type");
mPseudoFrame = aPseudoFrame;
// assign the correct |mValueAfter| value to a node that has been inserted
// Should be called immediately after calling |Insert|.
void Calc(nsCounterList* aList);
// The numeric value of the INCREMENT, SET or RESET.
// Note: numeric_limits<int32_t>::min() is used for content-based reversed()
// RESET nodes, and temporarily on INCREMENT nodes to signal that it should be
// initialized to -1 or 1 depending on if the scope is reversed() or not.
int32_t mChangeValue;
// True if the counter is reversed(). Only used on RESET nodes.
bool mIsReversed : 1;
// True if we've seen a SET node during the initialization of
// an IsContentBasedReset() node; always false on other nodes.
bool mSeenSetNode : 1;
inline nsCounterUseNode* nsCounterNode::UseNode() {
NS_ASSERTION(mType == USE, "wrong type");
return static_cast<nsCounterUseNode*>(this);
inline nsCounterChangeNode* nsCounterNode::ChangeNode() {
MOZ_ASSERT(mType == INCREMENT || mType == SET || mType == RESET);
return static_cast<nsCounterChangeNode*>(this);
inline void nsCounterNode::Calc(nsCounterList* aList, bool aNotify) {
if (mType == USE)
UseNode()->Calc(aList, aNotify);
inline bool nsCounterNode::IsContentBasedReset() {
return mType == RESET &&
ChangeNode()->mChangeValue == std::numeric_limits<int32_t>::min();
inline bool nsCounterNode::IsReversed() {
return mType == RESET && ChangeNode()->mIsReversed;
inline bool nsCounterNode::IsUnitializedIncrementNode() {
return mType == INCREMENT &&
ChangeNode()->mChangeValue == std::numeric_limits<int32_t>::min();
class nsCounterList : public nsGenConList {
nsCounterList(nsAtom* aCounterName, mozilla::ContainStyleScope* aScope)
: mCounterName(aCounterName), mScope(aScope) {
// Return the first node for aFrame on this list, or nullptr.
nsCounterNode* GetFirstNodeFor(nsIFrame* aFrame) const {
return static_cast<nsCounterNode*>(nsGenConList::GetFirstNodeFor(aFrame));
void Insert(nsCounterNode* aNode) {
// Don't SetScope if we're dirty -- we'll reset all the scopes anyway,
// and we can't usefully compute scopes right now.
if (MOZ_LIKELY(!IsDirty())) {
nsCounterNode* First() {
return static_cast<nsCounterNode*>(mList.getFirst());
static nsCounterNode* Next(nsCounterNode* aNode) {
return static_cast<nsCounterNode*>(nsGenConList::Next(aNode));
static nsCounterNode* Prev(nsCounterNode* aNode) {
return static_cast<nsCounterNode*>(nsGenConList::Prev(aNode));
static int32_t ValueBefore(nsCounterNode* aNode) {
if (!aNode->mScopePrev) {
return 0;
if (aNode->mType != nsCounterNode::USE &&
aNode->mScopePrev->mCrossesContainStyleBoundaries) {
return 0;
return aNode->mScopePrev->mValueAfter;
// Correctly set |aNode->mScopeStart| and |aNode->mScopePrev|
void SetScope(nsCounterNode* aNode);
// Recalculate |mScopeStart|, |mScopePrev|, and |mValueAfter| for
// all nodes and update text in text content nodes.
void RecalcAll();
bool IsDirty() const;
void SetDirty();
bool IsRecalculatingAll() const { return mRecalculatingAll; }
bool SetScopeByWalkingBackwardThroughList(
nsCounterNode* aNodeToSetScopeFor, const nsIContent* aNodeContent,
nsCounterNode* aNodeToBeginLookingAt);
RefPtr<nsAtom> mCounterName;
mozilla::ContainStyleScope* mScope;
bool mRecalculatingAll = false;
* The counter manager maintains an |nsCounterList| for each named
* counter to keep track of all scopes with that name.
class nsCounterManager {
explicit nsCounterManager(mozilla::ContainStyleScope* scope)
: mScope(scope) {}
// Returns true if dirty
bool AddCounterChanges(nsIFrame* aFrame);
// Gets the appropriate counter list, creating it if necessary.
// Guaranteed to return non-null. (Uses an infallible hashtable API.)
nsCounterList* GetOrCreateCounterList(nsAtom* aCounterName);
// Gets the appropriate counter list, returning null if it doesn't exist.
nsCounterList* GetCounterList(nsAtom* aCounterName);
// Clean up data in any dirty counter lists.
void RecalcAll();
// Set all counter lists dirty
void SetAllDirty();
// Destroy nodes for the frame in any lists, and return whether any
// nodes were destroyed.
bool DestroyNodesFor(nsIFrame* aFrame);
// Clear all data.
void Clear() { mNames.Clear(); }
// Set |aOrdinal| to the first used counter value for the given frame and
// return true. If no USE node for the given frame can be found, return false
// and do not change the value of |aOrdinal|.
bool GetFirstCounterValueForFrame(nsIFrame* aFrame,
mozilla::CounterValue& aOrdinal) const;
#if defined(DEBUG) || defined(MOZ_LAYOUT_DEBUGGER)
void Dump() const;
static int32_t IncrementCounter(int32_t aOldValue, int32_t aIncrement) {
// Addition of unsigned values is defined to be arithmetic
// modulo 2^bits (C++ 2011, 3.9.1 [basic.fundamental], clause 4);
// addition of signed values is undefined (and clang does
// something very strange if we use it here). Likewise integral
// conversion from signed to unsigned is also defined as modulo
// 2^bits (C++ 2011, 4.7 [conv.integral], clause 2); conversion
// from unsigned to signed is however undefined (ibid., clause 3),
// but to do what we want we must nonetheless depend on that
// small piece of undefined behavior.
int32_t newValue = int32_t(uint32_t(aOldValue) + uint32_t(aIncrement));
// The CSS Working Group resolved that a counter-increment that
// exceeds internal limits should not increment at all.
// (This means, for example, that if aIncrement is 5, the
// counter will get stuck at the largest multiple of 5 less than
// the maximum 32-bit integer.)
if ((aIncrement > 0) != (newValue > aOldValue)) {
newValue = aOldValue;
return newValue;
mozilla::ContainStyleScope* mScope;
nsClassHashtable<nsAtomHashKey, nsCounterList> mNames;
#endif /* nsCounterManager_h_ */