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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;
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;
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.
// (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 <ol reversed> RESET node?
inline bool IsContentBasedReset();
struct nsCounterUseNode : public nsCounterNode {
mozilla::CounterStylePtr mCounterStyle;
nsString mSeparator;
// false for counter(), true for counters()
bool mAllCounters = false;
bool mForLegacyBullet = false;
enum ForLegacyBullet { ForLegacyBullet };
explicit nsCounterUseNode(enum ForLegacyBullet)
: nsCounterNode(0, USE), mForLegacyBullet(true) {
mCounterStyle = nsGkAtoms::list_item;
// 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");
virtual bool InitTextFrame(nsGenConList* aList, nsIFrame* aPseudoFrame,
nsIFrame* aTextFrame) override;
bool InitBullet(nsGenConList* aList, nsIFrame* aBulletFrame);
// 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);
struct nsCounterChangeNode : public nsCounterNode {
int32_t mChangeValue; // the numeric value of the increment, set or reset
// |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)
: 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)),
mChangeValue(aChangeValue) {
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);
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();
class nsCounterList : public nsGenConList {
nsCounterList() : nsGenConList(), mDirty(false) {}
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) {
return aNode->mScopePrev ? aNode->mScopePrev->mValueAfter : 0;
// 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() { return mDirty; }
void SetDirty() { mDirty = true; }
bool mDirty;
* The counter manager maintains an |nsCounterList| for each named
* counter to keep track of all scopes with that name.
class nsCounterManager {
// 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* CounterListFor(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(); }
#ifdef DEBUG
void Dump();
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;
nsClassHashtable<nsRefPtrHashKey<nsAtom>, nsCounterList> mNames;
#endif /* nsCounterManager_h_ */