tor-browser

nsCounterManager.h (12922B)

---

/* -*- 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 http://mozilla.org/MPL/2.0/. */

/* implementation of CSS counters (for numbering things) */

#ifndef nsCounterManager_h_
#define nsCounterManager_h_

#include "CounterStyleManager.h"
#include "mozilla/Likely.h"
#include "nsClassHashtable.h"
#include "nsGenConList.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::StyleCounterStyle mCounterStyle;
 nsString mSeparator;

 // false for counter(), true for counters()
 bool mAllCounters = false;

 bool mForLegacyBullet = false;

 enum ForLegacyBullet { ForLegacyBullet };
 nsCounterUseNode(enum ForLegacyBullet,
                  const mozilla::StyleCounterStyle& aCounterStyle)
     : nsCounterNode(0, USE),
       mCounterStyle(aCounterStyle),
       mForLegacyBullet(true) {}

 // args go directly to member variables here and of nsGenConNode
 nsCounterUseNode(const mozilla::StyleCounterStyle& aCounterStyle,
                  nsString aSeparator, uint32_t aContentIndex,
                  bool aAllCounters)
     : nsCounterNode(aContentIndex, USE),
       mCounterStyle(aCounterStyle),
       mSeparator(std::move(aSeparator)),
       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)),
           aChangeType),
       mChangeValue(aChangeValue),
       mIsReversed(aIsReversed),
       mSeenSetNode(false) {
   NS_ASSERTION(aPropIndex >= 0, "out of range");
   NS_ASSERTION(
       aChangeType == INCREMENT || aChangeType == SET || aChangeType == RESET,
       "bad type");
   mPseudoFrame = aPseudoFrame;
   CheckFrameAssertions();
 }

 // 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);
 } else {
   ChangeNode()->Calc(aList);
 }
}

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 {
public:
 nsCounterList(nsAtom* aCounterName, mozilla::ContainStyleScope* aScope)
     : mCounterName(aCounterName), mScope(aScope) {
   MOZ_ASSERT(aScope);
 }

#if defined(DEBUG) || defined(MOZ_LAYOUT_DEBUGGER)
 void Dump();
#endif

 // 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) {
   nsGenConList::Insert(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())) {
     SetScope(aNode);
   }
 }

 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; }

private:
 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 {
public:
 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(); }

#ifdef ACCESSIBILITY
 // 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;
#endif

#if defined(DEBUG) || defined(MOZ_LAYOUT_DEBUGGER)
 void Dump() const;
#endif

 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.
   // http://lists.w3.org/Archives/Public/www-style/2013Feb/0392.html
   // (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;
 }

private:
 mozilla::ContainStyleScope* mScope;
 nsClassHashtable<nsAtomHashKey, nsCounterList> mNames;
};

#endif /* nsCounterManager_h_ */