layout/base/nsCounterManager.h
author Phil Ringnalda <philringnalda@gmail.com>
Fri, 19 Aug 2016 00:23:42 -0700
changeset 310244 43689d56cbf6891d3fb4cb3a3fff687884049313
parent 310232 6c347701d343570f7c71b0f8875756e490a17d7a
child 310459 9c46096fb15c24e67a65786820459c9d7520dcf7
permissions -rw-r--r--
Backed out 5 changesets (bug 1292618) for !mImageTracked assertion failures CLOSED TREE Backed out changeset 1d767147e160 (bug 1292618) Backed out changeset e6034e58efe4 (bug 1292618) Backed out changeset 928dd363efa0 (bug 1292618) Backed out changeset 8e274c66ae7f (bug 1292618) Backed out changeset 6c347701d343 (bug 1292618)

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
// 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 "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'
        USE        // counter() or counters() in 'content'
    };

    Type mType;

    // Counter value after this node
    int32_t mValueAfter;

    // 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;

    // 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;

    inline nsCounterUseNode* UseNode();
    inline nsCounterChangeNode* ChangeNode();

    // For RESET and INCREMENT nodes, aPseudoFrame need not be a
    // pseudo-element, and aContentIndex represents the index within the
    // 'counter-reset' or 'counter-increment' property instead of within
    // the 'content' property but offset to ensure that (reset,
    // increment, 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)
        , mValueAfter(0)
        , mScopeStart(nullptr)
        , mScopePrev(nullptr)
    {
    }

    // to avoid virtual function calls in the common case
    inline void Calc(nsCounterList* aList);
};

struct nsCounterUseNode : public nsCounterNode {
    // The same structure passed through the style system:  an array
    // containing the values in the counter() or counters() in the order
    // given in the CSS spec.
    RefPtr<nsCSSValue::Array> mCounterFunction;

    nsPresContext* mPresContext;
    RefPtr<mozilla::CounterStyle> mCounterStyle;

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

    // args go directly to member variables here and of nsGenConNode
    nsCounterUseNode(nsPresContext* aPresContext,
                     nsCSSValue::Array* aCounterFunction,
                     uint32_t aContentIndex, bool aAllCounters)
        : nsCounterNode(aContentIndex, USE)
        , mCounterFunction(aCounterFunction)
        , mPresContext(aPresContext)
        , mCounterStyle(nullptr)
        , mAllCounters(aAllCounters)
    {
        NS_ASSERTION(aContentIndex <= INT32_MAX, "out of range");
    }

    virtual bool InitTextFrame(nsGenConList* aList,
            nsIFrame* aPseudoFrame, nsIFrame* aTextFrame) override;

    mozilla::CounterStyle* GetCounterStyle();
    void SetCounterStyleDirty()
    {
        mCounterStyle = nullptr;
    }

    // assign the correct |mValueAfter| value to a node that has been inserted
    // Should be called immediately after calling |Insert|.
    void Calc(nsCounterList* aList);

    // 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 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' or 'counter-reset' property.
    nsCounterChangeNode(nsIFrame* aPseudoFrame,
                        nsCounterNode::Type aChangeType,
                        int32_t aChangeValue,
                        int32_t aPropIndex)
        : nsCounterNode(// Fake a content index for resets and increments
                        // that comes before all the real content, with
                        // the resets first, in order, and then the increments.
                        aPropIndex + (aChangeType == RESET
                                        ? (INT32_MIN) 
                                        : (INT32_MIN / 2)),
                        aChangeType)
        , mChangeValue(aChangeValue)
    {
        NS_ASSERTION(aPropIndex >= 0, "out of range");
        NS_ASSERTION(aChangeType == INCREMENT || 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);
};

inline nsCounterUseNode* nsCounterNode::UseNode()
{
    NS_ASSERTION(mType == USE, "wrong type");
    return static_cast<nsCounterUseNode*>(this);
}

inline nsCounterChangeNode* nsCounterNode::ChangeNode()
{
    NS_ASSERTION(mType == INCREMENT || mType == RESET, "wrong type");
    return static_cast<nsCounterChangeNode*>(this);
}

inline void nsCounterNode::Calc(nsCounterList* aList)
{
    if (mType == USE)
        UseNode()->Calc(aList);
    else
        ChangeNode()->Calc(aList);
}

class nsCounterList : public nsGenConList {
public:
    nsCounterList() : nsGenConList(),
                      mDirty(false)
    {}

    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*>(mFirstNode);
    }

    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; }

private:
    bool mDirty;
};

/**
 * The counter manager maintains an |nsCounterList| for each named
 * counter to keep track of all scopes with that name.
 */
class nsCounterManager {
public:
    nsCounterManager();
    // Returns true if dirty
    bool AddCounterResetsAndIncrements(nsIFrame *aFrame);

    // Gets the appropriate counter list, creating it if necessary.
    // Guaranteed to return non-null. (Uses an infallible hashtable API.)
    nsCounterList* CounterListFor(const nsSubstring& aCounterName);

    // Clean up data in any dirty counter lists.
    void RecalcAll();

    // Set all counter styles dirty
    void SetAllCounterStylesDirty();

    // 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();
#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:
    // for |AddCounterResetsAndIncrements| only
    bool AddResetOrIncrement(nsIFrame *aFrame, int32_t aIndex,
                               const nsStyleCounterData *aCounterData,
                               nsCounterNode::Type aType);

    nsClassHashtable<nsStringHashKey, nsCounterList> mNames;
};

#endif /* nsCounterManager_h_ */