gecko-dev/layout/xul/tree/nsTreeStyleCache.h

90 строки
2.7 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
#ifndef nsTreeStyleCache_h__
#define nsTreeStyleCache_h__
#include "mozilla/Attributes.h"
#include "nsAutoPtr.h"
#include "nsIAtom.h"
#include "nsCOMArray.h"
#include "nsICSSPseudoComparator.h"
#include "nsRefPtrHashtable.h"
#include "nsStyleContext.h"
typedef nsCOMArray<nsIAtom> AtomArray;
class nsTreeStyleCache
{
public:
nsTreeStyleCache()
: mNextState(0)
{
}
~nsTreeStyleCache()
{
Clear();
}
void Clear()
{
mTransitionTable = nullptr;
mCache = nullptr;
mNextState = 0;
}
nsStyleContext* GetStyleContext(nsICSSPseudoComparator* aComparator,
nsPresContext* aPresContext,
nsIContent* aContent,
nsStyleContext* aContext,
nsICSSAnonBoxPseudo* aPseudoElement,
const AtomArray & aInputWord);
protected:
typedef uint32_t DFAState;
class Transition final
{
public:
Transition(DFAState aState, nsIAtom* aSymbol);
bool operator==(const Transition& aOther) const;
uint32_t Hash() const;
private:
DFAState mState;
nsCOMPtr<nsIAtom> mInputSymbol;
};
typedef nsDataHashtable<nsGenericHashKey<Transition>, DFAState> TransitionTable;
// A transition table for a deterministic finite automaton. The DFA
// takes as its input a single pseudoelement and an ordered set of properties.
// It transitions on an input word that is the concatenation of the pseudoelement supplied
// with the properties in the array.
//
// It transitions from state to state by looking up entries in the transition table (which is
// a mapping from (S,i)->S', where S is the current state, i is the next
// property in the input word, and S' is the state to transition to.
//
// If S' is not found, it is constructed and entered into the hashtable
// under the key (S,i).
//
// Once the entire word has been consumed, the final state is used
// to reference the cache table to locate the style context.
nsAutoPtr<TransitionTable> mTransitionTable;
// The cache of all active style contexts. This is a hash from
// a final state in the DFA, Sf, to the resultant style context.
typedef nsRefPtrHashtable<nsUint32HashKey, nsStyleContext> StyleContextCache;
nsAutoPtr<StyleContextCache> mCache;
// An integer counter that is used when we need to make new states in the
// DFA.
DFAState mNextState;
};
#endif // nsTreeStyleCache_h__