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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/AtomArray.h"
#include "mozilla/Attributes.h"
#include "mozilla/UniquePtr.h"
#include "nsCOMArray.h"
#include "nsTHashMap.h"
#include "nsRefPtrHashtable.h"
#include "mozilla/ComputedStyle.h"
class nsIContent;
class nsTreeStyleCache {
public:
nsTreeStyleCache() : mNextState(0) {}
~nsTreeStyleCache() { Clear(); }
void Clear() {
mTransitionTable = nullptr;
mCache = nullptr;
mNextState = 0;
}
mozilla::ComputedStyle* GetComputedStyle(
nsPresContext* aPresContext, nsIContent* aContent,
mozilla::ComputedStyle* aStyle,
nsCSSAnonBoxPseudoStaticAtom* aPseudoElement,
const mozilla::AtomArray& aInputWord);
protected:
typedef uint32_t DFAState;
class Transition final {
public:
Transition(DFAState aState, nsAtom* aSymbol);
bool operator==(const Transition& aOther) const;
uint32_t Hash() const;
private:
DFAState mState;
RefPtr<nsAtom> mInputSymbol;
};
typedef nsTHashMap<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 ComputedStyle.
mozilla::UniquePtr<TransitionTable> mTransitionTable;
// The cache of all active ComputedStyles. This is a hash from
// a final state in the DFA, Sf, to the resultant ComputedStyle.
typedef nsRefPtrHashtable<nsUint32HashKey, mozilla::ComputedStyle>
ComputedStyleCache;
mozilla::UniquePtr<ComputedStyleCache> mCache;
// An integer counter that is used when we need to make new states in the
// DFA.
DFAState mNextState;
};
#endif // nsTreeStyleCache_h__
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