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89 lines
2.7 KiB
C++
89 lines
2.7 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsTreeStyleCache_h__
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#define nsTreeStyleCache_h__
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#include "mozilla/Attributes.h"
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#include "nsIAtom.h"
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#include "nsCOMArray.h"
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#include "nsICSSPseudoComparator.h"
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#include "nsRefPtrHashtable.h"
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#include "nsStyleContext.h"
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typedef nsCOMArray<nsIAtom> AtomArray;
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class nsTreeStyleCache
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{
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public:
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nsTreeStyleCache()
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: mNextState(0)
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{
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}
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~nsTreeStyleCache()
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{
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Clear();
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}
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void Clear()
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{
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mTransitionTable = nullptr;
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mCache = nullptr;
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mNextState = 0;
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}
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nsStyleContext* GetStyleContext(nsICSSPseudoComparator* aComparator,
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nsPresContext* aPresContext,
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nsIContent* aContent,
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nsStyleContext* aContext,
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nsIAtom* aPseudoElement,
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const AtomArray & aInputWord);
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protected:
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typedef uint32_t DFAState;
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class Transition MOZ_FINAL
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{
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public:
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Transition(DFAState aState, nsIAtom* aSymbol);
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bool operator==(const Transition& aOther) const;
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uint32_t Hash() const;
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private:
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DFAState mState;
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nsCOMPtr<nsIAtom> mInputSymbol;
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};
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typedef nsDataHashtable<nsGenericHashKey<Transition>, DFAState> TransitionTable;
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// A transition table for a deterministic finite automaton. The DFA
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// takes as its input a single pseudoelement and an ordered set of properties.
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// It transitions on an input word that is the concatenation of the pseudoelement supplied
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// with the properties in the array.
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//
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// It transitions from state to state by looking up entries in the transition table (which is
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// a mapping from (S,i)->S', where S is the current state, i is the next
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// property in the input word, and S' is the state to transition to.
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//
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// If S' is not found, it is constructed and entered into the hashtable
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// under the key (S,i).
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//
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// Once the entire word has been consumed, the final state is used
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// to reference the cache table to locate the style context.
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nsAutoPtr<TransitionTable> mTransitionTable;
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// The cache of all active style contexts. This is a hash from
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// a final state in the DFA, Sf, to the resultant style context.
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typedef nsRefPtrHashtable<nsUint32HashKey, nsStyleContext> StyleContextCache;
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nsAutoPtr<StyleContextCache> mCache;
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// An integer counter that is used when we need to make new states in the
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// DFA.
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DFAState mNextState;
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};
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#endif // nsTreeStyleCache_h__
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