1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/xul/tree/nsTreeStyleCache.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,111 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef nsTreeStyleCache_h__
1.10 +#define nsTreeStyleCache_h__
1.11 +
1.12 +#include "mozilla/Attributes.h"
1.13 +#include "nsHashtable.h"
1.14 +#include "nsIAtom.h"
1.15 +#include "nsCOMArray.h"
1.16 +#include "nsICSSPseudoComparator.h"
1.17 +#include "nsStyleContext.h"
1.18 +
1.19 +typedef nsCOMArray<nsIAtom> AtomArray;
1.20 +
1.21 +class nsDFAState : public nsHashKey
1.22 +{
1.23 +public:
1.24 + uint32_t mStateID;
1.25 +
1.26 + nsDFAState(uint32_t aID) :mStateID(aID) {}
1.27 +
1.28 + uint32_t GetStateID() { return mStateID; }
1.29 +
1.30 + uint32_t HashCode(void) const MOZ_OVERRIDE {
1.31 + return mStateID;
1.32 + }
1.33 +
1.34 + bool Equals(const nsHashKey *aKey) const MOZ_OVERRIDE {
1.35 + nsDFAState* key = (nsDFAState*)aKey;
1.36 + return key->mStateID == mStateID;
1.37 + }
1.38 +
1.39 + nsHashKey *Clone(void) const MOZ_OVERRIDE {
1.40 + return new nsDFAState(mStateID);
1.41 + }
1.42 +};
1.43 +
1.44 +class nsTransitionKey : public nsHashKey
1.45 +{
1.46 +public:
1.47 + uint32_t mState;
1.48 + nsCOMPtr<nsIAtom> mInputSymbol;
1.49 +
1.50 + nsTransitionKey(uint32_t aState, nsIAtom* aSymbol) :mState(aState), mInputSymbol(aSymbol) {}
1.51 +
1.52 + uint32_t HashCode(void) const MOZ_OVERRIDE {
1.53 + // Make a 32-bit integer that combines the low-order 16 bits of the state and the input symbol.
1.54 + int32_t hb = mState << 16;
1.55 + int32_t lb = (NS_PTR_TO_INT32(mInputSymbol.get()) << 16) >> 16;
1.56 + return hb+lb;
1.57 + }
1.58 +
1.59 + bool Equals(const nsHashKey *aKey) const MOZ_OVERRIDE {
1.60 + nsTransitionKey* key = (nsTransitionKey*)aKey;
1.61 + return key->mState == mState && key->mInputSymbol == mInputSymbol;
1.62 + }
1.63 +
1.64 + nsHashKey *Clone(void) const MOZ_OVERRIDE {
1.65 + return new nsTransitionKey(mState, mInputSymbol);
1.66 + }
1.67 +};
1.68 +
1.69 +class nsTreeStyleCache
1.70 +{
1.71 +public:
1.72 + nsTreeStyleCache() :mTransitionTable(nullptr), mCache(nullptr), mNextState(0) {}
1.73 + ~nsTreeStyleCache() { Clear(); }
1.74 +
1.75 + void Clear() { delete mTransitionTable; mTransitionTable = nullptr; delete mCache; mCache = nullptr; mNextState = 0; }
1.76 +
1.77 + nsStyleContext* GetStyleContext(nsICSSPseudoComparator* aComparator,
1.78 + nsPresContext* aPresContext,
1.79 + nsIContent* aContent,
1.80 + nsStyleContext* aContext,
1.81 + nsIAtom* aPseudoElement,
1.82 + const AtomArray & aInputWord);
1.83 +
1.84 + static bool DeleteDFAState(nsHashKey *aKey, void *aData, void *closure);
1.85 +
1.86 + static bool ReleaseStyleContext(nsHashKey *aKey, void *aData, void *closure);
1.87 +
1.88 +protected:
1.89 + // A transition table for a deterministic finite automaton. The DFA
1.90 + // takes as its input a single pseudoelement and an ordered set of properties.
1.91 + // It transitions on an input word that is the concatenation of the pseudoelement supplied
1.92 + // with the properties in the array.
1.93 + //
1.94 + // It transitions from state to state by looking up entries in the transition table (which is
1.95 + // a mapping from (S,i)->S', where S is the current state, i is the next
1.96 + // property in the input word, and S' is the state to transition to.
1.97 + //
1.98 + // If S' is not found, it is constructed and entered into the hashtable
1.99 + // under the key (S,i).
1.100 + //
1.101 + // Once the entire word has been consumed, the final state is used
1.102 + // to reference the cache table to locate the style context.
1.103 + nsObjectHashtable* mTransitionTable;
1.104 +
1.105 + // The cache of all active style contexts. This is a hash from
1.106 + // a final state in the DFA, Sf, to the resultant style context.
1.107 + nsObjectHashtable* mCache;
1.108 +
1.109 + // An integer counter that is used when we need to make new states in the
1.110 + // DFA.
1.111 + uint32_t mNextState;
1.112 +};
1.113 +
1.114 +#endif // nsTreeStyleCache_h__
