The Tor Browser / file comparison
comparison: layout/xul/tree/nsTreeStyleCache.h
layout/xul/tree/nsTreeStyleCache.h
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| 1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 #ifndef nsTreeStyleCache_h__ | |
| 7 #define nsTreeStyleCache_h__ | |
| 8 | |
| 9 #include "mozilla/Attributes.h" | |
| 10 #include "nsHashtable.h" | |
| 11 #include "nsIAtom.h" | |
| 12 #include "nsCOMArray.h" | |
| 13 #include "nsICSSPseudoComparator.h" | |
| 14 #include "nsStyleContext.h" | |
| 15 | |
| 16 typedef nsCOMArray<nsIAtom> AtomArray; | |
| 17 | |
| 18 class nsDFAState : public nsHashKey | |
| 19 { | |
| 20 public: | |
| 21 uint32_t mStateID; | |
| 22 | |
| 23 nsDFAState(uint32_t aID) :mStateID(aID) {} | |
| 24 | |
| 25 uint32_t GetStateID() { return mStateID; } | |
| 26 | |
| 27 uint32_t HashCode(void) const MOZ_OVERRIDE { | |
| 28 return mStateID; | |
| 29 } | |
| 30 | |
| 31 bool Equals(const nsHashKey *aKey) const MOZ_OVERRIDE { | |
| 32 nsDFAState* key = (nsDFAState*)aKey; | |
| 33 return key->mStateID == mStateID; | |
| 34 } | |
| 35 | |
| 36 nsHashKey *Clone(void) const MOZ_OVERRIDE { | |
| 37 return new nsDFAState(mStateID); | |
| 38 } | |
| 39 }; | |
| 40 | |
| 41 class nsTransitionKey : public nsHashKey | |
| 42 { | |
| 43 public: | |
| 44 uint32_t mState; | |
| 45 nsCOMPtr<nsIAtom> mInputSymbol; | |
| 46 | |
| 47 nsTransitionKey(uint32_t aState, nsIAtom* aSymbol) :mState(aState), mInputSymbol(aSymbol) {} | |
| 48 | |
| 49 uint32_t HashCode(void) const MOZ_OVERRIDE { | |
| 50 // Make a 32-bit integer that combines the low-order 16 bits of the state and the input symbol. | |
| 51 int32_t hb = mState << 16; | |
| 52 int32_t lb = (NS_PTR_TO_INT32(mInputSymbol.get()) << 16) >> 16; | |
| 53 return hb+lb; | |
| 54 } | |
| 55 | |
| 56 bool Equals(const nsHashKey *aKey) const MOZ_OVERRIDE { | |
| 57 nsTransitionKey* key = (nsTransitionKey*)aKey; | |
| 58 return key->mState == mState && key->mInputSymbol == mInputSymbol; | |
| 59 } | |
| 60 | |
| 61 nsHashKey *Clone(void) const MOZ_OVERRIDE { | |
| 62 return new nsTransitionKey(mState, mInputSymbol); | |
| 63 } | |
| 64 }; | |
| 65 | |
| 66 class nsTreeStyleCache | |
| 67 { | |
| 68 public: | |
| 69 nsTreeStyleCache() :mTransitionTable(nullptr), mCache(nullptr), mNextState(0) {} | |
| 70 ~nsTreeStyleCache() { Clear(); } | |
| 71 | |
| 72 void Clear() { delete mTransitionTable; mTransitionTable = nullptr; delete mCache; mCache = nullptr; mNextState = 0; } | |
| 73 | |
| 74 nsStyleContext* GetStyleContext(nsICSSPseudoComparator* aComparator, | |
| 75 nsPresContext* aPresContext, | |
| 76 nsIContent* aContent, | |
| 77 nsStyleContext* aContext, | |
| 78 nsIAtom* aPseudoElement, | |
| 79 const AtomArray & aInputWord); | |
| 80 | |
| 81 static bool DeleteDFAState(nsHashKey *aKey, void *aData, void *closure); | |
| 82 | |
| 83 static bool ReleaseStyleContext(nsHashKey *aKey, void *aData, void *closure); | |
| 84 | |
| 85 protected: | |
| 86 // A transition table for a deterministic finite automaton. The DFA | |
| 87 // takes as its input a single pseudoelement and an ordered set of properties. | |
| 88 // It transitions on an input word that is the concatenation of the pseudoelement supplied | |
| 89 // with the properties in the array. | |
| 90 // | |
| 91 // It transitions from state to state by looking up entries in the transition table (which is | |
| 92 // a mapping from (S,i)->S', where S is the current state, i is the next | |
| 93 // property in the input word, and S' is the state to transition to. | |
| 94 // | |
| 95 // If S' is not found, it is constructed and entered into the hashtable | |
| 96 // under the key (S,i). | |
| 97 // | |
| 98 // Once the entire word has been consumed, the final state is used | |
| 99 // to reference the cache table to locate the style context. | |
| 100 nsObjectHashtable* mTransitionTable; | |
| 101 | |
| 102 // The cache of all active style contexts. This is a hash from | |
| 103 // a final state in the DFA, Sf, to the resultant style context. | |
| 104 nsObjectHashtable* mCache; | |
| 105 | |
| 106 // An integer counter that is used when we need to make new states in the | |
| 107 // DFA. | |
| 108 uint32_t mNextState; | |
| 109 }; | |
| 110 | |
| 111 #endif // nsTreeStyleCache_h__ |
