michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef nsTreeStyleCache_h__
michael@0: #define nsTreeStyleCache_h__
michael@0: 
michael@0: #include "mozilla/Attributes.h"
michael@0: #include "nsHashtable.h"
michael@0: #include "nsIAtom.h"
michael@0: #include "nsCOMArray.h"
michael@0: #include "nsICSSPseudoComparator.h"
michael@0: #include "nsStyleContext.h"
michael@0: 
michael@0: typedef nsCOMArray<nsIAtom> AtomArray;
michael@0: 
michael@0: class nsDFAState : public nsHashKey
michael@0: {
michael@0: public:
michael@0:   uint32_t mStateID;
michael@0: 
michael@0:   nsDFAState(uint32_t aID) :mStateID(aID) {}
michael@0: 
michael@0:   uint32_t GetStateID() { return mStateID; }
michael@0: 
michael@0:   uint32_t HashCode(void) const MOZ_OVERRIDE {
michael@0:     return mStateID;
michael@0:   }
michael@0: 
michael@0:   bool Equals(const nsHashKey *aKey) const MOZ_OVERRIDE {
michael@0:     nsDFAState* key = (nsDFAState*)aKey;
michael@0:     return key->mStateID == mStateID;
michael@0:   }
michael@0: 
michael@0:   nsHashKey *Clone(void) const MOZ_OVERRIDE {
michael@0:     return new nsDFAState(mStateID);
michael@0:   }
michael@0: };
michael@0: 
michael@0: class nsTransitionKey : public nsHashKey
michael@0: {
michael@0: public:
michael@0:   uint32_t mState;
michael@0:   nsCOMPtr<nsIAtom> mInputSymbol;
michael@0: 
michael@0:   nsTransitionKey(uint32_t aState, nsIAtom* aSymbol) :mState(aState), mInputSymbol(aSymbol) {}
michael@0: 
michael@0:   uint32_t HashCode(void) const MOZ_OVERRIDE {
michael@0:     // Make a 32-bit integer that combines the low-order 16 bits of the state and the input symbol.
michael@0:     int32_t hb = mState << 16;
michael@0:     int32_t lb = (NS_PTR_TO_INT32(mInputSymbol.get()) << 16) >> 16;
michael@0:     return hb+lb;
michael@0:   }
michael@0: 
michael@0:   bool Equals(const nsHashKey *aKey) const MOZ_OVERRIDE {
michael@0:     nsTransitionKey* key = (nsTransitionKey*)aKey;
michael@0:     return key->mState == mState && key->mInputSymbol == mInputSymbol;
michael@0:   }
michael@0: 
michael@0:   nsHashKey *Clone(void) const MOZ_OVERRIDE {
michael@0:     return new nsTransitionKey(mState, mInputSymbol);
michael@0:   }
michael@0: };
michael@0: 
michael@0: class nsTreeStyleCache 
michael@0: {
michael@0: public:
michael@0:   nsTreeStyleCache() :mTransitionTable(nullptr), mCache(nullptr), mNextState(0) {}
michael@0:   ~nsTreeStyleCache() { Clear(); }
michael@0: 
michael@0:   void Clear() { delete mTransitionTable; mTransitionTable = nullptr; delete mCache; mCache = nullptr; mNextState = 0; }
michael@0: 
michael@0:   nsStyleContext* GetStyleContext(nsICSSPseudoComparator* aComparator,
michael@0:                                   nsPresContext* aPresContext, 
michael@0:                                   nsIContent* aContent, 
michael@0:                                   nsStyleContext* aContext,
michael@0:                                   nsIAtom* aPseudoElement,
michael@0:                                   const AtomArray & aInputWord);
michael@0: 
michael@0:   static bool DeleteDFAState(nsHashKey *aKey, void *aData, void *closure);
michael@0: 
michael@0:   static bool ReleaseStyleContext(nsHashKey *aKey, void *aData, void *closure);
michael@0: 
michael@0: protected:
michael@0:   // A transition table for a deterministic finite automaton.  The DFA
michael@0:   // takes as its input a single pseudoelement and an ordered set of properties.  
michael@0:   // It transitions on an input word that is the concatenation of the pseudoelement supplied
michael@0:   // with the properties in the array.
michael@0:   // 
michael@0:   // It transitions from state to state by looking up entries in the transition table (which is
michael@0:   // a mapping from (S,i)->S', where S is the current state, i is the next
michael@0:   // property in the input word, and S' is the state to transition to.
michael@0:   //
michael@0:   // If S' is not found, it is constructed and entered into the hashtable
michael@0:   // under the key (S,i).
michael@0:   //
michael@0:   // Once the entire word has been consumed, the final state is used
michael@0:   // to reference the cache table to locate the style context.
michael@0:   nsObjectHashtable* mTransitionTable;
michael@0: 
michael@0:   // The cache of all active style contexts.  This is a hash from 
michael@0:   // a final state in the DFA, Sf, to the resultant style context.
michael@0:   nsObjectHashtable* mCache;
michael@0: 
michael@0:   // An integer counter that is used when we need to make new states in the
michael@0:   // DFA.
michael@0:   uint32_t mNextState;
michael@0: };
michael@0: 
michael@0: #endif // nsTreeStyleCache_h__