gecko/layout/xul/tree/nsTreeStyleCache.h

111 lines
3.5 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsHashtable.h"
#include "nsIAtom.h"
#include "nsCOMArray.h"
#include "nsICSSPseudoComparator.h"
#include "nsStyleContext.h"
typedef nsCOMArray<nsIAtom> AtomArray;
class nsDFAState : public nsHashKey
{
public:
uint32_t mStateID;
nsDFAState(uint32_t aID) :mStateID(aID) {}
uint32_t GetStateID() { return mStateID; }
uint32_t HashCode(void) const {
return mStateID;
}
bool Equals(const nsHashKey *aKey) const {
nsDFAState* key = (nsDFAState*)aKey;
return key->mStateID == mStateID;
}
nsHashKey *Clone(void) const {
return new nsDFAState(mStateID);
}
};
class nsTransitionKey : public nsHashKey
{
public:
uint32_t mState;
nsCOMPtr<nsIAtom> mInputSymbol;
nsTransitionKey(uint32_t aState, nsIAtom* aSymbol) :mState(aState), mInputSymbol(aSymbol) {}
uint32_t HashCode(void) const {
// Make a 32-bit integer that combines the low-order 16 bits of the state and the input symbol.
int32_t hb = mState << 16;
int32_t lb = (NS_PTR_TO_INT32(mInputSymbol.get()) << 16) >> 16;
return hb+lb;
}
bool Equals(const nsHashKey *aKey) const {
nsTransitionKey* key = (nsTransitionKey*)aKey;
return key->mState == mState && key->mInputSymbol == mInputSymbol;
}
nsHashKey *Clone(void) const {
return new nsTransitionKey(mState, mInputSymbol);
}
};
class nsTreeStyleCache
{
public:
nsTreeStyleCache() :mTransitionTable(nullptr), mCache(nullptr), mNextState(0) {}
~nsTreeStyleCache() { Clear(); }
void Clear() { delete mTransitionTable; mTransitionTable = nullptr; delete mCache; mCache = nullptr; mNextState = 0; }
nsStyleContext* GetStyleContext(nsICSSPseudoComparator* aComparator,
nsPresContext* aPresContext,
nsIContent* aContent,
nsStyleContext* aContext,
nsIAtom* aPseudoElement,
const AtomArray & aInputWord);
static bool DeleteDFAState(nsHashKey *aKey, void *aData, void *closure);
static bool ReleaseStyleContext(nsHashKey *aKey, void *aData, void *closure);
protected:
// 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 style context.
nsObjectHashtable* mTransitionTable;
// The cache of all active style contexts. This is a hash from
// a final state in the DFA, Sf, to the resultant style context.
nsObjectHashtable* mCache;
// An integer counter that is used when we need to make new states in the
// DFA.
uint32_t mNextState;
};
#endif // nsTreeStyleCache_h__