gecko-dev/layout/style/nsNthIndexCache.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla.org code.
*
* The Initial Developer of the Original Code is
* Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2011
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Boris Zbarsky <bzbarsky@mit.edu> (original author)
* L. David Baron <dbaron@dbaron.org>
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsContentIndexCache_h__
#define nsContentIndexCache_h__
#include "nscore.h"
#include "js/HashTable.h"
#include "mozilla/dom/Element.h"
/*
* A class that computes and caches the indices used for :nth-* pseudo-class
* matching.
*/
class nsNthIndexCache {
private:
typedef mozilla::dom::Element Element;
public:
/**
* Constructor and destructor out of line so that we don't try to
* instantiate the hashtable template all over the place.
*/
nsNthIndexCache();
~nsNthIndexCache();
// Returns a 1-based index of the child in its parent. If the child
// is not in its parent's child list (i.e., it is anonymous content),
// returns 0.
// If aCheckEdgeOnly is true, the function will return 1 if the result
// is 1, and something other than 1 (maybe or maybe not a valid
// result) otherwise.
// This must only be called on nodes which have a non-null parent.
PRInt32 GetNthIndex(Element* aChild, bool aIsOfType, bool aIsFromEnd,
bool aCheckEdgeOnly);
void Reset();
private:
/**
* Returns true if aSibling and aElement should be considered in the same
* list for nth-index purposes, taking aIsOfType into account.
*/
inline bool SiblingMatchesElement(nsIContent* aSibling, Element* aElement,
bool aIsOfType);
// This node's index for this cache.
// If -2, needs to be computed.
// If -1, needs to be computed but known not to be 1.
// If 0, the node is not at any index in its parent.
typedef PRInt32 CacheEntry;
class SystemAllocPolicy {
public:
void *malloc_(size_t bytes) { return ::malloc(bytes); }
void *realloc_(void *p, size_t bytes) { return ::realloc(p, bytes); }
void free_(void *p) { ::free(p); }
void reportAllocOverflow() const {}
};
typedef js::HashMap<nsIContent*, CacheEntry, js::DefaultHasher<nsIContent*>,
SystemAllocPolicy> Cache;
/**
* Returns true if aResult has been set to the correct value for aChild and
* no more work needs to be done. Returns false otherwise.
*
* aResult is an inout parameter. The in value is the number of elements
* that are in the half-open range (aSibling, aChild] (so including aChild
* but not including aSibling) that match aChild. The out value is the
* correct index for aChild if this function returns true and the number of
* elements in the closed range [aSibling, aChild] that match aChild
* otherwise.
*/
inline bool IndexDeterminedFromPreviousSibling(nsIContent* aSibling,
Element* aChild,
bool aIsOfType,
bool aIsFromEnd,
const Cache& aCache,
PRInt32& aResult);
// Caches of indices for :nth-child(), :nth-last-child(),
// :nth-of-type(), :nth-last-of-type(), keyed by Element*.
//
// The first subscript is 0 for -child and 1 for -of-type, the second
// subscript is 0 for nth- and 1 for nth-last-.
Cache mCaches[2][2];
};
#endif /* nsContentIndexCache_h__ */