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93 lines
3.4 KiB
C++
93 lines
3.4 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsContentIndexCache_h__
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#define nsContentIndexCache_h__
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#include "nscore.h"
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#include "js/HashTable.h"
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#include "mozilla/dom/Element.h"
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/*
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* A class that computes and caches the indices used for :nth-* pseudo-class
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* matching.
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*/
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class nsNthIndexCache {
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private:
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typedef mozilla::dom::Element Element;
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public:
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/**
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* Constructor and destructor out of line so that we don't try to
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* instantiate the hashtable template all over the place.
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*/
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nsNthIndexCache();
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~nsNthIndexCache();
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// Returns a 1-based index of the child in its parent. If the child
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// is not in its parent's child list (i.e., it is anonymous content),
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// returns 0.
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// If aCheckEdgeOnly is true, the function will return 1 if the result
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// is 1, and something other than 1 (maybe or maybe not a valid
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// result) otherwise.
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// This must only be called on nodes which have a non-null parent.
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PRInt32 GetNthIndex(Element* aChild, bool aIsOfType, bool aIsFromEnd,
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bool aCheckEdgeOnly);
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void Reset();
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private:
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/**
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* Returns true if aSibling and aElement should be considered in the same
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* list for nth-index purposes, taking aIsOfType into account.
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*/
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inline bool SiblingMatchesElement(nsIContent* aSibling, Element* aElement,
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bool aIsOfType);
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// This node's index for this cache.
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// If -2, needs to be computed.
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// If -1, needs to be computed but known not to be 1.
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// If 0, the node is not at any index in its parent.
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typedef PRInt32 CacheEntry;
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class SystemAllocPolicy {
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public:
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void *malloc_(size_t bytes) { return ::malloc(bytes); }
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void *realloc_(void *p, size_t bytes) { return ::realloc(p, bytes); }
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void free_(void *p) { ::free(p); }
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void reportAllocOverflow() const {}
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};
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typedef js::HashMap<nsIContent*, CacheEntry, js::DefaultHasher<nsIContent*>,
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SystemAllocPolicy> Cache;
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/**
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* Returns true if aResult has been set to the correct value for aChild and
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* no more work needs to be done. Returns false otherwise.
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*
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* aResult is an inout parameter. The in value is the number of elements
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* that are in the half-open range (aSibling, aChild] (so including aChild
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* but not including aSibling) that match aChild. The out value is the
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* correct index for aChild if this function returns true and the number of
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* elements in the closed range [aSibling, aChild] that match aChild
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* otherwise.
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*/
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inline bool IndexDeterminedFromPreviousSibling(nsIContent* aSibling,
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Element* aChild,
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bool aIsOfType,
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bool aIsFromEnd,
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const Cache& aCache,
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PRInt32& aResult);
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// Caches of indices for :nth-child(), :nth-last-child(),
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// :nth-of-type(), :nth-last-of-type(), keyed by Element*.
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//
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// The first subscript is 0 for -child and 1 for -of-type, the second
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// subscript is 0 for nth- and 1 for nth-last-.
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Cache mCaches[2][2];
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};
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#endif /* nsContentIndexCache_h__ */
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