layout/style/nsNthIndexCache.cpp@7e26c7da4463 (annotated)
layout/style/nsNthIndexCache.cpp
Wed, 31 Dec 2014 06:55:50 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:55:50 +0100
- changeset 2
- 7e26c7da4463
- permissions
- -rw-r--r--
Added tag UPSTREAM_283F7C6 for changeset ca08bd8f51b2
| michael@0 | 1 | /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ |
| michael@0 | 2 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 3 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 4 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 5 | |
| michael@0 | 6 | /* |
| michael@0 | 7 | * A class that computes and caches the indices used for :nth-* pseudo-class |
| michael@0 | 8 | * matching. |
| michael@0 | 9 | */ |
| michael@0 | 10 | |
| michael@0 | 11 | #include "nsNthIndexCache.h" |
| michael@0 | 12 | #include "mozilla/dom/Element.h" |
| michael@0 | 13 | |
| michael@0 | 14 | nsNthIndexCache::nsNthIndexCache() |
| michael@0 | 15 | { |
| michael@0 | 16 | } |
| michael@0 | 17 | |
| michael@0 | 18 | nsNthIndexCache::~nsNthIndexCache() |
| michael@0 | 19 | { |
| michael@0 | 20 | } |
| michael@0 | 21 | |
| michael@0 | 22 | void |
| michael@0 | 23 | nsNthIndexCache::Reset() |
| michael@0 | 24 | { |
| michael@0 | 25 | mCaches[0][0].clear(); |
| michael@0 | 26 | mCaches[0][1].clear(); |
| michael@0 | 27 | mCaches[1][0].clear(); |
| michael@0 | 28 | mCaches[1][1].clear(); |
| michael@0 | 29 | } |
| michael@0 | 30 | |
| michael@0 | 31 | inline bool |
| michael@0 | 32 | nsNthIndexCache::SiblingMatchesElement(nsIContent* aSibling, Element* aElement, |
| michael@0 | 33 | bool aIsOfType) |
| michael@0 | 34 | { |
| michael@0 | 35 | return aSibling->IsElement() && |
| michael@0 | 36 | (!aIsOfType || |
| michael@0 | 37 | aSibling->NodeInfo()->NameAndNamespaceEquals(aElement->NodeInfo())); |
| michael@0 | 38 | } |
| michael@0 | 39 | |
| michael@0 | 40 | inline bool |
| michael@0 | 41 | nsNthIndexCache::IndexDeterminedFromPreviousSibling(nsIContent* aSibling, |
| michael@0 | 42 | Element* aChild, |
| michael@0 | 43 | bool aIsOfType, |
| michael@0 | 44 | bool aIsFromEnd, |
| michael@0 | 45 | const Cache& aCache, |
| michael@0 | 46 | int32_t& aResult) |
| michael@0 | 47 | { |
| michael@0 | 48 | if (SiblingMatchesElement(aSibling, aChild, aIsOfType)) { |
| michael@0 | 49 | Cache::Ptr siblingEntry = aCache.lookup(aSibling); |
| michael@0 | 50 | if (siblingEntry) { |
| michael@0 | 51 | int32_t siblingIndex = siblingEntry->value(); |
| michael@0 | 52 | NS_ASSERTION(siblingIndex != 0, |
| michael@0 | 53 | "How can a non-anonymous node have an anonymous sibling?"); |
| michael@0 | 54 | if (siblingIndex > 0) { |
| michael@0 | 55 | // At this point, aResult is a count of how many elements matching |
| michael@0 | 56 | // aChild we have seen after aSibling, including aChild itself. |
| michael@0 | 57 | // |siblingIndex| is the index of aSibling. |
| michael@0 | 58 | // So if aIsFromEnd, we want |aResult = siblingIndex - aResult| and |
| michael@0 | 59 | // otherwise we want |aResult = siblingIndex + aResult|. |
| michael@0 | 60 | aResult = siblingIndex + aResult * (1 - 2 * aIsFromEnd); |
| michael@0 | 61 | return true; |
| michael@0 | 62 | } |
| michael@0 | 63 | } |
| michael@0 | 64 | |
| michael@0 | 65 | ++aResult; |
| michael@0 | 66 | } |
| michael@0 | 67 | |
| michael@0 | 68 | return false; |
| michael@0 | 69 | } |
| michael@0 | 70 | |
| michael@0 | 71 | int32_t |
| michael@0 | 72 | nsNthIndexCache::GetNthIndex(Element* aChild, bool aIsOfType, |
| michael@0 | 73 | bool aIsFromEnd, bool aCheckEdgeOnly) |
| michael@0 | 74 | { |
| michael@0 | 75 | NS_ASSERTION(aChild->GetParent(), "caller should check GetParent()"); |
| michael@0 | 76 | |
| michael@0 | 77 | if (aChild->IsRootOfAnonymousSubtree()) { |
| michael@0 | 78 | return 0; |
| michael@0 | 79 | } |
| michael@0 | 80 | |
| michael@0 | 81 | Cache &cache = mCaches[aIsOfType][aIsFromEnd]; |
| michael@0 | 82 | |
| michael@0 | 83 | if (!cache.initialized() && !cache.init()) { |
| michael@0 | 84 | // Give up and just don't match. |
| michael@0 | 85 | return 0; |
| michael@0 | 86 | } |
| michael@0 | 87 | |
| michael@0 | 88 | Cache::AddPtr entry = cache.lookupForAdd(aChild); |
| michael@0 | 89 | |
| michael@0 | 90 | // Default the value to -2 when adding |
| michael@0 | 91 | if (!entry && !cache.add(entry, aChild, -2)) { |
| michael@0 | 92 | // No good; don't match. |
| michael@0 | 93 | return 0; |
| michael@0 | 94 | } |
| michael@0 | 95 | |
| michael@0 | 96 | int32_t &slot = entry->value(); |
| michael@0 | 97 | if (slot != -2 && (slot != -1 || aCheckEdgeOnly)) { |
| michael@0 | 98 | return slot; |
| michael@0 | 99 | } |
| michael@0 | 100 | |
| michael@0 | 101 | int32_t result = 1; |
| michael@0 | 102 | if (aCheckEdgeOnly) { |
| michael@0 | 103 | // The caller only cares whether or not the result is 1, so we can |
| michael@0 | 104 | // stop as soon as we see any other elements that match us. |
| michael@0 | 105 | if (aIsFromEnd) { |
| michael@0 | 106 | for (nsIContent *cur = aChild->GetNextSibling(); |
| michael@0 | 107 | cur; |
| michael@0 | 108 | cur = cur->GetNextSibling()) { |
| michael@0 | 109 | if (SiblingMatchesElement(cur, aChild, aIsOfType)) { |
| michael@0 | 110 | result = -1; |
| michael@0 | 111 | break; |
| michael@0 | 112 | } |
| michael@0 | 113 | } |
| michael@0 | 114 | } else { |
| michael@0 | 115 | for (nsIContent *cur = aChild->GetPreviousSibling(); |
| michael@0 | 116 | cur; |
| michael@0 | 117 | cur = cur->GetPreviousSibling()) { |
| michael@0 | 118 | if (SiblingMatchesElement(cur, aChild, aIsOfType)) { |
| michael@0 | 119 | result = -1; |
| michael@0 | 120 | break; |
| michael@0 | 121 | } |
| michael@0 | 122 | } |
| michael@0 | 123 | } |
| michael@0 | 124 | } else { |
| michael@0 | 125 | // In the common case, we already have a cached index for one of |
| michael@0 | 126 | // our previous siblings, so check that first. |
| michael@0 | 127 | for (nsIContent *cur = aChild->GetPreviousSibling(); |
| michael@0 | 128 | cur; |
| michael@0 | 129 | cur = cur->GetPreviousSibling()) { |
| michael@0 | 130 | if (IndexDeterminedFromPreviousSibling(cur, aChild, aIsOfType, |
| michael@0 | 131 | aIsFromEnd, cache, result)) { |
| michael@0 | 132 | slot = result; |
| michael@0 | 133 | return result; |
| michael@0 | 134 | } |
| michael@0 | 135 | } |
| michael@0 | 136 | |
| michael@0 | 137 | // Now if aIsFromEnd we lose: need to actually compute our index, |
| michael@0 | 138 | // since looking at previous siblings wouldn't have told us |
| michael@0 | 139 | // anything about it. Note that it doesn't make sense to do cache |
| michael@0 | 140 | // lookups on our following siblings, since chances are the cache |
| michael@0 | 141 | // is not primed for them. |
| michael@0 | 142 | if (aIsFromEnd) { |
| michael@0 | 143 | result = 1; |
| michael@0 | 144 | for (nsIContent *cur = aChild->GetNextSibling(); |
| michael@0 | 145 | cur; |
| michael@0 | 146 | cur = cur->GetNextSibling()) { |
| michael@0 | 147 | if (SiblingMatchesElement(cur, aChild, aIsOfType)) { |
| michael@0 | 148 | ++result; |
| michael@0 | 149 | } |
| michael@0 | 150 | } |
| michael@0 | 151 | } |
| michael@0 | 152 | } |
| michael@0 | 153 | |
| michael@0 | 154 | slot = result; |
| michael@0 | 155 | return result; |
| michael@0 | 156 | } |
