LCOV - code coverage report
Current view: directory - layout/style - nsNthIndexCache.cpp (source / functions) Found Hit Coverage
Test: app.info Lines: 65 4 6.2 %
Date: 2012-06-02 Functions: 6 2 33.3 %

       1                 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2                 : /* ***** BEGIN LICENSE BLOCK *****
       3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       4                 :  *
       5                 :  * The contents of this file are subject to the Mozilla Public License Version
       6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       7                 :  * the License. You may obtain a copy of the License at
       8                 :  * http://www.mozilla.org/MPL/
       9                 :  *
      10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      12                 :  * for the specific language governing rights and limitations under the
      13                 :  * License.
      14                 :  *
      15                 :  * The Original Code is Mozilla.org code.
      16                 :  *
      17                 :  * The Initial Developer of the Original Code is
      18                 :  * Mozilla Foundation.
      19                 :  * Portions created by the Initial Developer are Copyright (C) 2011
      20                 :  * the Initial Developer. All Rights Reserved.
      21                 :  *
      22                 :  * Contributor(s):
      23                 :  *    Boris Zbarsky <bzbarsky@mit.edu> (original author)
      24                 :  *    L. David Baron <dbaron@dbaron.org>
      25                 :  *
      26                 :  * Alternatively, the contents of this file may be used under the terms of
      27                 :  * either of the GNU General Public License Version 2 or later (the "GPL"),
      28                 :  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      29                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      30                 :  * of those above. If you wish to allow use of your version of this file only
      31                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      32                 :  * use your version of this file under the terms of the MPL, indicate your
      33                 :  * decision by deleting the provisions above and replace them with the notice
      34                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      35                 :  * the provisions above, a recipient may use your version of this file under
      36                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      37                 :  *
      38                 :  * ***** END LICENSE BLOCK ***** */
      39                 : 
      40                 : /*
      41                 :  * A class that computes and caches the indices used for :nth-* pseudo-class
      42                 :  * matching.
      43                 :  */
      44                 : 
      45                 : #include "nsNthIndexCache.h"
      46                 : #include "nsIContent.h"
      47                 : 
      48             110 : nsNthIndexCache::nsNthIndexCache()
      49                 : {
      50             110 : }
      51                 : 
      52             660 : nsNthIndexCache::~nsNthIndexCache()
      53                 : {
      54             660 : }
      55                 : 
      56                 : void
      57               0 : nsNthIndexCache::Reset()
      58                 : {
      59               0 :   mCaches[0][0].clear();
      60               0 :   mCaches[0][1].clear();
      61               0 :   mCaches[1][0].clear();
      62               0 :   mCaches[1][1].clear();
      63               0 : }
      64                 : 
      65                 : inline bool
      66               0 : nsNthIndexCache::SiblingMatchesElement(nsIContent* aSibling, Element* aElement,
      67                 :                                        bool aIsOfType)
      68                 : {
      69               0 :   return aSibling->IsElement() &&
      70               0 :     (!aIsOfType ||
      71               0 :      aSibling->NodeInfo()->NameAndNamespaceEquals(aElement->NodeInfo()));
      72                 : }
      73                 : 
      74                 : inline bool
      75               0 : nsNthIndexCache::IndexDeterminedFromPreviousSibling(nsIContent* aSibling,
      76                 :                                                     Element* aChild,
      77                 :                                                     bool aIsOfType,
      78                 :                                                     bool aIsFromEnd,
      79                 :                                                     const Cache& aCache,
      80                 :                                                     PRInt32& aResult)
      81                 : {
      82               0 :   if (SiblingMatchesElement(aSibling, aChild, aIsOfType)) {
      83               0 :     Cache::Ptr siblingEntry = aCache.lookup(aSibling);
      84               0 :     if (siblingEntry) {
      85               0 :       PRInt32 siblingIndex = siblingEntry->value;
      86               0 :       NS_ASSERTION(siblingIndex != 0,
      87                 :                    "How can a non-anonymous node have an anonymous sibling?");
      88               0 :       if (siblingIndex > 0) {
      89                 :         // At this point, aResult is a count of how many elements matching
      90                 :         // aChild we have seen after aSibling, including aChild itself.
      91                 :         // |siblingIndex| is the index of aSibling.
      92                 :         // So if aIsFromEnd, we want |aResult = siblingIndex - aResult| and
      93                 :         // otherwise we want |aResult = siblingIndex + aResult|.
      94                 :         NS_ABORT_IF_FALSE(aIsFromEnd == 0 || aIsFromEnd == 1,
      95                 :                           "Bogus bool value");
      96               0 :         aResult = siblingIndex + aResult * (1 - 2 * aIsFromEnd);
      97               0 :         return true;
      98                 :       }
      99                 :     }
     100                 :     
     101               0 :     ++aResult;
     102                 :   }
     103                 : 
     104               0 :   return false;
     105                 : }
     106                 : 
     107                 : PRInt32
     108               0 : nsNthIndexCache::GetNthIndex(Element* aChild, bool aIsOfType,
     109                 :                              bool aIsFromEnd, bool aCheckEdgeOnly)
     110                 : {
     111               0 :   NS_ASSERTION(aChild->GetParent(), "caller should check GetParent()");
     112                 : 
     113               0 :   if (aChild->IsRootOfAnonymousSubtree()) {
     114               0 :     return 0;
     115                 :   }
     116                 : 
     117               0 :   Cache &cache = mCaches[aIsOfType][aIsFromEnd];
     118                 : 
     119               0 :   if (!cache.initialized() && !cache.init()) {
     120                 :     // Give up and just don't match.
     121               0 :     return 0;
     122                 :   }
     123                 : 
     124               0 :   Cache::AddPtr entry = cache.lookupForAdd(aChild);
     125                 : 
     126                 :   // Default the value to -2 when adding
     127               0 :   if (!entry && !cache.add(entry, aChild, -2)) {
     128                 :     // No good; don't match.
     129               0 :     return 0;
     130                 :   }
     131                 : 
     132               0 :   PRInt32 &slot = entry->value;
     133               0 :   if (slot != -2 && (slot != -1 || aCheckEdgeOnly)) {
     134               0 :     return slot;
     135                 :   }
     136                 :   
     137               0 :   PRInt32 result = 1;
     138               0 :   if (aCheckEdgeOnly) {
     139                 :     // The caller only cares whether or not the result is 1, so we can
     140                 :     // stop as soon as we see any other elements that match us.
     141               0 :     if (aIsFromEnd) {
     142               0 :       for (nsIContent *cur = aChild->GetNextSibling();
     143                 :            cur;
     144               0 :            cur = cur->GetNextSibling()) {
     145               0 :         if (SiblingMatchesElement(cur, aChild, aIsOfType)) {
     146               0 :           result = -1;
     147               0 :           break;
     148                 :         }
     149                 :       }
     150                 :     } else {
     151               0 :       for (nsIContent *cur = aChild->GetPreviousSibling();
     152                 :            cur;
     153               0 :            cur = cur->GetPreviousSibling()) {
     154               0 :         if (SiblingMatchesElement(cur, aChild, aIsOfType)) {
     155               0 :           result = -1;
     156               0 :           break;
     157                 :         }
     158                 :       }
     159                 :     }
     160                 :   } else {
     161                 :     // In the common case, we already have a cached index for one of
     162                 :     // our previous siblings, so check that first.
     163               0 :     for (nsIContent *cur = aChild->GetPreviousSibling();
     164                 :          cur;
     165               0 :          cur = cur->GetPreviousSibling()) {
     166               0 :       if (IndexDeterminedFromPreviousSibling(cur, aChild, aIsOfType,
     167               0 :                                              aIsFromEnd, cache, result)) {
     168               0 :         slot = result;
     169               0 :         return result;
     170                 :       }
     171                 :     }
     172                 : 
     173                 :     // Now if aIsFromEnd we lose: need to actually compute our index,
     174                 :     // since looking at previous siblings wouldn't have told us
     175                 :     // anything about it.  Note that it doesn't make sense to do cache
     176                 :     // lookups on our following siblings, since chances are the cache
     177                 :     // is not primed for them.
     178               0 :     if (aIsFromEnd) {
     179               0 :       result = 1;
     180               0 :       for (nsIContent *cur = aChild->GetNextSibling();
     181                 :            cur;
     182               0 :            cur = cur->GetNextSibling()) {
     183               0 :         if (SiblingMatchesElement(cur, aChild, aIsOfType)) {
     184               0 :           ++result;
     185                 :         }
     186                 :       }
     187                 :     }
     188                 :   }
     189                 : 
     190               0 :   slot = result;
     191               0 :   return result;
     192                 : }

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