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      1 /*
      2  * Copyright (C) 1999 Lars Knoll (knoll (at) kde.org)
      3  *           (C) 1999 Antti Koivisto (koivisto (at) kde.org)
      4  *           (C) 2001 Dirk Mueller (mueller (at) kde.org)
      5  * Copyright (C) 2004, 2006, 2007, 2008 Apple Inc. All rights reserved.
      6  *
      7  * This library is free software; you can redistribute it and/or
      8  * modify it under the terms of the GNU Library General Public
      9  * License as published by the Free Software Foundation; either
     10  * version 2 of the License, or (at your option) any later version.
     11  *
     12  * This library is distributed in the hope that it will be useful,
     13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     15  * Library General Public License for more details.
     16  *
     17  * You should have received a copy of the GNU Library General Public License
     18  * along with this library; see the file COPYING.LIB.  If not, write to
     19  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     20  * Boston, MA 02110-1301, USA.
     21  */
     22 
     23 #include "config.h"
     24 #include "DynamicNodeList.h"
     25 
     26 #include "Document.h"
     27 #include "Element.h"
     28 
     29 namespace WebCore {
     30 
     31 DynamicNodeList::DynamicNodeList(PassRefPtr<Node> rootNode)
     32     : m_rootNode(rootNode)
     33     , m_caches(Caches::create())
     34     , m_ownsCaches(true)
     35 {
     36     m_rootNode->registerDynamicNodeList(this);
     37 }
     38 
     39 DynamicNodeList::DynamicNodeList(PassRefPtr<Node> rootNode, DynamicNodeList::Caches* caches)
     40     : m_rootNode(rootNode)
     41     , m_caches(caches)
     42     , m_ownsCaches(false)
     43 {
     44     m_rootNode->registerDynamicNodeList(this);
     45 }
     46 
     47 DynamicNodeList::~DynamicNodeList()
     48 {
     49     m_rootNode->unregisterDynamicNodeList(this);
     50 }
     51 
     52 unsigned DynamicNodeList::length() const
     53 {
     54     if (m_caches->isLengthCacheValid)
     55         return m_caches->cachedLength;
     56 
     57     unsigned length = 0;
     58 
     59     for (Node* n = m_rootNode->firstChild(); n; n = n->traverseNextNode(m_rootNode.get()))
     60         length += n->isElementNode() && nodeMatches(static_cast<Element*>(n));
     61 
     62     m_caches->cachedLength = length;
     63     m_caches->isLengthCacheValid = true;
     64 
     65     return length;
     66 }
     67 
     68 Node* DynamicNodeList::itemForwardsFromCurrent(Node* start, unsigned offset, int remainingOffset) const
     69 {
     70     ASSERT(remainingOffset >= 0);
     71     for (Node* n = start; n; n = n->traverseNextNode(m_rootNode.get())) {
     72         if (n->isElementNode() && nodeMatches(static_cast<Element*>(n))) {
     73             if (!remainingOffset) {
     74                 m_caches->lastItem = n;
     75                 m_caches->lastItemOffset = offset;
     76                 m_caches->isItemCacheValid = true;
     77                 return n;
     78             }
     79             --remainingOffset;
     80         }
     81     }
     82 
     83     return 0; // no matching node in this subtree
     84 }
     85 
     86 Node* DynamicNodeList::itemBackwardsFromCurrent(Node* start, unsigned offset, int remainingOffset) const
     87 {
     88     ASSERT(remainingOffset < 0);
     89     for (Node* n = start; n; n = n->traversePreviousNode(m_rootNode.get())) {
     90         if (n->isElementNode() && nodeMatches(static_cast<Element*>(n))) {
     91             if (!remainingOffset) {
     92                 m_caches->lastItem = n;
     93                 m_caches->lastItemOffset = offset;
     94                 m_caches->isItemCacheValid = true;
     95                 return n;
     96             }
     97             ++remainingOffset;
     98         }
     99     }
    100 
    101     return 0; // no matching node in this subtree
    102 }
    103 
    104 Node* DynamicNodeList::item(unsigned offset) const
    105 {
    106     int remainingOffset = offset;
    107     Node* start = m_rootNode->firstChild();
    108     if (m_caches->isItemCacheValid) {
    109         if (offset == m_caches->lastItemOffset)
    110             return m_caches->lastItem;
    111         else if (offset > m_caches->lastItemOffset || m_caches->lastItemOffset - offset < offset) {
    112             start = m_caches->lastItem;
    113             remainingOffset -= m_caches->lastItemOffset;
    114         }
    115     }
    116 
    117     if (remainingOffset < 0)
    118         return itemBackwardsFromCurrent(start, offset, remainingOffset);
    119     return itemForwardsFromCurrent(start, offset, remainingOffset);
    120 }
    121 
    122 Node* DynamicNodeList::itemWithName(const AtomicString& elementId) const
    123 {
    124     if (m_rootNode->isDocumentNode() || m_rootNode->inDocument()) {
    125         Element* node = m_rootNode->document()->getElementById(elementId);
    126         if (node && nodeMatches(node)) {
    127             for (Node* p = node->parentNode(); p; p = p->parentNode()) {
    128                 if (p == m_rootNode)
    129                     return node;
    130             }
    131         }
    132         if (!node)
    133             return 0;
    134         // In the case of multiple nodes with the same name, just fall through.
    135     }
    136 
    137     unsigned length = this->length();
    138     for (unsigned i = 0; i < length; i++) {
    139         Node* node = item(i);
    140         if (node->isElementNode() && static_cast<Element*>(node)->getIDAttribute() == elementId)
    141             return node;
    142     }
    143 
    144     return 0;
    145 }
    146 
    147 void DynamicNodeList::invalidateCache()
    148 {
    149     // This should only be called for node lists that own their own caches.
    150     ASSERT(m_ownsCaches);
    151     m_caches->reset();
    152 }
    153 
    154 DynamicNodeList::Caches::Caches()
    155     : lastItem(0)
    156     , isLengthCacheValid(false)
    157     , isItemCacheValid(false)
    158 {
    159 }
    160 
    161 PassRefPtr<DynamicNodeList::Caches> DynamicNodeList::Caches::create()
    162 {
    163     return adoptRef(new Caches());
    164 }
    165 
    166 void DynamicNodeList::Caches::reset()
    167 {
    168     lastItem = 0;
    169     isLengthCacheValid = false;
    170     isItemCacheValid = false;
    171 }
    172 
    173 } // namespace WebCore
    174