1 /*
2  * Copyright (C) 2007 Apple Inc. All rights reserved.
3  *           (C) 2008 Nikolas Zimmermann <zimmermann@kde.org>
4  *
5  * This library is free software; you can redistribute it and/or
6  * modify it under the terms of the GNU Library General Public
7  * License as published by the Free Software Foundation; either
8  * version 2 of the License, or (at your option) any later version.
9  *
10  * This library is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13  * Library General Public License for more details.
14  *
15  * You should have received a copy of the GNU Library General Public License
16  * along with this library; see the file COPYING.LIB.  If not, write to
17  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18  * Boston, MA 02110-1301, USA.
19  *
20  */
21 
22 #ifndef ContainerNodeAlgorithms_h
23 #define ContainerNodeAlgorithms_h
24 
25 #include <wtf/Assertions.h>
26 
27 namespace WebCore {
28 
29 class Node;
30 
31 namespace Private {
32 
33     template<class GenericNode, class GenericNodeContainer>
34     void addChildNodesToDeletionQueue(GenericNode*& head, GenericNode*& tail, GenericNodeContainer* container);
35 
36 };
37 
38 // Helper functions for TreeShared-derived classes, which have a 'Node' style interface
39 // This applies to 'ContainerNode' and 'SVGElementInstance'
40 template<class GenericNode, class GenericNodeContainer>
removeAllChildrenInContainer(GenericNodeContainer * container)41 void removeAllChildrenInContainer(GenericNodeContainer* container)
42 {
43     // List of nodes to be deleted.
44     GenericNode* head = 0;
45     GenericNode* tail = 0;
46 
47     Private::addChildNodesToDeletionQueue<GenericNode, GenericNodeContainer>(head, tail, container);
48 
49     GenericNode* n;
50     GenericNode* next;
51     while ((n = head) != 0) {
52         ASSERT(n->m_deletionHasBegun);
53 
54         next = n->nextSibling();
55         n->setNextSibling(0);
56 
57         head = next;
58         if (next == 0)
59             tail = 0;
60 
61         if (n->hasChildNodes())
62             Private::addChildNodesToDeletionQueue<GenericNode, GenericNodeContainer>(head, tail, static_cast<GenericNodeContainer*>(n));
63 
64         delete n;
65     }
66 }
67 
68 template<class GenericNode, class GenericNodeContainer>
appendChildToContainer(GenericNode * child,GenericNodeContainer * container)69 void appendChildToContainer(GenericNode* child, GenericNodeContainer* container)
70 {
71     child->setParent(container);
72 
73     GenericNode* lastChild = container->lastChild();
74     if (lastChild) {
75         child->setPreviousSibling(lastChild);
76         lastChild->setNextSibling(child);
77     } else
78         container->setFirstChild(child);
79 
80     container->setLastChild(child);
81 }
82 
83 // Helper methods for removeAllChildrenInContainer, hidden from WebCore namespace
84 namespace Private {
85 
86     template<class GenericNode, bool dispatchRemovalNotification>
87     struct NodeRemovalDispatcher {
dispatchNodeRemovalDispatcher88         static void dispatch(GenericNode*)
89         {
90             // no-op, by default
91         }
92     };
93 
94     template<class GenericNode>
95     struct NodeRemovalDispatcher<GenericNode, true> {
96         static void dispatch(GenericNode* node)
97         {
98             if (node->inDocument())
99                 node->removedFromDocument();
100         }
101     };
102 
103     template<class GenericNode>
104     struct ShouldDispatchRemovalNotification {
105         static const bool value = false;
106     };
107 
108     template<>
109     struct ShouldDispatchRemovalNotification<Node> {
110         static const bool value = true;
111     };
112 
113     template<class GenericNode, class GenericNodeContainer>
114     void addChildNodesToDeletionQueue(GenericNode*& head, GenericNode*& tail, GenericNodeContainer* container)
115     {
116         // We have to tell all children that their parent has died.
117         GenericNode* next = 0;
118         for (GenericNode* n = container->firstChild(); n != 0; n = next) {
119             ASSERT(!n->m_deletionHasBegun);
120 
121             next = n->nextSibling();
122             n->setPreviousSibling(0);
123             n->setNextSibling(0);
124             n->setParent(0);
125 
126             if (!n->refCount()) {
127 #ifndef NDEBUG
128                 n->m_deletionHasBegun = true;
129 #endif
130                 // Add the node to the list of nodes to be deleted.
131                 // Reuse the nextSibling pointer for this purpose.
132                 if (tail)
133                     tail->setNextSibling(n);
134                 else
135                     head = n;
136 
137                 tail = n;
138             } else
139                 NodeRemovalDispatcher<GenericNode, ShouldDispatchRemovalNotification<GenericNode>::value>::dispatch(n);
140         }
141 
142         container->setFirstChild(0);
143         container->setLastChild(0);
144     }
145 };
146 
147 } // namespace WebCore
148 
149 #endif // ContainerNodeAlgorithms_h
150