1 /*
2 * Copyright (C) 2013 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 * * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #ifndef TreeNode_h
32 #define TreeNode_h
33
34 #include "wtf/Assertions.h"
35
36 namespace WTF {
37
38 //
39 // TreeNode is generic, ContainerNode-like linked tree data structure.
40 // There are a few notable difference between TreeNode and Node:
41 //
42 // * Each TreeNode node is NOT ref counted. The user have to retain its lifetime somehow.
43 // FIXME: lifetime management could be parameterized so that ref counted implementations can be used.
44 // * It ASSERT()s invalid input. The callers have to ensure that given parameter is sound.
45 // * There is no branch-leaf difference. Every node can be a parent of other node.
46 //
47 // FIXME: oilpan: Trace tree node edges to ensure we don't have dangling pointers.
48 // As it is used in HTMLImport it is safe since they all die together.
49 template <class T>
50 class TreeNode {
51 public:
52 typedef T NodeType;
53
TreeNode()54 TreeNode()
55 : m_next(0)
56 , m_previous(0)
57 , m_parent(0)
58 , m_firstChild(0)
59 , m_lastChild(0)
60 {
61 }
62
next()63 NodeType* next() const { return m_next; }
previous()64 NodeType* previous() const { return m_previous; }
parent()65 NodeType* parent() const { return m_parent; }
firstChild()66 NodeType* firstChild() const { return m_firstChild; }
lastChild()67 NodeType* lastChild() const { return m_lastChild; }
here()68 NodeType* here() const { return static_cast<NodeType*>(const_cast<TreeNode*>(this)); }
69
orphan()70 bool orphan() const { return !m_parent && !m_next && !m_previous && !m_firstChild && !m_lastChild; }
hasChildren()71 bool hasChildren() const { return m_firstChild; }
72
insertBefore(NodeType * newChild,NodeType * refChild)73 void insertBefore(NodeType* newChild, NodeType* refChild)
74 {
75 ASSERT(!newChild->parent());
76 ASSERT(!newChild->next());
77 ASSERT(!newChild->previous());
78
79 ASSERT(!refChild || this == refChild->parent());
80
81 if (!refChild) {
82 appendChild(newChild);
83 return;
84 }
85
86 NodeType* newPrevious = refChild->previous();
87 newChild->m_parent = here();
88 newChild->m_next = refChild;
89 newChild->m_previous = newPrevious;
90 refChild->m_previous = newChild;
91 if (newPrevious)
92 newPrevious->m_next = newChild;
93 else
94 m_firstChild = newChild;
95 }
96
appendChild(NodeType * child)97 void appendChild(NodeType* child)
98 {
99 ASSERT(!child->parent());
100 ASSERT(!child->next());
101 ASSERT(!child->previous());
102
103 child->m_parent = here();
104
105 if (!m_lastChild) {
106 ASSERT(!m_firstChild);
107 m_lastChild = m_firstChild = child;
108 return;
109 }
110
111 ASSERT(!m_lastChild->m_next);
112 NodeType* oldLast = m_lastChild;
113 m_lastChild = child;
114
115 child->m_previous = oldLast;
116 oldLast->m_next = child;
117 }
118
removeChild(NodeType * child)119 NodeType* removeChild(NodeType* child)
120 {
121 ASSERT(child->parent() == this);
122
123 if (m_firstChild == child)
124 m_firstChild = child->next();
125 if (m_lastChild == child)
126 m_lastChild = child->previous();
127
128 NodeType* oldNext = child->next();
129 NodeType* oldPrevious = child->previous();
130 child->m_parent = child->m_next = child->m_previous = 0;
131
132 if (oldNext)
133 oldNext->m_previous = oldPrevious;
134 if (oldPrevious)
135 oldPrevious->m_next = oldNext;
136
137 return child;
138 }
139
takeChildrenFrom(NodeType * oldParent)140 void takeChildrenFrom(NodeType* oldParent)
141 {
142 ASSERT(oldParent != this);
143 while (oldParent->hasChildren()) {
144 NodeType* child = oldParent->firstChild();
145 oldParent->removeChild(child);
146 this->appendChild(child);
147 }
148 }
149
150 private:
151 NodeType* m_next;
152 NodeType* m_previous;
153 NodeType* m_parent;
154 NodeType* m_firstChild;
155 NodeType* m_lastChild;
156 };
157
158 template<class T>
159 inline typename TreeNode<T>::NodeType* traverseNext(const TreeNode<T>* current, const TreeNode<T>* stayWithin = 0)
160 {
161 if (typename TreeNode<T>::NodeType* next = current->firstChild())
162 return next;
163 if (current == stayWithin)
164 return 0;
165 if (typename TreeNode<T>::NodeType* next = current->next())
166 return next;
167 for (typename TreeNode<T>::NodeType* parent = current->parent(); parent; parent = parent->parent()) {
168 if (parent == stayWithin)
169 return 0;
170 if (typename TreeNode<T>::NodeType* next = parent->next())
171 return next;
172 }
173
174 return 0;
175 }
176
177 template<class T>
traverseFirstPostOrder(const TreeNode<T> * current)178 inline typename TreeNode<T>::NodeType* traverseFirstPostOrder(const TreeNode<T>* current)
179 {
180 typename TreeNode<T>::NodeType* first = current->here();
181 while (first->firstChild())
182 first = first->firstChild();
183 return first;
184 }
185
186 template<class T>
187 inline typename TreeNode<T>::NodeType* traverseNextPostOrder(const TreeNode<T>* current, const TreeNode<T>* stayWithin = 0)
188 {
189 if (current == stayWithin)
190 return 0;
191
192 typename TreeNode<T>::NodeType* next = current->next();
193 if (!next)
194 return current->parent();
195 while (next->firstChild())
196 next = next->firstChild();
197 return next;
198 }
199
200 }
201
202 using WTF::TreeNode;
203 using WTF::traverseNext;
204 using WTF::traverseNextPostOrder;
205
206 #endif
207