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 template <class T>
48 class TreeNode {
49 public:
50 typedef T NodeType;
51
TreeNode()52 TreeNode()
53 : m_next(0)
54 , m_previous(0)
55 , m_parent(0)
56 , m_firstChild(0)
57 , m_lastChild(0)
58 {
59 }
60
next()61 NodeType* next() const { return m_next; }
previous()62 NodeType* previous() const { return m_previous; }
parent()63 NodeType* parent() const { return m_parent; }
firstChild()64 NodeType* firstChild() const { return m_firstChild; }
lastChild()65 NodeType* lastChild() const { return m_lastChild; }
here()66 NodeType* here() const { return static_cast<NodeType*>(const_cast<TreeNode*>(this)); }
67
orphan()68 bool orphan() const { return !m_parent && !m_next && !m_previous && !m_firstChild && !m_lastChild; }
hasChildren()69 bool hasChildren() const { return m_firstChild; }
70
insertBefore(NodeType * newChild,NodeType * refChild)71 void insertBefore(NodeType* newChild, NodeType* refChild)
72 {
73 ASSERT(!newChild->parent());
74 ASSERT(!newChild->next());
75 ASSERT(!newChild->previous());
76
77 ASSERT(!refChild || this == refChild->parent());
78
79 if (!refChild) {
80 appendChild(newChild);
81 return;
82 }
83
84 NodeType* newPrevious = refChild->previous();
85 newChild->m_parent = here();
86 newChild->m_next = refChild;
87 newChild->m_previous = newPrevious;
88 refChild->m_previous = newChild;
89 if (newPrevious)
90 newPrevious->m_next = newChild;
91 else
92 m_firstChild = newChild;
93 }
94
appendChild(NodeType * child)95 void appendChild(NodeType* child)
96 {
97 ASSERT(!child->parent());
98 ASSERT(!child->next());
99 ASSERT(!child->previous());
100
101 child->m_parent = here();
102
103 if (!m_lastChild) {
104 ASSERT(!m_firstChild);
105 m_lastChild = m_firstChild = child;
106 return;
107 }
108
109 ASSERT(!m_lastChild->m_next);
110 NodeType* oldLast = m_lastChild;
111 m_lastChild = child;
112
113 child->m_previous = oldLast;
114 oldLast->m_next = child;
115 }
116
removeChild(NodeType * child)117 NodeType* removeChild(NodeType* child)
118 {
119 ASSERT(child->parent() == this);
120
121 if (m_firstChild == child)
122 m_firstChild = child->next();
123 if (m_lastChild == child)
124 m_lastChild = child->previous();
125
126 NodeType* oldNext = child->next();
127 NodeType* oldPrevious = child->previous();
128 child->m_parent = child->m_next = child->m_previous = 0;
129
130 if (oldNext)
131 oldNext->m_previous = oldPrevious;
132 if (oldPrevious)
133 oldPrevious->m_next = oldNext;
134
135 return child;
136 }
137
138 private:
139 NodeType* m_next;
140 NodeType* m_previous;
141 NodeType* m_parent;
142 NodeType* m_firstChild;
143 NodeType* m_lastChild;
144 };
145
146 template<class T>
147 inline typename TreeNode<T>::NodeType* traverseNext(const TreeNode<T>* current, const TreeNode<T>* stayWithin = 0)
148 {
149 if (typename TreeNode<T>::NodeType* next = current->firstChild())
150 return next;
151 if (current == stayWithin)
152 return 0;
153 if (typename TreeNode<T>::NodeType* next = current->next())
154 return next;
155 for (typename TreeNode<T>::NodeType* parent = current->parent(); parent; parent = parent->parent()) {
156 if (parent == stayWithin)
157 return 0;
158 if (typename TreeNode<T>::NodeType* next = parent->next())
159 return next;
160 }
161
162 return 0;
163 }
164
165 template<class T>
traverseFirstPostOrder(const TreeNode<T> * current)166 inline typename TreeNode<T>::NodeType* traverseFirstPostOrder(const TreeNode<T>* current)
167 {
168 typename TreeNode<T>::NodeType* first = current->here();
169 while (first->firstChild())
170 first = first->firstChild();
171 return first;
172 }
173
174 template<class T>
175 inline typename TreeNode<T>::NodeType* traverseNextPostOrder(const TreeNode<T>* current, const TreeNode<T>* stayWithin = 0)
176 {
177 if (current == stayWithin)
178 return 0;
179
180 typename TreeNode<T>::NodeType* next = current->next();
181 if (!next)
182 return current->parent();
183 while (next->firstChild())
184 next = next->firstChild();
185 return next;
186 }
187
188 }
189
190 using WTF::TreeNode;
191 using WTF::traverseNext;
192 using WTF::traverseNextPostOrder;
193
194 #endif
195