類型定義
在多叉樹(shù)中，葉子遍歷迭代器有只讀、讀寫、只讀反轉(zhuǎn)、讀寫反轉(zhuǎn)4種，在mtree容器中的定義如下：
1
typedef leaf_iterator_impl<false,false> leaf_iterator;
2 typedef leaf_iterator_impl<false,true> reverse_leaf_iterator;
3 typedef leaf_iterator_impl<true,false> const_leaf_iterator;
4 typedef leaf_iterator_impl<true,true> const_reverse_leaf_iterator;
接口定義 多叉樹(shù)的葉子遍歷是指訪問(wèn)某子樹(shù)的所有葉子結(jié)點(diǎn)，下面代碼是葉子遍歷迭代器的聲明：
1 template<bool is_const,bool is_reverse>
2 class leaf_iterator_impl : public iterator_base_impl<is_const>
3
{
4
friend class mtree<T,false>;
5 typedef iterator_base_impl<is_const> base_type;
6 typedef typename base_type::node_pointer_type node_pointer_type;
7 typedef typename base_type::tree_pointer_type tree_pointer_type;
8 using base_type::tree_;
9 using base_type::off_;
10 using base_type::root_;
11 public:
12 leaf_iterator_impl();
13 leaf_iterator_impl(const base_type& iter);
14 leaf_iterator_impl& operator++();
15 leaf_iterator_impl& operator--();
16 leaf_iterator_impl operator++(int);
17 leaf_iterator_impl operator--(int);
18 leaf_iterator_impl operator + (size_t off);
19 leaf_iterator_impl& operator += (size_t off);
20 leaf_iterator_impl operator - (size_t off);
21 leaf_iterator_impl& operator -= (size_t off);
22 leaf_iterator_impl begin() const;
23 leaf_iterator_impl end() const;
24 protected:
25 void first(no_reverse_tag);
26 void first(reverse_tag);
27 void last(no_reverse_tag);
28 void last(reverse_tag);
29 void increment(no_reverse_tag);
30 void increment(reverse_tag);
31 void decrement(no_reverse_tag);
32 void decrement(reverse_tag);
33 private:
34 void forward_first();
35 void forward_last();
36 void forward_next();
37 void forward_prev();
38
};
接口實(shí)現(xiàn) 下面重點(diǎn)講述葉子遍歷中4種定位方法的具體實(shí)現(xiàn)，隨后列出其它所有方法的實(shí)現(xiàn)代碼。 （1）forward_first：求正向第一個(gè)葉子，就是位于子樹(shù)最左側(cè)最深且沒(méi)有孩子的結(jié)點(diǎn)，代碼如下：
1 template<typename T>
2 template<bool is_const,bool is_reverse>
3 inline void mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::forward_first()
4 {
5 assert(tree_&&root_<tree_->size());
6 off_ = root_; node_pointer_type p_node = &(*tree_)[off_];
7 while (p_node->first_child_)
8
{
9 off_ += p_node->first_child_;
10 p_node = &(*tree_)[off_];
11
}
12 } （2）forward_last：求正向最后一個(gè)葉子，就是位于子樹(shù)最右側(cè)最深且沒(méi)有孩子的結(jié)點(diǎn)，代碼如下：
1 template<typename T>
2 template<bool is_const,bool is_reverse>
3 inline void mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::forward_last()
4 {
5 assert(tree_&&root_<tree_->size());
6 off_ = root_; node_pointer_type p_node = &(*tree_)[off_];
7 while (p_node->last_child_)
8 {
9 off_ += p_node->last_child_;
10 p_node = &(*tree_)[off_];
11 }
12 } （3）forward_next：求正向下一個(gè)葉子，步驟如下：a) 如果當(dāng)前結(jié)點(diǎn)不是子樹(shù)根結(jié)點(diǎn)且存在父親但沒(méi)有右兄弟，那么就一直向上回溯直到結(jié)點(diǎn)為子樹(shù)根結(jié)點(diǎn)或不存在父親或存在右兄弟為止，反之轉(zhuǎn)到b)。b) 如果當(dāng)前結(jié)點(diǎn)是子樹(shù)根結(jié)點(diǎn)或沒(méi)有父親，那么返回end，否則轉(zhuǎn)到c)。c) 這時(shí)存在右兄弟，那么沿該右兄弟的第一個(gè)孩子一直向下搜索直到?jīng)]有孩子結(jié)點(diǎn)為止。代碼如下：
1 template<typename T>
2 template<bool is_const,bool is_reverse>
3 inline void mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::forward_next()
4 {
5 node_pointer_type p_node = &(*tree_)[off_];
6 while (off_!=root_&&p_node->parent_&&!p_node->next_sibling_)
7 {
8 off_ -= p_node->parent_;
9 p_node = &(*tree_)[off_];
10 }
11 if (off_==root_||!p_node->parent_)
12 {
13 off_ = tree_->size();
14 return;
15 }
16 off_ += p_node->next_sibling_; p_node = &(*tree_)[off_];
17 while (p_node->first_child_)
18 {
19 off_ += p_node->first_child_;
20 p_node = &(*tree_)[off_];
21 }
22 } （4）forward_prev：求正向前一個(gè)葉子，步驟如下：a) 如果當(dāng)前結(jié)點(diǎn)不是子樹(shù)根結(jié)點(diǎn)且存在父親但沒(méi)有左兄弟，那么就一直向上回溯直到結(jié)點(diǎn)為子樹(shù)根結(jié)點(diǎn)或不存在父親或存在左兄弟為止，反之轉(zhuǎn)到b)。b) 如果當(dāng)前結(jié)點(diǎn)是子樹(shù)根結(jié)點(diǎn)或沒(méi)有父親，那么返回end，否則轉(zhuǎn)到c)。c) 這時(shí)存在左兄弟，那么沿該左兄弟的最后一個(gè)孩子一直向下搜索直到?jīng)]有孩子結(jié)點(diǎn)為止，代碼如下：
1 template<typename T>
2 template<bool is_const,bool is_reverse>
3 inline void mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::forward_prev()
4 {
5 node_pointer_type p_node = &(*tree_)[off_];
6 while (off_!=root_&&p_node->parent_&&!p_node->prev_sibling_)
7 {
8 off_ -= p_node->parent_;
9 p_node = &(*tree_)[off_];
10 }
11 if (off_==root_||!p_node->parent_)
12 {
13 off_ = tree_->size();
14 return;
15 }
16 off_ -= p_node->prev_sibling_; p_node = &(*tree_)[off_];
17 while (p_node->last_child_)
18 {
19 off_ += p_node->last_child_;
20 p_node = &(*tree_)[off_];
21 }
22 } （5）構(gòu)造函數(shù)的實(shí)現(xiàn)，代碼如下：
1 template<typename T>
2 template<bool is_const,bool is_reverse>
3 inline mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::leaf_iterator_impl()
4 :base_type()
5 {
6 root_ = 0;
7 }
8 template<typename T>
9 template<bool is_const,bool is_reverse>
10 inline mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::leaf_iterator_impl(const base_type& iter)
11 :base_type(iter)
12 {
13 root_ = off_;
14 } （6）公有方法的實(shí)現(xiàn)，代碼如下：
1 template<typename T>
2 template<bool is_const,bool is_reverse>
3 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>&
4 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator++()
5 {
6 increment(typename reverse_trait<is_reverse>::type());
7 return *this;
8 }
9 template<typename T>
10 template<bool is_const,bool is_reverse>
11 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>&
12 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator--()
13 {
14 decrement(typename reverse_trait<is_reverse>::type());
15 return *this;
16 }
17 template<typename T>
18 template<bool is_const,bool is_reverse>
19 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>
20 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator++(int)
21 {
22 leaf_iterator_impl<is_const,is_reverse> iter(*this);
23 ++(*this);
24 return iter;
25 }
26 template<typename T>
27 template<bool is_const,bool is_reverse>
28 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>
29 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator--(int)
30 {
31 leaf_iterator_impl<is_const,is_reverse> iter(*this);
32 --(*this);
33 return iter;
34 }
35 template<typename T>
36 template<bool is_const,bool is_reverse>
37 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>
38 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator + (size_t off)
39 {
40 leaf_iterator_impl<is_const,is_reverse> iter(*this);
41 iter += off;
42 return iter;
43 }
44 template<typename T>
45 template<bool is_const,bool is_reverse>
46 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>&
47 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator += (size_t off)
48 {
49 while (off)
50 {
51 if (base_type::is_null()) break;
52 ++(*this); --off;
53 }
54 return *this;
55 }
56 template<typename T>
57 template<bool is_const,bool is_reverse>
58 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>
59 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator - (size_t off)
60 {
61 leaf_iterator_impl<is_const,is_reverse> iter(*this);
62 iter -= off;
63 return iter;
64 }
65 template<typename T>
66 template<bool is_const,bool is_reverse>
67 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>&
68 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::operator -= (size_t off)
69 {
70 while (off)
71 {
72 if (base_type::is_null()) break;
73 --(*this); --off;
74 }
75 return *this;
76 }
77 template<typename T>
78 template<bool is_const,bool is_reverse>
79 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>
80 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::begin() const
81 {
82 leaf_iterator_impl<is_const,is_reverse> iter(*this);
83 iter.first(typename reverse_trait<is_reverse>::type());
84 return iter;
85 }
86 template<typename T>
87 template<bool is_const,bool is_reverse>
88 inline typename mtree<T,false>::template leaf_iterator_impl<is_const,is_reverse>
89 mtree<T,false>::leaf_iterator_impl<is_const,is_reverse>::end() const
90 {
91 leaf_iterator_impl<is_const,is_reverse> iter(*this);
92 if(tree_)
93 {
94 iter.off_ = tree_->size();
95 }
96 return iter;
97 }
使用示例 （1）正向遍歷某子樹(shù)的所有葉子，代碼如下：
1
mtree<int,false>::iterator_base node;
2 mtree<int,false>::leaf_iterator it = node;
3 mtree<int,false>::leaf_iterator last = --it.end();
4 for (it = it.begin();it!=it.end();++it)
5
{
6
cout << *it;
7 if (it!=last)
8 cout <<" ";
9
}
（2）反向遍歷某子樹(shù)的所有葉子，代碼如下：
1 mtree<int,false>::iterator_base node;
2 mtree<int,false>::reverse_leaf_iterator r_it = node;
3 mtree<int,false>::reverse_leaf_iterator r_last = --r_it.end();
4 for (r_it = r_it.begin();r_it!=r_it.end();++r_it)
5 {
6 cout << *r_it;
7 if (r_it!=r_last)
8 cout <<" ";
9 }
posted on 2011-08-25 10:35
春秋十二月 閱讀(2204)
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