1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
// Copyright Nat Goodspeed 2013.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSEstd::placeholders::_1_0.txt or copy at
// http://www.boost.org/LICENSEstd::placeholders::_1_0.txt)
#include <cstddef>
#include <cstdlib>
#include <iostream>
#include <iterator>
#include <string>
#include <utility>
#include <boost/coroutine2/all.hpp>
struct node {
typedef std::shared_ptr< node > ptr_t;
// Each tree node has an optional left subtree, an optional right subtree
// and a value of its own. The value is considered to be between the left
// subtree and the right.
ptr_t left, right;
std::string value;
// construct leaf
node(const std::string& v):
left(),right(),value(v) {
}
// construct nonleaf
node(ptr_t l, const std::string& v, ptr_t r):
left(l),right(r),value(v) {
}
static ptr_t create(const std::string& v) {
return ptr_t(new node(v));
}
static ptr_t create(ptr_t l, const std::string& v, ptr_t r) {
return ptr_t(new node(l, v, r));
}
};
node::ptr_t create_left_tree_from(const std::string& root) {
/* --------
root
/ \
b e
/ \
a c
-------- */
return node::create(
node::create(
node::create("a"),
"b",
node::create("c")),
root,
node::create("e"));
}
node::ptr_t create_right_tree_from(const std::string& root) {
/* --------
root
/ \
a d
/ \
c e
-------- */
return node::create(
node::create("a"),
root,
node::create(
node::create("c"),
"d",
node::create("e")));
}
// recursively walk the tree, delivering values in order
void traverse(node::ptr_t n, boost::coroutines2::coroutine<std::string>::push_type& out) {
if (n->left)
traverse(n->left,out);
out(n->value);
if (n->right)
traverse(n->right,out);
}
int main() {
{
node::ptr_t left_d(create_left_tree_from("d"));
node::ptr_t right_b(create_right_tree_from("b"));
node::ptr_t right_x(create_right_tree_from("x"));
{
boost::coroutines2::coroutine<std::string>::pull_type left_d_reader(
[&]( boost::coroutines2::coroutine<std::string>::push_type & out) {
traverse(left_d,out);
});
std::cout << "left tree from d:\n";
std::copy(std::begin(left_d_reader),
std::end(left_d_reader),
std::ostream_iterator<std::string>(std::cout, " "));
std::cout << std::endl;
boost::coroutines2::coroutine<std::string>::pull_type right_b_reader(
[&]( boost::coroutines2::coroutine<std::string>::push_type & out) {
traverse(right_b,out);
});
std::cout << "right tree from b:\n";
std::copy(std::begin(right_b_reader),
std::end(right_b_reader),
std::ostream_iterator<std::string>(std::cout, " "));
std::cout << std::endl;
boost::coroutines2::coroutine<std::string>::pull_type right_x_reader(
[&]( boost::coroutines2::coroutine<std::string>::push_type & out) {
traverse(right_x,out);
});
std::cout << "right tree from x:\n";
std::copy(std::begin(right_x_reader),
std::end(right_x_reader),
std::ostream_iterator<std::string>(std::cout, " "));
std::cout << std::endl;
}
}
{
node::ptr_t left_d(create_left_tree_from("d"));
node::ptr_t right_b(create_right_tree_from("b"));
{
boost::coroutines2::coroutine<std::string>::pull_type left_d_reader(
[&]( boost::coroutines2::coroutine<std::string>::push_type & out) {
traverse(left_d,out);
});
boost::coroutines2::coroutine<std::string>::pull_type right_b_reader(
[&]( boost::coroutines2::coroutine<std::string>::push_type & out) {
traverse(right_b,out);
});
std::cout << "left tree from d == right tree from b? "
<< std::boolalpha
<< std::equal(std::begin(left_d_reader),
std::end(left_d_reader),
std::begin(right_b_reader))
<< std::endl;
}
}
{
node::ptr_t left_d(create_left_tree_from("d"));
node::ptr_t right_x(create_right_tree_from("x"));
{
boost::coroutines2::coroutine<std::string>::pull_type left_d_reader(
[&]( boost::coroutines2::coroutine<std::string>::push_type & out) {
traverse(left_d,out);
});
boost::coroutines2::coroutine<std::string>::pull_type right_x_reader(
[&]( boost::coroutines2::coroutine<std::string>::push_type & out) {
traverse(right_x,out);
});
std::cout << "left tree from d == right tree from x? "
<< std::boolalpha
<< std::equal(std::begin(left_d_reader),
std::end(left_d_reader),
std::begin(right_x_reader))
<< std::endl;
}
}
std::cout << "Done" << std::endl;
return EXIT_SUCCESS;
}
|
