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
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
#include "diff.h"
#include <algorithm>
#include <iostream>
#include <sstream>
#include <boost/property_tree/xml_parser.hpp>
namespace pt = boost::property_tree;
Diff::Diff()
{
}
Diff::Diff(const std::string& old_version, const std::string& new_version)
{
create(old_version, new_version);
}
std::string Diff::apply(const std::string& old_version) const
{
std::string result{old_version};
if (m_pos0 <= m_pos1 && m_pos1 <= old_version.size()) {
result.erase(m_pos0, m_pos1 - m_pos0);
result.insert(m_pos0, m_data);
}
return result;
}
void Diff::create(const std::string& old_version, const std::string& new_version)
{
auto front_mismatch{std::mismatch(old_version.cbegin(), old_version.cend(), new_version.cbegin(), new_version.cend())};
std::string::difference_type old_pos0 {front_mismatch.first - old_version.cbegin()};
auto& new_pos0 {old_pos0};
// equal
if (old_pos0 == old_version.size() && new_pos0 == new_version.size()) {
m_pos0 = 0;
m_pos1 = 0;
m_data.clear();
return;
}
// append at end
if (old_pos0 == old_version.size()) {
m_pos0 = old_pos0;
m_pos1 = old_pos0;
m_data = new_version.substr(new_pos0);
return;
}
// remove from end
if (new_pos0 == new_version.size()) {
m_pos0 = old_pos0;
m_pos1 = old_version.size();
m_data.clear();
return;
}
auto back_mismatch{std::mismatch(old_version.crbegin(), old_version.crend(), new_version.crbegin(), new_version.crend())};
// i.e. the indices starting from which we can assume equality
size_t old_pos1 {old_version.size() - (back_mismatch.first - old_version.crbegin())};
size_t new_pos1 {new_version.size() - (back_mismatch.second - new_version.crbegin())};
// complete equality is already handled above
// insert at start
if (old_pos1 == 0) {
m_pos0 = 0;
m_pos1 = 0;
m_data = new_version.substr(0, new_pos1);
return;
}
// remove from start
if (new_pos1 == 0) {
m_pos0 = 0;
m_pos1 = old_pos1;
m_data.clear();
return;
}
// re-adjust if search crossed
if (old_pos0 > old_pos1) {
old_pos0 = old_pos1;
new_pos0 = old_pos1;
}
if (new_pos0 > new_pos1) {
old_pos0 = new_pos1;
new_pos0 = new_pos1;
}
// insert in the middle
if (old_pos0 == old_pos1) {
m_pos0 = old_pos0;
m_pos1 = old_pos0;
m_data = new_version.substr(new_pos0, new_pos1 - new_pos0);
return;
}
// remove from the middle
if (new_pos0 == new_pos1) {
m_pos0 = old_pos0;
m_pos1 = old_pos1;
m_data.clear();
return;
}
// last resort: remove and add in the middle
m_pos0 = old_pos0;
m_pos1 = old_pos1;
m_data = new_version.substr(old_pos0, new_pos1 - new_pos0);
}
Diff::Diff(const boost::property_tree::ptree& ptree)
{
create(ptree);
}
void Diff::create(const boost::property_tree::ptree& ptree)
{
m_pos0 = ptree.get<int>("diff.start");
m_pos1 = ptree.get<int>("diff.end");
if (m_pos0 > m_pos1)
throw std::runtime_error("Bad range in diff");
m_data = ptree.get<std::string>("diff.data");
}
Diff::Diff(const std::string& xml)
{
create(xml);
}
void Diff::create(const std::string& xml)
{
pt::ptree ptree;
std::istringstream ss{xml};
pt::read_xml(ss, ptree, pt::xml_parser::no_comments | pt::xml_parser::trim_whitespace);
create(ptree);
}
bool Diff::empty() const
{
return m_pos0 == m_pos1 && m_data.empty();
}
boost::property_tree::ptree Diff::get_structure() const
{
pt::ptree ptree;
ptree.put("diff.start", std::to_string(m_pos0));
ptree.put("diff.end", std::to_string(m_pos1));
ptree.put("diff.data", m_data);
return ptree;
}
std::string Diff::get_xml() const
{
pt::ptree ptree{get_structure()};
std::ostringstream oss;
// write_xml_element instead of write_xml to omit <!xml...> header
//pt::xml_parser::write_xml(oss, xml);
pt::xml_parser::write_xml_element(oss, {}, ptree, -1, boost::property_tree::xml_writer_settings<pt::ptree::key_type>{});
return oss.str();
}
extern "C" {
const char* diff_create(const char* old_version, const char* new_version)
{
Diff diff{old_version, new_version};
return strdup(diff.get_xml().c_str());
}
const char* diff_apply(const char* old_version, const char* diff)
{
Diff d{diff};
return strdup(d.apply(old_version).c_str());
}
}
|
