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
|
// Copyright 2016 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "time_zone_fixed.h"
#include <algorithm>
#include <cassert>
#include <chrono>
#include <cstring>
#include <string>
namespace absl {
namespace time_internal {
namespace cctz {
namespace {
// The prefix used for the internal names of fixed-offset zones.
const char kFixedOffsetPrefix[] = "Fixed/UTC";
const char kDigits[] = "0123456789";
char* Format02d(char* p, int v) {
*p++ = kDigits[(v / 10) % 10];
*p++ = kDigits[v % 10];
return p;
}
int Parse02d(const char* p) {
if (const char* ap = std::strchr(kDigits, *p)) {
int v = static_cast<int>(ap - kDigits);
if (const char* bp = std::strchr(kDigits, *++p)) {
return (v * 10) + static_cast<int>(bp - kDigits);
}
}
return -1;
}
} // namespace
bool FixedOffsetFromName(const std::string& name, seconds* offset) {
if (name.compare(0, std::string::npos, "UTC", 3) == 0) {
*offset = seconds::zero();
return true;
}
const std::size_t prefix_len = sizeof(kFixedOffsetPrefix) - 1;
const char* const ep = kFixedOffsetPrefix + prefix_len;
if (name.size() != prefix_len + 9) // <prefix>+99:99:99
return false;
if (!std::equal(kFixedOffsetPrefix, ep, name.begin()))
return false;
const char* np = name.data() + prefix_len;
if (np[0] != '+' && np[0] != '-')
return false;
if (np[3] != ':' || np[6] != ':') // see note below about large offsets
return false;
int hours = Parse02d(np + 1);
if (hours == -1) return false;
int mins = Parse02d(np + 4);
if (mins == -1) return false;
int secs = Parse02d(np + 7);
if (secs == -1) return false;
secs += ((hours * 60) + mins) * 60;
if (secs > 24 * 60 * 60) return false; // outside supported offset range
*offset = seconds(secs * (np[0] == '-' ? -1 : 1)); // "-" means west
return true;
}
std::string FixedOffsetToName(const seconds& offset) {
if (offset == seconds::zero()) return "UTC";
if (offset < std::chrono::hours(-24) || offset > std::chrono::hours(24)) {
// We don't support fixed-offset zones more than 24 hours
// away from UTC to avoid complications in rendering such
// offsets and to (somewhat) limit the total number of zones.
return "UTC";
}
int seconds = static_cast<int>(offset.count());
const char sign = (seconds < 0 ? '-' : '+');
int minutes = seconds / 60;
seconds %= 60;
if (sign == '-') {
if (seconds > 0) {
seconds -= 60;
minutes += 1;
}
seconds = -seconds;
minutes = -minutes;
}
int hours = minutes / 60;
minutes %= 60;
char buf[sizeof(kFixedOffsetPrefix) - 1 + sizeof("-24:00:00")];
std::strcpy(buf, kFixedOffsetPrefix);
char* ep = buf + sizeof(kFixedOffsetPrefix) - 1;
*ep++ = sign;
ep = Format02d(ep, hours);
*ep++ = ':';
ep = Format02d(ep, minutes);
*ep++ = ':';
ep = Format02d(ep, seconds);
*ep++ = '\0';
assert(ep == buf + sizeof(buf));
return buf;
}
std::string FixedOffsetToAbbr(const seconds& offset) {
std::string abbr = FixedOffsetToName(offset);
const std::size_t prefix_len = sizeof(kFixedOffsetPrefix) - 1;
if (abbr.size() == prefix_len + 9) { // <prefix>+99:99:99
abbr.erase(0, prefix_len); // +99:99:99
abbr.erase(6, 1); // +99:9999
abbr.erase(3, 1); // +999999
if (abbr[5] == '0' && abbr[6] == '0') { // +999900
abbr.erase(5, 2); // +9999
if (abbr[3] == '0' && abbr[4] == '0') { // +9900
abbr.erase(3, 2); // +99
}
}
}
return abbr;
}
} // namespace cctz
} // namespace time_internal
} // namespace absl
|
