1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include <string.h>
16
17 #include <cctype>
18 #include <cstdint>
19 #include <utility>
20
21 #include "absl/strings/match.h"
22 #include "absl/strings/string_view.h"
23 #include "absl/time/internal/cctz/include/cctz/time_zone.h"
24 #include "absl/time/time.h"
25
26 namespace cctz = absl::time_internal::cctz;
27
28 namespace absl {
29 ABSL_NAMESPACE_BEGIN
30
31 ABSL_DLL extern const char RFC3339_full[] = "%Y-%m-%d%ET%H:%M:%E*S%Ez";
32 ABSL_DLL extern const char RFC3339_sec[] = "%Y-%m-%d%ET%H:%M:%S%Ez";
33
34 ABSL_DLL extern const char RFC1123_full[] = "%a, %d %b %E4Y %H:%M:%S %z";
35 ABSL_DLL extern const char RFC1123_no_wday[] = "%d %b %E4Y %H:%M:%S %z";
36
37 namespace {
38
39 const char kInfiniteFutureStr[] = "infinite-future";
40 const char kInfinitePastStr[] = "infinite-past";
41
42 struct cctz_parts {
43 cctz::time_point<cctz::seconds> sec;
44 cctz::detail::femtoseconds fem;
45 };
46
unix_epoch()47 inline cctz::time_point<cctz::seconds> unix_epoch() {
48 return std::chrono::time_point_cast<cctz::seconds>(
49 std::chrono::system_clock::from_time_t(0));
50 }
51
52 // Splits a Time into seconds and femtoseconds, which can be used with CCTZ.
53 // Requires that 't' is finite. See duration.cc for details about rep_hi and
54 // rep_lo.
Split(absl::Time t)55 cctz_parts Split(absl::Time t) {
56 const auto d = time_internal::ToUnixDuration(t);
57 const int64_t rep_hi = time_internal::GetRepHi(d);
58 const int64_t rep_lo = time_internal::GetRepLo(d);
59 const auto sec = unix_epoch() + cctz::seconds(rep_hi);
60 const auto fem = cctz::detail::femtoseconds(rep_lo * (1000 * 1000 / 4));
61 return {sec, fem};
62 }
63
64 // Joins the given seconds and femtoseconds into a Time. See duration.cc for
65 // details about rep_hi and rep_lo.
Join(const cctz_parts & parts)66 absl::Time Join(const cctz_parts& parts) {
67 const int64_t rep_hi = (parts.sec - unix_epoch()).count();
68 const uint32_t rep_lo =
69 static_cast<uint32_t>(parts.fem.count() / (1000 * 1000 / 4));
70 const auto d = time_internal::MakeDuration(rep_hi, rep_lo);
71 return time_internal::FromUnixDuration(d);
72 }
73
74 } // namespace
75
FormatTime(absl::string_view format,absl::Time t,absl::TimeZone tz)76 std::string FormatTime(absl::string_view format, absl::Time t,
77 absl::TimeZone tz) {
78 if (t == absl::InfiniteFuture()) return std::string(kInfiniteFutureStr);
79 if (t == absl::InfinitePast()) return std::string(kInfinitePastStr);
80 const auto parts = Split(t);
81 return cctz::detail::format(std::string(format), parts.sec, parts.fem,
82 cctz::time_zone(tz));
83 }
84
FormatTime(absl::Time t,absl::TimeZone tz)85 std::string FormatTime(absl::Time t, absl::TimeZone tz) {
86 return FormatTime(RFC3339_full, t, tz);
87 }
88
FormatTime(absl::Time t)89 std::string FormatTime(absl::Time t) {
90 return absl::FormatTime(RFC3339_full, t, absl::LocalTimeZone());
91 }
92
ParseTime(absl::string_view format,absl::string_view input,absl::Time * time,std::string * err)93 bool ParseTime(absl::string_view format, absl::string_view input,
94 absl::Time* time, std::string* err) {
95 return absl::ParseTime(format, input, absl::UTCTimeZone(), time, err);
96 }
97
98 // If the input string does not contain an explicit UTC offset, interpret
99 // the fields with respect to the given TimeZone.
ParseTime(absl::string_view format,absl::string_view input,absl::TimeZone tz,absl::Time * time,std::string * err)100 bool ParseTime(absl::string_view format, absl::string_view input,
101 absl::TimeZone tz, absl::Time* time, std::string* err) {
102 auto strip_leading_space = [](absl::string_view* sv) {
103 while (!sv->empty()) {
104 if (!std::isspace(sv->front())) return;
105 sv->remove_prefix(1);
106 }
107 };
108
109 // Portable toolchains means we don't get nice constexpr here.
110 struct Literal {
111 const char* name;
112 size_t size;
113 absl::Time value;
114 };
115 static Literal literals[] = {
116 {kInfiniteFutureStr, strlen(kInfiniteFutureStr), InfiniteFuture()},
117 {kInfinitePastStr, strlen(kInfinitePastStr), InfinitePast()},
118 };
119 strip_leading_space(&input);
120 for (const auto& lit : literals) {
121 if (absl::StartsWith(input, absl::string_view(lit.name, lit.size))) {
122 absl::string_view tail = input;
123 tail.remove_prefix(lit.size);
124 strip_leading_space(&tail);
125 if (tail.empty()) {
126 *time = lit.value;
127 return true;
128 }
129 }
130 }
131
132 std::string error;
133 cctz_parts parts;
134 const bool b =
135 cctz::detail::parse(std::string(format), std::string(input),
136 cctz::time_zone(tz), &parts.sec, &parts.fem, &error);
137 if (b) {
138 *time = Join(parts);
139 } else if (err != nullptr) {
140 *err = std::move(error);
141 }
142 return b;
143 }
144
145 // Functions required to support absl::Time flags.
AbslParseFlag(absl::string_view text,absl::Time * t,std::string * error)146 bool AbslParseFlag(absl::string_view text, absl::Time* t, std::string* error) {
147 return absl::ParseTime(RFC3339_full, text, absl::UTCTimeZone(), t, error);
148 }
149
AbslUnparseFlag(absl::Time t)150 std::string AbslUnparseFlag(absl::Time t) {
151 return absl::FormatTime(RFC3339_full, t, absl::UTCTimeZone());
152 }
ParseFlag(const std::string & text,absl::Time * t,std::string * error)153 bool ParseFlag(const std::string& text, absl::Time* t, std::string* error) {
154 return absl::ParseTime(RFC3339_full, text, absl::UTCTimeZone(), t, error);
155 }
156
UnparseFlag(absl::Time t)157 std::string UnparseFlag(absl::Time t) {
158 return absl::FormatTime(RFC3339_full, t, absl::UTCTimeZone());
159 }
160
161 ABSL_NAMESPACE_END
162 } // namespace absl
163