1 files changed, 133 insertions, 0 deletions
diff --git a/absl/time/internal/cctz/src/time_zone_fixed.cc b/absl/time/internal/cctz/src/time_zone_fixed.cc
new file mode 100644
index 000000000000..8d3b1442524c
--- /dev/null
+++ b/absl/time/internal/cctz/src/time_zone_fixed.cc
@@ -0,0 +1,133 @@
+// 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 <chrono>
+#include <cstdio>
+#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/";
+
+int Parse02d(const char* p) {
+  static const char kDigits[] = "0123456789";
+  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, sys_seconds* offset) {
+  if (name.compare(0, std::string::npos, "UTC", 3) == 0) {
+    *offset = sys_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 + 12)  // "<prefix>UTC+99:99:99"
+    return false;
+  if (!std::equal(kFixedOffsetPrefix, ep, name.begin()))
+    return false;
+  const char* np = name.data() + prefix_len;
+  if (*np++ != 'U' || *np++ != 'T' || *np++ != 'C')
+    return false;
+  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 = sys_seconds(secs * (np[0] == '-' ? -1 : 1));  // "-" means west
+  return true;
+}
+
+std::string FixedOffsetToName(const sys_seconds& offset) {
+  if (offset == sys_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) + sizeof("UTC-24:00:00")];
+  snprintf(buf, sizeof(buf), "%sUTC%c%02d:%02d:%02d",
+           kFixedOffsetPrefix, sign, hours, minutes, seconds);
+  return buf;
+}
+
+std::string FixedOffsetToAbbr(const sys_seconds& offset) {
+  std::string abbr = FixedOffsetToName(offset);
+  const std::size_t prefix_len = sizeof(kFixedOffsetPrefix) - 1;
+  const char* const ep = kFixedOffsetPrefix + prefix_len;
+  if (abbr.size() >= prefix_len) {
+    if (std::equal(kFixedOffsetPrefix, ep, abbr.begin())) {
+      abbr.erase(0, prefix_len);
+      if (abbr.size() == 12) {                     // UTC+99:99:99
+        abbr.erase(9, 1);                          // UTC+99:9999
+        abbr.erase(6, 1);                          // UTC+999999
+        if (abbr[8] == '0' && abbr[9] == '0') {    // UTC+999900
+          abbr.erase(8, 2);                        // UTC+9999
+          if (abbr[6] == '0' && abbr[7] == '0') {  // UTC+9900
+            abbr.erase(6, 2);                      // UTC+99
+            if (abbr[4] == '0') {                  // UTC+09
+              abbr.erase(4, 1);                    // UTC+9
+            }
+          }
+        }
+      }
+    }
+  }
+  return abbr;
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl