Reapply "Refactor Date implementation in VM."

runtime/vm/os.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_OS_H_
 #define VM_OS_H_
 
 #include "vm/globals.h"
 
 // Forward declarations.
 class tm;
 
 namespace dart {
 
 // Forward declarations.
 class Isolate;
 
 // Interface to the underlying OS platform.
 class OS {
  public:
-  // Takes the seconds since epoch (midnight, January 1, 1970 UTC) and breaks it
-  // down into date and time in the UTC timezone.
-  // The returned year is offset by 1900. The returned month is 0-based.
-  // Returns true if the conversion succeeds, false otherwise.
-  static bool GmTime(int64_t seconds_since_epoch, tm* tm_result);
-
-  // Takes the seconds since epoch (midnight, January 1, 1970 UTC) and breaks it
-  // down into date and time in the local time.
-  // The returned year is offset by 1900. The returned month is 0-based.
-  // Returns true if the conversion succeeds, false otherwise.
-  static bool LocalTime(int64_t seconds_since_epoch, tm* tm_result);
-
-  // Takes the broken down date and time in UTC timezone and computes the
-  // seconds since epoch (midnight, January 1, 1970 UTC).
-  // The given year is offset by 1900. The given month is 0-based.
-  // Returns true if the conversion succeeds, false otherwise.
-  static bool MkGmTime(tm* tm, int64_t* seconds_result);
-
-  // Takes the broken down date and time in local timezone and computes the
-  // seconds since epoch (midnight, January 1, 1970 UTC).
-  // The given year is offset by 1900. The given month is 0-based.
-  // Returns true if the conversion succeeds, false otherwise.
-  static bool MkTime(tm* tm, int64_t* seconds_result);
-
   // Returns the abbreviated time-zone name for the given instant.
   // For example "CET" or "CEST".
-  static bool GetTimeZoneName(int64_t seconds_since_epoch,
-                              const char** name_result);
+  static const char* GetTimeZoneName(int64_t seconds_since_epoch);
 
   // Returns the difference in seconds between local time and UTC for the given
   // instant.
   // For example 3600 for CET, and 7200 for CEST.
-  static bool GetTimeZoneOffsetInSeconds(int64_t seconds_since_epoch,
-                                         int* offset_result);
+  static int GetTimeZoneOffsetInSeconds(int64_t seconds_since_epoch);
+
+  // Returns the difference in seconds between local time and UTC when no
+  // daylight saving is active.
+  // For example 3600 in CET and CEST.
+  static int GetLocalTimeZoneAdjustmentInSeconds();
 
   // Returns the current time in milliseconds measured
   // from midnight January 1, 1970 UTC.
   static int64_t GetCurrentTimeMillis();
 
   // Returns the current time in microseconds measured
   // from midnight January 1, 1970 UTC.
   static int64_t GetCurrentTimeMicros();
 
   // Returns the activation frame alignment constraint or zero if
@@ skipping 43 matching lines @@
   static void Shutdown();
 
   static void Abort();
 
   static void Exit(int code);
 };
 
 }  // namespace dart
 
 #endif  // VM_OS_H_