AceTime
1.0
Date and time classes for Arduino that support timezones from the TZ Database, and a system clock that can synchronize from an NTP server or an RTC chip.
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An implementation of ZoneProcessor that supports a subset of the zones containing in the TZ Database. More...
#include <BasicZoneProcessor.h>
Public Member Functions | |
BasicZoneProcessor (const basic::ZoneInfo *zoneInfo=nullptr) | |
Constructor. More... | |
const void * | getZoneInfo () const override |
Return the underlying ZoneInfo. More... | |
uint32_t | getZoneId () const override |
Return the unique stable zoneId. More... | |
TimeOffset | getUtcOffset (acetime_t epochSeconds) const override |
Return the total UTC offset at epochSeconds, including DST offset. More... | |
TimeOffset | getDeltaOffset (acetime_t epochSeconds) const override |
Return the DST delta offset at epochSeconds. More... | |
const char * | getAbbrev (acetime_t epochSeconds) const override |
Return the time zone abbreviation at epochSeconds. More... | |
OffsetDateTime | getOffsetDateTime (const LocalDateTime &ldt) const override |
void | printTo (Print &printer) const override |
Print a human-readable identifier (e.g. More... | |
void | printShortTo (Print &printer) const override |
Print a short human-readable identifier (e.g. More... | |
void | log () const |
Used only for debugging. More... | |
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uint8_t | getType () const |
Return the kTypeXxx of the current instance. More... | |
Static Public Member Functions | |
static basic::MonthDay | calcStartDayOfMonth (int16_t year, uint8_t month, uint8_t onDayOfWeek, int8_t onDayOfMonth) |
Calculate the actual (month, day) of the expresssion (onDayOfWeek >= onDayOfMonth) or (onDayOfWeek <= onDayOfMonth). More... | |
Additional Inherited Members | |
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static const uint8_t | kTypeBasic = 2 |
Indicate BasicZoneProcessor. More... | |
static const uint8_t | kTypeExtended = 3 |
Indicate ExtendedZoneProcessor. More... | |
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ZoneProcessor (const ZoneProcessor &)=delete | |
ZoneProcessor & | operator= (const ZoneProcessor &)=delete |
ZoneProcessor (uint8_t type) | |
Constructor. More... | |
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uint8_t | mType |
An implementation of ZoneProcessor that supports a subset of the zones containing in the TZ Database.
The supported list of zones, as well as the list of unsupported zones, are is listed in the zonedb/zone_info.h header file. The constructor expects a pointer to one of the ZoneInfo structures declared in the zone_infos.h file.
The internal ZoneRule and ZoneEra records that match the year of the given epochSeconds are cached for performance. The expectation is that repeated calls to the various methods will have epochSeconds which do not vary too greatly and will occur in the same year.
The Rule records are transition points which look like this:
* Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S *
Each record is represented by basic::ZoneRule and the entire collection is represented by basic::ZonePolicy.
The Zone records define the region which follows a specific set of Rules for certain time periods (given by UNTIL below):
* Zone NAME GMTOFF RULES FORMAT [UNTIL] *
Each record is represented by basic::ZoneEra and the entire collection is represented by basic::ZoneInfo.
This class assumes that the various components of ZoneInfo, ZoneEra, and ZonePolicy, ZoneRule have a number of limitations and constraints which simplify the implementation of this class. The tzcompiler.py script will remove zones which do not meet these constraints when generating the structs defined by zonedb/zone_infos.h. The constraints are at least the following (see tools/transformer.py for the authoratative algorithm):
Even with these limitations, zonedb/zone_info.h shows that 270 out of a total of 387 zones are supported by BasicZoneProcessor (as of v0.8).
Not thread-safe.
Definition at line 204 of file BasicZoneProcessor.h.
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inlineexplicit |
Constructor.
The ZoneInfo is given only for unit tests.
zoneInfo | pointer to a ZoneInfo. |
Definition at line 210 of file BasicZoneProcessor.h.
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inlinestatic |
Calculate the actual (month, day) of the expresssion (onDayOfWeek >= onDayOfMonth) or (onDayOfWeek <= onDayOfMonth).
There are 4 combinations:
* onDayOfWeek=0, onDayOfMonth=(1-31): exact match * onDayOfWeek=1-7, onDayOfMonth=1-31: dayOfWeek>=dayOfMonth * onDayOfWeek=1-7, onDayOfMonth=0: last{dayOfWeek} * onDayOfWeek=1-7, onDayOfMonth=-(1-31): dayOfWeek<=dayOfMonth *
Caveats: This method handles expressions which crosses month boundaries, but not year boundaries (e.g. Jan to Dec of the previous year, or Dec to Jan of the following year.)
Not private, used by ExtendedZoneProcessor.
Definition at line 352 of file BasicZoneProcessor.h.
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inlineoverridevirtual |
Return the time zone abbreviation at epochSeconds.
Returns an empty string ("") if an error occurs. The returned pointer points to a char buffer that could get overriden by subsequent method calls to this object. The pointer must not be stored permanently, it should be used as soon as possible (e.g. printed out).
This is an experimental method that has not been tested thoroughly. Use with caution.
Implements ace_time::ZoneProcessor.
Definition at line 235 of file BasicZoneProcessor.h.
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inlineoverridevirtual |
Return the DST delta offset at epochSeconds.
This is an experimental method that has not been tested thoroughly. Use with caution. Returns TimeOffset::forError() if an error occurs.
Implements ace_time::ZoneProcessor.
Definition at line 228 of file BasicZoneProcessor.h.
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inlineoverridevirtual |
The Transitions calculated by BasicZoneProcessor contain only the epochSeconds when each transition occurs. They do not contain the local date/time components of the transition. This design reduces the amount of memory required by BasicZoneProcessor, but this means that the information needed to implement this method correctly does not exist.
The implementation is somewhat of a hack:
0) Use the localDateTime to extract the offset, assuming that the localDatetime is UTC. This will get us within 12-14h of the correct UTC offset. 1) Use (localDateTime, offset0) to determine offset1. 2) Use (localdateTime, offset1) to determine offset2. 3) Finally, check if offset1 and offset2 are equal. If they are we reached equilibrium so we can just return (localDateTime, offset1). If they are not equal, then we have a cycle because the localDateTime occurred in a DST gap (STD->DST transition) or overlap (DST->STD transition). We arbitrarily pick the offset of the later epochSeconds since that seems to match closely to what most people would expect to happen in a gap or overlap (e.g. In the gap of 2am->3am, a 2:30am would get shifted to 3:30am.)
The code is written slightly ackwardly to try to encourage the compiler to perform Return Value Optimization. For example, I use only a single OffsetDateTime instance, and I don't use early return.
Implements ace_time::ZoneProcessor.
Definition at line 269 of file BasicZoneProcessor.h.
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inlineoverridevirtual |
Return the total UTC offset at epochSeconds, including DST offset.
Returns TimeOffset::forError() if an error occurs.
Implements ace_time::ZoneProcessor.
Definition at line 221 of file BasicZoneProcessor.h.
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inlineoverridevirtual |
Return the unique stable zoneId.
Implements ace_time::ZoneProcessor.
Definition at line 219 of file BasicZoneProcessor.h.
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inlineoverridevirtual |
Return the underlying ZoneInfo.
Implements ace_time::ZoneProcessor.
Definition at line 215 of file BasicZoneProcessor.h.
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inline |
Used only for debugging.
Definition at line 318 of file BasicZoneProcessor.h.
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overridevirtual |
Print a short human-readable identifier (e.g.
"Los_Angeles")
Implements ace_time::ZoneProcessor.
Definition at line 16 of file BasicZoneProcessor.cpp.
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overridevirtual |
Print a human-readable identifier (e.g.
"America/Los_Angeles").
Implements ace_time::ZoneProcessor.
Definition at line 12 of file BasicZoneProcessor.cpp.