{Basic,Extended}ZoneProcessor.h: replace range checks against startYe…

…ar(), untilYear()

After the recent clean up of tiny years, and the addition
ZoneContext.startYearAccurate() and ZoneContext.untilYearAccurate(), the range
checks against ZoneContext.startYear() and ZoneContext.untilYear() are not
valid. The zone processors will return something reasonable for all years, even
if the DST transitions are not accurate. Instead, use the hardcoded
LocalDate::kMinYear and LocalDate::kMaxYear, mostly for formatting reasons
(negative years, and years using more than 4 digits).

CHANGELOG.md

@@ -37,6 +37,16 @@
         * Add `zonedbc` database which is valid from `[1800,10000)`, which
           includes all transitions in the TZDB.
         * Add `--scope complete` to access the `zonedbc` database.
+    * Zone Processors
+        * Remove range checks against `ZoneContext.startYear()` and
+          `ZoneContext.untilYear()`
+        * Replace with hardcoded `LocalDate::kMinYear` and
+          `LocalDate::kMaxYear`, mostly for formatting reasons (prevent negative
+          years, and years with more than 4 digits).
+        * The zone processors will always return something reasonble across the
+          entire `int16_t` range.
+        * Only the accuracy suffers outside of the `startYearAccurate()` and
+         `untilYearAccurate()` limits.
     * Rename `src/tzonedb*` directories to `src/zonedb*testing` for consistency
       with other acetime libraries.
     * Move `ZoneContext`, `letters[]`, `fragments[]` into PROGMEM.

src/ace_time/BasicZoneProcessor.h

@@ -472,8 +472,7 @@ class BasicZoneProcessorTemplate: public ZoneProcessor {
       mEpochYear = Epoch::currentEpochYear();
       mNumTransitions = 0; // clear cache
 
-      if (year < mZoneInfoBroker.zoneContext().startYear() - 1
-          || mZoneInfoBroker.zoneContext().untilYear() < year) {
+      if (year < LocalDate::kMinYear || LocalDate::kMaxYear < year) {
         return false;
       }
 

src/ace_time/ExtendedZoneProcessor.h

@@ -321,14 +321,11 @@ class ExtendedZoneProcessorTemplate: public ZoneProcessor {
       mNumMatches = 0; // clear cache
       mTransitionStorage.init();
 
-      if (year < mZoneInfoBroker.zoneContext().startYear() - 1
-          || mZoneInfoBroker.zoneContext().untilYear() < year) {
+      if (year < LocalDate::kMinYear || LocalDate::kMaxYear < year) {
         if (ACE_TIME_EXTENDED_ZONE_PROCESSOR_DEBUG) {
           logging::printf(
               "initForYear(): Year %d out of valid range [%d, %d)\n",
-              year,
-              mZoneInfoBroker.zoneContext().startYear(),
-              mZoneInfoBroker.zoneContext().untilYear());
+              year, LocalDate::kMinYear, LocalDate::kMaxYear);
         }
         return false;
       }

tests/BasicZoneProcessorTest/BasicZoneProcessorTest.ino

@@ -414,28 +414,30 @@ test(BasicZoneProcessorTest, findByEpochSeconds_outOfBounds) {
   EpochYearContext context(2000); // set epoch year to 2000 temporarily
   OffsetDateTime dt;
   acetime_t epochSeconds;
-  FindResult result;
 
-  ZoneContextBroker broker = ZoneContextBroker(&kZoneContext);
-  assertEqual(1980, broker.startYear());
-  assertEqual(2200, broker.untilYear());
+  ZoneContextBroker zoneContextBroker = ZoneContextBroker(&kZoneContext);
+  assertEqual(1980, zoneContextBroker.startYear());
+  assertEqual(2200, zoneContextBroker.untilYear());
+  assertEqual(1980, zoneContextBroker.startYearAccurate());
+  assertEqual(ZoneContext::kMaxUntilYear,
+      zoneContextBroker.untilYearAccurate());
 
-  // 1970 > LocalDate::kMinYear so dt is valid, and
+  // 1970 > LocalDate::kMinYear so we can create an OffsetDateTime.
   dt = OffsetDateTime::forComponents(1970, 3, 11, 1, 59, 59,
       TimeOffset::forHours(-8));
   assertFalse(dt.isError());
-  // 1970 is within roughly 50 years of Epoch::currentEpochYear() of 2050
-  // so toEpochSeconds() still works.
+  // 1970 is less than 68 years (INT32_MAX seconds) away from
+  // Epoch::currentEpochYear() of 2000 so toEpochSeconds() works.
   epochSeconds = dt.toEpochSeconds();
   assertNotEqual(epochSeconds, LocalDate::kInvalidEpochSeconds);
-  // But 1998 < ZoneContext.startYear, so FindResult not found.
-  result = zoneProcessor.findByEpochSeconds(epochSeconds);
-  assertEqual((int)result.type, (int)FindResult::kTypeNotFound);
+  // FindResult still works, but since 1970 < startYearAccurate(), the
+  // DST transitions may not be accurate.
+  FindResult result = zoneProcessor.findByEpochSeconds(epochSeconds);
+  assertEqual((int)result.type, (int)FindResult::kTypeExact);
 
   // 10001 is beyond LocalDate::kMaxYear so should fail.
   dt = OffsetDateTime::forComponents(10001, 2, 1, 1, 0, 0,
       TimeOffset::forHours(-8));
-  // 10001 > LocalDate::kMaxYear, so fails
   assertTrue(dt.isError());
   // toEpochSeconds() returns invalid seconds
   epochSeconds = dt.toEpochSeconds();

tests/ExtendedZoneProcessorTest/ExtendedZoneProcessorTest.ino

@@ -920,18 +920,22 @@ test(ExtendedZoneProcessorTest, findByEpochSeconds_outOfBounds) {
   ZoneContextBroker zoneContextBroker(&kZoneContext);
   assertEqual(1980, zoneContextBroker.startYear());
   assertEqual(2200, zoneContextBroker.untilYear());
+  assertEqual(1980, zoneContextBroker.startYearAccurate());
+  assertEqual(ZoneContext::kMaxUntilYear,
+      zoneContextBroker.untilYearAccurate());
 
-  // 1970 > LocalDate::kMinYear so dt is valid, and
+  // 1970 > LocalDate::kMinYear so we can create an OffsetDateTime.
   dt = OffsetDateTime::forComponents(1970, 3, 11, 1, 59, 59,
       TimeOffset::forHours(-8));
   assertFalse(dt.isError());
-  // 1998 is within roughly 50 years of Epoch::currentEpochYear() of 2050 so
-  // toEpochSeconds() still works.
+  // 1970 is less than 68 years (INT32_MAX seconds) away from
+  // Epoch::currentEpochYear() of 2000 so toEpochSeconds() still works.
   epochSeconds = dt.toEpochSeconds();
   assertNotEqual(epochSeconds, LocalDate::kInvalidEpochSeconds);
-  // But 1998 < ZoneContext.startYear, so FindResult not found.
+  // FindResult still works, but since 1970 < startYearAccurate(), the
+  // DST transitions may not be accurate.
   FindResult result = zoneProcessor.findByEpochSeconds(epochSeconds);
-  assertEqual(result.type, FindResult::kTypeNotFound);
+  assertEqual(result.type, FindResult::kTypeExact);
 
   // 10001 is beyond LocalDate::kMaxYear so should fail.
   dt = OffsetDateTime::forComponents(10001, 2, 1, 1, 0, 0,
@@ -941,7 +945,6 @@ test(ExtendedZoneProcessorTest, findByEpochSeconds_outOfBounds) {
   // toEpochSeconds() returns invalid seconds
   epochSeconds = dt.toEpochSeconds();
   assertEqual(epochSeconds, LocalDate::kInvalidEpochSeconds);
-
   // findByEpochSeconds() results NotFound for kInvalidEpochSeconds
   result = zoneProcessor.findByEpochSeconds(epochSeconds);
   assertEqual(result.type, FindResult::kTypeNotFound);

tests/ZonedDateTimeBasicTest/ZonedDateTimeBasicTest.ino

@@ -51,8 +51,8 @@ test(ZonedDateTimeBasicTest, printTo) {
 test(ZonedDateTimeBasicTest, forComponents_isError) {
   TimeZone tz = basicZoneManager.createForZoneInfo(&kZoneAmerica_Los_Angeles);
 
-  // outside [1980, 10000) range, should generate error
-  ZonedDateTime dt = ZonedDateTime::forComponents(1970, 3, 11, 1, 59, 0, tz);
+  // outside [0, 10000) range, should generate error
+  ZonedDateTime dt = ZonedDateTime::forComponents(-100, 3, 11, 1, 59, 0, tz);
   assertTrue(dt.isError());
   dt = ZonedDateTime::forComponents(10001, 3, 11, 1, 59, 0, tz);
   assertTrue(dt.isError());

tests/ZonedDateTimeCompleteTest/ZonedDateTimeCompleteTest.ino

@@ -59,15 +59,15 @@ test(ZonedDateTimeCompleteTest, forComponents_isError) {
   TimeZone tz = completeZoneManager.createForZoneInfo(
       &kZoneAmerica_Los_Angeles);
 
-  // Cannot create dates roughly before ZoneContext.startYear.
-  ZonedDateTime dt = ZonedDateTime::forComponents(1970, 3, 11, 1, 59, 59, tz);
+  // outside [0, 10000) range, should generate error
+  ZonedDateTime dt = ZonedDateTime::forComponents(-200, 3, 11, 1, 59, 59, tz);
   const OffsetDateTime &odt = dt.offsetDateTime();
   assertTrue(odt.isError());
   const LocalDateTime &ldt = dt.localDateTime();
   assertTrue(ldt.isError());
   assertTrue(dt.isError());
 
-  // Cannot create dates roughly after ZoneContext.untilYear.
+  // outside [0, 10000) range, should generate error
   dt = ZonedDateTime::forComponents(10001, 3, 11, 1, 59, 59, tz);
   assertTrue(dt.isError());
 }

tests/ZonedDateTimeExtendedTest/ZonedDateTimeExtendedTest.ino

@@ -57,15 +57,15 @@ test(ZonedDateTimeExtendedTest, forComponents_isError) {
   TimeZone tz = extendedZoneManager.createForZoneInfo(
       &kZoneAmerica_Los_Angeles);
 
-  // Cannot create dates roughly before ZoneContext.startYear.
-  ZonedDateTime dt = ZonedDateTime::forComponents(1970, 3, 11, 1, 59, 59, tz);
+  // outside [0, 10000) range, should generate error
+  ZonedDateTime dt = ZonedDateTime::forComponents(-200, 3, 11, 1, 59, 59, tz);
   const OffsetDateTime &odt = dt.offsetDateTime();
   assertTrue(odt.isError());
   const LocalDateTime &ldt = dt.localDateTime();
   assertTrue(ldt.isError());
   assertTrue(dt.isError());
 
-  // Cannot create dates roughly after ZoneContext.untilYear.
+  // outside [0, 10000) range, should generate error
   dt = ZonedDateTime::forComponents(10001, 3, 11, 1, 59, 59, tz);
   assertTrue(dt.isError());
 }