hare

commit d175a565cee80690e09ee41d4a3e0b2beabfae94
parent 73967c5db7a596fe8d70d90a27d8492b21c82b7a
Author: Byron Torres <b@torresjrjr.com>
Date:   Wed, 15 Dec 2021 20:57:46 +0000

codify timezone transitions

Signed-off-by: Byron Torres <b@torresjrjr.com>

Diffstat:
M
datetime/timezone.ha
 | 
36
++++--------------------------------
M
time/chrono/chronology.ha
 | 
14
--------------
M
time/chrono/timezone.ha
 | 
36
++++++++++++++++++++----------------

3 files changed, 24 insertions(+), 62 deletions(-)
diff --git a/datetime/timezone.ha b/datetime/timezone.ha
@@ -24,15 +24,14 @@ export fn tzdb(name: str) chrono::timezone = {
 //
 
 // "Europe/Amsterdam" timezone
-export const TZ_Europe_Amsterdam: chrono::timezone = chrono::timezone {
-	aliasof = &TZ_CET,
+export const TZ_Europe_Amsterdam: chrono::tzalias = chrono::tzalias {
 	name = "Europe/Amsterdam",
-	...
+	tz = &TZ_CET,
 };
 
 // "CET", "Central European Time" timezone
 export const TZ_CET: chrono::timezone = chrono::timezone {
-	aliasof = void,
+	name = "CET",
 	scale = &chrono::UTC,
 	zones = [
 		chrono::zone {
@@ -48,32 +47,5 @@ export const TZ_CET: chrono::timezone = chrono::timezone {
 			dst = true,
 		},
 	],
-	applied = &zone_cet,
-	name = "CET",
-};
-
-fn zone_cet(m: chrono::moment) uint = {
-	const dt = datetime { ... };
-	// TODO: reconcile chrono::moment // datetime::datetime types
-	//conv_moment_datetime(m, &dt);
-	const dst = (
-		dt.date.month: int == 3 &&
-		dt.date.day: int == 28 &&
-		dt.time.hour: int >= 2
-	) || (
-		dt.date.month: int > 3 && dt.date.month: int < 8
-	) || (
-		dt.date.month: int == 8 &&
-		dt.date.day: int < 31
-	) || (
-		dt.date.month: int == 8 &&
-		dt.date.day: int == 31 &&
-		dt.time.hour: int <= 3
-	);
-
-	if (dst) {
-		return 1u;
-	} else {
-		return 0u;
-	};
+	trans = [],
 };
diff --git a/time/chrono/chronology.ha b/time/chrono/chronology.ha
@@ -1,13 +1,5 @@
 use time;
 
-//	// A chronological system for ordering days as dates and eras
-//	export type chronology = struct {
-//		to_taidate: nullable *fn(n: moment) moment,
-//		from_taidate: nullable *fn(n: moment) moment,
-//	
-//		scale: timescale,
-//	};
-
 // A date & time within a locality, to be contextualised in a chronology
 export type moment = struct {
 	date: epochal,
@@ -16,10 +8,4 @@ export type moment = struct {
 };
 
 // An ordinal day on earth since the calendar epoch (zeroth day) 1970-01-01
-//
-// Notes:
-// 1970-01-01 is "the Hare date-epoch". It was chosen out of simplicity to match
-// the UNIX timescale epoch. This shouldn't affect performance in calendar
-// implementations because they can convert to other epochs if they so desire.
-// (as of writing) datetime:: converts to the Julian epoch for calculations.
 export type epochal = i64;
diff --git a/time/chrono/timezone.ha b/time/chrono/timezone.ha
@@ -1,7 +1,7 @@
 use time;
 
 // Represents the locality of a datetime
-export type locality = (local | zoffset | *timezone);
+export type locality = (local | zoffset | *timezone | *tzalias);
 
 // Represents its associated datetime as local
 export type local = void;
@@ -9,6 +9,14 @@ export type local = void;
 // Represents a simple, constant zone offset
 export type zoffset = time::duration;
 
+// Represents a timezone; a political region with a ruleset regarding offsets
+export type timezone = struct {
+	name: str, // "Europe/Amsterdam"
+	scale: *timescale,
+	zones: []zone,
+	trans: []zonetran,
+};
+
 // Represents a conditional offset, dependant on the time of year
 export type zone = struct {
 	zoffset: zoffset, // 2 * time::HOUR
@@ -17,17 +25,18 @@ export type zone = struct {
 	dst: bool, // true
 };
 
-// Represents a timezone; a political region with a ruleset regarding offsets
-export type timezone = struct {
-	aliasof: (void | *timezone),
-	scale: *timescale,
-	zones: []zone,
-	applied: *fn(m: moment) uint,
-	name: str, // "Europe/Amsterdam"
+// Represents a timezone transition
+export type zonetran = struct {
+	when: time::instant,
+	zoneindex: int,
+};
+
+export type tzalias = struct {
+	name: str,
+	tz: *timezone,
 };
 
 export const TZ_UTC: timezone = timezone {
-	aliasof = void,
 	scale = &UTC,
 	zones = [
 		zone {
@@ -37,12 +46,11 @@ export const TZ_UTC: timezone = timezone {
 			dst = false,
 		},
 	],
-	applied = &zone_const,
+	trans = [],
 	name = "Etc/UTC",
 };
 
 export const TZ_TAI: timezone = timezone {
-	aliasof = void,
 	scale = &TAI,
 	zones = [
 		zone {
@@ -52,10 +60,6 @@ export const TZ_TAI: timezone = timezone {
 			dst = false,
 		},
 	],
-	applied = &zone_const,
+	trans = [],
 	name = "",
 };
-
-fn zone_const(m: moment) uint = {
-	return 0u;
-};