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Fix issue with legacy zones with initial named rules
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Rogier Schouten committed Feb 16, 2021
1 parent a32c284 commit 774d634
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Showing 3 changed files with 101 additions and 55 deletions.
136 changes: 81 additions & 55 deletions src/lib/tz-database.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1969,7 +1969,9 @@ class CachedRuleTransitions {
* @param dstOffset
*/
public firstTransitionWithoutDstAfter(
afterUtc: TimeStruct, standardOffset: Duration, dstOffset: Duration | undefined
afterUtc: TimeStruct,
standardOffset: Duration,
dstOffset: Duration | undefined
): RuleTransition | undefined {
// todo inefficient - optimize
let iterator = this.findFirst();
Expand Down Expand Up @@ -2075,7 +2077,7 @@ class CachedZoneTransitions {
constructor(zoneName: string, zoneInfos: ZoneInfo[], rules: Map<string, CachedRuleTransitions>) {
assert(zoneInfos.length > 0, "timezonecomplete.Argument.ZoneInfos", "zone '%s' without information", zoneName);
this._finalZoneInfo = zoneInfos[zoneInfos.length - 1];
this._initialState = this._calcInitialState(zoneName, zoneInfos);
this._initialState = this._calcInitialState(zoneName, zoneInfos, rules);
[this._transitions, this._finalRules] = this._calcTransitions(zoneName, this._initialState, zoneInfos, rules);
}

Expand Down Expand Up @@ -2155,9 +2157,14 @@ class CachedZoneTransitions {
* Calculate the initial state for the zone
* @param zoneName
* @param infos
* @param rules
* @throws timezonecomplete.InvalidTimeZoneData
*/
private _calcInitialState(zoneName: string, infos: ZoneInfo[]): ZoneState {
private _calcInitialState(
zoneName: string,
infos: ZoneInfo[],
rules: Map<string, CachedRuleTransitions>
): ZoneState {
// initial state
if (infos.length === 0) {
return {
Expand All @@ -2183,8 +2190,24 @@ class CachedZoneTransitions {
dstOffset: info.ruleOffset,
standardOffset: info.gmtoff
};
case RuleType.RuleName:
return throwError("InvalidTimeZoneData", "Zone '%s' has an initial named rule, which is not expected", zoneName);
case RuleType.RuleName: {
const rule = rules.get(info.ruleName);
if (!rule) {
throwError("InvalidTimeZoneData", "zone '%s' refers to non-existing rule '%s'", zoneName, info.ruleName);
}
// find first rule transition without DST so that we have a letter
let iterator = rule.findFirst();
while (iterator && iterator.transition.newState.dstOffset.nonZero()) {
iterator = rule.findNext(iterator);
}
const letter = iterator?.transition.newState.letter ?? "";
return {
abbreviation: zoneAbbreviation(info.format, false, letter),
dstOffset: hours(0),
letter,
standardOffset: info.gmtoff
};
}
default:
assert(false, "timezonecomplete.Assertion", "Unknown RuleType");
}
Expand All @@ -2198,44 +2221,45 @@ class CachedZoneTransitions {
* @param rules
*/
private _calcTransitions(
zoneName: string, initialState: ZoneState, zoneInfos: ZoneInfo[], rules: Map<string, CachedRuleTransitions>
zoneName: string,
initialState: ZoneState,
zoneInfos: ZoneInfo[],
rules: Map<string, CachedRuleTransitions>
): [ZoneTransition[], RuleInfo[]] {
if (zoneInfos.length === 0) {
return [[], []];
}
// walk through the zone records and add a transition for each
let transitions: ZoneTransition[] = [];
let prevState = initialState;
let prevUntil: TimeStruct | undefined = zoneInfos[0].until !== undefined ? new TimeStruct(zoneInfos[0].until) : undefined;
let prevUntil: TimeStruct | undefined;
let prevRules: CachedRuleTransitions | undefined;
for (let i = 1; i < zoneInfos.length; ++i) {
// only the last zoneInfo can have a missing UNTIL
if (prevUntil === undefined) {
return throwError("InvalidTimeZoneData", "TZ database contains invalid zone information for zone '%s'", zoneName);
}
const zoneInfo = zoneInfos[i];
for (const zoneInfo of zoneInfos) {
// zones can have a DST offset or they can refer to a rule set
switch (zoneInfo.ruleType) {
case RuleType.None:
case RuleType.Offset: {
transitions.push({
atUtc: prevUntil,
newState: {
abbreviation: zoneAbbreviation(zoneInfo.format, false, undefined),
letter: "",
dstOffset: zoneInfo.ruleType === RuleType.None ? hours(0) : zoneInfo.ruleOffset,
standardOffset: zoneInfo.gmtoff
}
});
prevRules = undefined;
if (prevUntil) {
transitions.push({
atUtc: prevUntil,
newState: {
abbreviation: zoneAbbreviation(zoneInfo.format, false, undefined),
letter: "",
dstOffset: zoneInfo.ruleType === RuleType.None ? hours(0) : zoneInfo.ruleOffset,
standardOffset: zoneInfo.gmtoff
}
});
prevRules = undefined;
}
} break;
case RuleType.RuleName: {
prevRules = rules.get(zoneInfo.ruleName);
if (!prevRules) {
const rule = rules.get(zoneInfo.ruleName);
if (!rule) {
return throwError("InvalidTimeZoneData", "Zone '%s' refers to non-existing rule '%s'", zoneName, zoneInfo.ruleName);
}
const t = this._zoneTransitions(prevUntil, zoneInfo, prevRules);
const t = this._zoneTransitions(prevUntil, zoneInfo, rule);
transitions = transitions.concat(t);
prevRules = rule;
} break;
default:
assert(false, "timezonecomplete.Assertion", "Unknown RuleType");
Expand All @@ -2250,11 +2274,11 @@ class CachedZoneTransitions {
* Creates all the transitions for a time zone from fromUtc (inclusive) to zoneInfo.until (exclusive).
* The result always contains an initial transition at fromUtc that signals the switch to this rule set
*
* @param fromUtc previous zone sub-record UNTIL time
* @param fromUtc previous zone sub-record UNTIL time; undefined for first zone record
* @param zoneInfo the current zone sub-record
* @param rule the corresponding rule transitions
*/
private _zoneTransitions(fromUtc: TimeStruct, zoneInfo: ZoneInfo, rule: CachedRuleTransitions): ZoneTransition[] {
private _zoneTransitions(fromUtc: TimeStruct | undefined, zoneInfo: ZoneInfo, rule: CachedRuleTransitions): ZoneTransition[] {
// from tz-how-to.html:
// One wrinkle, not fully explained in zic.8.txt, is what happens when switching to a named rule. To what values should the SAVE and
// LETTER data be initialized?
Expand All @@ -2264,35 +2288,37 @@ class CachedZoneTransitions {

const result: ZoneTransition[] = [];

// extra initial transition for switch to this rule set
let initial: ZoneTransition;
let initialRuleTransition = rule.findLastLessEqual(fromUtc, zoneInfo.gmtoff);
if (initialRuleTransition) {
initial = {
atUtc: fromUtc,
newState: {
abbreviation: zoneAbbreviation(zoneInfo.format, false, initialRuleTransition.newState.letter),
letter: initialRuleTransition.newState.letter ?? "",
dstOffset: hours(0),
standardOffset: zoneInfo.gmtoff
}
};
} else {
initialRuleTransition = rule.firstTransitionWithoutDstAfter(fromUtc, zoneInfo.gmtoff, undefined);
initial = {
atUtc: fromUtc,
newState: {
abbreviation: zoneAbbreviation(zoneInfo.format, false, initialRuleTransition?.newState.letter),
letter: initialRuleTransition?.newState.letter ?? "",
dstOffset: hours(0),
standardOffset: zoneInfo.gmtoff
}
};
// extra initial transition for switch to this rule set (but not for first zone info)
let initial: ZoneTransition | undefined;
if (fromUtc !== undefined) {
let initialRuleTransition = rule.findLastLessEqual(fromUtc, zoneInfo.gmtoff);
if (initialRuleTransition) {
initial = {
atUtc: fromUtc,
newState: {
abbreviation: zoneAbbreviation(zoneInfo.format, false, initialRuleTransition.newState.letter),
letter: initialRuleTransition.newState.letter ?? "",
dstOffset: hours(0),
standardOffset: zoneInfo.gmtoff
}
};
} else {
initialRuleTransition = rule.firstTransitionWithoutDstAfter(fromUtc, zoneInfo.gmtoff, undefined);
initial = {
atUtc: fromUtc,
newState: {
abbreviation: zoneAbbreviation(zoneInfo.format, false, initialRuleTransition?.newState.letter),
letter: initialRuleTransition?.newState.letter ?? "",
dstOffset: hours(0),
standardOffset: zoneInfo.gmtoff
}
};
}
result.push(initial);
}
result.push(initial);

// actual rule transitions
let prevDst = initial.newState.dstOffset;
// actual rule transitions; keep adding until the end of this zone info, or until only 'max' rules remain
let prevDst = initial?.newState.dstOffset ?? hours(0);
let iterator = rule.findFirst();
let effective: TimeStruct | undefined = iterator?.transition && ruleTransitionUtc(iterator.transition, zoneInfo.gmtoff, prevDst);
while (
Expand Down
7 changes: 7 additions & 0 deletions src/test/test-datetime.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1804,6 +1804,13 @@ describe("DateTime", (): void => {
expect(d.toString()).to.equal("2021-03-14T01:00:00.000 America/Detroit");
});
});

describe("issue with CET", (): void => {
it("should not error on using backward compatibility zone CET", (): void => {
const d = new DateTime("2021-01-01");
d.withZone(TimeZone.zone("CET"));
});
});
});


Expand Down
13 changes: 13 additions & 0 deletions src/test/test-tz-database.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -778,4 +778,17 @@ describe("TzDatabase", (): void => {
expect(utcTime).to.equal(TimeStruct.fromComponents(2021, 10, 31, 1, 0, 0).unixMillis, TimeStruct.fromUnix(utcTime ?? 0).toString());
});
});

describe("issue with CET", (): void => {
it("should calculate initial state", (): void => {
const ts = TimeStruct.fromComponents(1800, 1, 1);
expect(TzDatabase.instance().totalOffset("CET", ts.unixMillis).hours()).to.equal(1);
expect(TzDatabase.instance().abbreviation("CET", ts.unixMillis)).to.equal("CET");
});
it("should apply DST changes from the C-Eur ruleset", (): void => {
const ts = TimeStruct.fromComponents(1916, 5, 1);
expect(TzDatabase.instance().totalOffset("CET", ts.unixMillis).hours()).to.equal(2);
expect(TzDatabase.instance().abbreviation("CET", ts.unixMillis)).to.equal("CEST");
});
});
});

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