151 lines
3.5 KiB
JavaScript
151 lines
3.5 KiB
JavaScript
import { formatOffset, signedOffset } from "../impl/util.js";
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import Zone from "../zone.js";
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let singleton = null;
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/**
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* A zone with a fixed offset (meaning no DST)
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* @implements {Zone}
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*/
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export default class FixedOffsetZone extends Zone {
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/**
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* Get a singleton instance of UTC
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* @return {FixedOffsetZone}
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*/
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static get utcInstance() {
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if (singleton === null) {
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singleton = new FixedOffsetZone(0);
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}
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return singleton;
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}
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/**
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* Get an instance with a specified offset
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* @param {number} offset - The offset in minutes
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* @return {FixedOffsetZone}
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*/
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static instance(offset) {
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return offset === 0 ? FixedOffsetZone.utcInstance : new FixedOffsetZone(offset);
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}
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/**
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* Get an instance of FixedOffsetZone from a UTC offset string, like "UTC+6"
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* @param {string} s - The offset string to parse
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* @example FixedOffsetZone.parseSpecifier("UTC+6")
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* @example FixedOffsetZone.parseSpecifier("UTC+06")
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* @example FixedOffsetZone.parseSpecifier("UTC-6:00")
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* @return {FixedOffsetZone}
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*/
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static parseSpecifier(s) {
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if (s) {
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const r = s.match(/^utc(?:([+-]\d{1,2})(?::(\d{2}))?)?$/i);
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if (r) {
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return new FixedOffsetZone(signedOffset(r[1], r[2]));
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}
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}
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return null;
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}
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constructor(offset) {
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super();
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/** @private **/
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this.fixed = offset;
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}
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/**
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* The type of zone. `fixed` for all instances of `FixedOffsetZone`.
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* @override
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* @type {string}
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*/
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get type() {
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return "fixed";
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}
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/**
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* The name of this zone.
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* All fixed zones' names always start with "UTC" (plus optional offset)
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* @override
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* @type {string}
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*/
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get name() {
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return this.fixed === 0 ? "UTC" : `UTC${formatOffset(this.fixed, "narrow")}`;
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}
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/**
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* The IANA name of this zone, i.e. `Etc/UTC` or `Etc/GMT+/-nn`
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*
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* @override
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* @type {string}
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*/
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get ianaName() {
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if (this.fixed === 0) {
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return "Etc/UTC";
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} else {
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return `Etc/GMT${formatOffset(-this.fixed, "narrow")}`;
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}
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}
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/**
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* Returns the offset's common name at the specified timestamp.
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*
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* For fixed offset zones this equals to the zone name.
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* @override
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*/
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offsetName() {
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return this.name;
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}
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/**
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* Returns the offset's value as a string
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* @override
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* @param {number} ts - Epoch milliseconds for which to get the offset
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* @param {string} format - What style of offset to return.
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* Accepts 'narrow', 'short', or 'techie'. Returning '+6', '+06:00', or '+0600' respectively
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* @return {string}
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*/
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formatOffset(ts, format) {
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return formatOffset(this.fixed, format);
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}
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/**
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* Returns whether the offset is known to be fixed for the whole year:
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* Always returns true for all fixed offset zones.
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* @override
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* @type {boolean}
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*/
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get isUniversal() {
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return true;
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}
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/**
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* Return the offset in minutes for this zone at the specified timestamp.
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*
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* For fixed offset zones, this is constant and does not depend on a timestamp.
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* @override
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* @return {number}
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*/
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offset() {
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return this.fixed;
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}
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/**
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* Return whether this Zone is equal to another zone (i.e. also fixed and same offset)
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* @override
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* @param {Zone} otherZone - the zone to compare
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* @return {boolean}
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*/
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equals(otherZone) {
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return otherZone.type === "fixed" && otherZone.fixed === this.fixed;
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}
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/**
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* Return whether this Zone is valid:
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* All fixed offset zones are valid.
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* @override
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* @type {boolean}
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*/
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get isValid() {
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return true;
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}
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}
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