date-holidays-parser/src/DateFn.js

parser for worldwide holidays

import Parser from './Parser.js'
import Rule from './Rule.js'
import PostRule from './PostRule.js'
import CalEventFactory from './CalEventFactory.js'

/**
 * handles one rule
 */
export default class DateFn {
  /**
   * @param {string} rule - unparsed rule
   * @param {array} holidays - all holidays rules (required for bridge day calculations)
   */
  constructor (ruleStr, holidays) {
    const parser = new Parser()
    this.ruleStr = ruleStr
    this.rules = parser.parse(ruleStr)
    this.ok = !parser.error
    this.holidays = holidays
    this.opts = holidays ? holidays[ruleStr] : {}
    this.event = undefined
    this.cache = new Map()
  }

  /**
   * @param {number} year
   * @returns {this}
   */
  inYear (year) {
    if (this.cache.has(year)) {
      this.event = this.cache.get(year)
      return this
    }

    let ruleFn // current rule
    const postProc = new PostRule(this.ruleStr, this.opts, this.holidays)

    this.rules.forEach((rule) => {
      if (rule.fn) {
        const calEvent = new CalEventFactory(rule)
          .inYear(year - 1) // run over neighboring dates to catch overlaps
          .inYear(year)
          .inYear(year + 1)
        postProc.push(calEvent)
        ruleFn = new Rule(calEvent)
      } else {
        if (ruleFn.resolve(rule)) {
          postProc.resolve(rule, year)
        }
      }
    })

    const event = postProc.getEvent(year)
    this.cache.set(year, event)

    this.event = event
    return this
  }

  get (timezone) {
    return this.event.get(timezone)
  }
}