dsl.js

import spanner from './spanner.js'
import iso8601 from './iso8601.js'
const isNumber = n => n >= '0' && n <= '9'
const isAlpha = n => n >= 'a' && n <= 'z' || n >= 'A' && n <= 'Z'
const isAlphanumeric = n => isNumber(n) || isAlpha(n)
const isDef = n => isAlphanumeric(n) || n == '_'
const isOperation = n => n == '+' || n == '-' || n == '*'
const isEmpty = n => n == ' ' || n == '\t' || n == '\n'
const isSpannerOperation = n => n == '/' || n == '+' || n == '-' || n == '('
const isSpannerChar = n => isAlphanumeric(n) || ['_', '+', '-', '(', ')', '/'].indexOf(n) != -1

export default moment => ({
  parse: (s, inschedules, inconstants) => {
    const constants = { now: moment.utc() }
    const schedules = {}
    let i = 0

    const printContext = () => {
      let back = 0
      while (back < 10 && i - back - 1 >= 0 && s[i - back - 1] != '\n')
        back++
      let forward = 0
      while (back < 10 && i + forward < s.length && s[i + forward] != '\n')
        forward++
      const context = s.substring(i - back, i + forward)
      let position = ''
      for (let x = 1; x < back; x++) position += ' '
      position += '^'
      console.log(context)
      console.log(position)
    }

    const emitError = msg => {
      printContext()
      throw new Error(msg)
    }

    const forward = () => {
      while (i < s.length && isEmpty(s[i])) i++
      if (i + 1 < s.length && s[i] == '/' && s[i + 1] == '/')
        while (i < s.length && s[i] != '\n') i++
      if (i < s.length && isEmpty(s[i])) forward()
    }

    const readdef = () => {
      if (i < s.length && !isAlpha(s[i]))
        emitError(`Expecting definition, not ${s[i]}`)
      let n = 0
      while (i + n < s.length && isDef(s[i+n])) n++
      const res = s.substring(i, i + n)
      i += n
      return res
    }

    // 2018-07-01T00:00:00Z
    const readISO8601 = () => {
      if (i + 20 >= s.length) emitError('Incomplete date')
      const dateString = s.substr(i, i + 20)
      const date = moment.utc(dateString, iso8601)
      if (!date.isValid()) emitError(`'${dateString}'' is not a valid date`)
      i += 20
      return date
    }

    const readSpannerContent = () => {
      let n = 0
      let brackets = 0
      while (i < s.length && isSpannerChar(s[i + n])) {
        if (s[i + n] == '(') brackets++
        else if (s[i + n] == ')') {
          if (brackets == 0) break
          brackets--
        }
        n++
      }
      const adjustment = s.substring(i, i + n)
      i += n
      return adjustment
    }

    const readSpanner = (anchor) => {
      const adjustment = readSpannerContent()
      return spanner(anchor, adjustment, null, Object.assign({}, inconstants, constants))
    }

    const readCountAndUnit = () => {
      let n = 0
      while (i < s.length && isNumber(s[i + n])) n++
      if (i < s.length && s[i + n] == '.') {
        n++
        while (i < s.length && isNumber(s[i + n])) n++
      }
      const count = parseFloat(s.substring(i, i + n))
      i += n
      if (i >= s.length) emitError('Expecting unit')
      n = 0
      while (i < s.length && isAlpha(s[i + n])) n++
      const unit = s.substring(i, i + n)
      i += n
      return {
        count: count,
        unit: unit
      }
    }

    const readInterval = () => {
      i++
      forward()
      if (i >= s.length) emitError('Expecting interval params')
      const start = readSpannerContent()
      forward()
      if (i + 1 >= s.length || s[i] != ',')
        emitError('Expecting interval params')
      i++
      forward()
      if (i >= s.length) emitError('Expecting interval params')
      const duration = readSpannerContent()
      forward()
      if (i + 1 >= s.length || s[i] != ',')
        emitError('Expecting interval params')
      i++
      forward()
      if (i >= s.length) emitError('Expecting interval params')
      const adjustment = readCountAndUnit()
      forward()
      if (i >= s.length || s[i] != ')')
        emitError('Expecting interval close bracket')
      i++
      return {
        type: 'interval',
        start: start,
        count: adjustment.count,
        unit: adjustment.unit,
        duration: duration
      }
    }

    const readRange = () => {
      i++
      forward()
      if (i >= s.length) emitError('Expecting range params')
      const start = readSpannerContent()
      forward()
      if (i + 1 >= s.length || s[i] != ',')
        emitError('Expecting range params')
      i++
      forward()
      if (i >= s.length) emitError('Expecting range params')
      const end = readSpannerContent()
      forward()
      if (i >= s.length || s[i] != ')')
        emitError('Expecting range close bracket')
      i++
      return {
        type: 'rang',
        start: start,
        end: end
      }
    }

    const readReference = () => {
      const id = readdef()
      if (schedules[id]) return schedules[id]
      else if (inschedules[id]) return inschedules[id]
      else emitError(`Schedule ${id} not found`)
    }

    const readSchedule = (def) => {
      let res = null
      const operation = s[i]
      i++
      forward()
      if (i >= s.length) emitError('Expecting schedule terms')
      const id = readdef()
      forward()
      if (i < s.length && s[i] == '(') {
        if (id == 'interval') res = readInterval()
        else if (id == 'range') res = readRange()
        else emitError(`Unknown function ${id}`)
      } else res = {
        type: 'schedule',
        schedule: id
      }
      res.operation = operation == '+'
        ? 'or'
        : operation == '-'
        ? 'not'
        : operation == '*'
        ? 'and'
        : null
      return res
    }

    const readConstant = () => {
      let anchor = null
      if (isNumber(s[i])){
        anchor = readISO8601()
      } else {
        const id = readdef()
        if (constants[id]) anchor = constants[id].clone()
        else if (inconstants[id]) anchor = inconstants[id].clone()
        else emitError(`Constant ${id} not found`)
      }
      if (i < s.length && isSpannerOperation(s[i])) return readSpanner(anchor)
      return anchor
    }

    while (i < s.length) {
      forward()
      const def = readdef()
      forward()
      if (def == '' && i >= s.length) break
      if (i >= s.length) emitError('Expecting : after definition')
      if (i < s.length && s[i] != ':')
        emitError('Expecting : after definition')
      i++
      forward()
      if (i >= s.length) emitError('Expecting definition terms')
      if (isOperation(s[i])) {
        const schedule = []
        while (i < s.length && isOperation(s[i])) {
          schedule.push(readSchedule(def))
          forward()
        }
        schedules[def] = schedule
      }
      else constants[def] = readConstant()
    }

    return { schedules, constants }
  }
})