feat: add parse function to buddhistEra plugin

src/plugin/buddhistEra/index.js

@@ -1,17 +1,65 @@
 import { FORMAT_DEFAULT } from '../../constant'
 
 export default (o, c) => { // locale needed later
+  const formatTokens = /(\[[^\]]+])|BBBB|BB/g
+
+  const match2 = /\d\d/ // 00 - 99
+  const match4 = /\d{4}/ // 0000 - 9999
+
+  const yearBias = 543
+
+  const parseTwoDigitYear = function (input) {
+    return ((input + 2500) - yearBias) % 100
+  }
+
   const proto = c.prototype
   const oldFormat = proto.format
   // extend en locale here
   proto.format = function (formatStr) {
-    const yearBias = 543
     const str = formatStr || FORMAT_DEFAULT
-    const result = str.replace(/(\[[^\]]+])|BBBB|BB/g, (match, a) => {
+    const result = str.replace(formatTokens, (match, a) => {
       const year = String(this.$y + yearBias)
       const args = match === 'BB' ? [year.slice(-2), 2] : [year, 4]
       return a || this.$utils().s(...args, '0')
     })
     return oldFormat.bind(this)(result)
   }
+
+  // parse in Buddhist era
+  const oldParse = proto.parse
+  proto.parse = function (cfg) {
+    const [date, format] = cfg.args
+    let formatString = format || FORMAT_DEFAULT
+    const array = formatString.match(formatTokens)
+    let newDate
+    if (array) {
+      array.forEach((match) => {
+        formatString = formatString.replace(match, (_, i) => {
+          const yearString = cfg.args[0].substring(
+            i,
+            i + Math.min(match.length, 4)
+          )
+          let year
+          if (yearString.match(match4)) {
+            // replace buddhist era with common era
+            year = parseInt(yearString, 10) - yearBias
+          } else if (yearString.match(match2)) {
+            year = parseTwoDigitYear(parseInt(yearString, 10))
+          }
+          newDate =
+            date.substring(0, i) +
+            (year || yearString) +
+            date.substring(i + year.toString().length, date.length)
+          // replace formatting with common era's
+          return match.length === 4 ? 'YYYY' : 'YY'
+        })
+      })
+    }
+    // passes the date string with common era to other parsers
+    oldParse.call(this, {
+      ...cfg,
+      args: [newDate || date, formatString],
+      date: newDate || date
+    })
+  }
 }

test/plugin/buddhistEra.test.js

@@ -36,3 +36,16 @@ it('Skips format strings inside brackets', () => {
   expect(dayjs().format('[BBBB]')).toBe('BBBB')
   expect(dayjs().format('[BB]')).toBe('BB')
 })
+
+it('Parses Buddhist Era 2 digits', () => {
+  expect(dayjs('02/29/67', 'MM/DD/BB').valueOf()).toBe(moment('02/29/24').valueOf())
+  expect(dayjs('01/01/00', 'MM/DD/BB').valueOf()).toBe(moment('01/01/57').valueOf())
+  expect(dayjs('01/01/99', 'MM/DD/BB').valueOf()).toBe(moment('01/01/56').valueOf())
+})
+
+it('Parses Buddhist Era 4 digits', () => {
+  expect(dayjs('02/29/2567', 'MM/DD/BBBB').valueOf()).toBe(moment('02/29/2024').valueOf())
+  expect(dayjs('01/01/2500', 'MM/DD/BBBB').valueOf()).toBe(moment('01/01/1957').valueOf())
+  expect(dayjs('01/01/2599', 'MM/DD/BBBB').valueOf()).toBe(moment('01/01/2056').valueOf())
+  expect(dayjs('01/01/2499', 'MM/DD/BBBB').valueOf()).toBe(moment('01/01/1956').valueOf())
+})