feat: array_to_sentence_string and number_of_words filters from Jekyll, #443

src/filters/string.ts

@@ -3,8 +3,20 @@
  *
  * * prefer stringify() to String() since `undefined`, `null` should eval ''
  */
+
+// Han (Chinese) characters: \u4E00-\u9FFF
+// Additional Han characters: \uF900-\uFAFF (CJK Compatibility Ideographs)
+// Additional Han characters: \u3400-\u4DBF (CJK Unified Ideographs Extension A)
+// Katakana (Japanese): \u30A0-\u30FF
+// Hiragana (Japanese): \u3040-\u309F
+// Hangul (Korean): \uAC00-\uD7AF
 import { assert, escapeRegExp, stringify } from '../util'
 
+const rCJKWord = /[\u4E00-\u9FFF\uF900-\uFAFF\u3400-\u4DBF\u3040-\u309F\u30A0-\u30FF\uAC00-\uD7AF]/gu
+
+// Word boundary followed by word characters (for detecting words)
+const rNonCJKWord = /[^\u4E00-\u9FFF\uF900-\uFAFF\u3400-\u4DBF\u3040-\u309F\u30A0-\u30FF\uAC00-\uD7AF\s]+/gu
+
 export function append (v: string, arg: string) {
   assert(arguments.length === 2, 'append expect 2 arguments')
   return stringify(v) + stringify(arg)
@@ -32,16 +44,16 @@ export function upcase (str: string) {
 }
 
 export function remove (v: string, arg: string) {
-  return stringify(v).split(String(arg)).join('')
+  return stringify(v).split(stringify(arg)).join('')
 }
 
 export function remove_first (v: string, l: string) {
-  return stringify(v).replace(String(l), '')
+  return stringify(v).replace(stringify(l), '')
 }
 
 export function remove_last (v: string, l: string) {
   const str = stringify(v)
-  const pattern = String(l)
+  const pattern = stringify(l)
   const index = str.lastIndexOf(pattern)
   if (index === -1) return str
   return str.substring(0, index) + str.substring(index + pattern.length)
@@ -56,7 +68,7 @@ export function rstrip (str: string, chars?: string) {
 }
 
 export function split (v: string, arg: string) {
-  const arr = stringify(v).split(String(arg))
+  const arr = stringify(v).split(stringify(arg))
   // align to ruby split, which is the behavior of shopify/liquid
   // see: https://ruby-doc.org/core-2.4.0/String.html#method-i-split
   while (arr.length && arr[arr.length - 1] === '') arr.pop()
@@ -83,19 +95,19 @@ export function capitalize (str: string) {
 }
 
 export function replace (v: string, pattern: string, replacement: string) {
-  return stringify(v).split(String(pattern)).join(replacement)
+  return stringify(v).split(stringify(pattern)).join(replacement)
 }
 
 export function replace_first (v: string, arg1: string, arg2: string) {
-  return stringify(v).replace(String(arg1), arg2)
+  return stringify(v).replace(stringify(arg1), arg2)
 }
 
 export function replace_last (v: string, arg1: string, arg2: string) {
   const str = stringify(v)
-  const pattern = String(arg1)
+  const pattern = stringify(arg1)
   const index = str.lastIndexOf(pattern)
   if (index === -1) return str
-  const replacement = String(arg2)
+  const replacement = stringify(arg2)
   return str.substring(0, index) + replacement + str.substring(index + pattern.length)
 }
 
@@ -117,3 +129,34 @@ export function normalize_whitespace (v: string) {
   v = stringify(v)
   return v.replace(/\s+/g, ' ')
 }
+
+export function number_of_words (input: string, mode?: 'cjk' | 'auto') {
+  input = stringify(input).trim()
+  if (!input) return 0
+  switch (mode) {
+    case 'cjk':
+      // Count CJK characters and words
+      return (input.match(rCJKWord) || []).length + (input.match(rNonCJKWord) || []).length
+    case 'auto':
+      // Count CJK characters, if none, count words
+      return rCJKWord.test(input)
+        ? input.match(rCJKWord)!.length + (input.match(rNonCJKWord) || []).length
+        : input.split(/\s+/).length
+    default:
+      // Count words only
+      return input.split(/\s+/).length
+  }
+}
+
+export function array_to_sentence_string (array: unknown[], connector = 'and') {
+  switch (array.length) {
+    case 0:
+      return ''
+    case 1:
+      return array[0]
+    case 2:
+      return `${array[0]} ${connector} ${array[1]}`
+    default:
+      return `${array.slice(0, -1).join(', ')}, ${connector} ${array[array.length - 1]}`
+  }
+}