feat: pop/shift/unshift filters from Jekyll

src/util/underscore.ts

@@ -46,6 +46,22 @@ export function stringify (value: any): string {
   return String(value)
 }
 
+export function toEnumerable<T = unknown> (val: any): T[] {
+  val = toValue(val)
+  if (isArray(val)) return val
+  if (isString(val) && val.length > 0) return [val] as unknown as T[]
+  if (isIterable(val)) return Array.from(val)
+  if (isObject(val)) return Object.keys(val).map((key) => [key, val[key]]) as unknown as T[]
+  return []
+}
+
+export function toArray (val: any) {
+  val = toValue(val)
+  if (isNil(val)) return []
+  if (isArray(val)) return val
+  return [ val ]
+}
+
 export function toValue (value: any): any {
   return (value instanceof Drop && isFunction(value.valueOf)) ? value.valueOf() : value
 }