Add prefer function

[aleclarson]

The prefer function creates a custom sorting comparator based on a list of preferences. It allows you to define a specific order for elements, prioritizing certain values or conditions. The function can handle both direct value comparisons and custom conditional logic, making it flexible for various sorting scenarios.

import { isFunction } from 'radashi'

type Fn = (...args: any[]) => any

export function prefer<T>(...prefs: (Exclude<T, Fn> | ((value: T) => boolean))[]) {
  return (a: T, b: T): number => {
    for (const pref of prefs) {
      if (isFunction(pref)) {
        if (pref(a)) return -1
        if (pref(b)) return 1
      } else {
        if (Object.is(a, pref)) return -1
        if (Object.is(b, pref)) return 1
      }
    }
    return 0
  }
}

Example usage

The example below prefers 0 first, then odd numbers next. Anything else goes to the end.

const nums = [4, 3, 2, 1, 0]

nums.sort(prefer(0, n => n % 2 === 1))
// => [0, 3, 1, 4, 2]