comparison.ts

export interface Comparable<T, U = ComparisonResult> {
  compare(other: T): U;
}

export namespace Comparable {
  export function compare<T extends Comparable<T, U>, U = ComparisonResult>(o1: T, o2: T): U {
    return o1.compare(o2);
  }
}

export type Comparator<T, U = ComparisonResult> = (first: T, second: T) => U;
export enum ComparisonResult {
  /** (a < b) - ascending order */
  Lower = -1,
  Same = 0,
  /** (a > b) - descending order */
  Higher = 1,
}

export function comparePrimitives<T extends number | string>(a: T, b: T): ComparisonResult {
  return a > b
    ? ComparisonResult.Higher
    : a < b
      ? ComparisonResult.Lower
      : ComparisonResult.Same;
}

export function compareStrings(a: string, b: string, ignoreCase = true): ComparisonResult {
  return comparePrimitives(
    ignoreCase ? a.toLowerCase() : a,
    ignoreCase ? b.toLowerCase() : b
  );
}