如何在angular 2的required中添加多个OR条件

import { AbstractControl, ValidatorFn } from '@angular/forms';

export function multiOrValidator(validators: ValidatorFn[]): ValidatorFn {
  return (control: AbstractControl): { [key: string]: any } | null => {
    for (const validator of validators) {
      const result = validator(control);
      if (result === null) {
        return null; // 任意一个条件满足即返回null，表示验证通过
      }
    }
    return { multiOr: true }; // 所有条件都不满足，返回一个自定义错误标识
  };
}

import { Component } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';
import { multiOrValidator } from './multi-or-validator';

@Component({
  selector: 'app-my-form',
  template: `
    <form [formGroup]="myForm">
      <input formControlName="myControl">
      <div *ngIf="myForm.get('myControl').hasError('multiOr')">At least one condition must be satisfied.</div>
    </form>
  `,
})
export class MyFormComponent {
  myForm: FormGroup;

  constructor() {
    this.myForm = new FormGroup({
      myControl: new FormControl('', multiOrValidator([
        Validators.required, // 第一个条件：必填
        Validators.pattern('[a-zA-Z]+'), // 第二个条件：字母字符
        Validators.minLength(5), // 第三个条件：最小长度为5
      ])),
    });
  }
}