text: // Copyright 2017 The Kubernetes Authors.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  import {Validator} from '../../common/validators/validator';
  
  /**
   * @final
   * @extends {Validator}
   */
  export class LabelValuePatternValidator extends Validator {
    constructor() {
      super();
  
      /** @type {!RegExp} */
      this.labelValuePattern = /^(([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?$/;
    }
  
    /**
     * Returns true if the label value is an empty string ("") or matches a lowercase
     * alphanumeric character (upper or lower case) optionally followed by alphanumeric
     * or -_. and ending with an alphanumeric character (upper or lower case), otherwise
     * returns false.
     *
     * @override
     */
    isValid(value) {
      return this.labelValuePattern.test(value);
    }
  }
  