/**
   * @fileoverview A class of identifiers generator for code path segments.
   *
   * Each rule uses the identifier of code path segments to store additional
   * information of the code path.
   *
   * @author Toru Nagashima
   */
  
  "use strict";
  
  //------------------------------------------------------------------------------
  // Public Interface
  //------------------------------------------------------------------------------
  
  /**
   * A generator for unique ids.
   */
  class IdGenerator {
  
      /**
       * @param {string} prefix - Optional. A prefix of generated ids.
       */
      constructor(prefix) {
          this.prefix = String(prefix);
          this.n = 0;
      }
  
      /**
       * Generates id.
       *
       * @returns {string} A generated id.
       */
      next() {
          this.n = 1 + this.n | 0;
  
          /* istanbul ignore if */
          if (this.n < 0) {
              this.n = 1;
          }
  
          return this.prefix + this.n;
      }
  }
  
  module.exports = IdGenerator;