Line data    Source code

       1             : import { StringDistribution } from "../types.ts";
       2           1 : import { integer } from "./integer.ts";
       3             : 
       4             : // tslint:disable:unified-signatures
       5             : 
       6             : // has 2**x chars, for faster uniform distribution
       7           1 : const DEFAULT_STRING_POOL =
       8           1 :   "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-";
       9             : 
      10             : /**
      11             :  * Returns a distribution that returns a random string using numbers,
      12             :  * uppercase and lowercase letters, `_`, and `-` of length `length`.
      13             :  * @param length Length of the result string
      14             :  */
      15             : export function string(): StringDistribution;
      16             : /**
      17             :  * Returns a distribution that returns a random string using the provided
      18             :  * string pool as the possible characters to choose from of length `length`.
      19             :  * @param length Length of the result string
      20             :  */
      21             : export function string(pool: string): StringDistribution;
      22           1 : export function string(pool: string = DEFAULT_STRING_POOL): StringDistribution {
      23           3 :   const poolLength = pool.length;
      24           0 :   if (!poolLength) {
      25           0 :     throw new Error("Expected pool not to be an empty string");
      26           0 :   }
      27             : 
      28           3 :   const distribution = integer(0, poolLength - 1);
      29           0 :   return (engine, length) => {
      30           0 :     let result = "";
      31           0 :     for (let i = 0; i < length; ++i) {
      32           0 :       const j = distribution(engine);
      33           0 :       result += pool.charAt(j);
      34           0 :     }
      35           0 :     return result;
      36           0 :   };
      37           1 : }