com.paypal.cascade.common.random.RandomUtil.scala Maven / Gradle / Ivy

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/**
 * Copyright 2013-2014 PayPal
 *
 * 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.
 */
package com.paypal.cascade.common.random

import scala.util.Random

/**
 * Convenience methods for accessing random values inside of certain datatypes
 */
object RandomUtil {

  private val r = new Random(System.currentTimeMillis)

  /**
   * Given a list, choose a random value from that list
   * @param list the list
   * @tparam T the type of values in the list
   * @return a random value of type `T`
   */
  def pickRandomValue[T](list: List[T]): Option[T] = {
    for {
      _ <- Option(list)
      _ <- list.headOption
    } yield {
      list(r.nextInt(list.length))
    }
  }

  /**
   * Given a map of String key-value pairs, for all values which are defined for the `convert` function,
   * choose a random value from the map and apply the `convert` function to it, returning the result.
   * @param map the map of String key-value pairs
   * @param convert the function by which to convert values
   * @tparam T the resultant type after conversion
   * @return a random converted value of type `T`
   */
  def pickRandomValue[T <: AnyRef](map: Map[String, String], convert: String => Option[T]): Option[T] = {
    (for {
      _ <- Option(map)
      _ <- map.headOption
      value <- Random.shuffle(map.values).find(convert(_).isDefined)
    } yield {
      value
    }).flatMap(convert)
  }

}