LangUtil.scala

/*
Copyright 2018 Google LLC.

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

https://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. 
*/
 
object LangUtil
{

  /**
    * Given two operands that are the same concrete Option type, and a binary
    * function, return the result of the operation as an option in a default
    * way.
    *
    * @param val1
    * @param val2
    * @param op
    * @tparam U
    * @tparam V
    * @return
    */
  def optionGenericOp[U,V](val1: Option[U], val2: Option[U], op: (U,U) => V): Option[V] = {
    (val1, val2) match {
      case (Some(a), Some(b)) => Option(op(a, b))
      case (None, None)       => None
      case (_, None)          => None
      case (None, _)          => None
      case _                  => None // redundant
    }
  }

  /**
    * Provide the logical equivalent of && for Option[Boolean]
    *
    * @param b1
    */
  def optionAnd(b1: Option[Boolean], b2: Option[Boolean]): Option[Boolean] = {
    optionGenericOp(b1, b2, (x: Boolean, y: Boolean) => x && y)
  }

  /**
    * Provide the logical equivalent of || for Option[Boolean]
    * @param b1
    * @param b2
    * @return
    */
  def optionOr(b1: Option[Boolean], b2: Option[Boolean]): Option[Boolean] = {
    optionGenericOp(b1, b2, (x: Boolean, y: Boolean) => x || y)
  }

  //
  // pretty-printing util fns
  //

  def prettyPrintableMap[K,V](m: Map[K,V]): String = {
    val keys = m.keys.toSeq
    val kvLines = keys.map(k => s"\t$k -> \t${m(k)}")
    kvLines.mkString("\n")
  }

  def prettyPrintableSortableMap[K,V,B](m: Map[K,V], keySortBy: K => B)(implicit ord: math.Ordering[B]): String = {
    val keys = m.keys.toSeq.sortBy(keySortBy)
    val kvLines = keys.map(k => s"\t$k -> \t${m(k)}")
    kvLines.mkString("\n")
  }

  def prettyPrintableSortableMap[K <: Ordered[K],V](m: Map[K,V]): String = {
    val keys = m.keys.toSeq.sorted
    val kvLines = keys.map(k => s"\t$k -> \t${m(k)}")
    kvLines.mkString("\n")
  }

}