org.wartremover.contrib.warts.UnintendedLaziness.scala Maven / Gradle / Ivy

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package org.wartremover
package contrib.warts

object UnintendedLaziness extends WartTraverser {
  val (errorForFilterKeys: String, errorForMapValues: String) = {
    def error(name: String) =
      s"""Map#$name is disabled because it implicitly creates lazily evaluated collections.
         |To create lazy collections, use the explicit view method""".stripMargin

    (error("filterKeys"), error("mapValues"))
  }

  def apply(u: WartUniverse): u.Traverser = {
    import u.universe._

    val collectionMapSymbol = rootMirror.staticClass("scala.collection.Map")
    val filterKeys = TermName("filterKeys")
    val mapValues = TermName("mapValues")

    new u.Traverser {
      override def traverse(tree: Tree): Unit = {
        tree match {
          // Ignore trees marked by SuppressWarnings
          case t if hasWartAnnotation(u)(t) =>

          case t @ Apply(Select(map, `filterKeys`), _) if map.tpe.baseType(collectionMapSymbol) != NoType =>
            error(u)(t.pos, errorForFilterKeys)

          case t @ Apply(TypeApply(Select(map, `mapValues`), _), _)
              if map.tpe.baseType(collectionMapSymbol) != NoType =>
            error(u)(t.pos, errorForMapValues)

          case _ =>
            super.traverse(tree)
        }
      }
    }
  }
}