net.ruippeixotog.scalascraper.dsl.ToQuery.scala Maven / Gradle / Ivy

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package net.ruippeixotog.scalascraper.dsl

import net.ruippeixotog.scalascraper.model._

/** A type class indicating that an [[net.ruippeixotog.scalascraper.model.ElementQuery]] of some
  * [[net.ruippeixotog.scalascraper.model.Element]] type can be created from an object of a given type.
  *
  * @tparam A
  *   the type of the object to be made into an `ElementQuery`
  */
trait ToQuery[A] {

  /** The type of the element in the `ElementQuery`.
    */
  type Out <: Element

  /** Creates an `ElementQuery` for an object of type `A`.
    *
    * @param a
    *   the object for which an `ElementQuery` is to be created
    * @return
    *   an `ElementQuery` for the given object.
    */
  def apply(a: A): ElementQuery[Out]
}

object ToQuery extends LowerPriorityToQuery {
  type Aux[A, E <: Element] = ToQuery[A] { type Out = E }

  def apply[A](implicit toQuery: ToQuery[A]): Aux[A, toQuery.Out] = toQuery

  implicit def queryToQuery[E <: Element]: ToQuery.Aux[ElementQuery[E], E] =
    new ToQuery[ElementQuery[E]] {
      type Out = E
      def apply(query: ElementQuery[E]) = query
    }

  implicit def typedElemToQuery[E <: Element.Strict[E]]: ToQuery.Aux[E, E] =
    new ToQuery[E] {
      type Out = E
      def apply(elem: E) = ElementQuery(elem)
    }

  implicit def typedDocToQuery[D <: Document, E <: Element.Strict[E]](implicit
      ev: D <:< Document.Typed[E]
  ): ToQuery.Aux[D, E] =
    new ToQuery[D] {
      type Out = E
      def apply(doc: D) = ElementQuery(ev(doc).root)
    }
}

trait LowerPriorityToQuery {

  implicit def elemToQuery[E <: Element]: ToQuery.Aux[E, Element] =
    new ToQuery[E] {
      type Out = Element
      def apply(elem: E) = ElementQuery[Element](elem)
    }

  implicit def docToQuery[D <: Document]: ToQuery.Aux[D, Element] =
    new ToQuery[D] {
      type Out = Element
      def apply(doc: D) = ElementQuery[Element](doc.root)
    }
}