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calasql-query_3.0.1.9.source-code.JoinOps.scala Maven / Gradle / Ivy

package scalasql.query

import scalasql.core.{Expr, WithSqlExpr}

trait JoinOps[C[_, _], Q, R] extends WithSqlExpr[Q] {

  /**
   * Performs a `JOIN`/`INNER JOIN` on the given [[other]], typically a [[Table]] or [[Select]].
   */
  def join[Q2, R2, QF, RF](other: Joinable[Q2, R2])(on: (Q, Q2) => Expr[Boolean])(
      implicit ja: JoinAppend[Q, Q2, QF, RF]
  ): C[QF, RF] = join0("JOIN", other, Some(on))

  /**
   * Performs a `CROSS JOIN`, which is an `INNER JOIN` but without the `ON` clause
   */
  def crossJoin[Q2, R2, QF, RF](other: Joinable[Q2, R2])(
      implicit ja: JoinAppend[Q, Q2, QF, RF]
  ): C[QF, RF] = join0("CROSS JOIN", other, None)

  protected def join0[Q2, R2, QF, RF](
      prefix: String,
      other: Joinable[Q2, R2],
      on: Option[(Q, Q2) => Expr[Boolean]]
  )(
      implicit ja: JoinAppend[Q, Q2, QF, RF]
  ): C[QF, RF]

  protected def joinInfo[Q2, R2](
      joinPrefix: String,
      other: Joinable[Q2, R2],
      on: Option[(Q, Q2) => Expr[Boolean]]
  ) = {

    val (otherFrom, otherExpr) = Joinable.toFromExpr(other)

    val otherOn = on.map(_(expr, otherExpr))
    val otherJoin = Join(joinPrefix, Seq(Join.From(otherFrom, otherOn)))

    (Seq(otherJoin), otherExpr)
  }

}

object JoinOps {

  def join0[C[_, _], Q, R, Q2, R2, QF, RF](
      v: JoinOps[C, Q, R],
      prefix: String,
      other: Joinable[Q2, R2],
      on: Option[(Q, Q2) => Expr[Boolean]]
  )(
      implicit ja: JoinAppend[Q, Q2, QF, RF]
  ) = {
    v.join0[Q2, R2, QF, RF](prefix, other, on)
  }
}