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fastpath.scala
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fastpath.scala
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// Copyright (c) 2013-2018 Rob Norris and Contributors
// This software is licensed under the MIT License (MIT).
// For more information see LICENSE or https://opensource.org/licenses/MIT
package doobie.postgres.free
import cats.~>
import cats.effect.Async
import cats.free.{ Free => FF } // alias because some algebras have an op called Free
import java.lang.String
import java.sql.ResultSet
import org.postgresql.fastpath.FastpathArg
import org.postgresql.fastpath.{ Fastpath => PGFastpath }
@SuppressWarnings(Array("org.wartremover.warts.Overloading"))
object fastpath { module =>
// Algebra of operations for PGFastpath. Each accepts a visitor as an alternatie to pattern-matching.
sealed trait FastpathOp[A] {
def visit[F[_]](v: FastpathOp.Visitor[F]): F[A]
}
// Free monad over FastpathOp.
type FastpathIO[A] = FF[FastpathOp, A]
// Module of instances and constructors of FastpathOp.
object FastpathOp {
// Given a PGFastpath we can embed a FastpathIO program in any algebra that understands embedding.
implicit val FastpathOpEmbeddable: Embeddable[FastpathOp, PGFastpath] =
new Embeddable[FastpathOp, PGFastpath] {
def embed[A](j: PGFastpath, fa: FF[FastpathOp, A]) = Embedded.Fastpath(j, fa)
}
// Interface for a natural tansformation FastpathOp ~> F encoded via the visitor pattern.
// This approach is much more efficient than pattern-matching for large algebras.
trait Visitor[F[_]] extends (FastpathOp ~> F) {
final def apply[A](fa: FastpathOp[A]): F[A] = fa.visit(this)
// Common
def raw[A](f: PGFastpath => A): F[A]
def embed[A](e: Embedded[A]): F[A]
def delay[A](a: () => A): F[A]
def handleErrorWith[A](fa: FastpathIO[A], f: Throwable => FastpathIO[A]): F[A]
def async[A](k: (Either[Throwable, A] => Unit) => Unit): F[A]
// PGFastpath
def addFunction(a: String, b: Int): F[Unit]
def addFunctions(a: ResultSet): F[Unit]
def fastpath(a: Int, b: Array[FastpathArg]): F[Array[Byte]]
def fastpath(a: Int, b: Boolean, c: Array[FastpathArg]): F[AnyRef]
def fastpath(a: String, b: Array[FastpathArg]): F[Array[Byte]]
def fastpath(a: String, b: Boolean, c: Array[FastpathArg]): F[AnyRef]
def getData(a: String, b: Array[FastpathArg]): F[Array[Byte]]
def getID(a: String): F[Int]
def getInteger(a: String, b: Array[FastpathArg]): F[Int]
def getLong(a: String, b: Array[FastpathArg]): F[Long]
def getOID(a: String, b: Array[FastpathArg]): F[Long]
}
// Common operations for all algebras.
final case class Raw[A](f: PGFastpath => A) extends FastpathOp[A] {
def visit[F[_]](v: Visitor[F]) = v.raw(f)
}
final case class Embed[A](e: Embedded[A]) extends FastpathOp[A] {
def visit[F[_]](v: Visitor[F]) = v.embed(e)
}
final case class Delay[A](a: () => A) extends FastpathOp[A] {
def visit[F[_]](v: Visitor[F]) = v.delay(a)
}
final case class HandleErrorWith[A](fa: FastpathIO[A], f: Throwable => FastpathIO[A]) extends FastpathOp[A] {
def visit[F[_]](v: Visitor[F]) = v.handleErrorWith(fa, f)
}
final case class Async1[A](k: (Either[Throwable, A] => Unit) => Unit) extends FastpathOp[A] {
def visit[F[_]](v: Visitor[F]) = v.async(k)
}
// PGFastpath-specific operations.
final case class AddFunction(a: String, b: Int) extends FastpathOp[Unit] {
def visit[F[_]](v: Visitor[F]) = v.addFunction(a, b)
}
final case class AddFunctions(a: ResultSet) extends FastpathOp[Unit] {
def visit[F[_]](v: Visitor[F]) = v.addFunctions(a)
}
final case class Fastpath(a: Int, b: Array[FastpathArg]) extends FastpathOp[Array[Byte]] {
def visit[F[_]](v: Visitor[F]) = v.fastpath(a, b)
}
final case class Fastpath1(a: Int, b: Boolean, c: Array[FastpathArg]) extends FastpathOp[AnyRef] {
def visit[F[_]](v: Visitor[F]) = v.fastpath(a, b, c)
}
final case class Fastpath2(a: String, b: Array[FastpathArg]) extends FastpathOp[Array[Byte]] {
def visit[F[_]](v: Visitor[F]) = v.fastpath(a, b)
}
final case class Fastpath3(a: String, b: Boolean, c: Array[FastpathArg]) extends FastpathOp[AnyRef] {
def visit[F[_]](v: Visitor[F]) = v.fastpath(a, b, c)
}
final case class GetData(a: String, b: Array[FastpathArg]) extends FastpathOp[Array[Byte]] {
def visit[F[_]](v: Visitor[F]) = v.getData(a, b)
}
final case class GetID(a: String) extends FastpathOp[Int] {
def visit[F[_]](v: Visitor[F]) = v.getID(a)
}
final case class GetInteger(a: String, b: Array[FastpathArg]) extends FastpathOp[Int] {
def visit[F[_]](v: Visitor[F]) = v.getInteger(a, b)
}
final case class GetLong(a: String, b: Array[FastpathArg]) extends FastpathOp[Long] {
def visit[F[_]](v: Visitor[F]) = v.getLong(a, b)
}
final case class GetOID(a: String, b: Array[FastpathArg]) extends FastpathOp[Long] {
def visit[F[_]](v: Visitor[F]) = v.getOID(a, b)
}
}
import FastpathOp._
// Smart constructors for operations common to all algebras.
val unit: FastpathIO[Unit] = FF.pure[FastpathOp, Unit](())
def pure[A](a: A): FastpathIO[A] = FF.pure[FastpathOp, A](a)
def raw[A](f: PGFastpath => A): FastpathIO[A] = FF.liftF(Raw(f))
def embed[F[_], J, A](j: J, fa: FF[F, A])(implicit ev: Embeddable[F, J]): FF[FastpathOp, A] = FF.liftF(Embed(ev.embed(j, fa)))
def delay[A](a: => A): FastpathIO[A] = FF.liftF(Delay(() => a))
def handleErrorWith[A](fa: FastpathIO[A], f: Throwable => FastpathIO[A]): FastpathIO[A] = FF.liftF[FastpathOp, A](HandleErrorWith(fa, f))
def raiseError[A](err: Throwable): FastpathIO[A] = delay(throw err)
def async[A](k: (Either[Throwable, A] => Unit) => Unit): FastpathIO[A] = FF.liftF[FastpathOp, A](Async1(k))
// Smart constructors for Fastpath-specific operations.
def addFunction(a: String, b: Int): FastpathIO[Unit] = FF.liftF(AddFunction(a, b))
def addFunctions(a: ResultSet): FastpathIO[Unit] = FF.liftF(AddFunctions(a))
def fastpath(a: Int, b: Array[FastpathArg]): FastpathIO[Array[Byte]] = FF.liftF(Fastpath(a, b))
def fastpath(a: Int, b: Boolean, c: Array[FastpathArg]): FastpathIO[AnyRef] = FF.liftF(Fastpath1(a, b, c))
def fastpath(a: String, b: Array[FastpathArg]): FastpathIO[Array[Byte]] = FF.liftF(Fastpath2(a, b))
def fastpath(a: String, b: Boolean, c: Array[FastpathArg]): FastpathIO[AnyRef] = FF.liftF(Fastpath3(a, b, c))
def getData(a: String, b: Array[FastpathArg]): FastpathIO[Array[Byte]] = FF.liftF(GetData(a, b))
def getID(a: String): FastpathIO[Int] = FF.liftF(GetID(a))
def getInteger(a: String, b: Array[FastpathArg]): FastpathIO[Int] = FF.liftF(GetInteger(a, b))
def getLong(a: String, b: Array[FastpathArg]): FastpathIO[Long] = FF.liftF(GetLong(a, b))
def getOID(a: String, b: Array[FastpathArg]): FastpathIO[Long] = FF.liftF(GetOID(a, b))
// FastpathIO is an Async
implicit val AsyncFastpathIO: Async[FastpathIO] =
new Async[FastpathIO] {
val M = FF.catsFreeMonadForFree[FastpathOp]
def pure[A](x: A): FastpathIO[A] = M.pure(x)
def handleErrorWith[A](fa: FastpathIO[A])(f: Throwable => FastpathIO[A]): FastpathIO[A] = module.handleErrorWith(fa, f)
def raiseError[A](e: Throwable): FastpathIO[A] = module.raiseError(e)
def async[A](k: (Either[Throwable,A] => Unit) => Unit): FastpathIO[A] = module.async(k)
def flatMap[A, B](fa: FastpathIO[A])(f: A => FastpathIO[B]): FastpathIO[B] = M.flatMap(fa)(f)
def tailRecM[A, B](a: A)(f: A => FastpathIO[Either[A, B]]): FastpathIO[B] = M.tailRecM(a)(f)
def suspend[A](thunk: => FastpathIO[A]): FastpathIO[A] = M.flatten(module.delay(thunk))
}
}