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scodec-core
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/*
 * Copyright (c) 2013, Scodec
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors
 *    may be used to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package scodec

/** Typeclass that describes type constructors that support the `exmap` operation. */
trait Transform[F[_]]:

  /** Transforms supplied `F[A]` to an `F[B]` using two functions, `A => Attempt[B]` and `B => Attempt[A]`.
    */
  extension [A, B](fa: F[A]) def exmap(f: A => Attempt[B], g: B => Attempt[A]): F[B]

  /** Transforms supplied `F[A]` to an `F[B]` using the isomorphism described by two functions,
    * `A => B` and `B => A`.
    */
  extension [A, B](fa: F[A])
    def xmap(f: A => B, g: B => A): F[B] =
      fa.exmap(a => Attempt.successful(f(a)), b => Attempt.successful(g(b)))

  /** Curried version of [[xmap]]. */
  extension [A, B](fa: F[A]) inline def xmapc(f: A => B)(g: B => A): F[B] = fa.xmap(f, g)

  /** Transforms supplied `F[A]` to an `F[B]` using two functions, `A => Attempt[B]` and `B => A`.
    *
    * The supplied functions form an injection from `B` to `A`. Hence, converting a `F[A]` to a `F[B]` converts from
    * a larger to a smaller type. Hence, the name `narrow`.
    */
  extension [A, B](fa: F[A])
    def narrow(f: A => Attempt[B], g: B => A): F[B] =
      fa.exmap(f, b => Attempt.successful(g(b)))

  /** Transforms supplied `F[A]` to an `F[B]` using two functions, `A => B` and `B => Attempt[A]`.
    *
    * The supplied functions form an injection from `A` to `B`. Hence, converting a `F[A]` to a `F[B]` converts from
    * a smaller to a larger type. Hence, the name `widen`.
    */
  extension [A, B](fa: F[A])
    def widen(f: A => B, g: B => Attempt[A]): F[B] =
      fa.exmap(a => Attempt.successful(f(a)), g)

  /** Transforms supplied `F[A]` to an `F[B]` using two functions, `A => B` and `B => Option[A]`.
    *
    * Particularly useful when combined with case class apply/unapply. E.g., `widenOpt(fa, Foo.apply, Foo.unapply)`.
    */
  extension [A, B](fa: F[A])
    def widenOpt(f: A => B, g: B => Option[A]): F[B] =
      fa.exmap(
        a => Attempt.successful(f(a)),
        b => Attempt.fromOption(g(b), Err(s"widening failed: $b"))
      )