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/*
* Copyright 2021-2024 Disney Streaming
*
* Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://disneystreaming.github.io/TOST-1.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package smithy4s
import scala.util.control.NonFatal
/**
* A surjection of a partial function A => Either[String, B] and a total function B => A.
*
* A surjection MUST abide by the round-tripping property, namely, for all input A that passes the
* validation function
*
* surjection(input).map(surjection.from) == Right(input)
*/
trait Surjection[A, B] extends Function[A, Either[String, B]] { outer =>
def to(a: A): Either[String, B]
def from(b: B): A
final def apply(a: A): Either[String, B] = to(a)
final def imapFull[A0, B0](
sourceBijection: Bijection[A, A0],
targetBijection: Bijection[B, B0]
): Surjection[A0, B0] = new Surjection[A0, B0] {
def to(a0: A0): Either[String, B0] =
outer.to(sourceBijection.from(a0)).map(targetBijection)
def from(b0: B0): A0 = sourceBijection(outer.from(targetBijection.from(b0)))
}
final def imapSource[A0](bijection: Bijection[A, A0]): Surjection[A0, B] =
imapFull(bijection, Bijection.identity)
final def imapTarget[B0](bijection: Bijection[B, B0]): Surjection[A, B0] =
imapFull(Bijection.identity, bijection)
}
object Surjection {
def apply[A, B](to: A => Either[String, B], from: B => A): Surjection[A, B] =
new Impl[A, B](to, from)
def catching[A, B](to: A => B, from: B => A): Surjection[A, B] =
new Impl(
a =>
try { Right(to(a)) }
catch { case NonFatal(e) => Left(e.getMessage) },
from
)
private class Impl[A, B](
toFunction: A => Either[String, B],
fromFunction: B => A
) extends Surjection[A, B] {
def to(a: A): Either[String, B] = toFunction(a)
def from(b: B): A = fromFunction(b)
}
}
