org.jetbrains.kotlin.container.PlatformSpecificExtension.kt Maven / Gradle / Ivy
/*
* Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
* that can be found in the license/LICENSE.txt file.
*/
package org.jetbrains.kotlin.container
/**
* This is a marker-interface for components which are needed for common resolve
* facilities (like resolve, or deserialization), but are platform-specific.
*
* PlatformSpecificExtensions has to be present in the container in exactly one
* instance (hence common pattern with providing no-op DEFAULT/EMPTY implementation
* in the corresponding interface)
*
* In multiplatform modules such components require special treatment. Namely,
* if several components of the same type are provided, then it's not an illegal state;
* rather, we have to carefully resolve clash on case-by-case basis.
* See also [PlatformExtensionsClashResolver].
*/
interface PlatformSpecificExtension>
/**
* Allows to specify which [PlatformSpecificExtension] should be used if there were two or more registrations
* for [applicableTo] class in the container.
*
* [PlatformExtensionsClashResolver] should be registred in the container via [useClashResolver]-extension.
*
* NB. YOU DON'T NEED this mechanism for the most popular case of "one or several default vs.
* zero or one non-default". Just use [DefaultImplementation], and default instances will be automatically
* discriminated (see respective KDoc).
* Use [PlatformExtensionsClashResolver] only for cases when you need more invloved logic.
*
* Example: [org.jetbrains.kotlin.resolve.IdentifierChecker]. It is used in platform-agnostic code,
* which resolves and checks identifiers for correctness. Each platform has it's own rules
* regarding identifier correctness. In MPP modules we can't choose only one IdentifierChecker;
* instead, we have to provide a "composite" IdentifierChecker which will launch checks of *each*
* platform.
*
*/
abstract class PlatformExtensionsClashResolver>(val applicableTo: Class) {
abstract fun resolveExtensionsClash(extensions: List): E
class FallbackToDefault>(
private val defaultValue: E,
applicableTo: Class
) : PlatformExtensionsClashResolver(applicableTo) {
override fun resolveExtensionsClash(extensions: List): E = defaultValue
}
}