org.jetbrains.kotlin.types.TypeCapabilities.kt Maven / Gradle / Ivy

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/*
 * Copyright 2010-2015 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 org.jetbrains.kotlin.types

import org.jetbrains.kotlin.descriptors.PossiblyInnerType
import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor

interface TypeCapability

interface TypeCapabilities {
    object NONE : TypeCapabilities {
        override fun  getCapability(capabilityClass: Class): T? = null
    }

    fun  getCapability(capabilityClass: Class): T?
}

class CompositeTypeCapabilities(private val first: TypeCapabilities, private val second: TypeCapabilities) : TypeCapabilities {
    override fun  getCapability(capabilityClass: Class): T? =
            first.getCapability(capabilityClass) ?: second.getCapability(capabilityClass)
}

class SingletonTypeCapabilities(private val clazz: Class<*>, private val typeCapability: TypeCapability) : TypeCapabilities {
    override fun  getCapability(capabilityClass: Class): T? {
        if (capabilityClass == clazz) return typeCapability as T
        return null
    }
}

inline fun  KotlinType.getCapability(): T? = getCapability(T::class.java)

interface Specificity : TypeCapability {

    enum class Relation {
        LESS_SPECIFIC,
        MORE_SPECIFIC,
        DONT_KNOW
    }

    fun getSpecificityRelationTo(otherType: KotlinType): Relation
}

fun KotlinType.getSpecificityRelationTo(otherType: KotlinType) =
        this.getCapability(Specificity::class.java)?.getSpecificityRelationTo(otherType) ?: Specificity.Relation.DONT_KNOW

fun oneMoreSpecificThanAnother(a: KotlinType, b: KotlinType) =
        a.getSpecificityRelationTo(b) != Specificity.Relation.DONT_KNOW || b.getSpecificityRelationTo(a) != Specificity.Relation.DONT_KNOW

// To facilitate laziness, any KotlinType implementation may inherit from this trait,
// even if it turns out that the type an instance represents is not actually a type variable
// (i.e. it is not derived from a type parameter), see isTypeVariable
interface CustomTypeVariable : TypeCapability {
    val isTypeVariable: Boolean

    // If typeParameterDescriptor != null <=> isTypeVariable == true, this is not a type variable
    val typeParameterDescriptor: TypeParameterDescriptor?

    // Throws an exception when isTypeVariable == false
    fun substitutionResult(replacement: KotlinType): KotlinType
}

fun KotlinType.isCustomTypeVariable(): Boolean = this.getCapability(CustomTypeVariable::class.java)?.isTypeVariable ?: false
fun KotlinType.getCustomTypeVariable(): CustomTypeVariable? =
        this.getCapability(CustomTypeVariable::class.java)?.let {
            if (it.isTypeVariable) it else null
        }

interface SubtypingRepresentatives : TypeCapability {
    val subTypeRepresentative: KotlinType
    val superTypeRepresentative: KotlinType

    fun sameTypeConstructor(type: KotlinType): Boolean
}

fun KotlinType.getSubtypeRepresentative(): KotlinType =
        this.getCapability(SubtypingRepresentatives::class.java)?.subTypeRepresentative ?: this

fun KotlinType.getSupertypeRepresentative(): KotlinType =
        this.getCapability(SubtypingRepresentatives::class.java)?.superTypeRepresentative ?: this

fun sameTypeConstructors(first: KotlinType, second: KotlinType): Boolean {
    val typeRangeCapability = SubtypingRepresentatives::class.java
    return first.getCapability(typeRangeCapability)?.sameTypeConstructor(second) ?: false
           || second.getCapability(typeRangeCapability)?.sameTypeConstructor(first) ?: false
}

interface CustomSubstitutionCapability : TypeCapability {
    val substitution: TypeSubstitution?
    val substitutionToComposeWith: TypeSubstitution?
}

interface PossiblyInnerTypeCapability : TypeCapability {
    val possiblyInnerType: PossiblyInnerType?
}