org.jetbrains.kotlin.types.StarProjectionImpl.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.builtins.KotlinBuiltIns
import org.jetbrains.kotlin.descriptors.ClassifierDescriptorWithTypeParameters
import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
import org.jetbrains.kotlin.resolve.descriptorUtil.builtIns
import org.jetbrains.kotlin.types.checker.KotlinTypeRefiner
import org.jetbrains.kotlin.types.refinement.TypeRefinement

class StarProjectionImpl(
    private val typeParameter: TypeParameterDescriptor
) : TypeProjectionBase() {
    override fun isStarProjection() = true

    override fun getProjectionKind() = Variance.OUT_VARIANCE

    // No synchronization here: there's no problem in accidentally computing this twice
    private val _type: KotlinType by lazy(LazyThreadSafetyMode.PUBLICATION) {
        typeParameter.starProjectionType()
    }

    override fun getType() = _type

    @TypeRefinement
    override fun refine(kotlinTypeRefiner: KotlinTypeRefiner): TypeProjection = this
}

fun TypeParameterDescriptor.starProjectionType(): KotlinType {
    val classDescriptor = this.containingDeclaration as ClassifierDescriptorWithTypeParameters
    val typeParameters = classDescriptor.typeConstructor.parameters.map { it.typeConstructor }
    return TypeSubstitutor.create(
        object : TypeConstructorSubstitution() {
            override fun get(key: TypeConstructor) =
                if (key in typeParameters)
                    TypeUtils.makeStarProjection(key.declarationDescriptor as TypeParameterDescriptor)
                else null

        }
    ).substitute(this.upperBounds.first(), Variance.OUT_VARIANCE) ?: builtIns.defaultBound
}

// It should only be used in rare cases when type parameter for the relevant argument is not available
class StarProjectionForAbsentTypeParameter(
    kotlinBuiltIns: KotlinBuiltIns
) : TypeProjectionBase() {
    private val nullableAnyType: KotlinType = kotlinBuiltIns.nullableAnyType

    override fun isStarProjection() = true

    override fun getProjectionKind() = Variance.OUT_VARIANCE

    override fun getType() = nullableAnyType

    @TypeRefinement
    override fun refine(kotlinTypeRefiner: KotlinTypeRefiner): TypeProjection = this
}