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/*
* Copyright 2010-2016 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.typesApproximation
import org.jetbrains.kotlin.builtins.KotlinBuiltIns
import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
import org.jetbrains.kotlin.renderer.ClassifierNamePolicy
import org.jetbrains.kotlin.renderer.DescriptorRenderer
import org.jetbrains.kotlin.resolve.calls.inference.CapturedTypeConstructor
import org.jetbrains.kotlin.resolve.calls.inference.isCaptured
import org.jetbrains.kotlin.resolve.descriptorUtil.builtIns
import org.jetbrains.kotlin.types.*
import org.jetbrains.kotlin.types.checker.KotlinTypeChecker
import org.jetbrains.kotlin.types.typeUtil.builtIns
import java.util.*
data class ApproximationBounds(
val lower: T,
val upper: T
)
private class TypeArgument(
val typeParameter: TypeParameterDescriptor,
val inProjection: KotlinType,
val outProjection: KotlinType
) {
val isConsistent: Boolean
get() = KotlinTypeChecker.DEFAULT.isSubtypeOf(inProjection, outProjection)
}
private fun TypeArgument.toTypeProjection(): TypeProjection {
assert(isConsistent) {
val descriptorRenderer = DescriptorRenderer.withOptions {
classifierNamePolicy = ClassifierNamePolicy.FULLY_QUALIFIED
}
"Only consistent enhanced type projection can be converted to type projection, but " +
"[${descriptorRenderer.render(typeParameter)}: <${descriptorRenderer.renderType(inProjection)}, ${descriptorRenderer.renderType(outProjection)}>]" +
" was found"
}
fun removeProjectionIfRedundant(variance: Variance) = if (variance == typeParameter.variance) Variance.INVARIANT else variance
return when {
inProjection == outProjection -> TypeProjectionImpl(inProjection)
KotlinBuiltIns.isNothing(inProjection) && typeParameter.variance != Variance.IN_VARIANCE ->
TypeProjectionImpl(removeProjectionIfRedundant(Variance.OUT_VARIANCE), outProjection)
KotlinBuiltIns.isNullableAny(outProjection) -> TypeProjectionImpl(removeProjectionIfRedundant(Variance.IN_VARIANCE), inProjection)
else -> TypeProjectionImpl(removeProjectionIfRedundant(Variance.OUT_VARIANCE), outProjection)
}
}
private fun TypeProjection.toTypeArgument(typeParameter: TypeParameterDescriptor) =
when (TypeSubstitutor.combine(typeParameter.variance, this)) {
Variance.INVARIANT -> TypeArgument(typeParameter, type, type)
Variance.IN_VARIANCE -> TypeArgument(typeParameter, type, typeParameter.builtIns.nullableAnyType)
Variance.OUT_VARIANCE -> TypeArgument(typeParameter, typeParameter.builtIns.nothingType, type)
}
fun approximateCapturedTypesIfNecessary(typeProjection: TypeProjection?, approximateContravariant: Boolean): TypeProjection? {
if (typeProjection == null) return null
if (typeProjection.isStarProjection) return typeProjection
val type = typeProjection.type
if (!TypeUtils.contains(type, { it.isCaptured() })) {
return typeProjection
}
val howThisTypeIsUsed = typeProjection.projectionKind
if (howThisTypeIsUsed == Variance.OUT_VARIANCE) {
// only 'return' type containing captured types should be over-approximated
val approximation = approximateCapturedTypes(type)
return TypeProjectionImpl(howThisTypeIsUsed, approximation.upper)
}
if (approximateContravariant) {
// TODO: assert that howThisTypeIsUsed is always IN
val approximation = approximateCapturedTypes(type).lower
return TypeProjectionImpl(howThisTypeIsUsed, approximation)
}
return substituteCapturedTypesWithProjections(typeProjection)
}
private fun substituteCapturedTypesWithProjections(typeProjection: TypeProjection): TypeProjection? {
val typeSubstitutor = TypeSubstitutor.create(object : TypeConstructorSubstitution() {
override fun get(key: TypeConstructor): TypeProjection? {
val capturedTypeConstructor = key as? CapturedTypeConstructor ?: return null
if (capturedTypeConstructor.typeProjection.isStarProjection) {
return TypeProjectionImpl(Variance.OUT_VARIANCE, capturedTypeConstructor.typeProjection.type)
}
return capturedTypeConstructor.typeProjection
}
})
return typeSubstitutor.substituteWithoutApproximation(typeProjection)
}
// todo: dynamic & raw type?
fun approximateCapturedTypes(type: KotlinType): ApproximationBounds {
if (type.isFlexible()) {
val boundsForFlexibleLower = approximateCapturedTypes(type.lowerIfFlexible())
val boundsForFlexibleUpper = approximateCapturedTypes(type.upperIfFlexible())
return ApproximationBounds(
KotlinTypeFactory.flexibleType(boundsForFlexibleLower.lower.lowerIfFlexible(), boundsForFlexibleUpper.lower.upperIfFlexible()),
KotlinTypeFactory.flexibleType(boundsForFlexibleLower.upper.lowerIfFlexible(), boundsForFlexibleUpper.upper.upperIfFlexible()))
}
val typeConstructor = type.constructor
if (type.isCaptured()) {
val typeProjection = (typeConstructor as CapturedTypeConstructor).typeProjection
fun KotlinType.makeNullableIfNeeded() = TypeUtils.makeNullableIfNeeded(this, type.isMarkedNullable)
val bound = typeProjection.type.makeNullableIfNeeded()
return when (typeProjection.projectionKind) {
Variance.IN_VARIANCE -> ApproximationBounds(bound, type.builtIns.nullableAnyType)
Variance.OUT_VARIANCE -> ApproximationBounds(type.builtIns.nothingType.makeNullableIfNeeded(), bound)
else -> throw AssertionError("Only nontrivial projections should have been captured, not: $typeProjection")
}
}
if (type.arguments.isEmpty() || type.arguments.size != typeConstructor.parameters.size) {
return ApproximationBounds(type, type)
}
val lowerBoundArguments = ArrayList()
val upperBoundArguments = ArrayList()
for ((typeProjection, typeParameter) in type.arguments.zip(typeConstructor.parameters)) {
val typeArgument = typeProjection.toTypeArgument(typeParameter)
// Protection from infinite recursion caused by star projection
if (typeProjection.isStarProjection) {
lowerBoundArguments.add(typeArgument)
upperBoundArguments.add(typeArgument)
}
else {
val (lower, upper) = approximateProjection(typeArgument)
lowerBoundArguments.add(lower)
upperBoundArguments.add(upper)
}
}
val lowerBoundIsTrivial = lowerBoundArguments.any { !it.isConsistent }
return ApproximationBounds(
if (lowerBoundIsTrivial) type.builtIns.nothingType else type.replaceTypeArguments(lowerBoundArguments),
type.replaceTypeArguments(upperBoundArguments))
}
private fun KotlinType.replaceTypeArguments(newTypeArguments: List): KotlinType {
assert(arguments.size == newTypeArguments.size) { "Incorrect type arguments $newTypeArguments" }
return replace(newTypeArguments.map { it.toTypeProjection() })
}
private fun approximateProjection(typeArgument: TypeArgument): ApproximationBounds {
val (inLower, inUpper) = approximateCapturedTypes(typeArgument.inProjection)
val (outLower, outUpper) = approximateCapturedTypes(typeArgument.outProjection)
return ApproximationBounds(
lower = TypeArgument(typeArgument.typeParameter, inUpper, outLower),
upper = TypeArgument(typeArgument.typeParameter, inLower, outUpper))
}