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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.resolve.calls.inference
import org.jetbrains.kotlin.builtins.createFunctionType
import org.jetbrains.kotlin.builtins.isBuiltinExtensionFunctionalType
import org.jetbrains.kotlin.builtins.isExtensionFunctionType
import org.jetbrains.kotlin.builtins.isSuspendFunctionType
import org.jetbrains.kotlin.descriptors.TypeParameterDescriptor
import org.jetbrains.kotlin.descriptors.annotations.Annotations
import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.EQUAL
import org.jetbrains.kotlin.resolve.calls.inference.ConstraintSystemBuilderImpl.ConstraintKind.SUB_TYPE
import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.Bound
import org.jetbrains.kotlin.resolve.calls.inference.TypeBounds.BoundKind.*
import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPosition
import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind
import org.jetbrains.kotlin.resolve.calls.inference.constraintPosition.ConstraintPositionKind.TYPE_BOUND_POSITION
import org.jetbrains.kotlin.resolve.calls.results.SimpleConstraintSystem
import org.jetbrains.kotlin.resolve.descriptorUtil.hasExactAnnotation
import org.jetbrains.kotlin.resolve.descriptorUtil.hasNoInferAnnotation
import org.jetbrains.kotlin.types.*
import org.jetbrains.kotlin.types.TypeUtils.DONT_CARE
import org.jetbrains.kotlin.types.checker.TypeCheckingProcedure
import org.jetbrains.kotlin.types.checker.TypeCheckingProcedureCallbacks
import org.jetbrains.kotlin.types.typeUtil.builtIns
import org.jetbrains.kotlin.types.typeUtil.defaultProjections
import org.jetbrains.kotlin.types.typeUtil.isDefaultBound
import java.lang.IllegalArgumentException
import java.lang.IllegalStateException
import java.util.*
open class ConstraintSystemBuilderImpl(private val mode: Mode = ConstraintSystemBuilderImpl.Mode.INFERENCE) : ConstraintSystem.Builder {
enum class Mode {
INFERENCE,
SPECIFICITY
}
internal data class Constraint(
val kind: ConstraintKind, val subtype: KotlinType, val superType: KotlinType, val position: ConstraintPosition
)
enum class ConstraintKind(val bound: TypeBounds.BoundKind) {
SUB_TYPE(UPPER_BOUND),
EQUAL(EXACT_BOUND)
}
internal val allTypeParameterBounds = LinkedHashMap()
internal val usedInBounds = HashMap>()
internal val errors = ArrayList()
internal val initialConstraints = ArrayList()
override val typeVariableSubstitutors = LinkedHashMap()
private fun storeSubstitutor(call: CallHandle, substitutor: TypeSubstitutor): TypeSubstitutor {
if (typeVariableSubstitutors.containsKey(call)) {
throw IllegalStateException("Type variables for the same call can be registered only once: $call")
}
typeVariableSubstitutors[call] = substitutor
return substitutor
}
override fun registerTypeVariables(
call: CallHandle, typeParameters: Collection, external: Boolean
): TypeSubstitutor {
if (typeParameters.isEmpty()) return storeSubstitutor(call, TypeSubstitutor.EMPTY)
val typeVariables = if (external) {
typeParameters.map {
TypeVariable(call, it, it, true)
}
}
else {
val freshTypeParameters = ArrayList(typeParameters.size)
DescriptorSubstitutor.substituteTypeParameters(
typeParameters.toList(), TypeSubstitution.EMPTY, typeParameters.first().containingDeclaration, freshTypeParameters
)
freshTypeParameters.zip(typeParameters).map {
val (fresh, original) = it
TypeVariable(call, fresh, original, external)
}
}
for ((descriptor, typeVariable) in typeParameters.zip(typeVariables)) {
allTypeParameterBounds.put(typeVariable, TypeBoundsImpl(typeVariable))
}
for ((typeVariable, typeBounds) in allTypeParameterBounds) {
for (declaredUpperBound in typeVariable.freshTypeParameter.upperBounds) {
if (declaredUpperBound.isDefaultBound()) continue //todo remove this line (?)
val context = ConstraintContext(TYPE_BOUND_POSITION.position(typeVariable.originalTypeParameter.index))
addBound(typeVariable, declaredUpperBound, UPPER_BOUND, context)
}
}
return storeSubstitutor(call, TypeSubstitutor.create(TypeConstructorSubstitution.createByParametersMap(
typeParameters.zip(typeVariables.map { it.type }.defaultProjections()).toMap()
)))
}
private fun KotlinType.isProper() = !TypeUtils.contains(this) {
type -> type.constructor.declarationDescriptor.let { it is TypeParameterDescriptor && isMyTypeVariable(it) }
}
internal fun getNestedTypeVariables(type: KotlinType): List =
type.getNestedTypeParameters().mapNotNull { getMyTypeVariable(it) }
override fun addSubtypeConstraint(constrainingType: KotlinType?, subjectType: KotlinType?, constraintPosition: ConstraintPosition) {
addConstraint(SUB_TYPE, constrainingType, subjectType, ConstraintContext(constraintPosition, initial = true, initialReduction = true))
}
fun addConstraint(
constraintKind: ConstraintKind,
subType: KotlinType?,
superType: KotlinType?,
constraintContext: ConstraintContext
) {
val constraintPosition = constraintContext.position
// when processing nested constraints, `derivedFrom` information should be reset
val newConstraintContext = ConstraintContext(constraintContext.position, derivedFrom = null, initial = false,
initialReduction = constraintContext.initialReduction)
val typeCheckingProcedure = TypeCheckingProcedure(object : TypeCheckingProcedureCallbacks {
private var depth = 0
override fun assertEqualTypes(a: KotlinType, b: KotlinType, typeCheckingProcedure: TypeCheckingProcedure): Boolean {
depth++
doAddConstraint(EQUAL, a, b, newConstraintContext, typeCheckingProcedure)
depth--
return true
}
override fun assertEqualTypeConstructors(a: TypeConstructor, b: TypeConstructor): Boolean {
return a == b
}
override fun assertSubtype(subtype: KotlinType, supertype: KotlinType, typeCheckingProcedure: TypeCheckingProcedure): Boolean {
depth++
doAddConstraint(SUB_TYPE, subtype, supertype, newConstraintContext, typeCheckingProcedure)
depth--
return true
}
override fun capture(type: KotlinType, typeProjection: TypeProjection): Boolean {
if (isMyTypeVariable(typeProjection.type) || depth > 0) return false
val myTypeVariable = getMyTypeVariable(type)
if (myTypeVariable != null && constraintPosition.isParameter()) {
generateTypeParameterCaptureConstraint(myTypeVariable, typeProjection, newConstraintContext, type.isMarkedNullable)
return true
}
return false
}
override fun noCorrespondingSupertype(subtype: KotlinType, supertype: KotlinType): Boolean {
errors.add(newTypeInferenceOrParameterConstraintError(constraintPosition))
return true
}
})
doAddConstraint(constraintKind, subType, superType, constraintContext, typeCheckingProcedure)
}
private fun isErrorOrSpecialType(type: KotlinType?, constraintPosition: ConstraintPosition): Boolean {
if (TypeUtils.isDontCarePlaceholder(type) || ErrorUtils.isUninferredParameter(type)) {
return true
}
if (type == null || (type.isError && !type.isFunctionPlaceholder)) {
errors.add(ErrorInConstrainingType(constraintPosition))
return true
}
return false
}
private fun doAddConstraint(
constraintKind: ConstraintKind,
subType: KotlinType?,
superType: KotlinType?,
constraintContext: ConstraintContext,
typeCheckingProcedure: TypeCheckingProcedure
) {
val constraintPosition = constraintContext.position
if (isErrorOrSpecialType(subType, constraintPosition) || isErrorOrSpecialType(superType, constraintPosition)) return
if (subType == null || superType == null) return
if (constraintContext.initialReduction && (subType.hasExactAnnotation() || superType.hasExactAnnotation()) && (constraintKind != EQUAL)) {
return doAddConstraint(EQUAL, subType, superType, constraintContext, typeCheckingProcedure)
}
assert(!superType.isFunctionPlaceholder) { "The type for $constraintPosition shouldn't be a placeholder for function type" }
// function literal { x -> ... } goes without declaring receiver type
// and can be considered as extension function if one is expected
val newSubType = if (constraintKind == SUB_TYPE && subType.isFunctionPlaceholder) {
if (isMyTypeVariable(superType)) {
// the constraint binds type parameter and a function type,
// we don't add it without knowing whether it's a function type or an extension function type
return
}
createTypeForFunctionPlaceholder(subType, superType)
}
else {
subType
}
fun simplifyConstraint(subType: KotlinType, superType: KotlinType) {
if (isMyTypeVariable(subType)) {
generateTypeParameterBound(subType, superType, constraintKind.bound, constraintContext)
return
}
if (isMyTypeVariable(superType)) {
generateTypeParameterBound(superType, subType, constraintKind.bound.reverse(), constraintContext)
return
}
val subType2 = simplifyType(subType, constraintContext.initial)
val superType2 = simplifyType(superType, constraintContext.initial)
val result = if (constraintKind == EQUAL) {
typeCheckingProcedure.equalTypes(subType2, superType2)
}
else {
typeCheckingProcedure.isSubtypeOf(subType2, superType)
}
if (!result) errors.add(newTypeInferenceOrParameterConstraintError(constraintPosition))
}
if (constraintContext.initial) {
storeInitialConstraint(constraintKind, subType, superType, constraintPosition)
}
if (subType.hasNoInferAnnotation() || superType.hasNoInferAnnotation()) return
simplifyConstraint(newSubType, superType)
}
private fun simplifyType(type: KotlinType, isInitialConstraint: Boolean): KotlinType =
if (mode == Mode.SPECIFICITY || !isInitialConstraint)
type
else {
// if subType is nullable and superType is not nullable, unsafe call or type mismatch error will be generated later,
// but constraint system should be solved anyway
TypeUtils.makeNotNullable(type)
}
internal fun addBound(
typeVariable: TypeVariable,
constrainingType: KotlinType,
kind: TypeBounds.BoundKind,
constraintContext: ConstraintContext
) {
val bound = Bound(typeVariable, constrainingType, kind, constraintContext.position,
constrainingType.isProper(), constraintContext.derivedFrom ?: emptySet())
val typeBounds = getTypeBounds(typeVariable)
if (typeBounds.bounds.contains(bound)) return
typeBounds.addBound(bound)
if (!bound.isProper) {
for (dependentTypeVariable in getNestedTypeVariables(bound.constrainingType)) {
val dependentBounds = usedInBounds.getOrPut(dependentTypeVariable) { arrayListOf() }
dependentBounds.add(bound)
}
}
incorporateBound(bound)
}
private fun generateTypeParameterBound(
parameterType: KotlinType,
constrainingType: KotlinType,
boundKind: TypeBounds.BoundKind,
constraintContext: ConstraintContext
) {
val typeVariable = getMyTypeVariable(parameterType)!!
var newConstrainingType = constrainingType
// Here we are handling the case when T! gets a bound Foo (or Foo?)
// In this case, type parameter T is supposed to get the bound Foo!
// Example:
// val c: Collection = Collections.singleton(null : Foo?)
// Constraints for T are:
// Foo? <: T!
// Foo >: T!
// both Foo and Foo? transform to Foo! here
if (parameterType.isFlexible()) {
val customTypeVariable = parameterType.getCustomTypeVariable()
if (customTypeVariable != null) {
newConstrainingType = customTypeVariable.substitutionResult(constrainingType)
}
}
if (!parameterType.isMarkedNullable || !TypeUtils.isNullableType(newConstrainingType)) {
addBound(typeVariable, newConstrainingType, boundKind, constraintContext)
return
}
// For parameter type T:
// constraint T? = Int? should transform to T >: Int and T <: Int?
// constraint T? = Int! should transform to T >: Int and T <: Int!
// constraints T? >: Int?; T? >: Int! should transform to T >: Int
val notNullConstrainingType = TypeUtils.makeNotNullable(newConstrainingType)
if (boundKind == EXACT_BOUND || boundKind == LOWER_BOUND) {
addBound(typeVariable, notNullConstrainingType, LOWER_BOUND, constraintContext)
}
// constraints T? <: Int?; T? <: Int! should transform to T <: Int?; T <: Int! correspondingly
if (boundKind == EXACT_BOUND || boundKind == UPPER_BOUND) {
addBound(typeVariable, newConstrainingType, UPPER_BOUND, constraintContext)
}
}
private fun generateTypeParameterCaptureConstraint(
typeVariable: TypeVariable,
constrainingTypeProjection: TypeProjection,
constraintContext: ConstraintContext,
isTypeMarkedNullable: Boolean
) {
if (!typeVariable.originalTypeParameter.upperBounds.let { it.size == 1 && it.single().isDefaultBound() } &&
constrainingTypeProjection.projectionKind == Variance.IN_VARIANCE) {
errors.add(CannotCapture(constraintContext.position, typeVariable))
}
val typeProjection = if (isTypeMarkedNullable) {
TypeProjectionImpl(constrainingTypeProjection.projectionKind, TypeUtils.makeNotNullable(constrainingTypeProjection.type))
}
else {
constrainingTypeProjection
}
val capturedType = createCapturedType(typeProjection)
addBound(typeVariable, capturedType, EXACT_BOUND, constraintContext)
}
internal fun getTypeBounds(variable: TypeVariable): TypeBoundsImpl {
return allTypeParameterBounds[variable] ?:
throw IllegalArgumentException("TypeParameterDescriptor is not a type variable for constraint system: $variable")
}
private fun isMyTypeVariable(typeParameter: TypeParameterDescriptor) =
getMyTypeVariable(typeParameter) != null
internal fun isMyTypeVariable(type: KotlinType): Boolean =
getMyTypeVariable(type) != null
internal fun getMyTypeVariable(type: KotlinType): TypeVariable? {
return getMyTypeVariable(type.constructor.declarationDescriptor as? TypeParameterDescriptor ?: return null)
}
private fun getMyTypeVariable(typeParameter: TypeParameterDescriptor): TypeVariable? =
allTypeParameterBounds.keys.find { it.freshTypeParameter == typeParameter }
private fun storeInitialConstraint(constraintKind: ConstraintKind, subType: KotlinType, superType: KotlinType, position: ConstraintPosition) {
initialConstraints.add(Constraint(constraintKind, subType, superType, position))
}
private fun fixVariable(typeVariable: TypeVariable) {
val typeBounds = getTypeBounds(typeVariable)
if (typeBounds.isFixed) return
typeBounds.setFixed()
val nestedTypeVariables = typeBounds.bounds.flatMap { getNestedTypeVariables(it.constrainingType) }
nestedTypeVariables.forEach { fixVariable(it) }
val value = typeBounds.value ?: return
addBound(typeVariable, value, TypeBounds.BoundKind.EXACT_BOUND, ConstraintContext(ConstraintPositionKind.FROM_COMPLETER.position()))
}
override fun add(other: ConstraintSystem.Builder) {
if (other !is ConstraintSystemBuilderImpl) {
throw IllegalArgumentException("Unknown constraint system builder implementation: $other")
}
if (!Collections.disjoint(typeVariableSubstitutors.keys, other.typeVariableSubstitutors.keys)) {
throw IllegalArgumentException(
"Combining two constraint systems only makes sense when they were created for different calls. " +
"Calls of the first system: ${typeVariableSubstitutors.keys}, second: ${other.typeVariableSubstitutors.keys}"
)
}
if (!Collections.disjoint(other.allTypeParameterBounds.keys, allTypeParameterBounds.keys)) {
throw IllegalArgumentException(
"Combining two constraint systems only makes sense when they have no common variables. " +
"First system variables: ${allTypeParameterBounds.keys}, second: ${other.allTypeParameterBounds.keys}"
)
}
allTypeParameterBounds.putAll(other.allTypeParameterBounds)
usedInBounds.putAll(other.usedInBounds)
errors.addAll(other.errors)
initialConstraints.addAll(other.initialConstraints)
typeVariableSubstitutors.putAll(other.typeVariableSubstitutors)
}
override fun fixVariables() {
// todo variables should be fixed in the right order
val (external, functionTypeParameters) = allTypeParameterBounds.keys.partition { it.isExternal }
external.forEach { fixVariable(it) }
functionTypeParameters.forEach { fixVariable(it) }
}
override fun build(): ConstraintSystem {
return ConstraintSystemImpl(allTypeParameterBounds, usedInBounds, errors, initialConstraints, typeVariableSubstitutors)
}
companion object {
fun forSpecificity(): SimpleConstraintSystem = object : ConstraintSystemBuilderImpl(Mode.SPECIFICITY), SimpleConstraintSystem {
var counter = 0
override fun registerTypeVariables(typeParameters: Collection) =
registerTypeVariables(CallHandle.NONE, typeParameters)
override fun addSubtypeConstraint(subType: UnwrappedType, superType: UnwrappedType) =
addSubtypeConstraint(subType, superType, ConstraintPositionKind.VALUE_PARAMETER_POSITION.position(counter++))
override fun hasContradiction(): Boolean {
fixVariables()
return build().status.hasContradiction()
}
}
}
}
internal fun createTypeForFunctionPlaceholder(
functionPlaceholder: KotlinType,
expectedType: KotlinType
): KotlinType {
if (!functionPlaceholder.isFunctionPlaceholder) return functionPlaceholder
val functionPlaceholderTypeConstructor = functionPlaceholder.constructor as FunctionPlaceholderTypeConstructor
val isExtension = expectedType.isBuiltinExtensionFunctionalType
val newArgumentTypes = if (!functionPlaceholderTypeConstructor.hasDeclaredArguments) {
val typeParamSize = expectedType.constructor.parameters.size
// the first parameter is receiver (if present), the last one is return type,
// the remaining are function arguments
val functionArgumentsSize = if (isExtension) typeParamSize - 2 else typeParamSize - 1
val result = arrayListOf()
(1..functionArgumentsSize).forEach { result.add(DONT_CARE) }
result
}
else {
functionPlaceholderTypeConstructor.argumentTypes
}
val receiverType = if (isExtension) DONT_CARE else null
return createFunctionType(functionPlaceholder.builtIns, Annotations.EMPTY, receiverType, newArgumentTypes, null, DONT_CARE,
suspendFunction = expectedType.isSuspendFunctionType)
}