org.jetbrains.kotlin.resolve.checkers.ClassifierUsageChecker.kt Maven / Gradle / Ivy

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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.checkers

import com.intellij.psi.PsiElement
import org.jetbrains.kotlin.config.LanguageVersionSettings
import org.jetbrains.kotlin.descriptors.ClassDescriptor
import org.jetbrains.kotlin.descriptors.ClassifierDescriptor
import org.jetbrains.kotlin.descriptors.DeclarationDescriptorWithSource
import org.jetbrains.kotlin.lexer.KtTokens
import org.jetbrains.kotlin.psi.KtNameReferenceExpression
import org.jetbrains.kotlin.psi.KtReferenceExpression
import org.jetbrains.kotlin.psi.KtTreeVisitorVoid
import org.jetbrains.kotlin.resolve.BindingContext
import org.jetbrains.kotlin.resolve.BindingTrace
import org.jetbrains.kotlin.resolve.DescriptorUtils

interface ClassifierUsageChecker {
    fun check(
            targetDescriptor: ClassifierDescriptor,
            trace: BindingTrace,
            element: PsiElement,
            languageVersionSettings: LanguageVersionSettings
    )

    companion object {
        fun check(
                declarations: Collection,
                trace: BindingTrace,
                languageVersionSettings: LanguageVersionSettings,
                checkers: Iterable
        ) {
            val visitor = object : KtTreeVisitorVoid() {
                override fun visitReferenceExpression(expression: KtReferenceExpression) {
                    super.visitReferenceExpression(expression)

                    if (expression is KtNameReferenceExpression && expression.getReferencedNameElementType() == KtTokens.SUPER_KEYWORD) {
                        // Do not run checkers here because super expressions is not a proper expression. For example,
                        // it doesn't make sense to report deprecation on "super" in "super.foo()" if the super class is deprecated.
                        return
                    }

                    val target = getReferencedClassifier(expression) ?: return

                    runCheckersWithTarget(target, expression)

                    if (isReferenceToCompanionViaOuterClass(expression, target)) {
                        val outerClass = target.containingDeclaration as ClassDescriptor
                        runCheckersWithTarget(outerClass, expression)
                    }
                }

                private fun runCheckersWithTarget(target: ClassifierDescriptor, expression: KtReferenceExpression) {
                    for (checker in checkers) {
                        checker.check(target, trace, expression, languageVersionSettings)
                    }
                }

                private fun getReferencedClassifier(expression: KtReferenceExpression): ClassifierDescriptor? {
                    val target = trace.get(BindingContext.REFERENCE_TARGET, expression) as? ClassifierDescriptor
                    if (target != null) return target

                    // "Comparable" in "import java.lang.Comparable" references both a class and a SAM constructor and prevents
                    // REFERENCE_TARGET from being recorded in favor of AMBIGUOUS_REFERENCE_TARGET. But we must still run checkers
                    // to report if there's something wrong with the class. We characterize this case below by the following properties:
                    // 1) Exactly one of the references is a classifier
                    // 2) All references refer to the same source element, i.e. their source is the same
                    val targets = trace.get(BindingContext.AMBIGUOUS_REFERENCE_TARGET, expression) ?: return null
                    if (targets.groupBy { (it as? DeclarationDescriptorWithSource)?.source }.size != 1) return null
                    return targets.filterIsInstance().singleOrNull()
                }

                /**
                 * @return true iff [expression] references the companion of a class Foo via the name Foo, e.g. in `Foo.bar()`
                 */
                private fun isReferenceToCompanionViaOuterClass(expression: KtReferenceExpression, target: ClassifierDescriptor?): Boolean {
                    return DescriptorUtils.isCompanionObject(target) &&
                           trace.get(BindingContext.SHORT_REFERENCE_TO_COMPANION_OBJECT, expression) != null
                }
            }

            for (declaration in declarations) {
                declaration.accept(visitor)
            }
        }
    }
}