Deprecate KotlinSourceSet.getSourceSetHierarchy in favour of 'resolveAllDependsOnSourceSets' and general purpose 'transitiveClosure'

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/ResolveKotlinSourceSetsTest.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+/* Associate compilations are not yet supported by the IDE. KT-34102 */
+@file:Suppress("invisible_reference", "invisible_member", "FunctionName", "DuplicatedCode")
+
+package org.jetbrains.kotlin.gradle
+
+import org.gradle.api.Project
+import org.gradle.testfixtures.ProjectBuilder
+import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
+import org.jetbrains.kotlin.gradle.plugin.sources.resolveAllDependsOnSourceSets
+import org.jetbrains.kotlin.gradle.plugin.sources.resolveAllSourceSetsDependingOn
+import org.junit.Test
+import kotlin.test.BeforeTest
+import kotlin.test.assertEquals
+
+class ResolveKotlinSourceSetsTest {
+    private lateinit var project: Project
+    private lateinit var kotlin: KotlinMultiplatformExtension
+
+    @BeforeTest
+    fun setup() {
+        project = ProjectBuilder.builder().build()
+        project.plugins.apply("kotlin-multiplatform")
+        kotlin = project.extensions.getByName("kotlin") as KotlinMultiplatformExtension
+
+    }
+
+    @Test
+    fun resolveAllSourceSetsDependingOn() {
+        val commonMain = kotlin.sourceSets.getByName("commonMain")
+        val nativeMain = kotlin.sourceSets.create("nativeMain")
+        val linuxMain = kotlin.sourceSets.create("linuxMain")
+        val macosMain = kotlin.sourceSets.create("macosMain")
+        val jvmMain = kotlin.sourceSets.create("jvmMain")
+
+        jvmMain.dependsOn(commonMain)
+        nativeMain.dependsOn(commonMain)
+        linuxMain.dependsOn(nativeMain)
+        macosMain.dependsOn(nativeMain)
+
+        assertEquals(
+            setOf(nativeMain, linuxMain, macosMain, jvmMain),
+            kotlin.resolveAllSourceSetsDependingOn(commonMain)
+        )
+
+        assertEquals(
+            setOf(linuxMain, macosMain),
+            kotlin.resolveAllSourceSetsDependingOn(nativeMain)
+        )
+
+        assertEquals(emptySet(), kotlin.resolveAllSourceSetsDependingOn(linuxMain))
+        assertEquals(emptySet(), kotlin.resolveAllSourceSetsDependingOn(macosMain))
+        assertEquals(emptySet(), kotlin.resolveAllSourceSetsDependingOn(jvmMain))
+    }
+
+    @Test
+    fun resolveAllDependsOnSourceSets() {
+        val commonMain = kotlin.sourceSets.getByName("commonMain")
+        val nativeMain = kotlin.sourceSets.create("nativeMain")
+        val linuxMain = kotlin.sourceSets.create("linuxMain")
+        val macosMain = kotlin.sourceSets.create("macosMain")
+        val jvmMain = kotlin.sourceSets.create("jvmMain")
+
+        jvmMain.dependsOn(commonMain)
+        nativeMain.dependsOn(commonMain)
+        linuxMain.dependsOn(nativeMain)
+        macosMain.dependsOn(nativeMain)
+
+        assertEquals(
+            setOf(nativeMain, commonMain), linuxMain.resolveAllDependsOnSourceSets()
+        )
+
+        assertEquals(
+            setOf(commonMain), nativeMain.resolveAllDependsOnSourceSets()
+        )
+
+        assertEquals(
+            emptySet(), commonMain.resolveAllDependsOnSourceSets()
+        )
+
+        assertEquals(
+            setOf(commonMain), jvmMain.resolveAllDependsOnSourceSets()
+        )
+    }
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/sources/DefaultKotlinSourceSet.kt

@@ -11,16 +11,14 @@ import org.gradle.api.Project
 import org.gradle.api.file.SourceDirectorySet
 import org.gradle.util.ConfigureUtil
 import org.jetbrains.kotlin.build.DEFAULT_KOTLIN_SOURCE_FILES_EXTENSIONS
+import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
 import org.jetbrains.kotlin.gradle.plugin.KotlinDependencyHandler
 import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
 import org.jetbrains.kotlin.gradle.plugin.LanguageSettingsBuilder
 import org.jetbrains.kotlin.gradle.plugin.mpp.*
-import org.jetbrains.kotlin.gradle.plugin.mpp.GranularMetadataTransformation
-import org.jetbrains.kotlin.gradle.plugin.mpp.MetadataDependencyResolution
 import org.jetbrains.kotlin.gradle.plugin.whenEvaluated
 import org.jetbrains.kotlin.gradle.utils.*
 import java.io.File
-import java.lang.reflect.Constructor
 import java.util.*
 
 const val METADATA_CONFIGURATION_NAME_SUFFIX = "DependenciesMetadata"
@@ -72,7 +70,7 @@ class DefaultKotlinSourceSet(
     }
 
     override fun languageSettings(configure: LanguageSettingsBuilder.() -> Unit): LanguageSettingsBuilder =
-            languageSettings.apply { configure(this) }
+        languageSettings.apply { configure(this) }
 
     override fun getName(): String = displayName
 
@@ -232,6 +230,12 @@ internal fun KotlinSourceSet.disambiguateName(simpleName: String): String {
 private fun createDefaultSourceDirectorySet(project: Project, name: String?): SourceDirectorySet =
     project.objects.sourceDirectorySet(name, name)
 
+
+@Deprecated(
+    "Use 'getAllDependsOnSourceSets' instead",
+    level = DeprecationLevel.WARNING,
+    replaceWith = ReplaceWith("getAllDependsOnSourceSets")
+)
 internal fun KotlinSourceSet.getSourceSetHierarchy(): Set<KotlinSourceSet> {
     val result = mutableSetOf<KotlinSourceSet>()
 
@@ -245,10 +249,14 @@ internal fun KotlinSourceSet.getSourceSetHierarchy(): Set<KotlinSourceSet> {
     return result
 }
 
+internal fun KotlinSourceSet.resolveAllDependsOnSourceSets(): Set<KotlinSourceSet> {
+    return transitiveClosure { dependsOn }
+}
 
-private fun <T> Class<T>.constructorOrNull(vararg parameterTypes: Class<*>): Constructor<T>? =
+internal fun Iterable<KotlinSourceSet>.resolveAllDependsOnSourceSets(): Set<KotlinSourceSet> {
-    try {
+    return flatMapTo(mutableSetOf()) { it.resolveAllDependsOnSourceSets() }
-        getConstructor(*parameterTypes)
+}
-    } catch (e: NoSuchMethodException) {
+
-        null
+internal fun KotlinMultiplatformExtension.resolveAllSourceSetsDependingOn(sourceSet: KotlinSourceSet): Set<KotlinSourceSet> {
-    }
+    return sourceSet.transitiveClosure { sourceSets.filter { otherSourceSet -> this in otherSourceSet.dependsOn } }
+}

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/utils/transitiveClosure.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.gradle.utils
+
+/**
+ * General purpose implementation of a transitive closure
+ * - Recursion free
+ * - Predictable amount of allocations
+ * - Handles loops and self references gracefully
+ * @param edges: Producer function from one node to all its children. This implementation can handle loops and self references gracefully.
+ * @return Note: No guarantees given about the order ot this [Set]
+ */
+internal inline fun <reified T> T.transitiveClosure(edges: T.() -> Iterable<T>): Set<T> {
+    // Fast path when initial edges are empty
+    val initialEdges = edges()
+    if (initialEdges is Collection && initialEdges.isEmpty()) return emptySet()
+
+    val queue = deque<T>()
+    val results = mutableSetOf<T>()
+    queue.addAll(initialEdges)
+    while (queue.isNotEmpty()) {
+        // ArrayDeque implementation will optimize this call to 'removeFirst'
+        val resolved = queue.removeAt(0)
+        if (resolved != this && results.add(resolved)) {
+            queue.addAll(resolved.edges())
+        }
+    }
+
+    return results.toSet()
+}
+
+@OptIn(ExperimentalStdlibApi::class)
+private inline fun <reified T> deque(): MutableList<T> {
+    return if (KotlinVersion.CURRENT.isAtLeast(1, 4)) ArrayDeque()
+    else mutableListOf()
+}

libraries/tools/kotlin-gradle-plugin/src/test/kotlin/org/jetbrains/kotlin/gradle/utils/TransitiveClosureTest.kt

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.gradle.utils
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class TransitiveClosureTest {
+    private class Node(val value: String, val children: MutableList<Node> = mutableListOf()) {
+
+        override fun toString(): String {
+            return value
+        }
+
+        override fun equals(other: Any?): Boolean {
+            if (other !is Node) return false
+            return other.value == value
+        }
+
+        override fun hashCode(): Int {
+            return value.hashCode()
+        }
+    }
+
+    private fun Node.transitiveClosure() = transitiveClosure { children }
+
+    @Test
+    fun `transitiveClosure does not include root node`() {
+        val closure = Node("a", mutableListOf(Node("b"), Node("c"))).transitiveClosure()
+        assertEquals(setOf(Node("b"), Node("c")), closure, "Expected transitiveClosure to not include root node")
+    }
+
+    @Test
+    fun `transitiveClosure handles loop and self references`() {
+        val nodeA = Node("a")
+        val nodeB = Node("b")
+        val nodeC = Node("c")
+        val nodeD = Node("d")
+
+        // a -> b -> c -> d
+        nodeA.children.add(nodeB)
+        nodeB.children.add(nodeC)
+        nodeC.children.add(nodeD)
+
+        // add self reference to b
+        nodeB.children.add(nodeB)
+
+        // add loop from c -> a
+        nodeC.children.add(nodeA)
+
+        val closure = nodeA.transitiveClosure()
+        assertEquals(
+            setOf(nodeB, nodeC, nodeD), closure,
+            "Expected transitiveClosure to be robust against loops and self references"
+        )
+    }
+}