[Commonizer] Add getParentEntityId() method to CirEntityId

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/CirName.kt

@@ -102,9 +102,12 @@ class CirEntityId private constructor(val packageName: CirPackageName, val relat
         relativeNameSegments.joinTo(this, ".")
     }
 
+    val isNestedEntity: Boolean get() = relativeNameSegments.size > 1
+
     fun createNestedEntityId(entityName: CirName): CirEntityId = create(packageName, relativeNameSegments + entityName)
 
-    val isNestedEntity: Boolean get() = relativeNameSegments.size > 1
+    fun getParentEntityId(): CirEntityId? =
+        if (isNestedEntity) create(packageName, relativeNameSegments.copyOfRange(0, relativeNameSegments.size - 1)) else null
 
     companion object {
         fun create(entityId: String): CirEntityId {

native/commonizer/tests/org/jetbrains/kotlin/descriptors/commonizer/core/CirEntityIdTest.kt

@@ -170,6 +170,30 @@ class CirEntityIdTest {
         }
     }
 
+    @Test
+    fun isNested() {
+        listOf(
+            "" to false,
+            "/" to false,
+            "foo/" to false,
+            "foo/bar/" to false,
+            "My" to false,
+            "My.Test" to true,
+            "My.Test.Class" to true,
+            "/My" to false,
+            "/My.Test" to true,
+            "/My.Test.Class" to true,
+            "foo/My" to false,
+            "foo/My.Test" to true,
+            "foo/My.Test.Class" to true,
+            "foo/bar/My" to false,
+            "foo/bar/My.Test" to true,
+            "foo/bar/My.Test.Class" to true,
+        ).forEach { (rawEntityId, isNested) ->
+            assertEquals(isNested, CirEntityId.create(rawEntityId).isNestedEntity)
+        }
+    }
+
     @Test
     fun createNested() {
         val nested1 = CirName.create("Nested1")
@@ -203,26 +227,24 @@ class CirEntityIdTest {
     }
 
     @Test
-    fun isNested() {
+    fun createParent() {
         listOf(
-            "" to false,
-            "/" to false,
-            "foo/" to false,
-            "foo/bar/" to false,
-            "My" to false,
-            "My.Test" to true,
-            "My.Test.Class" to true,
-            "/My" to false,
-            "/My.Test" to true,
-            "/My.Test.Class" to true,
-            "foo/My" to false,
-            "foo/My.Test" to true,
-            "foo/My.Test.Class" to true,
-            "foo/bar/My" to false,
-            "foo/bar/My.Test" to true,
-            "foo/bar/My.Test.Class" to true,
-        ).forEach { (rawEntityId, isNested) ->
-            assertEquals(isNested, CirEntityId.create(rawEntityId).isNestedEntity)
+            "" to null,
+            "foo/" to null,
+            "foo/bar/" to null,
+            "Outer" to null,
+            "foo/Outer" to null,
+            "foo/bar/Outer" to null,
+            "Outer.Nested1" to "Outer",
+            "foo/Outer.Nested1" to "foo/Outer",
+            "foo/bar/Outer.Nested1" to "foo/bar/Outer",
+            "Outer.Nested1.Nested2" to "Outer.Nested1",
+            "foo/Outer.Nested1.Nested2" to "foo/Outer.Nested1",
+            "foo/bar/Outer.Nested1.Nested2" to "foo/bar/Outer.Nested1"
+        ).forEach { (rawEntityId, rawParentEntityId) ->
+            val entityId = CirEntityId.create(rawEntityId)
+            val parentEntityId = rawParentEntityId?.let(CirEntityId::create)
+            assertSame(parentEntityId, entityId.getParentEntityId())
         }
     }
 }