[kotlin-tooling-core] Implement HasExtras utils

^KT-55112 Verification Pending

libraries/tools/kotlin-tooling-core/src/main/kotlin/org/jetbrains/kotlin/tooling/core/HasExtras.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2010-2022 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.tooling.core
+
+import kotlin.reflect.KProperty
+
+
+interface HasExtras {
+    val extras: Extras
+}
+
+interface HasMutableExtras : HasExtras {
+    override val extras: MutableExtras
+}
+
+operator fun <T : Any> Extras.Key<T>.getValue(receiver: HasExtras, property: KProperty<*>): T? {
+    return receiver.extras[this]
+}
+
+
+operator fun <T : Any> Extras.Key<T>.setValue(receiver: HasMutableExtras, property: KProperty<*>, value: T?) {
+    if (value == null) {
+        receiver.extras.remove(this)
+    } else {
+        receiver.extras[this] = value
+    }
+}

libraries/tools/kotlin-tooling-core/src/test/kotlin/org/jetbrains/kotlin/tooling/core/HasExtrasTest.kt

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2010-2022 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.tooling.core
+
+import org.jetbrains.kotlin.tooling.core.HasExtrasTest.Subject.Companion.value1
+import org.jetbrains.kotlin.tooling.core.HasExtrasTest.Subject.Companion.value2
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class HasExtrasTest {
+
+    class Subject : HasMutableExtras {
+        override val extras: MutableExtras = mutableExtrasOf()
+
+        companion object {
+            var Subject.value1: Int? by extrasKeyOf()
+            var Subject.value2: Int? by extrasKeyOf("2")
+        }
+    }
+
+    @Test
+    fun `test - non-null value`() {
+        val subject = Subject()
+        assertNull(subject.value1)
+        assertNull(subject.value2)
+
+        subject.value1 = 1
+        assertEquals(1, subject.value1)
+        assertNull(subject.value2)
+
+        subject.value2 = 2
+        assertEquals(1, subject.value1)
+        assertEquals(2, subject.value2)
+    }
+
+    @Test
+    fun `test - set null`() {
+        val subject = Subject()
+        subject.value1 = 1
+        assertEquals(1, subject.value1)
+
+        subject.value1 = null
+        assertNull(subject.value1)
+    }
+}