[minor] Renames and rearrangements for clarity

libraries/scripting/common/src/kotlin/script/experimental/util/propertyBag.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+@file:Suppress("unused")
+
+package kotlin.script.experimental.util
+
+import kotlin.reflect.KProperty
+
+data class TypedKey<T>(val name: String)
+
+class TypedKeyDelegate<T> {
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): TypedKey<T> = TypedKey(property.name)
+}
+
+fun <T> typedKey() = TypedKeyDelegate<T>()
+
+class ChainedPropertyBag(private val parent: ChainedPropertyBag? = null, pairs: Iterable<Pair<TypedKey<*>, Any?>>) {
+    constructor(pairs: Iterable<Pair<TypedKey<*>, Any?>>) : this(null, pairs)
+    constructor(parent: ChainedPropertyBag, vararg pairs: Pair<TypedKey<*>, Any?>) : this(parent, pairs.asIterable())
+    constructor(vararg pairs: Pair<TypedKey<*>, Any?>) : this(null, pairs.asIterable())
+
+    private val data = HashMap<TypedKey<*>, Any?>().also { it.putAll(pairs) }
+
+    inline operator fun <reified T> get(key: TypedKey<T>): T = getUnchecked(key) as T
+
+    fun <T> getUnchecked(key: TypedKey<T>): Any? =
+        when {
+            data.containsKey(key) -> data[key]
+            parent != null -> parent.getUnchecked(key)
+            else -> throw IllegalArgumentException("Unknown key $key")
+        }
+
+    inline fun <reified T> getOrNull(key: TypedKey<T>): T? = getOrNullUnchecked(key)?.let { it as T }
+
+    fun <T> getOrNullUnchecked(key: TypedKey<T>): Any? = data[key] ?: parent?.getOrNullUnchecked(key)
+}
+