Add `TypeSafeMap`

mirai-core-utils/src/commonMain/kotlin/TypeSafeMap.kt

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2019-2021 Mamoe Technologies and contributors.
+ *
+ *  此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
+ *  Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
+ *
+ *  https://github.com/mamoe/mirai/blob/master/LICENSE
+ */
+
+@file:Suppress("NOTHING_TO_INLINE")
+
+package net.mamoe.mirai.utils
+
+import java.util.concurrent.ConcurrentHashMap
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
+
+@JvmInline
+public value class TypeKey<out T>(public val name: String) {
+    override fun toString(): String = "Key($name)"
+
+    public inline infix fun <T> to(value: T): TypeSafeMap = buildTypeSafeMap { set(this@TypeKey, value) }
+}
+
+@JvmInline
+public value class TypeSafeMap(
+    private val map: MutableMap<TypeKey<*>, Any?> = ConcurrentHashMap()
+) {
+    public operator fun <T> get(key: TypeKey<T>): T =
+        map[key]?.uncheckedCast() ?: throw NoSuchElementException(key.toString())
+
+    public operator fun <T> contains(key: TypeKey<T>): Boolean = get(key) != null
+    public operator fun <T> set(key: TypeKey<T>, value: T) {
+        map[key] = value
+    }
+
+    public fun <T> remove(key: TypeKey<T>): T? = map.remove(key).uncheckedCast()
+}
+
+public inline fun buildTypeSafeMap(block: TypeSafeMap.() -> Unit): TypeSafeMap {
+    contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) }
+    return TypeSafeMap().apply(block)
+}