From e769130829ca46be6e2a9ea952ff5250295ffcef Mon Sep 17 00:00:00 2001
From: Him188 <Him188@mamoe.net>
Date: Tue, 11 May 2021 09:01:12 +0800
Subject: [PATCH] Improve ComponentStorage.plus: accept nullable arguments

---
 .../kotlin/network/component/ComponentStorage.kt      | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/mirai-core/src/commonMain/kotlin/network/component/ComponentStorage.kt b/mirai-core/src/commonMain/kotlin/network/component/ComponentStorage.kt
index 4af814a5d..b565decb4 100644
--- a/mirai-core/src/commonMain/kotlin/network/component/ComponentStorage.kt
+++ b/mirai-core/src/commonMain/kotlin/network/component/ComponentStorage.kt
@@ -31,10 +31,17 @@ internal interface ComponentStorage {
     val keys: Set<ComponentKey<*>>
 
     override fun toString(): String
+
+    companion object {
+        val EMPTY: ComponentStorage by lazy { ConcurrentComponentStorage() }
+    }
 }
 
-internal operator fun ComponentStorage.plus(fallback: ComponentStorage): ComponentStorage =
-    CombinedComponentStorage(this, fallback)
+internal operator fun ComponentStorage?.plus(fallback: ComponentStorage?): ComponentStorage {
+    if (this == null) return fallback ?: return ComponentStorage.EMPTY
+    if (fallback == null) return this
+    return CombinedComponentStorage(this, fallback)
+}
 
 private class CombinedComponentStorage(
     val main: ComponentStorage,