From e37156a305532819533eeeb05be96a6935edf849 Mon Sep 17 00:00:00 2001
From: Joakim Hassila <jocke@ordo.one>
Date: Sat, 16 Apr 2022 11:25:44 +0200
Subject: [PATCH] Keep the underlying storage capacity when clearing the
 FlatBufferBuilder. Gives a significant performance boost for serialisation of
 many small messages. (#7250)

---
 swift/Sources/FlatBuffers/FlatBufferBuilder.swift | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/swift/Sources/FlatBuffers/FlatBufferBuilder.swift b/swift/Sources/FlatBuffers/FlatBufferBuilder.swift
index 5ccc7e44c..223f7ffa9 100644
--- a/swift/Sources/FlatBuffers/FlatBufferBuilder.swift
+++ b/swift/Sources/FlatBuffers/FlatBufferBuilder.swift
@@ -127,8 +127,8 @@ public struct FlatBufferBuilder {
   mutating public func clear() {
     _minAlignment = 0
     isNested = false
-    stringOffsetMap = [:]
-    _vtables = []
+    stringOffsetMap.removeAll(keepingCapacity: true)
+    _vtables.removeAll(keepingCapacity: true)
     _vtableStorage.clear()
     _bb.clear()
   }