From 217415226e104bb699f66a85bc4c1fe92df20abb Mon Sep 17 00:00:00 2001
From: Sahan Fernando <sahan.h.fernando@gmail.com>
Date: Thu, 8 Jul 2021 00:58:46 +1000
Subject: [PATCH] AK: Add helper type for serializing structures into buffer

---
 AK/BinaryBufferWriter.h | 47 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 AK/BinaryBufferWriter.h

diff --git a/AK/BinaryBufferWriter.h b/AK/BinaryBufferWriter.h
new file mode 100644
index 00000000000..db7ea998de2
--- /dev/null
+++ b/AK/BinaryBufferWriter.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2021, Sahan Fernando <sahan.h.fernando@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Span.h>
+#include <AK/StdLibExtraDetails.h>
+
+namespace AK {
+
+class BinaryBufferWriter {
+public:
+    BinaryBufferWriter(Bytes target)
+        : m_target(target)
+    {
+    }
+
+    template<typename T>
+    requires(AK::Detail::IsTriviallyConstructible<T>) T& append_structure()
+    {
+        VERIFY((reinterpret_cast<FlatPtr>(m_target.data()) + m_offset) % alignof(T) == 0);
+        VERIFY(m_offset + sizeof(T) <= m_target.size());
+        T* allocated = new (m_target.data() + m_offset) T;
+        m_offset += sizeof(T);
+        return *allocated;
+    }
+
+    void skip_bytes(size_t num_bytes)
+    {
+        VERIFY(m_offset + num_bytes <= m_target.size());
+        m_offset += num_bytes;
+    }
+
+    [[nodiscard]] size_t current_offset() const
+    {
+        return m_offset;
+    }
+
+private:
+    Bytes m_target;
+    size_t m_offset { 0 };
+};
+
+}