From 29bef137f5c33a599f2629fecc0b756611dd126b Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Mon, 25 Dec 2023 22:16:13 +0800
Subject: Add proxy stream (not completed).

---
 include/cru/common/Base.h           |  2 +-
 include/cru/common/io/ProxyStream.h | 51 +++++++++++++++++++++++++++++++++++++
 src/common/CMakeLists.txt           |  1 +
 src/common/io/ProxyStream.cpp       | 18 +++++++++++++
 4 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 include/cru/common/io/ProxyStream.h
 create mode 100644 src/common/io/ProxyStream.cpp

diff --git a/include/cru/common/Base.h b/include/cru/common/Base.h
index 899cfc13..34faf779 100644
--- a/include/cru/common/Base.h
+++ b/include/cru/common/Base.h
@@ -1,5 +1,5 @@
 #pragma once
-#include "PreConfig.h"
+#include "PreConfig.h" // IWYU pragma: keep 
 
 #ifdef CRU_PLATFORM_WINDOWS
 #ifdef CRU_BASE_EXPORT_API
diff --git a/include/cru/common/io/ProxyStream.h b/include/cru/common/io/ProxyStream.h
new file mode 100644
index 00000000..688f714a
--- /dev/null
+++ b/include/cru/common/io/ProxyStream.h
@@ -0,0 +1,51 @@
+#pragma once
+
+#include "Stream.h"
+
+#include <functional>
+
+namespace cru::io {
+struct ProxyStreamHandlers {
+  std::function<Index(Index offset, Stream::SeekOrigin origin)> seek;
+  std::function<Index(std::byte* buffer, Index offset, Index size)> read;
+  std::function<Index(const std::byte* buffer, Index offset, Index size)> write;
+  std::function<void()> flush;
+
+  /**
+   * @brief This method will be only called once when `Close` is called or the
+   * stream is destructed.
+   */
+  std::function<void()> close;
+};
+
+class ProxyStream : public Stream {
+ public:
+  explicit ProxyStream(ProxyStreamHandlers handlers);
+
+  CRU_DELETE_COPY(ProxyStream)
+  CRU_DELETE_MOVE(ProxyStream)
+
+  ~ProxyStream() override;
+
+ public:
+  bool CanSeek() override;
+  Index Seek(Index offset, SeekOrigin origin = SeekOrigin::Current) override;
+
+  bool CanRead() override;
+  Index Read(std::byte* buffer, Index offset, Index size) override;
+
+  bool CanWrite() override;
+  Index Write(const std::byte* buffer, Index offset, Index size) override;
+
+  void Flush() override;
+
+  void Close() override;
+
+ private:
+  void DoClose();
+
+ private:
+  bool closed_;
+  ProxyStreamHandlers handlers_;
+};
+}  // namespace cru::io
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 714a4636..45688deb 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -9,6 +9,7 @@ add_library(CruBase
 	SubProcess.cpp
 	io/CFileStream.cpp
 	io/Stream.cpp
+	io/ProxyStream.cpp
 	io/Resource.cpp
 	io/MemoryStream.cpp
 	log/Logger.cpp
diff --git a/src/common/io/ProxyStream.cpp b/src/common/io/ProxyStream.cpp
new file mode 100644
index 00000000..9fd6be76
--- /dev/null
+++ b/src/common/io/ProxyStream.cpp
@@ -0,0 +1,18 @@
+#include "cru/common/io/ProxyStream.h"
+#include "cru/common/io/Stream.h"
+
+namespace cru::io {
+ProxyStream::ProxyStream(ProxyStreamHandlers handlers)
+    : closed_(false), handlers_(std::move(handlers)) {}
+
+ProxyStream::~ProxyStream() { DoClose(); }
+
+void ProxyStream::DoClose() {
+  if (!closed_) {
+    if (handlers_.close) {
+      handlers_.close();
+    }
+    closed_ = true;
+  }
+}
+}  // namespace cru::io
-- 
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