Add proxy stream (not completed).

2 files changed, 52 insertions, 1 deletions

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