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include/fs/ISource.h

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+#pragma once
+
+#include "fs/IStreamSource.h"
+#include "fs/Api.h"
+#include "tl/flag_set2.h"
+
+namespace fs
+{
+
+//Design rationale:
+// Sources are throw-away objects representing a data source or sink (the Sink).
+// They are not supposed to be reused. 
+// There is only one owner of the source, enforced by the tl::unique_ref wrapper. Due to this, sources are NOT thread safe.
+// There is no open/close for sources as the open is done in the constructor and close in the destructor. This is to reinforce the idea of throw-away objects.
+// If you need a persistent source to be able to reload your data, hold a 
+//		path to the source instead of the source. This is to allow the underlying file system to change (due to DLC for example). When you need the source again, request a new one from the file system.
+
+class FS_API ISource : public IStreamSource
+{
+public:
+	enum class Flag : uint8_t
+	{
+		Unbuffered,
+		Uncached,
+		SequentialHint, //takes prio over the random hint flag
+		RandomHint,
+	};
+	typedef tl::flag_set2<Flag> Flags;
+
+	ISource() = default;
+	~ISource() override = default;
+
+	ISource(ISource&&) = default;
+	ISource& operator=(ISource&&) = default;
+
+	//Changes the cursor either to an absolute offset or a relative one
+	virtual void seekBeg(uint64_t offset) = 0;
+	virtual void seekRel(int64_t offset) = 0;
+
+	//returns the current cursor position. This is always between 0 and size
+	virtual uint64_t tell() const = 0;
+
+	//returns the size of the source in bytes
+	virtual uint64_t getSize() const = 0;
+};
+
+}