Add custom RWops class which works with arbitrary container as a storage

CMakeLists.txt

@@ -34,6 +34,7 @@ SET(LIBRARY_SOURCES
 
 SET(LIBRARY_HEADERS
 	SDL2pp/Exception.hh
+	SDL2pp/ExtraRWops.hh
 	SDL2pp/Point.hh
 	SDL2pp/RWops.hh
 	SDL2pp/Rect.hh

SDL2pp/ExtraRWops.hh

@@ -0,0 +1,93 @@
+/*
+  libSDL2pp - C++ wrapper for libSDL2
+  Copyright (C) 2014 Dmitry Marakasov <amdmi3@amdmi3.ru>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef SDL2PP_EXTRARWOPS_HH
+#define SDL2PP_EXTRARWOPS_HH
+
+#include <SDL2pp/RWops.hh>
+#include <SDL2pp/Exception.hh>
+
+namespace SDL2pp {
+
+template<typename C>
+class ContainerRWops : public CustomRWops {
+protected:
+	C& container_;
+	size_t position_;
+
+public:
+	ContainerRWops(C& container) : container_(container), position_(0) {
+	}
+
+	ContainerRWops(const ContainerRWops&) = default;
+	ContainerRWops& operator=(const ContainerRWops&) = default;
+	ContainerRWops(ContainerRWops&&) = default;
+	ContainerRWops& operator=(ContainerRWops&&) = default;
+
+	virtual Sint64 Seek(Sint64 offset, int whence) override {
+		switch (whence) {
+		case RW_SEEK_SET:
+			position_ = offset;
+			break;
+		case RW_SEEK_CUR:
+			position_ = position_ + offset;
+			break;
+		case RW_SEEK_END:
+			position_ = container_.size() + offset;
+			break;
+		default:
+			throw Exception("Unexpected whence value for WritableMemRWops::Seek");
+		}
+		return position_;
+	}
+
+	virtual size_t Read(void* ptr, size_t size, size_t maxnum) override {
+		if (position_ + size > container_.size())
+			return 0;
+
+		int toread = std::min((container_.size() - position_), maxnum * size);
+
+		std::copy(container_.begin() + position_, container_.begin() + position_ + toread, reinterpret_cast<unsigned char*>(ptr));
+
+		position_ += toread;
+
+		return toread / size;
+	}
+
+	virtual size_t Write(const void* ptr, size_t size, size_t maxnum) override {
+		if (position_ + size * maxnum > container_.size())
+			container_.resize(position_ + size * maxnum);
+
+		std::copy(reinterpret_cast<const unsigned char*>(ptr), reinterpret_cast<const unsigned char*>(ptr) + size * maxnum, container_.begin() + position_);
+
+		position_ += size * maxnum;
+
+		return maxnum;
+	}
+
+	virtual int Close() override {
+		return 0;
+	}
+};
+
+}
+
+#endif

SDL2pp/SDL2pp.hh

@@ -30,5 +30,6 @@
 #include <SDL2pp/Rect.hh>
 #include <SDL2pp/Point.hh>
 #include <SDL2pp/RWops.hh>
+#include <SDL2pp/ExtraRWops.hh>
 
 #endif