Add io::expanding_memory_ostream that writes to std::vector<char>

libs/io/include/psemek/io/memory_stream.hpp

@@ -3,6 +3,7 @@
 #include <psemek/io/stream.hpp>
 
 #include <string_view>
+#include <vector>
 
 namespace psemek::io
 {
@@ -131,4 +132,55 @@ namespace psemek::io
 		char * end_ = nullptr;
 	};
 
+	struct expanding_memory_ostream
+		: ostream
+	{
+		expanding_memory_ostream() = default;
+
+		expanding_memory_ostream(std::vector<char> & storage)
+			: buffer_(&storage)
+		{}
+
+		expanding_memory_ostream(expanding_memory_ostream && s)
+			: storage_(std::move(s.storage_))
+			, buffer_(s.buffer_)
+		{
+			s.reset();
+		}
+
+		expanding_memory_ostream & operator = (expanding_memory_ostream && s)
+		{
+			if (this != &s)
+			{
+				storage_ = std::move(s.storage_);
+				buffer_ = s.buffer_;
+				s.reset();
+			}
+
+			return *this;
+		}
+
+		void reset()
+		{
+			storage_.clear();
+			buffer_ = &storage_;
+		}
+
+		void swap(expanding_memory_ostream & s)
+		{
+			std::swap(storage_, s.storage_);
+			std::swap(buffer_, s.buffer_);
+		}
+
+		char * data() const { return buffer_->data(); }
+
+		std::vector<char> & buffer() { return *buffer_; }
+
+		std::size_t write(char const * p, std::size_t size) override;
+
+	private:
+		std::vector<char> storage_;
+		std::vector<char> * buffer_ = &storage_;
+	};
+
 }

libs/io/source/memory_stream.cpp

@@ -23,4 +23,10 @@ namespace psemek::io
 		return size;
 	}
 
+	std::size_t expanding_memory_ostream::write(char const * p, std::size_t size)
+	{
+		buffer_->insert(buffer_->end(), p, p + size);
+		return size;
+	}
+
 }