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MonoDevelop Can be used to open and manipulate Visual Studio project on a Mac.
It can however only open .csproj files, not the legacy .vcproj. You can convert your old project to a compatible one, using Visual Studio Conversion Wizard.
As you are working with C++, you are however free to use any IDE or editor you like. As long as loosing your project metadata files isn't a problem, you can just open the files in Xcode, TextMate, Sublime Editor or any editor of choice.