How can I find implementations of the C++ Standard Library?

I'm curious about learning how certain C++ features work. I'm trying to learn C++11 concepts such as std::function, but I keep hitting walls like INVOKE(function, arguments, return) that I don't understand. People tell me, "Oh, just ignore it and use auto" but I want to have a truly deep understanding of how C++ and its standard library works, so I wanted to find the source code of the standard library.

I would guess that the C++ Standard Library is somewhat related with the C Standard Library and the messy assembly/binary implementations at the lowest level for stuff like std::iostream and such, but I'm interested in more higher-level abstractions like smart pointers and std::function. Given that many of the C++11 libraries were once Boost ones, how might I find the source for C++ Standard Library implementations?

Solution

The two most popular open source implementations of standard C++ library are:

libstdc++, part of gcc project
libc++, part of LLVM project

Both websites contain links to git/svn repositories with source code.