infinite_grid.cpp is a small utility that does a templated 2 dimensional array that's "infinite". By "infinite" it means it's of size -2147483648 to 2147483647 in both dimensions. It could easily be modified to be a bit bigger since it's "wasting" about 7 bits at the moment. But I feel that's big enough of a grid.
I tried looking for a good example of how to do an infinite grid, but failed to find one.
infinite_grid dynamically creates a bunch of smaller 2d arrays (128 x 128 by default) based on the coordinates of the cell that you're asking for. It puts these 2d arrays into a std::map sorted by their coordinates.
Do what ever you feel with it. I highly recommend just hacking it.
This will most likely be added to the poro framework. https://github.com/gummikana/poro So the future versions and bug fixes are probably in the poro framework. Look in there for a newer version. It's probably under utils/infinitegrid
infinite_grid.cpp is provided under a MIT style license