Light Cell Geometry

[JacquesOlivierLachaud]

PR Description

This PR changes the data structure for storing cell covers in CellGeometry. Previous one was a CubicalComplex, which is based on a std::unordered_map Cell -> Data (here Data is not used). We use instead a new class UnorderedSetByBlock to store set of Points (Cells are represented by their Khalimsky points). The UnorderedSetByBlock is an std::unordered_map Point -> Word, where points are gathered by blocks of 32 consecutive points along x axis. If any point in a block is present, the corresponding element is present and bits to 1 in the word correspond to points present in the set. On average, memory occupancy is divided by four, the structure is four times faster for traversal and approximately same speed for queries/insertion/erase.
CellGeometry and DigitalConvexity use now this data structure. A drawback is that this version is not fully backward compatible with the first version since the few operations involving CubicalComplex are removed.

Checklist

• Unit-test of your feature with Catch.
• Doxygen documentation of the code completed (classes, methods, types, members...)
• Documentation module page added or updated.
• New entry in the ChangeLog.md added.
• No warning raised in Debug cmake mode (otherwise, Travis C.I. will fail).
• All continuous integration tests pass (Travis & appveyor)

[dcoeurjo]

nice PR. Couple of comments..

[rolanddenis]

Thanks for the PR! Besides the indentation issues, I have some questions about bitwise operations and an unknown random function 😉

[rolanddenis]

Thanks for the update, some minor requested changes 👌

[JacquesOlivierLachaud]

Finally it works. I do not know where was the problem (since it was working fine on my laptop), so I static_cast everywhere possible. There was an implicit conversion that went bad on some system certainly. So I think the PR is ready now.

[dcoeurjo]

thx merging