Amoeba -- the constraint solving algorithm in pure C
Amoeba is a pure C implement of Cassowary algorithm. Amoeba use Clean C, which is the cross set of ANSI C89 and C++, like the Lua language.
Amoeba is a single-file library, for more single-file library, see the stb project here.
Amoeba ships a hand written Lua binding.
Amoeba has the same license with the Lua language.