Giving C++ std::regex a C makeover
Suppose you’re working in C using one of the major toolchains — that is, it’s mainly a C++ implementation — and you need regular expressions. You could integrate a library, but there’s a regex implementation in the C++ standard library included with your compiler, just within reach. As a resourceful engineer, using an asset already in hand seems prudent. But it’s a C++ interface, and you’re using C instead of C++ for a reason, perhaps to avoid dealing with C++. Have no worries. This article is about wrapping std::regex in a tidy C interface which not only hides all the C++ machinery, but utterly tames it. It’s not so much practical as a potpourri of interesting techniques.
If you’d like to skip ahead, here’s the full source up front. Tested with w64devkit, MSVC cl, and clang-cl: scratch/regex-wrap
Longtime readers will find it familiar: my favorite non-owning, counted strings form in place of null-terminated strings — similar to C++ std::string_view — and arena allocation. Yes, such fundamental types wouldn’t “belong” to a regex library like this, but imagine they’re standardized by the project or whatever. Also, this is purely a C header, not a C/C++ polyglot, and will not be used by the C++ portion.
