Package-level declarations

One parsed function prototype. signature is the normalized one-line declaration text.

Which grammar parses this header: plain C (default), or the C++14 grammar for simple C++ headers.

Extracts function prototypes from a header file using the vendored ANTLR grammars-v4 C11/C++14 grammars (see specification/cheader/support/NOTICE.md) -- not a full compiler: no macro expansion, no #include resolution, no type checking, and (for C++) no class-member or template extraction, only free/namespace-scope and extern "C" functions. If a header fails to parse under the grammar (e.g. heavy conditional-compilation/macro use this importer does not expand), parsing falls back to a plain-text regex scan of the same declarative shape the grammar looks for -- resilience against one malformed header, not a substitute for the grammar's own accuracy.