pycparser

pycparser is a complete, standards-compliant C99 parser written in pure Python, producing an Abstract Syntax Tree (AST) that can be traversed, modified, and re-emitted as C code. Current version is 3.0, released January 2026, which replaced the bundled PLY (Lex/Yacc) backend with a hand-written lexer and recursive-descent parser—eliminating all external dependencies and improving parse speed by ~30%. Release cadence is irregular; major versions are rare (2.x spanned 2012–2025).