classfile

Low-level but easy-to-use reader and writer for the JVM classfile format.

Both the reader and the writer expose a stream-based, visitor-style API: you walk the classfile section by section and decide for each item whether to inspect it, transform it, or simply pass it through. Structured types for every section and for the supported attributes are provided on top of that, so you get most of the ergonomics of a tree API while keeping the memory profile of a streaming one.

See examples/print.rs for a read-only dump of every section, and examples/pipe.rs for a read-then-write round trip that copies a classfile from stdin to stdout.

Feature flags

The crate is no_std in every configuration. With alloc enabled the alloc crate is additionally linked, which provides:

• alloc::vec::Vec<u8> as a writing buffer, so a classfile can be written straight into a Vec<u8> as shown in examples/pipe.rs.
• Support for some attributes that is hard to present without vectors.