| The `rustc_ast` crate contains those things concerned purely with syntax | |
| – that is, the AST ("abstract syntax tree"), parser, pretty-printer, | |
| lexer, macro expander, and utilities for traversing ASTs. | |
| For more information about how these things work in rustc, see the | |
| rustc dev guide: | |
| - [Parsing](https://rustc-dev-guide.rust-lang.org/the-parser.html) | |
| - [Macro Expansion](https://rustc-dev-guide.rust-lang.org/macro-expansion.html) |