Nicholas Nethercote 28236ab703 Move various token stream things from rustc_parse to rustc_ast.
Specifically: `TokenCursor`, `TokenTreeCursor`,
`LazyAttrTokenStreamImpl`, `FlatToken`, `make_attr_token_stream`,
`ParserRange`, `NodeRange`. `ParserReplacement`, and `NodeReplacement`.
These are all related to token streams, rather than actual parsing.

This will facilitate the simplifications in the next commit.
2025-04-29 12:14:27 +10:00
..

The rustc_ast crate contains those things concerned purely with syntax that is, the AST ("abstract syntax tree"), along with some definitions for tokens and token streams, data structures/traits for mutating ASTs, and shared definitions for other AST-related parts of the compiler (like the lexer and macro-expansion).

For more information about how these things work in rustc, see the rustc dev guide: