Rust grammar for tree-sitter.

• Speed — When initially parsing a file, tree-sitter-rust takes around two to three times as long as rustc's hand-written parser.

  $ wc -l examples/ast.rs
    2157 examples/ast.rs
  
  $ rustc -Z unpretty=ast-tree -Z time-passes examples/ast.rs | head -n0
    time:   0.002; rss:   55MB ->   60MB (   +5MB)  parse_crate
  
  $ tree-sitter parse examples/ast.rs --quiet --time
    examples/ast.rs    6.48 ms        9908 bytes/ms

  But if you edit the file after parsing it, tree-sitter can generally update the previous existing syntax tree to reflect your edit in less than a millisecond, thanks to its incremental parsing system.

• The Rust Reference — While Rust does not have a specification, the reference tries to describe its working in detail. It tends to be out of date.
• Keywords and Operators and Symbols.