1 //! # Chapter 8: Debugging 2 //! 3 //! When things inevitably go wrong, you can introspect the parsing state by running your test case 4 //! with `--features winnow/debug`: 5 //! 6 //!  7 //! 8 //! You can extend your own parsers to show up by wrapping their body with 9 //! [`trace`][crate::combinator::trace]. Going back to [`do_nothing_parser`][super::chapter_1]. 10 //! ```rust 11 //! # use winnow::PResult; 12 //! # use winnow::Parser; 13 //! use winnow::combinator::trace; 14 //! 15 //! pub fn do_nothing_parser<'s>(input: &mut &'s str) -> PResult<&'s str> { 16 //! trace( 17 //! "do_nothing_parser", 18 //! |i: &mut _| Ok("") 19 //! ).parse_next(input) 20 //! } 21 //! # 22 //! # fn main() { 23 //! # let mut input = "0x1a2b Hello"; 24 //! # 25 //! # let output = do_nothing_parser.parse_next(&mut input).unwrap(); 26 //! # // Same as: 27 //! # // let output = do_nothing_parser(&mut input).unwrap(); 28 //! # 29 //! # assert_eq!(input, "0x1a2b Hello"); 30 //! # assert_eq!(output, ""); 31 //! # } 32 //! ``` 33 34 pub use super::chapter_7 as previous; 35 pub use crate::_tutorial as table_of_contents; 36
