Example of using rust-peg parser and chic error messages

Cargo.toml

[package]
name = "parserator"
version = "0.1.0"
authors = ["Zicklag"]
edition = "2018"

[dependencies]
peg = "0.6.1"
anyhow = "1.0.26"
chic = "1.2.2"
thiserror = "1.0.10"

example_output.txt

error: Parser error
  |
4 | [ 1, 3,4, 5,
5 | 6,
6 | 
7 | 8, 9, 10, 7,10d]
  |               ^ Expected: one of ",", "]"
  |

lib.rs

#[derive(thiserror::Error, Debug)]
#[error("Parser error")]
struct ParseratorError {
    error: peg::error::ParseError<peg::str::LineCol>,
    src: String,
}

impl ParseratorError {
    fn new(error: peg::error::ParseError<peg::str::LineCol>, src: &str) -> Self {
        ParseratorError {
            error,
            src: src.to_string(),
        }
    }
}

peg::parser! {
  grammar list_parser() for str {
    // Whitespace character
    rule whitespace_char() = ['\t' | ' ']

    // Line comment
    rule line_comment() = "//" (!"\n" [_])* ("\n" / ![_])

    // Inline comment
    rule inline_comment() = "/*" (!"*/" [_])* "*/"

    // Whitespace including comments
    rule w() = quiet!{ (whitespace_char() / inline_comment())* }

    // Whitespace including newlines and line comments
    rule wn() = quiet!{ (whitespace_char() / "\n" / inline_comment() / line_comment())* }

    rule number() -> u32
        = quiet!{
                n:$(['0'..='9']+) { n.parse().unwrap() }
            } / expected!("number")

    pub rule list() -> Vec<u32>
      = "[" wn() n:number() ** (wn() "," wn()) "]" { n }
  }
}

pub fn run() {
    if let Err(e) = execute() {
        if let Some(parserator_err) = e.downcast_ref::<ParseratorError>() {
            let peg_err = &parserator_err.error;
            let msg = chic::Error::new("Parser error")
                .error(
                    peg_err.location.line,
                    peg_err.location.offset + peg_err.location.line - 1,
                    peg_err.location.offset + peg_err.location.line,
                    &parserator_err.src,
                    format!("Expected: {}", peg_err.expected),
                )
                .to_string();

            eprintln!("{}", msg);
        }
    }
}
fn execute() -> anyhow::Result<()> {
    dbg!(parse_list(
"[ 1, 3,4, 5,
6,

8, 9, 10, 7,10d]"
    )?);

    Ok(())
}

fn parse_list(data: &str) -> anyhow::Result<Vec<u32>> {
    Ok(list_parser::list(data).map_err(|e| ParseratorError::new(e, data))?)
}

main.rs

use parserator;

fn main() {
    parserator::run();
}