我正在嘗試按照本教程使用 nom 和 nom_locate 進行決議。我只想要以下格式的輸出：
Error: line 5, column 1
但目前我得到：
Error: Parsing Failure: ParseError { span: LocatedSpan { offset: 37, line: 5, fragment: "{{G]\nK(1)key [J]\n", extra: () }, message: "Error: line 5, column 1" }
相關代碼：
pub type Span<'a> = LocatedSpan<&'a str>;
pub type IResult<'a, O> = nom::IResult<Span<'a>, O, ParseError<'a>>;
#[derive(Debug, PartialEq)]
pub struct ParseError<'a> {
span: Span<'a>,
message: String,
}
impl<'a> ParseError<'a> {
pub fn new(message: String, span: Span<'a>) -> Self {
Self {
span,
message,
}
}
}
impl<'a> nom::error::ParseError<Span<'a>> for ParseError<'a> {
fn from_error_kind(input: Span<'a>, _: nom::error::ErrorKind) -> Self {
Self::new(format!("Error: line {}, column {}", input.location_line(), input.location_line()), input)
}
fn append(input: Span<'a>, _: nom::error::ErrorKind, _: Self) -> Self {
Self::new(format!("Error: line {}, column {}", input.location_line(), input.location_line()), input)
}
fn from_char(input: Span<'a>, _: char) -> Self {
Self::new(format!("Error: line {}, column {}", input.location_line(), input.location_line()), input)
}
}
pub fn job(s: Span) -> IResult<Vec<entities::Step>> {
let (s, steps) = many1(job_lines)(s)?;
Ok((s, steps))
}
fn job_lines(s: Span) -> IResult<entities::Step> {
let (s, name) = match step_name(s) {
Ok((s, name)) => (s, name),
Err(nom::Err::Error(_)) => {
let line = s.location_line();
let column = s.get_column();
return Err(nom::Err::Failure(ParseError::new(
format!("Error: line {}, column {}", line, column),
s,
)));
},
Err(e) => return Err(e),
};
Ok((s, name))
}
main中的相關錯誤代碼：
let steps = match input::parsers::job(input::parsers::Span::new(&input)) {
Ok((_, steps)) => steps,
Err(error) => {
eprintln!("{}", error);
std::process::exit(1)
}
};
我需要做什么才能獲得簡短的錯誤訊息而不是廣泛的錯誤訊息？
編輯：我從自定義 ParseError 中洗掉了 span 屬性，然后錯誤輸出變為：
Parsing Failure: ParseError { message: "Error: line 5, column 1" }
好多了，但問題仍然存在：我可以得到除訊息本身之外的所有內容嗎？
uj5u.com熱心網友回復：
正如您所推測的那樣，erroris a nom::Err::Errwhich is an enum，因此您需要匹配它以獲得內部錯誤：
let steps = match input::parsers::job(input::parsers::Span::new(&input)) {
Ok((_, steps)) => steps,
Err(nom::Err::Failure (error)) => {
eprintln!("{}", error.message);
std::process::exit(1)
},
Err(error) => {
eprintln!("Unknown error: {}", error);
std::process::exit(1)
},
};
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