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use std::error::Error;
use std::fmt;
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub enum ParseError<L,T,E> {
InvalidToken {
location: L
},
UnrecognizedToken {
token: Option<(L, T, L)>,
expected: Vec<String>
},
ExtraToken {
token: (L, T, L),
},
User {
error: E,
},
}
impl<L, T, E> fmt::Display for ParseError<L, T, E>
where L: fmt::Display,
T: fmt::Display,
E: fmt::Display
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::ParseError::*;
match *self {
InvalidToken { ref location } =>
write!(f, "Invalid token at {}", location),
UnrecognizedToken { ref token, ref expected } => {
match *token {
Some((ref start, ref token, ref end)) =>
try!(write!(f, "Unrecognized token {} found at {}:{}", token, start, end)),
None =>
try!(write!(f, "Unrecognized EOF")),
}
if !expected.is_empty() {
try!(writeln!(f, ""));
for (i, e) in expected.iter().enumerate() {
let sep = match i {
0 => "Expected one of",
_ if i < expected.len() - 1 => ",",
_ => " or",
};
try!(write!(f, "{} {}", sep, e));
}
}
Ok(())
}
ExtraToken { token: (ref start, ref token, ref end) } => {
write!(f, "Extra token {} found at {}:{}", token, start, end)
}
User { ref error } =>
write!(f, "{}", error)
}
}
}
impl<L, T, E> Error for ParseError<L, T, E>
where L: fmt::Debug + fmt::Display,
T: fmt::Debug + fmt::Display,
E: fmt::Debug + fmt::Display
{
fn description(&self) -> &str {
"parse error"
}
}
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub struct ErrorRecovery<L, T, E> {
pub error: ParseError<L, T, E>,
pub dropped_tokens: Vec<(L, T, L)>,
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test() {
let err = ParseError::UnrecognizedToken::<i32, &str, &str> {
token: Some((1, "t0", 2)),
expected: vec!["t1", "t2", "t3"]
.into_iter()
.map(|s| s.to_string())
.collect()
};
assert_eq!(format!("{}", err), "Unrecognized token t0 found at 1:2\n\
Expected one of t1, t2 or t3");
}
}