I'm trying to split a log line on space and commas in order to create a Vector
of Token
s of Field
and Separator
as shown in the code below.
My problem is that nom doesn't seem to consume the entire log line, it leaves the last part unparsed - in this case 08:33:58)
.
main.rs
#![feature(rust_2018_preview)]
#[macro_use] extern crate nom;
#[derive(Debug, PartialEq)]
pub enum Token<'a> {
Separator(&'a [u8]),
Field(&'a [u8]),
}
named!(separator, is_a!(" ,"));
named!(not_sep, is_not!(" ,"));
named!(
token<Token>,
alt_complete!(
separator => { |s| Token::Separator(s) } |
not_sep => { |n| Token::Field(n) }
)
);
named!(sequence<Vec<Token>>, many1!(token));
pub fn scan(input: &[u8]) -> Vec<Token> {
let (_, seq) = sequence(input).unwrap();
seq
}
fn main() {
}
#[cfg(test)]
mod tests {
use std::str;
use crate::Token;
use crate::scan;
#[test]
fn parse_stuff() {
let log = &b"docker INFO 2019-10-01 08:33:58,878 [1] schedule:run Running job Every 1 hour do _precache_systems_streaks() (last run: 2018-09-21 07:33:58, next run: 2018-09-21 08:33:58)";
let seq = scan(&log[..]);
for t in seq {
let text = match t {
Token::Field(data) => format!("f[{}]", str::from_utf8(data).unwrap()),
Token::Separator(data) => format!("s[{}]", str::from_utf8(data).unwrap()),
};
println!("{}", text);
}
}
}
Cargo.toml
[dependencies]
nom = "4.0"
output
f[docker]
s[ ]
f[INFO]
s[ ]
f[2019-10-01]
s[ ]
f[08:33:58]
s[,]
f[878]
s[ ]
f[[1]]
s[ ]
f[schedule:run]
s[ ]
f[Running]
s[ ]
f[job]
s[ ]
f[Every]
s[ ]
f[1]
s[ ]
f[hour]
s[ ]
f[do]
s[ ]
f[_precache_systems_streaks()]
s[ ]
f[(last]
s[ ]
f[run:]
s[ ]
f[2018-09-21]
s[ ]
f[07:33:58]
s[, ]
f[next]
s[ ]
f[run:]
s[ ]
f[2018-09-21]
s[ ]
For completeness, I implemented the following changes according to @Zarenor's answer and the parser now consumes the entire input.
changes to main.rs
The issue you're running into is that Nom is designed to always assume that there may be more input, unless you tell it otherwise. Since you know your input here is complete, you need to feed the parsers your literal wrapped in a
CompleteByteSlice
(or if you used a&str
, aCompleteStr
). These types are thin wrappers that Nom uses to indicate that we know there isn't more input coming. It will make it so a parser that fails to make a complete match returns anError
instead of anIncomplete
, and in this case, will instruct the the parser to consume that final token, rather than ask for more characters.