https://docs.rs/combine/4.0.1/combine/fn.from_str.html
from_str(count_min_max::<String, _, _>(min, max, digit()))
Easiest way, as long as the error message from
parse::<i32> is acceptable
Otherwise you can use
and_then like from_str does and substitute your own message https://github.com/Marwes/combine/blob/a358c88933bb58c4df0d9a0212b4a33d2b24be7b/src/parser/combinator.rs#L1165-L1169
I did stumble onto StreamErrorFor::<Input>::other eventually yesterday, and ended up with
fn n_digits<Input>(min: usize, max: usize) -> impl Parser<Input, Output = i32>
where
Input: Stream<Token = char>,
// Necessary due to rust-lang/rust#24159
Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
{
count_min_max(min, max, digit()).and_then(|s: String| {
s.parse().map_err(StreamErrorFor::<Input>::other)
})
}Which was acceptable. I'll try out from_str tonight though and compare the error messages that they generate, looks like they may arrive at different errors, though I'm not sure how they'll differ.
It works in a toy example with types inferred, but if I try to make a function using
captures I get some incredible error spam that's hard to sort through.
In particular, this works fine:
fn main() {
let mut p =
captures(Regex::new(r"<((?:\\\\|\\>|[^>\n])*)>").unwrap())
.map(|captures: Vec<&str>| String::from(captures[1]));
let input = "<hello>";
let result = p.easy_parse(input);
match result {
Ok((value, _remaining_input)) => println!("{:?}", value),
Err(err) => println!("{}", err)
}
}
But this gives me a great deal of errors:
fn custom_status<Input>() -> impl Parser<Input, Output = String>
where
Input: Stream<Token = char>,
// Necessary due to rust-lang/rust#24159
Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
{
captures(Regex::new("<(\\\\|\\>|[^>\n])>").unwrap()).map(|captures: Vec<&str>| String::from(captures[1]))
}
Goddam, I am not nearly familiar enough with Rust to be doing this, but I did figure out how to make my function compile:
/**
* Parses a status.
*/
fn custom_status<'a, Input: 'a>() -> impl Parser<Input, Output = String> + 'a
where
Input: Stream<Token = char>,
Input: RangeStreamOnce<Range = &'a str>,
// Necessary due to rust-lang/rust#24159
Input::Error: ParseError<Input::Token, Input::Range, Input::Position>,
{
captures(Regex::new(r"<((?:\\\\|\\>|[^>\n])*)>").unwrap()).map(|captures: Vec<&str>| String::from(captures[1]))
}I am dubious that this is the easiest way though...
i have been increasingly writing parsers that have chains of the form
.then(|val| {
value(val)
.and(.........and I figure that there could be a combinator here that passes in the output of the previous parser as an immutable ref for dispatching but then just forwards that value through without consuming it
yeah
And the argument to
self.1
So that may be overkill :)
:+1:
these are the relevant
self.1 calls?
(It should probably be a named field instead of a tuple)
If it compiles I'd expect it to be fine :)
alright cool, thanks for the help. I'll give this a shot later today.
:D
You could validate that the headers are in the correct order after parsing
return an
Error if something's required isn't present
hi all. i'm struggling with zero-copy parsing, and i'm not really making any headway. how can i write a parser function which can take an
&str, outputs an &str, doesn't do extra copies, and restricts the input type as little as possible? you can find here my flailing attempt (see the symbol function): https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=ecd82417fdf8a3aaeed27e9151ef1152 help is appreciated! thanks
i think if i wanted to return
String i could use map on the output of many1 but since i want to borrow i don't know what to do
Should do it