65 lines
2 KiB
Rust
65 lines
2 KiB
Rust
use std::collections::HashMap;
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use std::iter::Iterator;
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use winnow::ascii::alphanumeric1;
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use winnow::combinator::iterator;
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use winnow::combinator::{separated_pair, terminated};
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use winnow::prelude::*;
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fn main() {
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let mut data = "abcabcabcabc";
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fn parser<'s>(i: &mut &'s str) -> ModalResult<&'s str> {
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"abc".parse_next(i)
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}
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// `from_fn` (available from Rust 1.34) can create an iterator
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// from a closure
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let it = std::iter::from_fn(move || parser.parse_next(&mut data).ok());
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for value in it {
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println!("parser returned: {value}");
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}
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println!("\n********************\n");
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let mut data = "abcabcabcabc";
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// if `from_fn` is not available, it is possible to fold
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// over an iterator of functions
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let res = std::iter::repeat(parser)
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.take(3)
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.try_fold(Vec::new(), |mut acc, mut parser| {
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parser.parse_next(&mut data).map(|o| {
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acc.push(o);
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acc
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})
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});
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// will print "parser iterator returned: Ok(("abc", ["abc", "abc", "abc"]))"
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println!("\nparser iterator returned: {res:?}");
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println!("\n********************\n");
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let data = "key1:value1,key2:value2,key3:value3,;";
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// `winnow::combinator::iterator` will return an iterator
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// producing the parsed values. Compared to the previous
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// solutions:
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// - we can work with a normal iterator like `from_fn`
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// - we can get the remaining input afterwards, like with the `try_fold` trick
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let mut winnow_it = iterator(
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data,
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terminated(separated_pair(alphanumeric1, ":", alphanumeric1), ","),
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);
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let res = winnow_it
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.map(|(k, v)| (k.to_uppercase(), v))
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.collect::<HashMap<_, _>>();
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let parser_result: ModalResult<(_, _), ()> = winnow_it.finish();
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let (remaining_input, ()) = parser_result.unwrap();
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// will print "iterator returned {"key1": "value1", "key3": "value3", "key2": "value2"}, remaining input is ';'"
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println!("iterator returned {res:?}, remaining input is '{remaining_input}'");
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}
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