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added and_then docs

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Trevor Settles 2024-03-03 12:34:56 -07:00
parent 3f2d2dd908
commit 3cb0edf958
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crates/compiler/parse/src/parser.rs
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@ -834,6 +834,48 @@ where
}
}
/// Creates a parser from two other parser.
/// However, the second parser is created based on the results of the first parser
///
/// # Examples
///
/// ## Success Case
/// ```
/// # use roc_parse::state::{State};
/// # use crate::roc_parse::parser::{Parser, Progress, and_then, word};
/// # use roc_region::all::Position;
/// # use bumpalo::Bump;
/// # #[derive(Debug, PartialEq)]
/// # enum Problem {
/// # NotFound(Position),
/// # }
/// # let arena = Bump::new();
/// let parser1 = word("hello", Problem::NotFound);
/// let parser = and_then(parser1, move |p,b| word(", ", Problem::NotFound));
/// let (progress, output, state) = parser.parse(&arena, State::new("hello, world".as_bytes()), 0).unwrap();
///
/// assert_eq!(progress, Progress::MadeProgress);
/// assert_eq!(output, ());
/// assert_eq!(state.pos(), Position::new(7));
/// ```
/// ## Failure Case
/// ```
/// # use roc_parse::state::{State};
/// # use crate::roc_parse::parser::{Parser, Progress, and_then, word};
/// # use roc_region::all::Position;
/// # use bumpalo::Bump;
/// # #[derive(Debug, PartialEq)]
/// # enum Problem {
/// # NotFound(Position),
/// # }
/// # let arena = Bump::new();
/// let parser1 = word("hello", Problem::NotFound);
/// let parser = and_then(parser1, move |p,b| word("!! ", Problem::NotFound));
/// let (progress, problem) = parser.parse(&arena, State::new("hello, world".as_bytes()), 0).unwrap_err();
///
/// assert_eq!(progress, Progress::NoProgress);
/// assert_eq!(problem, Problem::NotFound(Position::new(5)));
/// ```
pub fn and_then<'a, P1, P2, F, Before, After, Error>(
parser: P1,
transform: F,