pups_text 0.1.5

Pretty Understandable Parsers
Documentation 
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// Copyright Rob Gage 2025

use crate::{
    Character,
    TextInput
};
use pups_core::{
    Input,
    Mode,
    ModeResult::{
        self,
        Failure,
        Success,
    },
    Parser
};

/// Parses whitespace
pub struct Whitespace;

impl<'a, C, I> Parser<'a, I> for Whitespace
where
    C: Character,
    I: Input<'a, Item = C> + TextInput,
{
    type Output = I::Slice;

    type Error = ();

    type Message = ();

    fn apply<_Mode: Mode>(
        &self,
        input: &'a I
    ) -> ModeResult<I::Slice , (), (), _Mode> {
        let start: usize = input.save_cursor();
        loop {
            let cursor: usize = input.save_cursor();
            let Some (character) = input.next() else { break };
            if !character.is_whitespace() { input.restore_cursor(cursor); break }
        }
        let length: usize = input.save_cursor() - start;
        if length > 0 {
            input.restore_cursor(start);
            Success (
                _Mode::convert_output(input.consume(length).unwrap()),
                _Mode::new_message_container()
            )
        }
        else { Failure (_Mode::convert_error(()), _Mode::new_message_container())}
    }

}