elyze 1.5.5

Elyze is an extensible general purpose framework parser allowing to parser any type of data without allocation.
Documentation 
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//! Recognize whitespaces

use crate::bytes::token::Token;
use crate::errors::{ParseError, ParseResult};
use crate::recognizer::Recognizable;
use crate::scanner::Scanner;
use crate::visitor::Visitor;

/// Recognize at least one whitespace
pub struct Whitespaces;

/// Recognize zero or more whitespaces
pub struct OptionalWhitespaces;

impl<'a> Visitor<'a, u8> for Whitespaces {
    fn accept(scanner: &mut Scanner<'a, u8>) -> ParseResult<Self> {
        let mut found = false;

        while Token::Whitespace.recognize(scanner)?.is_some() {
            if scanner.is_empty() {
                return Ok(Whitespaces);
            }

            found = true;
        }
        if !found {
            return Err(ParseError::UnexpectedToken);
        }
        Ok(Whitespaces)
    }
}

impl<'a> Visitor<'a, u8> for OptionalWhitespaces {
    fn accept(scanner: &mut Scanner<'a, u8>) -> ParseResult<Self> {
        if scanner.is_empty() {
            return Ok(OptionalWhitespaces);
        }
        while Token::Whitespace.recognize(scanner)?.is_some() {
            if scanner.is_empty() {
                return Ok(OptionalWhitespaces);
            }
        }
        Ok(OptionalWhitespaces)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    // ensure that the scanner consumes all final whitespaces
    #[test]
    fn test_whitespaces() {
        let mut scanner = Scanner::new(b"         ");
        let result = Whitespaces::accept(&mut scanner);
        assert!(result.is_ok());
        assert!(scanner.is_empty());

        let mut scanner = Scanner::new(b"aaaaaaaaa");
        let result = Whitespaces::accept(&mut scanner);
        assert!(!result.is_ok());
        assert!(!scanner.is_empty());
    }

    // ensure that the scanner consumes all final optional whitespaces
    #[test]
    fn test_optional_whitespaces() {
        let mut scanner = Scanner::new(b"aaaaaaaaa");
        let result = OptionalWhitespaces::accept(&mut scanner);
        assert!(result.is_ok());
        assert!(!scanner.is_empty());

        let mut scanner = Scanner::new(b"        ");
        let result = OptionalWhitespaces::accept(&mut scanner);
        assert!(result.is_ok());
        assert!(scanner.is_empty());
    }
}