|_| Some(Token::Keyword), r"\d+" => |s: &str| Some(Token::Number(s.parse().unwrap())), r"\{" => |_| Some(Token::Left), r"\}" => |_| Some(Token::Right), r"\s" => |_| None ]; lex(&regexes, input) } fn main() { assert_eq!( lexer(&"kw { 12 53 }".to_string()), Ok(vec![ Token::Keyword, Token::Left, Token::Number(12), Token::Number(53), Token::Right ]) ); assert_eq!(lexer(&"kw ERROR! { 12 53 }".to_string()), Err(3)); }">

use reglex::{RuleList, rule_list, lex};

#[derive(Debug, PartialEq)]
enum Token {
    Keyword,
    Number(u64),
    Left,
    Right,
}

fn lexer(input: &String) -> Result<Vec
   , 
   usize> {
    
   let regexes: RuleList
   <Token
   > 
   = 
   rule_list! [
        
   "kw" 
   => 
   |_
   | 
   Some(Token
   ::Keyword),
        
   r"\d+" 
   => 
   |s: 
   &
   str
   | 
   Some(Token
   ::
   Number(s.
   parse().
   unwrap())),
        
   r"\{" 
   => 
   |_
   | 
   Some(Token
   ::Left),
        
   r"\}" 
   => 
   |_
   | 
   Some(Token
   ::Right),
        
   r"\s" 
   => 
   |_
   | 
   None
    ];

    
   lex(
   &regexes, input)
}


   fn 
   main() {
    
   assert_eq!(
        
   lexer(
   &
   "kw  { 12 53 }".
   to_string()),
        
   Ok(
   vec![
            Token
   ::Keyword,
            Token
   ::Left,
            Token
   ::
   Number(
   12),
            Token
   ::
   Number(
   53),
            Token
   ::Right
        ])
    );

    
   assert_eq!(
   lexer(
   &
   "kw ERROR! { 12 53 }".
   to_string()), 
   Err(
   3));
}