Created
December 3, 2019 04:41
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Lexer test
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| use std::iter::Peekable; | |
| use std::str::Chars; | |
| #[derive(Debug, PartialEq)] | |
| pub enum Token { | |
| Plus, | |
| Minus, | |
| Equal, | |
| Number(i32), | |
| Illegal, | |
| EOF | |
| } | |
| pub struct Lexer<'a> { | |
| input: Peekable<Chars<'a>> | |
| } | |
| impl<'a> Lexer<'a> { | |
| pub fn new(input: &'a str) -> Self { | |
| Lexer { input: input.chars().peekable() } | |
| } | |
| pub fn read_number(&mut self, c: char) -> i32 { | |
| let mut numero = c.to_string(); | |
| while let Some(&x) = self.input.peek() { | |
| if !x.is_numeric() { | |
| break; | |
| } | |
| numero.push(self.input.next().unwrap()); | |
| } | |
| numero.parse::<i32>().unwrap() | |
| } | |
| pub fn skip_whitespace(&mut self) { | |
| while let Some(&c) = self.input.peek() { | |
| if !c.is_whitespace() { break; } | |
| self.input.next(); | |
| } | |
| } | |
| pub fn next_token(&mut self) -> Token { | |
| self.skip_whitespace(); | |
| match self.input.next() { | |
| Some('+') => Token::Plus, | |
| Some('-') => Token::Minus, | |
| Some(c @ _) => { | |
| if c.is_numeric() { | |
| let n = self.read_number(c); | |
| Token::Number(n) | |
| } else { | |
| Token::Illegal | |
| } | |
| }, | |
| None => Token::EOF | |
| } | |
| } | |
| } | |
| fn main() { | |
| let mut l = Lexer::new(" 12+ 64 - 90+983"); | |
| let mut tokens: Vec<Token> = vec![]; | |
| loop { | |
| tokens.push(l.next_token()); | |
| if tokens.last().unwrap() == &Token::EOF { | |
| break; | |
| } | |
| } | |
| println!("{:?}", tokens); | |
| } | |
| #[cfg(test)] | |
| mod tests { | |
| use super::*; | |
| #[test] | |
| fn text_x() { | |
| } | |
| } |
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