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use std::{str::Chars, iter::Peekable};
#[derive(Debug, PartialEq)]
enum TokenType {
TEXT,
NEWLINE,
HASH,
BACKTICK,
}
#[derive(Debug, PartialEq)]
struct Token {
token_type: TokenType,
value: String,
location: (u8, u8),
}
#[derive(Debug)]
struct Scanner {
tokens: Vec<Token>,
input_string: String,
position: (u8, u8), //Line, index
}
impl Scanner {
fn new(source: &str) -> Self {
let string = source.to_string();
Scanner { input_string: string.clone(), tokens: Vec::new(), position: (0, 0) }
}
fn scan(&mut self) {
let string = self.input_string.clone();
let mut chars = string.chars().peekable();
loop {
let character = chars.next();
match character {
Some(c) => {
self.scan_token(c, &mut chars);
},
None => { break }
}
}
}
fn scan_token(&mut self, token: char, iter: &mut Peekable<Chars>) {
match token {
'#' => {
let token = Token { token_type: TokenType::HASH, value: token.to_string(), location: self.position };
self.position.1 += 1;
self.tokens.push(token);
},
'\n' => {
let token = Token { token_type: TokenType::NEWLINE, value: token.to_string(), location: self.position };
self.position.0 += 1;
self.position.1 = 0;
self.tokens.push(token);
},
_ => {
let mut text = String::from(token);
let mut position = 1;
loop {
let peeked = iter.peek();
match peeked {
Some(peek) => {
if *peek == '\n' {
break;
}
text.push(peek.to_owned());
position += 1;
iter.next();
},
None => {break;}
};
};
let token = Token { token_type: TokenType::TEXT, value: text, location: self.position };
self.position.1 += position;
self.tokens.push(token);
},
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn init() {
let source = "## This is a heading\nI am a bunch of paragraph text. I can get pretty long.";
let mut scanner = Scanner::new(source);
scanner.scan();
let tokens = vec![
Token { token_type: TokenType::HASH, value: "#".to_string(), location: (0, 0) },
Token { token_type: TokenType::HASH, value: "#".to_string(), location: (0, 1) },
Token { token_type: TokenType::TEXT, value: " This is a heading".to_string(), location: (0, 2) },
Token { token_type: TokenType::NEWLINE, value: "\n".to_string(), location: (0, 20) },
Token { token_type: TokenType::TEXT, value: "I am a bunch of paragraph text. I can get pretty long.".to_string(), location: (1, 0) },
];
assert_eq!(tokens.len(), scanner.tokens.len());
for (index, token) in scanner.tokens.iter().enumerate() {
assert_eq!(tokens.get(index).unwrap(), token);
}
}
}
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