84 lines
1.8 KiB
Rust
84 lines
1.8 KiB
Rust
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use std::io;
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#[derive(Debug)]
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enum Symbol {
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Number,
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LeftBracket,
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RightBracket,
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Add,
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Sub,
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Mul,
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Div,
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}
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#[derive(Debug)]
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enum ParseError {
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WrongTokenError { pos: usize },
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}
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fn main() {
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loop {
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let user_input = get_user_input().expect("No input");
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match tokenize(&user_input) {
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Ok(tokenized_input) => {
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for el in &tokenized_input {
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println!("{:?}", el);
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}
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}
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Err(ParseError::WrongTokenError { pos }) => {
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for _ in 0..pos {
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print!("-");
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}
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println!("^");
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println!("Syntax Error\n");
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}
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}
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}
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}
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fn get_user_input() -> io::Result<String> {
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let mut buffer = String::new();
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let stdin = io::stdin();
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stdin.read_line(&mut buffer)?;
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Ok(buffer)
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}
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fn tokenize(input: &str) -> Result<Vec<Symbol>, ParseError> {
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let mut tokens: Vec<Symbol> = vec![];
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for (i, c) in input.chars().enumerate() {
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match c {
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' ' => {
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continue;
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}
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'(' => {
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tokens.push(Symbol::LeftBracket);
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}
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')' => {
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tokens.push(Symbol::RightBracket);
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}
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'+' => {
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tokens.push(Symbol::Add);
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}
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'-' => {
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tokens.push(Symbol::Sub);
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}
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'*' => {
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tokens.push(Symbol::Mul);
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}
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'/' => {
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tokens.push(Symbol::Div);
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}
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'0'..='9' => {
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tokens.push(Symbol::Number);
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}
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'\n' => {
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break;
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}
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_ => return Err(ParseError::WrongTokenError { pos: i }),
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}
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}
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Ok(tokens)
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}
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