initial commit

src/main.rs

@@ -0,0 +1,83 @@
+use std::io;
+
+#[derive(Debug)]
+enum Symbol {
+    Number,
+
+    LeftBracket,
+    RightBracket,
+    Add,
+    Sub,
+    Mul,
+    Div,
+}
+
+#[derive(Debug)]
+enum ParseError {
+    WrongTokenError { pos: usize },
+}
+
+fn main() {
+    loop {
+        let user_input = get_user_input().expect("No input");
+        match tokenize(&user_input) {
+            Ok(tokenized_input) => {
+                for el in &tokenized_input {
+                    println!("{:?}", el);
+                }
+            }
+            Err(ParseError::WrongTokenError { pos }) => {
+                for _ in 0..pos {
+                    print!("-");
+                }
+                println!("^");
+                println!("Syntax Error\n");
+            }
+        }
+    }
+}
+
+fn get_user_input() -> io::Result<String> {
+    let mut buffer = String::new();
+    let stdin = io::stdin();
+    stdin.read_line(&mut buffer)?;
+    Ok(buffer)
+}
+
+fn tokenize(input: &str) -> Result<Vec<Symbol>, ParseError> {
+    let mut tokens: Vec<Symbol> = vec![];
+
+    for (i, c) in input.chars().enumerate() {
+        match c {
+            ' ' => {
+                continue;
+            }
+            '(' => {
+                tokens.push(Symbol::LeftBracket);
+            }
+            ')' => {
+                tokens.push(Symbol::RightBracket);
+            }
+            '+' => {
+                tokens.push(Symbol::Add);
+            }
+            '-' => {
+                tokens.push(Symbol::Sub);
+            }
+            '*' => {
+                tokens.push(Symbol::Mul);
+            }
+            '/' => {
+                tokens.push(Symbol::Div);
+            }
+            '0'..='9' => {
+                tokens.push(Symbol::Number);
+            }
+            '\n' => {
+                break;
+            }
+            _ => return Err(ParseError::WrongTokenError { pos: i }),
+        }
+    }
+    Ok(tokens)
+}