From 2601dcd274eb78a7ed07f0e87b126386d166aee9 Mon Sep 17 00:00:00 2001
From: Charlie Root <charlie@charlieroot.dev>
Date: Sat, 29 Mar 2025 00:57:25 +0100
Subject: [PATCH] werks

---
 src/main.rs | 138 +++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 126 insertions(+), 12 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 00af292..692b899 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,9 +1,8 @@
-use std::io;
+use std::{error::Error, io};
 
 #[derive(Debug, PartialEq, Eq)]
 enum Symbol {
-    Number(i32),
-
+    Number { value: u64 },
     LeftBracket,
     RightBracket,
     Add,
@@ -13,6 +12,26 @@ enum Symbol {
     Exp,
 }
 
+#[derive(Clone, Debug)]
+enum Node {
+    Add { left: Box<Node>, right: Box<Node> },
+    Sub { left: Box<Node>, right: Box<Node> },
+    Mul { left: Box<Node>, right: Box<Node> },
+    Number { value: u64 },
+}
+
+fn eval(expr: &Node) -> i64 {
+    match expr {
+        Node::Add { left, right } => eval(left) + eval(right),
+        Node::Sub { left, right } => eval(left) - eval(right),
+        Node::Mul { left, right } => eval(left) * eval(right),
+        Node::Number { value } => {
+            // println!("Evaling number {value}");
+            *value as i64
+        }
+    }
+}
+
 #[derive(Debug)]
 enum ParseError {
     WrongTokenError { pos: usize },
@@ -23,8 +42,19 @@ fn main() {
         let user_input = get_user_input().expect("No input");
         match tokenize(&user_input) {
             Ok(tokenized_input) => {
-                for el in &tokenized_input {
-                    println!("{:?}", el);
+                // for el in &tokenized_input {
+                // println!("lol {:?}", el);
+                // }
+                let ast = ast(tokenized_input);
+                // println!("{:?}", ast);
+                match ast {
+                    Ok(ast) => {
+                        let evaled = eval(&ast);
+                        println!("{}", evaled);
+                    }
+                    _ => {
+                        continue;
+                    }
                 }
             }
             Err(ParseError::WrongTokenError { pos }) => {
@@ -51,11 +81,31 @@ fn try_tokenizing() {
     let tokenized_input: Vec<Vec<Symbol>> = input.iter().map(|s| tokenize(s).unwrap()).collect();
 
     let result: Vec<Vec<Symbol>> = vec![
-        vec![Symbol::Number(1), Symbol::Add, Symbol::Number(2)],
-        vec![Symbol::Number(3), Symbol::Sub, Symbol::Number(4)],
-        vec![Symbol::Number(5), Symbol::Mul, Symbol::Number(6)],
-        vec![Symbol::Number(7), Symbol::Div, Symbol::Number(8)],
-        vec![Symbol::Number(8), Symbol::Exp, Symbol::Number(9)],
+        vec![
+            Symbol::Number { value: 1 },
+            Symbol::Add,
+            Symbol::Number { value: 2 },
+        ],
+        vec![
+            Symbol::Number { value: 3 },
+            Symbol::Sub,
+            Symbol::Number { value: 4 },
+        ],
+        vec![
+            Symbol::Number { value: 5 },
+            Symbol::Mul,
+            Symbol::Number { value: 6 },
+        ],
+        vec![
+            Symbol::Number { value: 7 },
+            Symbol::Div,
+            Symbol::Number { value: 8 },
+        ],
+        vec![
+            Symbol::Number { value: 8 },
+            Symbol::Exp,
+            Symbol::Number { value: 9 },
+        ],
     ];
     assert!(tokenized_input == result);
 }
@@ -66,7 +116,11 @@ fn tokenize(input: &str) -> Result<Vec<Symbol>, ParseError> {
 
     for (i, c) in input.chars().enumerate() {
         if !c.is_ascii_digit() && !acc.is_empty() {
-            tokens.push(Symbol::Number(acc.parse().unwrap_or(0)));
+            tokens.push(Symbol::Number {
+                value: acc
+                    .parse()
+                    .map_err(|_| ParseError::WrongTokenError { pos: 1 })?,
+            });
             acc.clear();
         };
         match c {
@@ -87,8 +141,68 @@ fn tokenize(input: &str) -> Result<Vec<Symbol>, ParseError> {
         }
     }
     if !acc.is_empty() {
-        tokens.push(Symbol::Number(acc.parse().unwrap_or(0)));
+        tokens.push(Symbol::Number {
+            value: acc
+                .parse()
+                .map_err(|_| ParseError::WrongTokenError { pos: 1 })?,
+        });
     }
 
     Ok(tokens)
 }
+
+fn ast(input: Vec<Symbol>) -> Result<Node, ParseError> {
+    let mut stack = Vec::<Node>::new();
+    // println!("{}", input.len());
+    let length = input.len();
+    let mut i = 0;
+
+    while i < length {
+        // println!("Count: {}", i);
+        let s = &input[i];
+        // println!("Symbol: {:?}", s);
+        match s {
+            Symbol::Number { value } => {
+                stack.push(Node::Number { value: *value });
+                // println!("pushed {value}")
+            }
+            Symbol::Add => {
+                let left = stack.pop();
+                // increment
+                let right = input.get(i + 1);
+                i += 1;
+
+                match (left, right) {
+                    (Some(left), Some(right)) => {
+                        match right {
+                            Symbol::Number { value } => {
+                                stack.push(Node::Add {
+                                    left: (Box::new(left)),
+                                    right: (Box::new(Node::Number { value: *value })),
+                                });
+                            }
+                            _ => return Err(ParseError::WrongTokenError { pos: 1 }),
+                        }
+                        {}
+                    }
+                    _ => {
+                        return Err(ParseError::WrongTokenError { pos: 1 });
+                    }
+                }
+            }
+            Symbol::Sub => {}
+            Symbol::Mul => {}
+            Symbol::Div => {}
+            _ => {
+                continue;
+            }
+        }
+        i += 1;
+    }
+    // println!("Stack length: {}", stack.len());
+    // println!("Stack: {:?}", stack);
+    if stack.len() != 1 {
+        return Err(ParseError::WrongTokenError { pos: 1 });
+    }
+    Ok(stack[0].clone())
+}