Get parsing REPL working

src/main.rs

@@ -11,6 +11,9 @@ use simplerepl::{REPL, ReplState};
 use tokenizer::tokenize;
 mod tokenizer;
 
+use parser::{ParseResult, parse};
+mod parser;
+
 
 fn main() {
     let args: Vec<String> = std::env::args().collect();
@@ -55,7 +58,9 @@ impl ReplState for InterpreterState {
 fn repl_handler(input: &str, state: &mut InterpreterState) -> String {
     if state.show_tokens {
         format!("Tokens: {:?}", tokenize(input))
+    } else if state.show_parse{
+        format!("Parse: {:?}", parse(tokenize(input)))
     } else {
-        format!("{:?}", tokenize(input))
+        format!("{:?}", parse(tokenize(input)))
     }
 }

src/parser.rs

@@ -0,0 +1,30 @@
+use tokenizer::Token;
+
+/* grammar
+
+   expr : term ((PLUS|MIMUS) term)*
+   term : factor ((MUL | DIV) factor)*
+   factor  : NUM | LPAREN expr RPAREN
+
+*/
+
+#[derive(Debug)]
+enum AST {
+    BinOp(Box<AST>, Box<AST>, Box<AST>),
+    Number(f64),
+    Name(String),
+}
+
+#[derive(Debug)]
+pub struct ParseError {
+    err: String
+}
+
+pub type ParseResult = Result<AST, ParseError>;
+
+pub fn parse(input: Vec<Token>) -> ParseResult {
+    let mut current_token: Token;
+
+    return Err(ParseError { err: "error!".to_string() });
+}
+