Resuming project. Refactored project

src/lexer/mod.rs

@@ -89,6 +89,7 @@ impl<'a> Lexer<'a> {
             None => false,
         }
     }
+    
     fn peek_is_ascii_digit(&mut self) -> bool {
         match self.input.peek() {
             Some(v) => v.is_ascii_digit(),

src/main.rs

@@ -8,4 +8,3 @@ mod repl;
 fn main() {
     repl::init();
 }
-

src/parser/ast/mod.rs

@@ -1,10 +1,41 @@
 use crate::lexer::Lexer;
 
-#[derive(Debug)]
-pub struct LetStatement {
-    name: String,
+pub trait Node {
+    fn token_literal(&self) -> String;
+}
+pub trait Statement: Node {
+    fn parse(&self, &mut Lexer) -> Box<dyn Statement>;
 }
 
-impl LetStatement {
-    pub fn parse(lexer: &mut Lexer) -> Self {}
+pub trait Expression: Node {}
+
+pub struct Let {
+    name: Identifier,
+    // value: dyn Expression,
 }
+
+impl Node for Let {
+    fn token_literal(&self) -> String {
+        "let".to_owned()
+    }
+}
+
+impl Statement for Let {
+    fn parse(&self, lexer: &mut Lexer) -> Vec<dyn Statement> {
+        vec![Let {
+            name: Identifier { name: "potato" },
+            // value: "",
+        }]
+    }
+}
+
+pub struct Identifier {
+    name: &'static str,
+}
+
+impl Node for Identifier {
+    fn token_literal(&self) -> String {
+        "IDENT".to_owned()
+    }
+}
+impl Expression for Identifier {}

src/parser/mod.rs

@@ -1,35 +1,32 @@
 mod ast;
-mod statement;
 
-use self::statement::Statement;
-use crate::lexer::{Lexer, Token};
+use self::ast::{Let, Statement};
+use super::lexer::Lexer;
 
-pub struct Parser<'a> {
-    lexer: Lexer<'a>,
+pub struct Program {
+    statements: Vec<Box<dyn Statement>>,
 }
 
-impl<'a> Parser<'a> {
-    pub fn new(lexer: Lexer<'a>) -> Parser<'a> {
-        return Parser { lexer };
-    }
-}
-
-impl<'a> Iterator for Parser<'a> {
-    type Item = Statement;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        match self.lexer.next() {
-            Some(Token::Let) => Statement::Let.parse(&mut self.lexer),
-            _ => None,
-            None => None,
+impl Program {
+    pub fn token_literal(&self) -> String {
+        if self.statements.len() > 0 {
+            self.statements[0].token_literal()
+        } else {
+            "".to_owned()
         }
     }
+
+    pub fn parse(lexer: Lexer) -> Program {
+        let mut statements = vec![];
+
+        Program { statements }
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use crate::lexer::Lexer;
-    use crate::parser::Parser;
+    use crate::parser::Program;
 
     #[test]
     fn let_statements() {
@@ -40,11 +37,13 @@ mod tests {
         ";
 
         let lexer = Lexer::new(ip);
+        let ast_tree = Program::parse(lexer);
 
-        let stmts = Parser::new(lexer);
-
-        for stmt in stmts {
-            println!("{:?}", stmt);
+        if ast_tree.statements.len() != 3 {
+            eprintln!(
+                "statements length not equal to 3. got {}",
+                ast_tree.statements
+            );
         }
     }
 }

src/parser/statement/mod.rs

@@ -1,21 +0,0 @@
-use super::ast;
-use crate::lexer::Lexer;
-
-#[derive(Debug)]
-pub enum Statement {
-    Let,
-}
-
-impl Statement {
-    pub fn token_literal(&self) -> String {
-        match self {
-            Let => "let".to_owned(),
-        }
-    }
-
-    pub fn parse(&self, lexer: &mut Lexer) -> ast::Statement {
-        match self {
-            Let => Statement::Let(ast::LetStatement::parse(lexer)),
-        }
-    }
-}

src/repl.rs

@@ -1,4 +1,4 @@
-use crate::{lexer::Lexer, parser::Parser};
+use crate::{lexer::Lexer, parser::Program};
 use std::io::{self, BufRead, Write};
 
 const PROMPT: &'static str = ">> ";
@@ -24,6 +24,6 @@ fn start<R: BufRead, W: Write>(mut ip: R, mut out: W) {
             println!("{:?}", token);
         }
 
-        let parser = Parser::new(tokens);
+        let parser = Program::parse(tokens);
     }
 }