update

src/lexer/mod.rs

@@ -1,23 +1,61 @@
+use super::token;
+use super::token::Token;
+
 struct Lexer {
     input: String,
     position: Option<i32>,
     read_pos: Option<i32>,
-    ch: Option<i8>,
+    ch: Option<u8>,
+}
+
+trait LexerTraits {
+    fn read_char(&mut self);
+    fn next_token(&self) -> Token;
 }
 
 fn new(input_str: String) -> Lexer {
-    let l: Lexer = Lexer {
+    let mut l: Lexer = Lexer {
         input: input_str,
-        position: None,
-        read_pos: None,
-        ch: None,
+        position: Some(0),
+        read_pos: Some(1),
+        ch: Some(0),
     };
+    l.read_char();
     l
 }
 
-fn read_char(l: Lexer) {
-    let read_pos = usize::try_from(l.read_pos.unwrap());
-    if read_pos >= l.input.len() {
-        l.ch = 0;
+impl LexerTraits for Lexer {
+    fn read_char(&mut self) {
+        let read_pos = usize::try_from(self.read_pos.unwrap());
+        if read_pos.unwrap() >= self.input.len() {
+            self.ch = Some(0);
+        } else {
+            let bytes = self.input.as_bytes();
+            for (i, &item) in bytes.iter().enumerate() {
+                if i == read_pos.unwrap() {
+                    self.ch = Some(item);
+                }
+            }
+        }
+        self.position = self.read_pos;
+        let new_read_pos = self.read_pos.unwrap() + 1;
+        self.read_pos = Some(new_read_pos);
+    }
+
+    fn next_token(&self) -> Token {
+        let tok = Token {
+           type_: String::from(""),
+            literal: 
+        }
+
+        match self.ch {}
     }
 }
+
+fn new_token(token_type: String, ch: &u8) {
+        let lit = String::from_utf8_lossy(ch);
+        let token = Token {
+            type_: token_type,
+            literal: lit
+        };
+    }