From a1fc32d7a3feb8a3f465bb05d0bdfbe96f9a962f Mon Sep 17 00:00:00 2001
From: YannAhlgrim <yann@ahlgrim.net>
Date: Tue, 12 May 2026 16:24:31 +0200
Subject: [PATCH] idents and numbers

---
 src/lexer/mod.rs | 36 +++++++++++++++++++++++++++++++++---
 src/main.rs      |  4 ++--
 src/token/mod.rs | 10 ++++++++++
 3 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/src/lexer/mod.rs b/src/lexer/mod.rs
index 0db092b..347966a 100644
--- a/src/lexer/mod.rs
+++ b/src/lexer/mod.rs
@@ -1,3 +1,5 @@
+use crate::token::lookup_ident;
+
 use super::token::ASSIGN;
 use super::token::COMMA;
 use super::token::EOF;
@@ -25,6 +27,8 @@ pub trait LexerTraits {
     fn read_char(&mut self);
     fn next_token(&mut self) -> Token;
     fn read_identifier(&mut self) -> String;
+    fn skip_whitespace(&mut self);
+    fn read_number(&mut self) -> String;
 }
 
 pub fn new(input_str: String) -> Lexer {
@@ -59,6 +63,7 @@ impl LexerTraits for Lexer {
     fn next_token(&mut self) -> Token {
         #[allow(unused_assignments)]
         let mut tok = Token::default();
+        self.skip_whitespace();
         let lit = self.ch.unwrap();
         let c = char::from(lit);
 
@@ -73,8 +78,12 @@ impl LexerTraits for Lexer {
             '}' => tok = new_token(RBRACE, lit),
             _ => {
                 if c.is_alphabetic() {
-                    let _lit_ = self.read_identifier();
-                    return tok;
+                    let lit = self.read_identifier();
+                    let tok_type = lookup_ident(&lit);
+                    return new_token(tok_type, lit.as_bytes()[0]);
+                } else if c.is_ascii_digit() {
+                    let lit = self.read_number();
+                    return new_token(INT, lit.as_bytes()[0]);
                 } else {
                     tok = new_token(ILLEGAL, lit);
                 }
@@ -95,10 +104,31 @@ impl LexerTraits for Lexer {
         let res = &res[position..read_pos];
         String::from(res)
     }
+
+    fn skip_whitespace(&mut self) {
+        while char::from(self.ch.unwrap()) == ' '
+            || char::from(self.ch.unwrap()) == '\n'
+            || char::from(self.ch.unwrap()) == '\r'
+        {
+            self.read_char();
+        }
+    }
+
+    fn read_number(&mut self) -> String {
+        let position = self.position.unwrap();
+        while self.ch.unwrap().is_ascii_digit() {
+            self.read_char();
+        }
+        let read_pos = self.position.unwrap() as usize;
+        let position = position as usize;
+        let res = &self.input;
+        let res = &res[position..read_pos];
+        String::from(res)
+    }
 }
 
 fn new_token(token_type: &str, ch: u8) -> Token {
-    let lit = ch.to_string();
+    let lit = String::from(char::from(ch));
     let token_type = String::from(token_type);
     Token {
         type_: token_type,
diff --git a/src/main.rs b/src/main.rs
index 79c572f..c3714cd 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -14,7 +14,7 @@ fn main() {
 
     let mut l = new(input.to_string());
 
-    for (i, tok) in (0..10).map(|_| l.next_token()).enumerate() {
-        println!("{}: {:?}", i, tok.type_);
+    for (i, tok) in (0..36).map(|_| l.next_token()).enumerate() {
+        println!("{}: {:?}", tok.type_, tok.literal);
     }
 }
diff --git a/src/token/mod.rs b/src/token/mod.rs
index 6e652c6..c4555d5 100644
--- a/src/token/mod.rs
+++ b/src/token/mod.rs
@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 #[derive(Default)]
 pub struct Token {
     pub type_: String,
@@ -18,3 +20,11 @@ pub const LBRACE: &str = "{";
 pub const RBRACE: &str = "}";
 pub const FUNCTION: &str = "FUNCTION";
 pub const LET: &str = "LET";
+
+pub fn lookup_ident(ident: &str) -> &str {
+    match ident {
+        "fn" => FUNCTION,
+        "let" => LET,
+        _ => ILLEGAL,
+    }
+}