+ skip comment (#39)

interpreter/src/evaluator/mod.rs

@@ -1225,4 +1225,21 @@ f()
 
         assert_eq!(Some(object::Object::Int(5)), eval(input));
     }
+
+    #[test]
+    fn test_comment() {
+        let tests = vec![
+            (
+                "let identity = fn(x) { // function defination here
+x; // just x
+};
+identity(5); // run with param 5",
+                Some(object::Object::Int(5)),
+            ),
+        ];
+
+        for (input, expect) in tests {
+            assert_eq!(expect, eval(input));
+        }
+    }
 }

interpreter/src/lexer/mod.rs

@@ -63,7 +63,15 @@ impl Lexer {
         let tok = match self.ch {
             '+' => Token::Plus,
             '-' => Token::Minus,
-            '/' => Token::Slash,
+            '/' => {
+                if self.next_is('/') {
+                    self.walk_char();
+                    self.skip_comment();
+                    return self.next_token();
+                } else {
+                    Token::Slash
+                }
+            },
             '*' => Token::Asterisk,
             '<' => {
                 if self.next_is('=') {
@@ -181,6 +189,13 @@ impl Lexer {
         }
     }
 
+    fn skip_comment(&mut self) {
+        while !matches!(self.next_ch(), '\n' | '\0') {
+            self.walk_char();
+        }
+        self.walk_char();
+    }
+
     fn consume_identifier(&mut self) -> Token {
         let start_pos = self.pos;
 
@@ -331,6 +346,9 @@ if (5 < 10) {
 "foobar";
 "foo bar";
 'foo bar';
+"foobar";//
+"foo bar"; // just a comment
+'foo bar';        // 一段注释
 
 [1, 2];
 
@@ -433,6 +451,12 @@ if (5 < 10) {
             Token::Semicolon,
             Token::String(String::from("foo bar")),
             Token::Semicolon,
+            Token::String(String::from("foobar")),
+            Token::Semicolon,
+            Token::String(String::from("foo bar")),
+            Token::Semicolon,
+            Token::String(String::from("foo bar")),
+            Token::Semicolon,
             Token::Blank,
             Token::LBracket,
             Token::Int(1),

interpreter/src/parser/mod.rs

@@ -1891,6 +1891,29 @@ return 993322;
         );
     }
 
+    #[test]
+    fn test_comment() {
+        let input = "fn(x, y){
+x + y // just return x + y 即可
+}";
+
+        let mut parser = Parser::new(Lexer::new(input));
+        let program = parser.parse();
+
+        check_parse_errors(&mut parser);
+        assert_eq!(
+            vec![Stmt::Expr(Expr::Function {
+                params: vec![Ident(String::from("x")), Ident(String::from("y"))],
+                body: vec![Stmt::Expr(Expr::Infix(
+                    Infix::Plus,
+                    Box::new(Expr::Ident(Ident(String::from("x")))),
+                    Box::new(Expr::Ident(Ident(String::from("y")))),
+                ))],
+            })],
+            program,
+        );
+    }
+
     /// errors panic
 
     #[test]