Merge pull request #75 from meloalright/master

补齐 "." 访问语法

README.md

@@ -265,6 +265,7 @@ Five types of literals are implemented.
 };
 
 载体["name"];
+载体.name;
 载体["a" + "ge"];
 载体[三七五];
 载体[99];

src/evaluator/mod.rs

@@ -581,7 +581,9 @@ let two = "two";
     fn test_hash_index_expr() {
         let tests = vec![
             ("{\"foo\": 5}[\"foo\"]", Some(Object::Int(5))),
+            ("{\"foo\": 5}.foo", Some(Object::Int(5))),
             ("{\"foo\": 5}[\"bar\"]", Some(Object::Null)),
+            ("{\"foo\": 5}.bar", Some(Object::Null)),
             ("let key = \"foo\"; {\"foo\": 5}[key]", Some(Object::Int(5))),
             ("{}[\"foo\"]", Some(Object::Null)),
             ("{5: 5}[5]", Some(Object::Int(5))),

src/lexer/mod.rs

@@ -197,6 +197,7 @@ impl Lexer {
             '}' => Token::Rbrace,
             '[' => Token::Lbracket,
             ']' => Token::Rbracket,
+            '.' => Token::Dot,
             ',' => Token::Comma,
             ';' => Token::Semicolon,
             ':' => Token::Colon,

src/parser/mod.rs

@@ -51,6 +51,7 @@ impl Parser {
             Token::Plus | Token::Minus => Precedence::Sum,
             Token::Slash | Token::Asterisk => Precedence::Product,
             Token::Lbracket => Precedence::Index,
+            Token::Dot => Precedence::Index,
             Token::Lparen => Precedence::Call,
             _ => Precedence::Lowest,
         }
@@ -267,6 +268,10 @@ impl Parser {
                     self.bump();
                     left = self.parse_index_expr(left.unwrap());
                 }
+                Token::Dot => {
+                    self.bump();
+                    left = self.parse_dot_access_expr(left.unwrap());
+                }
                 Token::Lparen => {
                     self.bump();
                     left = self.parse_call_expr(left.unwrap());
@@ -432,6 +437,20 @@ impl Parser {
         Some(Expr::Index(Box::new(left), Box::new(index)))
     }
 
+    fn parse_dot_access_expr(&mut self, left: Expr) -> Option<Expr> {
+        self.bump();
+
+        match self.parse_ident() {
+            Some(name) => match name {
+                Ident(str) => {
+                    Some(Expr::Index(Box::new(left), Box::new(Expr::Literal(Literal::String(str)))))
+                },
+                _ => return None
+            },
+            None => return None,
+        }
+    }
+
     fn parse_grouped_expr(&mut self) -> Option<Expr> {
         self.bump();
 
@@ -858,6 +877,23 @@ return 993322;
         );
     }
 
+    #[test]
+    fn test_dot_access_expr() {
+        let input = "myHash.key";
+
+        let mut parser = Parser::new(Lexer::new(input));
+        let program = parser.parse();
+
+        check_parse_errors(&mut parser);
+        assert_eq!(
+            vec![Stmt::Expr(Expr::Index(
+                Box::new(Expr::Ident(Ident(String::from("myHash")))),
+                Box::new(Expr::Literal(Literal::String(String::from("key")))),
+            ))],
+            program
+        );
+    }
+
     #[test]
     fn test_prefix_expr() {
         let tests = vec![

src/token.rs

@@ -42,6 +42,7 @@ pub enum Token {
     Rbrace,
     Lbracket,
     Rbracket,
+    Dot,
 
     // Reseved keywords
     Func,