Implement index access syntax for classes

playground/src/pages/docs.tsx

@@ -134,8 +134,13 @@ const Docs: React.FC = () => (
             </Link>
           </li>
           <li className="nav-item">
-            <Link className="nav-link" to="#inheritance ">
-              Inheritance
+            <Link className="nav-link" to="#classes-inheritance">
+              Class Inheritance
+            </Link>
+          </li>
+          <li className="nav-item">
+            <Link className="nav-link" to="#classes-index-access">
+              Class Field/Method Index Access
             </Link>
           </li>
         </ul>
@@ -413,8 +418,8 @@ const Docs: React.FC = () => (
           height="300px"
         />
         <DocCard
-          title="Inheritance"
-          anchor="inheritance"
+          title="Class Inheritance"
+          anchor="classes-inheritance"
           code={[
             'class Greeter {',
             '  let greeting;',
@@ -442,6 +447,29 @@ const Docs: React.FC = () => (
           height="400px"
         />
 
+        <DocCard
+          title="Class Field/Method Index Access"
+          anchor="classes-index-access"
+          code={[
+            'class Box {',
+            '  let value;',
+            '',
+            '  fn init(value) {',
+            '    this["value"] = value;',
+            '  }',
+            '',
+            '  fn get() {',
+            '    return this["value"];',
+            '  }',
+            '}',
+            '',
+            'let box = Box(123);',
+            '',
+            'print box.get(); // out: 123',
+          ]}
+          height="275px"
+        />
+
         <div className="shadow rounded p-3 vstack gap-3">
           <h2 id="errors">
             Errors{' '}

res/examples/field/index_access_get_method_on_instance.locks

@@ -0,0 +1,15 @@
+class Box {
+  let value;
+
+  fn init(value) {
+    this.value = value;
+  }
+
+  fn get() {
+    return this.value;
+  }
+}
+
+let box = Box(123);
+
+print box["get"](); // out: 123

res/examples/field/index_access_get_nested.locks

@@ -0,0 +1,23 @@
+class Object {
+  let box;
+
+  fn init(value) {
+    this.box = Box(value);
+  }
+}
+
+class Box {
+  let value;
+
+  fn init(value) {
+    this.value = value;
+  }
+
+  fn get() {
+    return this.value;
+  }
+}
+
+let obj = Object(123);
+
+print obj["box"]["get"](); // out: 123

res/examples/field/index_access_get_set_on_super.locks

@@ -0,0 +1,25 @@
+class Parent {
+  let value;
+
+  fn init(value) {
+    this["value"] = value;
+  }
+
+  fn get() {
+    return this["value"];
+  }
+}
+
+class Child extends Parent {
+  fn init(value) {
+    super["init"](value);
+  }
+
+  fn get() {
+    return this.value;
+  }
+}
+
+let child = Child(123);
+
+print child.get(); // out: 123

res/examples/field/index_access_get_set_on_this.locks

@@ -0,0 +1,15 @@
+class Box {
+  let value;
+
+  fn init(value) {
+    this["value"] = value;
+  }
+
+  fn get() {
+    return this["value"];
+  }
+}
+
+let box = Box(123);
+
+print box.get(); // out: 123

res/examples/field/index_access_get_undefined.locks

@@ -0,0 +1,6 @@
+class Object {
+}
+
+let obj = Object();
+
+print obj["key"]; // out: AttributeError: "Object" object has no attribute "key"

res/examples/field/index_access_set_method_on_instance.locks

@@ -0,0 +1,15 @@
+class Box {
+  let value;
+
+  fn init(value) {
+    this.value = value;
+  }
+
+  fn get() {
+    return this.value;
+  }
+}
+
+let box = Box(123);
+
+box["get"] = 123; // out: TypeError: methods on instances can not be reassigned (e.g. instance<Box>.get = "...")

res/examples/field/index_access_set_undefined.locks

@@ -0,0 +1,6 @@
+class Object {
+}
+
+let obj = Object();
+
+obj["key"] = "new value"; // out: AttributeError: "Object" object has no attribute "key"

res/examples/field/index_access_with_expr.locks

@@ -0,0 +1,12 @@
+class Record {
+  let key = "value";
+}
+
+let key = "key";
+let record = Record();
+
+print record[key]; // out: value
+
+record[key] = "new value";
+
+print record[key]; // out: new value

res/examples/field/index_access_with_string.locks

@@ -0,0 +1,11 @@
+class Record {
+  let key = "value";
+}
+
+let record = Record();
+
+print record["key"]; // out: value
+
+record["key"] = "new value";
+
+print record["key"]; // out: new value

res/grammar.lalrpop

@@ -121,6 +121,10 @@ ExprAssign = {
         })),
     <object:Spanned<ExprCall>> "." <name:identifier> "=" <value:ExprS> =>
         ast::Expr::Set(Box::new(ast::ExprSet { <> })),
+    <object:Spanned<ExprCall>> "[" <name:identifier> "]" "=" <value:ExprS> =>
+        ast::Expr::Set(Box::new(ast::ExprSet { <> })),
+    <object:Spanned<ExprCall>> "[" <name:string> "]" "=" <value:ExprS> =>
+        ast::Expr::Set(Box::new(ast::ExprSet { <> })),
     ExprLogicOr,
 }
 
@@ -172,6 +176,10 @@ ExprCall: ast::Expr = {
         ast::Expr::Call(Box::new(ast::ExprCall { callee, args })),
     <object:Spanned<ExprCall>> "." <name:identifier> =>
         ast::Expr::Get(Box::new(ast::ExprGet { <> })),
+    <object:Spanned<ExprCall>> "[" <name:string> "]" =>
+        ast::Expr::Get(Box::new(ast::ExprGet { <> })),
+    <object:Spanned<ExprCall>> "[" <name:identifier> "]" =>
+        ast::Expr::Get(Box::new(ast::ExprGet { <> })),
     "super" "." <name:identifier> =>
         ast::Expr::Super(ast::ExprSuper {
             super_: ast::Identifier {
@@ -180,6 +188,22 @@ ExprCall: ast::Expr = {
             },
             name,
         }),
+    "super" "[" <name:string> "]" =>
+        ast::Expr::Super(ast::ExprSuper {
+            super_: ast::Identifier {
+                name: "super".to_string(),
+                depth: None,
+            },
+            name,
+        }),
+    "super" "[" <name:identifier> "]" =>
+        ast::Expr::Super(ast::ExprSuper {
+            super_: ast::Identifier {
+                name: "super".to_string(),
+                depth: None,
+            },
+            name,
+        }),
     ExprPrimary,
 }
 
@@ -253,6 +277,8 @@ extern {
         ")" => lexer::Token::RtParen,
         "{" => lexer::Token::LtBrace,
         "}" => lexer::Token::RtBrace,
+        "[" => lexer::Token::LtBracket,
+        "]" => lexer::Token::RtBracket,
         "," => lexer::Token::Comma,
         "." => lexer::Token::Dot,
         "-" => lexer::Token::Minus,

src/syntax/lexer.rs

@@ -70,6 +70,10 @@ pub enum Token {
     LtBrace,
     #[token("}")]
     RtBrace,
+    #[token("[")]
+    LtBracket,
+    #[token("]")]
+    RtBracket,
     #[token(",")]
     Comma,
     #[token(".")]

src/vm/mod.rs

@@ -788,10 +788,6 @@ impl VM {
     /// Create a new [`ObjectInstance`] of an [`ObjectClass`].
     ///
     /// Calls the `init` method if it exists on the [`ObjectClass`].
-    ///
-    /// ```
-    /// let instance = Class();
-    /// ```
     fn call_class(&mut self, class: *mut ObjectClass, arg_count: usize) -> Result<()> {
         let instance = self.alloc(ObjectInstance::new(class));