Implement `delete` operator in the vm (#1649)

boa/src/bytecompiler.rs

@@ -370,7 +370,29 @@ impl ByteCompiler {
                     UnaryOp::DecrementPre => todo!(),
                     UnaryOp::IncrementPost => todo!(),
                     UnaryOp::DecrementPost => todo!(),
-                    UnaryOp::Delete => todo!(),
+                    UnaryOp::Delete => match unary.target() {
+                        Node::GetConstField(ref get_const_field) => {
+                            let index = self.get_or_insert_name(get_const_field.field());
+                            self.compile_expr(get_const_field.obj(), true);
+                            self.emit(Opcode::DeletePropertyByName, &[index]);
+                            None
+                        }
+                        Node::GetField(ref get_field) => {
+                            self.compile_expr(get_field.field(), true);
+                            self.compile_expr(get_field.obj(), true);
+                            self.emit(Opcode::DeletePropertyByValue, &[]);
+                            None
+                        }
+                        // TODO: implement delete on references.
+                        Node::Identifier(_) => {
+                            self.emit(Opcode::PushFalse, &[]);
+                            None
+                        }
+                        _ => {
+                            self.emit(Opcode::PushTrue, &[]);
+                            None
+                        }
+                    },
                     UnaryOp::Minus => Some(Opcode::Neg),
                     UnaryOp::Plus => Some(Opcode::Pos),
                     UnaryOp::Not => Some(Opcode::LogicalNot),
@@ -382,12 +404,12 @@ impl ByteCompiler {
                 if let Some(opcode) = opcode {
                     self.compile_expr(unary.target(), true);
                     self.emit(opcode, &[]);
+                }
 
                 if !use_expr {
                     self.emit(Opcode::Pop, &[]);
                 }
             }
-            }
             Node::BinOp(binary) => {
                 self.compile_expr(binary.lhs(), true);
                 match binary.op() {

boa/src/syntax/ast/node/operator/unary_op/mod.rs

@@ -114,16 +114,9 @@ impl Executable for UnaryOp {
                         .__delete__(&field.to_property_key(context)?, context)?;
                     return Ok(JsValue::new(res));
                 }
+                // TODO: implement delete on references.
                 Node::Identifier(_) => JsValue::new(false),
-                Node::ArrayDecl(_)
-                | Node::Block(_)
-                | Node::Const(_)
-                | Node::FunctionDecl(_)
-                | Node::FunctionExpr(_)
-                | Node::New(_)
-                | Node::Object(_)
-                | Node::UnaryOp(_) => JsValue::new(true),
-                _ => return context.throw_syntax_error(format!("wrong delete argument {}", self)),
+                _ => JsValue::new(true),
             },
             op::UnaryOp::TypeOf => JsValue::new(self.target().run(context)?.type_of()),
         })

boa/src/vm/code_block.rs

@@ -159,7 +159,8 @@ impl CodeBlock {
             | Opcode::GetName
             | Opcode::SetName
             | Opcode::GetPropertyByName
-            | Opcode::SetPropertyByName => {
+            | Opcode::SetPropertyByName
+            | Opcode::DeletePropertyByName => {
                 let operand = self.read::<u32>(*pc);
                 *pc += size_of::<u32>();
                 format!("{:04}: '{}'", operand, self.variables[operand as usize])
@@ -207,6 +208,7 @@ impl CodeBlock {
             | Opcode::Neg
             | Opcode::GetPropertyByValue
             | Opcode::SetPropertyByValue
+            | Opcode::DeletePropertyByValue
             | Opcode::ToBoolean
             | Opcode::Throw
             | Opcode::This

boa/src/vm/mod.rs

@@ -397,6 +397,21 @@ impl Context {
                 let key = key.to_property_key(self)?;
                 object.set(key, value, true, self)?;
             }
+            Opcode::DeletePropertyByName => {
+                let index = self.vm.read::<u32>();
+                let key = self.vm.frame().code.variables[index as usize].clone();
+                let object = self.vm.pop();
+                let result = object.to_object(self)?.__delete__(&key.into(), self)?;
+                self.vm.push(result);
+            }
+            Opcode::DeletePropertyByValue => {
+                let object = self.vm.pop();
+                let key = self.vm.pop();
+                let result = object
+                    .to_object(self)?
+                    .__delete__(&key.to_property_key(self)?, self)?;
+                self.vm.push(result);
+            }
             Opcode::Throw => {
                 let value = self.vm.pop();
                 return Err(value);

boa/src/vm/opcode.rs

@@ -442,6 +442,24 @@ pub enum Opcode {
     /// Stack: value, key, object **=>**
     SetPropertyByValue,
 
+    /// Deletes a property by name of an object.
+    ///
+    /// Like `delete object.key.`
+    ///
+    /// Operands: name_index: `u32`
+    ///
+    /// Stack: object **=>**
+    DeletePropertyByName,
+
+    /// Deletes a property by value of an object.
+    ///
+    /// Like `delete object[key]`
+    ///
+    /// Operands:
+    ///
+    /// Stack: key, object **=>**
+    DeletePropertyByValue,
+
     /// Unconditional jump to address.
     ///
     /// Operands: address: `u32`
@@ -605,6 +623,8 @@ impl Opcode {
             Opcode::GetPropertyByValue => "GetPropertyByValue",
             Opcode::SetPropertyByName => "SetPropertyByName",
             Opcode::SetPropertyByValue => "SetPropertyByValue",
+            Opcode::DeletePropertyByName => "DeletePropertyByName",
+            Opcode::DeletePropertyByValue => "DeletePropertyByValue",
             Opcode::Jump => "Jump",
             Opcode::JumpIfFalse => "JumpIfFalse",
             Opcode::JumpIfTrue => "JumpIfTrue",