syntax: implement `delete` as proper operator

Turn `delete` into a proper operator mimicking ECMAScript semantics.

Also ensure to transparently turn deprecated `delete(obj, propname)`
function calls into `delete obj.propname` expressions during compilation.

When strict mode is active, legacy delete() calls throw a syntax error
instead.

Finally drop the `delete()` function from the stdlib as it is shadowed
by the delete operator syntax now.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 29 insertions, 0 deletions

diff --git a/vm.c b/vm.c
index 5b7b5e8..8a503a0 100644
--- a/vm.c
+++ b/vm.c
@@ -1918,6 +1918,31 @@ uc_vm_insn_print(uc_vm *vm, enum insn_type insn)
 	ucv_put(v);
 }
 
+static void
+uc_vm_insn_delete(uc_vm *vm, enum insn_type insn)
+{
+	uc_value_t *k = uc_vm_stack_pop(vm);
+	uc_value_t *v = uc_vm_stack_pop(vm);
+	bool rv;
+
+	switch (ucv_type(v)) {
+	case UC_OBJECT:
+		rv = uc_delval(vm, v, k);
+		uc_vm_stack_push(vm, ucv_boolean_new(rv));
+		break;
+
+	default:
+		uc_vm_raise_exception(vm, EXCEPTION_REFERENCE,
+		                      "left-hand side expression is %s",
+		                      v ? "not an object" : "null");
+
+		break;
+	}
+
+	ucv_put(k);
+	ucv_put(v);
+}
+
 static uc_value_t *
 uc_vm_callframe_pop(uc_vm *vm)
 {
@@ -2186,6 +2211,10 @@ uc_vm_execute_chunk(uc_vm *vm)
 			uc_vm_insn_print(vm, insn);
 			break;
 
+		case I_DELETE:
+			uc_vm_insn_delete(vm, insn);
+			break;
+
 		default:
 			uc_vm_raise_exception(vm, EXCEPTION_RUNTIME, "unknown opcode %d", insn);
 			break;