Add support for the "#foo in obj" syntax

This is the ergonomic brand checks for private fields proposal that is in the ES2022 spec. https://github.com/tc39/proposal-private-fields-in-in Requires a new bytecode that checks the scope of the `#foo` private name, and then only pushes the var corresponding to it to the stack.

Author: takikawa

quickjs-opcode.h

@@ -277,6 +277,7 @@ def(scope_delete_var, 7, 0, 1, atom_u16) /* emitted in phase 1, removed in phase
 def( scope_make_ref, 11, 0, 2, atom_label_u16) /* emitted in phase 1, removed in phase 2 */
 def( scope_get_ref, 7, 0, 2, atom_u16) /* emitted in phase 1, removed in phase 2 */
 def(scope_put_var_init, 7, 0, 2, atom_u16) /* emitted in phase 1, removed in phase 2 */
+def(scope_ref_private_field, 7, 1, 1, atom_u16) /* obj -> value, emitted in phase 1, removed in phase 2 */
 def(scope_get_private_field, 7, 1, 1, atom_u16) /* obj -> value, emitted in phase 1, removed in phase 2 */
 def(scope_get_private_field2, 7, 1, 2, atom_u16) /* obj -> obj value, emitted in phase 1, removed in phase 2 */
 def(scope_put_private_field, 7, 1, 1, atom_u16) /* obj value ->, emitted in phase 1, removed in phase 2 */

quickjs.c

@@ -7357,7 +7357,9 @@ static int JS_AddBrand(JSContext *ctx, JSValueConst obj, JSValueConst home_obj)
  return 0;
 }
 
-static int JS_CheckBrand(JSContext *ctx, JSValueConst obj, JSValueConst func)
+/* return -1 if exception or TRUE/FALSE */
+static int JS_CheckBrand(JSContext *ctx, JSValueConst obj, JSValueConst func,
+ BOOL should_throw_for_brand)
 {
  JSObject *p, *p1, *home_obj;
  JSShapeProperty *prs;
@@ -7378,8 +7380,11 @@ static int JS_CheckBrand(JSContext *ctx, JSValueConst obj, JSValueConst func)
  goto not_obj;
  prs = find_own_property(&pr, home_obj, JS_ATOM_Private_brand);
  if (!prs) {
- JS_ThrowTypeError(ctx, "expecting <brand> private field");
- return -1;
+ if (should_throw_for_brand) {
+ JS_ThrowTypeError(ctx, "expecting <brand> private field");
+ return -1;
+ }
+ return FALSE;
  }
  brand = pr->u.value;
  /* safety check */
@@ -7392,10 +7397,13 @@ static int JS_CheckBrand(JSContext *ctx, JSValueConst obj, JSValueConst func)
  p = JS_VALUE_GET_OBJ(obj);
  prs = find_own_property(&pr, p, js_symbol_to_atom(ctx, (JSValue)brand));
  if (!prs) {
- JS_ThrowTypeError(ctx, "invalid brand on object");
- return -1;
+ if (should_throw_for_brand) {
+ JS_ThrowTypeError(ctx, "invalid brand on object");
+ return -1;
+ }
+ return FALSE;
  }
- return 0;
+ return TRUE;
 }
 
 static uint32_t js_string_obj_get_length(JSContext *ctx,
@@ -14757,11 +14765,16 @@ static __exception int js_operator_in(JSContext *ctx, JSValue *sp)
  JS_ThrowTypeError(ctx, "invalid 'in' operand");
  return -1;
  }
- atom = JS_ValueToAtom(ctx, op1);
- if (unlikely(atom == JS_ATOM_NULL))
- return -1;
- ret = JS_HasProperty(ctx, op2, atom);
- JS_FreeAtom(ctx, atom);
+ if (JS_VALUE_GET_TAG(op1) != JS_TAG_OBJECT) {
+ atom = JS_ValueToAtom(ctx, op1);
+ if (unlikely(atom == JS_ATOM_NULL))
+ return -1;
+ ret = JS_HasProperty(ctx, op2, atom);
+ JS_FreeAtom(ctx, atom);
+ } else {
+ /* This case can occur if the LHS is a private method name */
+ ret = JS_CheckBrand(ctx, op2, op1, FALSE);
+ }
  if (ret < 0)
  return -1;
  JS_FreeValue(ctx, op1);
@@ -16754,7 +16767,7 @@ static JSValue JS_CallInternal(JSContext *caller_ctx, JSValueConst func_obj,
  }
  BREAK;
  CASE(OP_check_brand):
- if (JS_CheckBrand(ctx, sp[-2], sp[-1]) < 0)
+ if (JS_CheckBrand(ctx, sp[-2], sp[-1], TRUE) < 0)
  goto exception;
  BREAK;
  CASE(OP_add_brand):
@@ -24472,6 +24485,19 @@ static __exception int js_parse_postfix_expr(JSParseState *s, int parse_flags)
  return -1;
  emit_op(s, OP_push_true);
  break;
+ case TOK_PRIVATE_NAME:
+ {
+ JSAtom name;
+ if (peek_token(s, FALSE) != TOK_IN)
+ return -1;
+ name = JS_DupAtom(s->ctx, s->token.u.ident.atom);
+ if (next_token(s))
+ return -1;
+ emit_op(s, OP_scope_ref_private_field);
+ emit_u32(s, name);
+ emit_u16(s, s->cur_func->scope_level);
+ break;
+ }
  case TOK_IDENT:
  {
  JSAtom name;
@@ -30106,6 +30132,10 @@ static int resolve_scope_private_field(JSContext *ctx, JSFunctionDef *s,
  return -1;
  assert(var_kind != JS_VAR_NORMAL);
  switch (op) {
+ /* this case is used for `in` operator LHS references */
+ case OP_scope_ref_private_field:
+ get_loc_or_ref(bc, is_ref, idx);
+ break;
  case OP_scope_get_private_field:
  case OP_scope_get_private_field2:
  switch(var_kind) {
@@ -30884,6 +30914,7 @@ static __exception int resolve_variables(JSContext *ctx, JSFunctionDef *s)
  JS_FreeAtom(ctx, var_name);
  }
  break;
+ case OP_scope_ref_private_field:
  case OP_scope_get_private_field:
  case OP_scope_get_private_field2:
  case OP_scope_put_private_field: