bool expr_this(pass_opt_t* opt, ast_t* ast)
{
typecheck_t* t = &opt->check;
if(t->frame->def_arg != NULL)
{
ast_error(ast, "can't reference 'this' in a default argument");
return false;
}
sym_status_t status;
ast_get(ast, stringtab("this"), &status);
if(status == SYM_CONSUMED)
{
ast_error(ast, "can't use a consumed 'this' in an expression");
return false;
}
assert(status == SYM_NONE);
token_id cap = cap_for_this(t);
if(!cap_sendable(cap) && (t->frame->recover != NULL))
cap = TK_TAG;
bool make_arrow = false;
if(cap == TK_BOX)
{
cap = TK_REF;
make_arrow = true;
}
ast_t* type = type_for_this(opt, ast, cap, TK_NONE, false);
if(make_arrow)
{
BUILD(arrow, ast, NODE(TK_ARROW, NODE(TK_THISTYPE) TREE(type)));
type = arrow;
}
// Get the nominal type, which may be the right side of an arrow type.
ast_t* nominal;
bool arrow;
if(ast_id(type) == TK_NOMINAL)
{
nominal = type;
arrow = false;
} else {
nominal = ast_childidx(type, 1);
arrow = true;
}
ast_t* typeargs = ast_childidx(nominal, 2);
ast_t* typearg = ast_child(typeargs);
while(typearg != NULL)
{
if(!expr_nominal(opt, &typearg))
{
ast_error(ast, "couldn't create a type for 'this'");
ast_free(type);
return false;
}
typearg = ast_sibling(typearg);
}
if(!expr_nominal(opt, &nominal))
{
ast_error(ast, "couldn't create a type for 'this'");
ast_free(type);
return false;
}
if(arrow)
type = ast_parent(nominal);
else
type = nominal;
ast_settype(ast, type);
return true;
}
bool expr_this(pass_opt_t* opt, ast_t* ast)
{
typecheck_t* t = &opt->check;
if(t->frame->def_arg != NULL)
{
ast_error(opt->check.errors, ast,
"can't reference 'this' in a default argument");
return false;
}
sym_status_t status;
ast_get(ast, stringtab("this"), &status);
if(status == SYM_CONSUMED)
{
ast_error(opt->check.errors, ast,
"can't use a consumed 'this' in an expression");
return false;
}
assert(status == SYM_NONE);
token_id cap = cap_for_this(t);
if(!cap_sendable(cap) && (t->frame->recover != NULL))
{
ast_t* parent = ast_parent(ast);
if(ast_id(parent) != TK_DOT)
cap = TK_TAG;
}
bool make_arrow = false;
if(cap == TK_BOX)
{
cap = TK_REF;
make_arrow = true;
}
ast_t* type = type_for_this(opt, ast, cap, TK_NONE, false);
if(make_arrow)
{
BUILD(arrow, ast, NODE(TK_ARROW, NODE(TK_THISTYPE) TREE(type)));
type = arrow;
}
// Get the nominal type, which may be the right side of an arrow type.
ast_t* nominal;
bool arrow;
if(ast_id(type) == TK_NOMINAL)
{
nominal = type;
arrow = false;
} else {
nominal = ast_childidx(type, 1);
arrow = true;
}
ast_t* typeargs = ast_childidx(nominal, 2);
ast_t* typearg = ast_child(typeargs);
while(typearg != NULL)
{
if(!expr_nominal(opt, &typearg))
{
ast_error(opt->check.errors, ast, "couldn't create a type for 'this'");
ast_free(type);
return false;
}
typearg = ast_sibling(typearg);
}
if(!expr_nominal(opt, &nominal))
{
ast_error(opt->check.errors, ast, "couldn't create a type for 'this'");
ast_free(type);
return false;
}
// Unless this is a field lookup, treat an incomplete `this` as a tag.
ast_t* parent = ast_parent(ast);
bool incomplete_ok = false;
if((ast_id(parent) == TK_DOT) && (ast_child(parent) == ast))
{
ast_t* right = ast_sibling(ast);
assert(ast_id(right) == TK_ID);
ast_t* find = lookup_try(opt, ast, nominal, ast_name(right));
if(find != NULL)
{
switch(ast_id(find))
{
case TK_FVAR:
case TK_FLET:
case TK_EMBED:
incomplete_ok = true;
break;
default: {}
}
}
}
if(!incomplete_ok && is_this_incomplete(t, ast))
{
ast_t* tag_type = set_cap_and_ephemeral(nominal, TK_TAG, TK_NONE);
ast_replace(&nominal, tag_type);
}
if(arrow)
type = ast_parent(nominal);
else
type = nominal;
ast_settype(ast, type);
return true;
}