static void set_fields_undefined(ast_t* ast)
{
assert(ast_id(ast) == TK_NEW);
ast_t* members = ast_parent(ast);
ast_t* member = ast_child(members);
while(member != NULL)
{
switch(ast_id(member))
{
case TK_FVAR:
case TK_FLET:
case TK_EMBED:
{
AST_GET_CHILDREN(member, id, type, expr);
// If this field has an initialiser, we accept SYM_DEFINED for it.
if(ast_id(expr) != TK_NONE)
break;
// Mark this field as SYM_UNDEFINED.
ast_setstatus(ast, ast_name(id), SYM_UNDEFINED);
break;
}
default: {}
}
member = ast_sibling(member);
}
}
bool expr_consume(pass_opt_t* opt, ast_t* ast)
{
AST_GET_CHILDREN(ast, cap, term);
ast_t* type = ast_type(term);
if(is_typecheck_error(type))
return false;
const char* name = NULL;
switch(ast_id(term))
{
case TK_VARREF:
case TK_LETREF:
case TK_PARAMREF:
{
ast_t* id = ast_child(term);
name = ast_name(id);
break;
}
case TK_THIS:
{
name = stringtab("this");
break;
}
default:
ast_error(opt->check.errors, ast,
"consume must take 'this', a local, or a parameter");
return false;
}
// Can't consume from an outer scope while in a loop condition.
if((opt->check.frame->loop_cond != NULL) &&
!ast_within_scope(opt->check.frame->loop_cond, ast, name))
{
ast_error(opt->check.errors, ast,
"can't consume from an outer scope in a loop condition");
return false;
}
ast_setstatus(ast, name, SYM_CONSUMED);
token_id tcap = ast_id(cap);
ast_t* c_type = consume_type(type, tcap);
if(c_type == NULL)
{
ast_error(opt->check.errors, ast, "can't consume to this capability");
ast_error_continue(opt->check.errors, term, "expression type is %s",
ast_print_type(type));
return false;
}
ast_settype(ast, c_type);
return true;
}
static bool assign_id(typecheck_t* t, ast_t* ast, bool let, bool need_value)
{
assert(ast_id(ast) == TK_ID);
const char* name = ast_name(ast);
sym_status_t status;
ast_get(ast, name, &status);
switch(status)
{
case SYM_UNDEFINED:
if(need_value)
{
ast_error(ast, "the left side is undefined but its value is used");
return false;
}
ast_setstatus(ast, name, SYM_DEFINED);
return true;
case SYM_DEFINED:
if(let)
{
ast_error(ast,
"can't assign to a let or embed definition more than once");
return false;
}
return true;
case SYM_CONSUMED:
{
bool ok = true;
if(need_value)
{
ast_error(ast, "the left side is consumed but its value is used");
ok = false;
}
if(let)
{
ast_error(ast,
"can't assign to a let or embed definition more than once");
ok = false;
}
if(t->frame->try_expr != NULL)
{
ast_error(ast,
"can't reassign to a consumed identifier in a try expression");
ok = false;
}
if(ok)
ast_setstatus(ast, name, SYM_DEFINED);
return ok;
}
default: {}
}
assert(0);
return false;
}