bool is_sub_cap_and_ephemeral(ast_t* sub, ast_t* super)
{
ast_t* sub_cap = fetch_cap(sub);
ast_t* sub_eph = ast_sibling(sub_cap);
ast_t* super_cap = fetch_cap(super);
ast_t* super_eph = ast_sibling(super_cap);
return is_cap_sub_cap(ast_id(sub_cap), ast_id(sub_eph), ast_id(super_cap),
ast_id(super_eph));
}
bool is_sub_cap_and_ephemeral(ast_t* sub, ast_t* super)
{
ast_t* sub_cap = fetch_cap(sub);
ast_t* sub_eph = ast_sibling(sub_cap);
ast_t* super_cap = fetch_cap(super);
ast_t* super_eph = ast_sibling(super_cap);
token_id t_sub_cap = ast_id(sub_cap);
token_id t_sub_eph = ast_id(sub_eph);
token_id t_super_cap = ast_id(super_cap);
token_id t_super_eph = ast_id(super_eph);
token_id t_alt_cap = t_sub_cap;
// Adjusted for borrowing.
if(t_sub_eph == TK_BORROWED)
{
switch(t_alt_cap)
{
case TK_ISO: t_alt_cap = TK_TAG; break;
case TK_TRN: t_alt_cap = TK_BOX; break;
case TK_ANY_GENERIC: t_alt_cap = TK_TAG; break;
default: {}
}
}
switch(t_super_eph)
{
case TK_EPHEMERAL:
// Sub must be ephemeral if t_sub_cap != t_alt_cap. Otherwise, we don't
// have to be ephemeral, since, for example, a ref can be a subtype of
// a ref^, but an iso is not a subtype of an iso^.
if((t_sub_cap != t_alt_cap) && (t_sub_eph != TK_EPHEMERAL))
return false;
// Capability must be a sub-capability.
return is_cap_sub_cap(t_sub_cap, t_super_cap);
case TK_NONE:
// Check the adjusted capability.
return is_cap_sub_cap(t_alt_cap, t_super_cap);
case TK_BORROWED:
// Borrow a capability.
if(t_sub_cap == t_super_cap)
return true;
// Or alias a capability.
return is_cap_sub_cap(t_alt_cap, t_super_cap);
default: {}
}
assert(0);
return false;
}
static bool is_nominal_eq_nominal(ast_t* sub, ast_t* super)
{
ast_t* sub_cap = fetch_cap(sub);
ast_t* sub_eph = ast_sibling(sub_cap);
ast_t* super_cap = fetch_cap(super);
ast_t* super_eph = ast_sibling(super_cap);
token_id t_sub_cap = ast_id(sub_cap);
token_id t_sub_eph = ast_id(sub_eph);
token_id t_super_cap = ast_id(super_cap);
token_id t_super_eph = ast_id(super_eph);
if((t_sub_cap != t_super_cap) || (t_sub_eph != t_super_eph))
return false;
ast_t* sub_def = (ast_t*)ast_data(sub);
ast_t* super_def = (ast_t*)ast_data(super);
// If we are the same nominal type, our typeargs must be the same.
if(sub_def == super_def)
return is_eq_typeargs(sub, super);
return false;
}
