ast_t* viewpoint_type(ast_t* l_type, ast_t* r_type)
{
switch(ast_id(l_type))
{
case TK_TUPLETYPE:
case TK_UNIONTYPE:
case TK_ISECTTYPE:
{
// Only occurs in codegen.
return r_type;
}
case TK_NOMINAL:
{
if(ast_id(r_type) == TK_ARROW)
return make_arrow_type(l_type, r_type);
AST_GET_CHILDREN(l_type, pkg, id, typeargs, cap, eph);
token_id tcap = ast_id(cap);
if(tcap == TK_CAP_READ)
return make_arrow_type(l_type, r_type);
return viewpoint_cap(tcap, ast_id(eph), r_type);
}
case TK_TYPEPARAMREF:
{
if(ast_id(r_type) == TK_ARROW)
return make_arrow_type(l_type, r_type);
AST_GET_CHILDREN(l_type, id, cap, eph);
token_id tcap = ast_id(cap);
if(tcap == TK_CAP_READ)
return make_arrow_type(l_type, r_type);
return viewpoint_cap(tcap, ast_id(eph), r_type);
}
case TK_ARROW:
case TK_BOXTYPE:
case TK_THISTYPE:
return make_arrow_type(l_type, r_type);
default: {}
}
return NULL;
}
ast_t* viewpoint_cap(token_id cap, token_id eph, ast_t* type)
{
if(cap == TK_TAG)
return NULL;
switch(ast_id(type))
{
case TK_UNIONTYPE:
case TK_ISECTTYPE:
case TK_TUPLETYPE:
{
// Adapt all elements.
ast_t* r_type = ast_from(type, ast_id(type));
ast_t* child = ast_child(type);
while(child != NULL)
{
ast_append(r_type, viewpoint_cap(cap, eph, child));
child = ast_sibling(child);
}
return r_type;
}
case TK_NOMINAL:
return viewpoint_for_type(cap, eph, type, 3);
case TK_TYPEPARAMREF:
return viewpoint_for_type(cap, eph, type, 1);
case TK_ARROW:
{
// Adapt the lower bounds.
ast_t* lower = viewpoint_lower(type);
ast_t* r_type = viewpoint_cap(cap, eph, lower);
if(r_type != lower)
ast_free_unattached(lower);
return r_type;
}
default: {}
}
assert(0);
return NULL;
}
ast_t* viewpoint_type(ast_t* l_type, ast_t* r_type)
{
switch(ast_id(l_type))
{
case TK_TUPLETYPE:
case TK_UNIONTYPE:
case TK_ISECTTYPE:
{
// Only occurs in codegen.
return r_type;
}
case TK_NOMINAL:
{
if(ast_id(r_type) == TK_ARROW)
return make_arrow_type(l_type, r_type);
AST_GET_CHILDREN(l_type, pkg, id, typeargs, cap, eph);
return viewpoint_cap(ast_id(cap), ast_id(eph), r_type);
}
case TK_TYPEPARAMREF:
{
if(ast_id(r_type) == TK_ARROW)
return make_arrow_type(l_type, r_type);
// If the left side is a type parameter, return an arrow type if the
// capability is box, otherwise adapt the type.
AST_GET_CHILDREN(l_type, id, cap, eph);
token_id tcap = ast_id(cap);
if(tcap == TK_BOX_GENERIC)
return make_arrow_type(l_type, r_type);
return viewpoint_cap(tcap, ast_id(eph), r_type);
}
case TK_ARROW:
case TK_BOXTYPE:
case TK_THISTYPE:
return make_arrow_type(l_type, r_type);
default: {}
}
return NULL;
}
static token_id partial_application_cap(ast_t* ftype, ast_t* receiver,
ast_t* positional)
{
// Check if the apply method in the generated object literal can accept a box
// receiver. If not, it must be a ref receiver. It can accept a box receiver
// if box->receiver <: lhs->receiver and box->arg <: lhs->param.
AST_GET_CHILDREN(ftype, cap, typeparams, params, result);
ast_t* type = ast_type(receiver);
ast_t* view_type = viewpoint_cap(TK_BOX, TK_NONE, type);
ast_t* need_type = set_cap_and_ephemeral(type, ast_id(cap), TK_NONE);
bool ok = is_subtype(view_type, need_type);
ast_free_unattached(view_type);
ast_free_unattached(need_type);
if(!ok)
return TK_REF;
ast_t* param = ast_child(params);
ast_t* arg = ast_child(positional);
while(arg != NULL)
{
if(ast_id(arg) != TK_NONE)
{
type = ast_type(arg);
view_type = viewpoint_cap(TK_BOX, TK_NONE, type);
need_type = ast_childidx(param, 1);
ok = is_subtype(view_type, need_type);
ast_free_unattached(view_type);
ast_free_unattached(need_type);
if(!ok)
return TK_REF;
}
arg = ast_sibling(arg);
param = ast_sibling(param);
}
return TK_BOX;
}
ast_t* viewpoint_upper(ast_t* type)
{
if(ast_id(type) == TK_ARROW)
{
AST_GET_CHILDREN(type, left, right);
ast_t* r_right = viewpoint_upper(right);
return viewpoint_cap(TK_BOX, TK_NONE, r_right);
}
return type;
}
bool flatten_arrows(ast_t** astp, bool errors)
{
ast_t* ast = *astp;
ast_t* node_type = ast_type(ast);
if(node_type != NULL)
{
if(!flatten_arrows(&node_type, errors))
return false;
}
if(ast_id(ast) == TK_ARROW)
{
AST_GET_CHILDREN(ast, left, right);
ast_t* flat;
if(!flatten_arrows(&right, errors))
return false;
if((ast_id(left) == TK_BOXTYPE) && (ast_id(right) != TK_ARROW))
flat = viewpoint_cap(TK_BOX, TK_NONE, right);
else
flat = viewpoint_type(left, right);
if(flat == NULL)
{
if(errors)
ast_error(ast, "can't flatten arrow type");
return false;
}
ast_replace(astp, flat);
return true;
}
ast_t* child = ast_child(ast);
while(child != NULL)
{
if(!flatten_arrows(&child, errors))
return false;
child = ast_sibling(child);
}
return true;
}
ast_t* viewpoint_lower(ast_t* type)
{
switch(ast_id(type))
{
case TK_TUPLETYPE:
case TK_UNIONTYPE:
case TK_ISECTTYPE:
{
// Adapt all elements.
ast_t* r_type = ast_from(type, ast_id(type));
ast_t* child = ast_child(type);
while(child != NULL)
{
ast_append(r_type, viewpoint_lower(child));
child = ast_sibling(child);
}
return r_type;
}
case TK_NOMINAL:
return viewpoint_lower_for_type(type, 3);
case TK_TYPEPARAMREF:
return viewpoint_lower_for_type(type, 1);
case TK_ARROW:
{
AST_GET_CHILDREN(type, left, right);
// If left is a boxtype, right's lower bounds is its actual type.
if(ast_id(left) == TK_BOXTYPE)
return viewpoint_cap(TK_BOX, TK_NONE, right);
// If left is a thistype or a typeparamref type, right's lower bounds is
// calculated on its own.
return viewpoint_lower(right);
}
default: {}
}
return NULL;
}