Skip to content

Add class template argument deduction (CTAD) for template user defined types (UDT) #369

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

Add class template argument deduction (CTAD) for template user defined types (UDT) #369

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
72 changes: 72 additions & 0 deletions source/cppfront.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5027,6 +5027,13 @@ class cppfront
{
printer.print_cpp2( " final", n.position() );
}

// CTAD
struct ctad_details {
std::string args;
std::string types;
};
auto ctads = std::vector<ctad_details>{};

// Type definition

Expand All @@ -5052,6 +5059,52 @@ class cppfront

if (decl->is_constructor()) {
found_constructor = true;

if (n.template_parameters) {
if (auto func = std::get_if<declaration_node::a_function>(&decl->type)) {
const auto& params = (*func)->parameters->parameters;
auto can_generate_ctad = std::equal(
std::cbegin(params)+1, std::cend(params),
std::cbegin(n.template_parameters->parameters), std::cend(n.template_parameters->parameters),
[](const auto& arg, const auto& type) -> bool {
if (const auto* arg_type = std::get_if<declaration_node::an_object>(&arg->declaration->type)) {
assert(type->name());
return (*arg_type)->get_token() && (*arg_type)->get_token()->as_string_view() == type->name()->as_string_view();
} else {
return false;
}
}
);
if (can_generate_ctad) {
ctads.emplace_back();
std::for_each(std::cbegin(params)+1, std::cend(params), [&](const auto& arg) {
if (const auto* type = std::get_if<declaration_node::an_object>(&arg->declaration->type)) {
auto& arg_t = *type;
assert(arg_t->get_token());
auto type_name = arg_t->get_token()->to_string(true);
auto arg_type = print_to_string(*arg_t);
switch (arg->pass) {
case passing_style::in : arg_type += " const &"; break;
case passing_style::out : arg_type = "cpp2::deferred_init<" + arg_type + ">*"; break;
case passing_style::inout : arg_type += "&"; break;
case passing_style::move :
case passing_style::forward: arg_type += "&&"; break;
case passing_style::copy : break;
default: assert(!"ICE: invalid argument passing style");
}

if (ctads.back().args.empty()) {
ctads.back().args = arg_type;
ctads.back().types = type_name;
} else {
ctads.back().args += ", " + arg_type;
ctads.back().types += ", " + type_name;
}
}
});
}
}
}
}
if (decl->is_constructor_with_that()) {
found_that_constructor = true;
Expand Down Expand Up @@ -5145,6 +5198,25 @@ class cppfront
}

printer.print_cpp2("};\n", compound_stmt->close_brace);

if (!ctads.empty()) {
printer.print_cpp2("\n", n.position());
}

for (const auto& ctad : ctads) {
printer.print_cpp2("template", n.position());
emit(*n.template_parameters, false, true);
printer.print_cpp2(" ", n.position());

printer.print_cpp2(n.name()->to_string(true), n.position());
printer.print_cpp2("(", n.position());

printer.print_cpp2(ctad.args, n.position());
printer.print_cpp2(") -> ", n.position());
printer.print_cpp2(n.name()->to_string(true) + "<", n.position());
printer.print_cpp2(ctad.types, n.position());
printer.print_cpp2(">;\n", n.position());
}
}
}

Expand Down