nihil.cli/registry.ccm


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// This source code is released into the public domain.
export module nihil.cli:registry;

import nihil.std;

namespace nihil {

export struct command;

///////////////////////////////////////////////////////////////////////
// Command registry storage.  This is where command::command() registers
// itself when the global command objects are constructed at startup.
//
// Because we sometimes create stub commands dynamically, the registry
// storage is a list of shared_ptr<command>.  The "real" commands (which
// refer to global objects) will be created with a null deleter so they
// are never deleted.  This allows real and stub commands to mix in the
// same command_tree.

//  Get the current registry.
auto get_registry() -> std::vector<std::shared_ptr<command>> &
{
	static auto commands = std::vector<std::shared_ptr<command>>();
	return commands;
}

// Register a new command.
auto register_command(command *cmd) noexcept -> void
{
	auto constexpr null_deleter = [] (command const *) -> void {};
	get_registry().emplace_back(cmd, null_deleter);
}

// Unregister a command.  This is not very efficient, but it shouldn't usually be called
// except during testing.
auto unregister_command(command *cmd) noexcept -> void
{
	auto &registry = get_registry();

	auto it = std::ranges::find_if(registry, [=] (auto c) -> bool {
		return c.get() == cmd;
	});

	if (it != std::ranges::end(registry))
		registry.erase(it);
}

} // namespace nihil