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/*
* This source code is released into the public domain.
*/
module;
#include <expected>
#include <functional>
#include <iostream>
#include <print>
#include <string>
// For EX_USAGE. While <sysexits.h> is deprecated, there's no other standard
// exit code for 'usage error'; some programs use 2 (common on Linux), but
// 2 is also used for many other exit codes.
#include <sysexits.h>
module nihil.cli;
import nihil.error;
import :registry;
namespace nihil {
command::command(std::string_view path, std::string_view usage,
command_function_t handler)
: command_node(path)
, m_usage(usage)
, m_handler(std::move(handler))
{
register_command(this);
}
auto command::usage(this command const &self) noexcept -> std::string_view
{
return self.m_usage;
}
auto command::invoke(int argc, char **argv) const
-> std::expected<int, error>
{
try {
return std::invoke(m_handler, argc, argv);
} catch (usage_error const &err) {
std::print(std::cerr, "{}\n", err.what());
std::print(std::cerr, "usage: {} {}", path(), usage());
return EX_USAGE;
}
}
} // namespace nihil
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