fe::cli Namespace Reference

A small command-line parser for a single command - no subcommands. More...

Classes
struct	Group
	Starts a new section in the help output; see fe::cli::group. More...
class	Opt
	One option or positional argument; build one with fe::cli::opt, fe::cli::arg, or fe::cli::help. More...
class	Cli
	Holds the Opts, parses argc/argv, and renders the help. More...

Functions
template<class T>
Opt	opt (T &target)
	A flag: sets target to true - or invokes it with true - each time it occurs.
template<class T>
Opt	opt (T &target, std::string hint)
	An option that takes a value; hint names it in the help as <hint>.
template<class T>
Opt	arg (T &target, std::string hint)
	A positional argument; hint names it in the help as <hint>.
Group	group (std::string name)
	Opens a section named name that all following Cli options are listed under.
Opt	help (bool &target)
	The -h/--help flag; chain ["-?"] to give it further names.

Detailed Description

A small command-line parser for a single command - no subcommands.

Declare the switches by piping fe::cli::opt / fe::cli::arg into an fe::cli::Cli and bind each one to a variable:

bool show_help = false, verbose = false;
std::string out, in;
std::vector<std::string> plugins;
 
auto cli = fe::cli::Cli("mim", "The MimIR compiler.")
         | fe::cli::help(show_help)
         | fe::cli::opt(verbose           )["-V"]["--verbose"]("Be verbose.")
         | fe::cli::opt(plugins, "plugin" )["-p"]["--plugin" ]("Loads a plugin; repeatable.")
         | fe::cli::group("Output")
         | fe::cli::opt(out,     "file"   )["-o"]["--output" ]("Where to write the result.")
         | fe::cli::arg(in,      "file"   )                   ("Input file.");
 
if (auto err = cli.parse(argc, argv)) throw std::invalid_argument(*err);
if (show_help) std::cout << cli;

A target may be a bool (for a flag), a std::string, an integral type, a std::vector of those, or a callable - invoked with true for a flag and with the std::string value otherwise. Such a callable may return a std::string to reject that value; a non-empty one becomes the error of Cli::parse. An fe::cli::opt without a hint is a flag; one with a hint takes a value.

The parser understands --name value, --name=value, -n value, -nvalue, clustered short flags (-abc), and -- to end option processing.

Cli::help lays the switches out for a terminal - wrapped to its width and colored via fe::term - whereas Cli::markdown renders the same information as Markdown tables; fe::cli::group splits both into sections.

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Class Documentation

fe::cli::Group

struct fe::cli::Group

Starts a new section in the help output; see fe::cli::group.

Definition at line 55 of file cli.h.

Class Members
string	name

Function Documentation

arg()

template<class T>

Opt fe::cli::arg	(	T &	target,
		std::string	hint )

A positional argument; hint names it in the help as <hint>.

Bind a std::vector to soak up all remaining ones.

Definition at line 186 of file cli.h.

group()

Group fe::cli::group ( std::string name )

inline

Opens a section named name that all following Cli options are listed under.

Definition at line 60 of file cli.h.

References group().

Referenced by group().

help()

Opt fe::cli::help ( bool & target )

inline

The -h/--help flag; chain ["-?"] to give it further names.

Definition at line 193 of file cli.h.

References help(), and opt().

Referenced by help().

opt() [1/2]

template<class T>

Opt fe::cli::opt

(

T &

target

)

A flag: sets target to true - or invokes it with true - each time it occurs.

Definition at line 159 of file cli.h.

Referenced by help().

opt() [2/2]

template<class T>

Opt fe::cli::opt	(	T &	target,
		std::string	hint )

An option that takes a value; hint names it in the help as <hint>.

Definition at line 173 of file cli.h.