= Lyra
// tag::intro[]
[.tagline] A simple to use, composing, header only, command line arguments parser for C++ 11 and beyond.
[horizontal.shields] Obtain:: image:https://img.shields.io/github/downloads/bfgroup/Lyra/total.svg?label=GitHub[GitHub All Releases, link="https://github.com/bfgroup/Lyra/releases"] image:https://img.shields.io/badge/package-Conan-blue[Conan Center, link="https://conan.io/center/lyra"] License:: image:https://img.shields.io/badge/license-BSL%201.0-blue.svg["Boost Software License 1.0", link="LICENSE.txt"] Standards:: image:https://img.shields.io/badge/standard-PFL-orange.svg["Pitchfork Layout", link="https://github.com/vector-of-bool/pitchfork"] image:https://img.shields.io/badge/standard-C%2B%2B%2011-blue.svg?logo=C%2B%2B["C++ 11", link="https://isocpp.org/"] image:https://img.shields.io/badge/standard-C%2B%2B%2014-blue.svg?logo=C%2B%2B["C++ 14", link="https://isocpp.org/"] image:https://img.shields.io/badge/standard-C%2B%2B%2017-blue.svg?logo=C%2B%2B["C++ 17", link="https://isocpp.org/"] image:https://img.shields.io/badge/standard-C%2B%2B%2020-blue.svg?logo=C%2B%2B["C++ 20", link="https://isocpp.org/"] Stats:: image:https://img.shields.io/github/languages/code-size/bfgroup/Lyra.svg[GitHub code size in bytes, link="https://github.com/bfgroup/Lyra"] image:https://img.shields.io/github/issues/bfgroup/Lyra.svg[GitHub issues, link="https://github.com/bfgroup/Lyra/issues"] image:https://img.shields.io/github/stars/bfgroup/Lyra.svg?label=%E2%98%85[GitHub stars, link="https://github.com/bfgroup/Lyra/stargazers"] Tests:: image:https://img.shields.io/azure-devops/build/bfgroup/6b664745-b518-4d13-8e46-807d74231e73/2/release?label=release&logo=azuredevops["Azure DevOps", link="https://dev.azure.com/bfgroup/Lyra"] image:https://img.shields.io/azure-devops/build/bfgroup/6b664745-b518-4d13-8e46-807d74231e73/2/develop?label=develop&logo=azuredevops["Azure DevOps", link="https://dev.azure.com/bfgroup/Lyra"] image:https://img.shields.io/appveyor/build/bfgroup/lyra/release?label=release&logo=appveyor["AppVeyor", link="https://ci.appveyor.com/project/bfgroup/lyra"] image:https://img.shields.io/appveyor/build/bfgroup/lyra/develop?label=develop&logo=appveyor["AppVeyor", link="https://ci.appveyor.com/project/bfgroup/lyra"]
// end::intro[]
== License
// tag::license[]
Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
// end::license[]
== Features
// tag::features[]
std
library).opt
or arg
is an independent parser. Combine these to
produce a composite parser -- this can be done in stages across multiple
function calls -- or even projects.ostream <<
), with error handling, behind the scenes.arg
-s from one to many.// end::features[]
== Using
// tag::using[]
To use, just #include <lyra/lyra.hpp>
A parser for a single option can be created like this:
You can use this parser directly like this:
auto result = cli.parse( { argc, argv } ); if ( !result ) { std::cerr << "Error in command line: " << result.message() << std::endl; exit(1); }
Note that exceptions are not used for error handling.
You can combine parsers by composing with |
, like this:
opt
specifies options that start with a short dash (-
) or long dash (--
).
Options can be argument taking (such as -w 42
), in which case
the opt
takes a second argument -- a hint, or they are pure flags (such as
-d
), in which case the opt
has only one argument -- which must be a boolean.
The option names are provided in one or more sets of square brackets, and a
description string can be provided in parentheses. The first argument to an
opt
is any variable, local, global member, of any type that can be converted
from a string using std::ostream
.
arg
specifies arguments that are not tied to options, and so have no square
bracket names. They otherwise work just like opt
.
A usage string can be obtained by inserting the parser into a stream. The usage string is built from the information supplied.
As a convenience, the standard help options (-h
, --help
and -?
) can be
specified using the help
parser, which just takes a boolean to bind to.
// end::using[]
== More
There is a single-header version that is generated from the source files.
You can find it at data/single_include/lyra/lyra.hpp
. Some caveats for it:
For more information and documentation see the link:https://bfgroup.github.io/Lyra/[web site].