cli

Command-line parsing and an application scaffold. Namespace core::cli, directory src/core/cli/, target core::cli. It depends on base and log and builds for WebAssembly.

Imported from contour's crispy CLI and App at 6777ff05, where they were crispy::cli and crispy::App.

Header	What it has
<core/cli/CLI.hpp>	the command syntax (Command, Option, Value), parse() into a FlagStore, helpText() and usageText(), and about::registerProjects() for a license listing
<core/cli/App.hpp>	core::cli::App, a main() scaffold: it parses argv against the syntax an application declares, dispatches to the handler of the command given, and provides help, version and license; it applies LOG from its core::Environment and installs --log/--log-file output through log

The syntax

A command has options and subcommands. Options are spelled POSIX-style (--timeout=1.0, -t 1.0) or naturally (timeout 1.0); a boolean needs no value. parse() fills a FlagStore whose keys are the dotted path of each option, tool.fetch.timeout for the timeout option of the fetch subcommand of tool, prefilled with every default:

auto const syntax = core::cli::Command {
    .name = "tool",
    .options = { core::cli::Option { .name = "verbose", .v = core::cli::Value { false } } },
};
auto const flags = core::cli::parse(syntax, argc, argv);
if (!flags)
{
    std::println(stderr, "tool: {}", flags.error().message);
    return EXIT_FAILURE;
}
verbose = flags->get<bool>("tool.verbose");

A malformed command line is a value, never an exception: parse() returns std::expected<FlagStore, ParseError>, and a ParseError has a kind (ParseErrorKind: not enough arguments, an invalid value, an explicit empty value for a non-string option, an unexpected token, a missing required option), the index of the token at fault and a message for the user. A number is read whole: 12abc is refused rather than read as 12, and -1 is not an unsigned.