[Console] Add completion values to input definition

[GromNaN]

Q	A
Branch?	6.1
Bug fix?	no
New feature?	yes
Deprecations?	no
Tickets	n/a
License	MIT
Doc PR	symfony/symfony-docs#...

During implementation of bash completion to core commands, I found the code quite verbose. The completion for all options and arguments are mixed into the same method.

Example of current code

symfony/src/Symfony/Component/Console/Command/HelpCommand.php

Lines 85 to 98 in 098ff62

	public function complete(CompletionInput $input, CompletionSuggestions $suggestions): void
	{
	if ($input->mustSuggestArgumentValuesFor('command_name')) {
	$descriptor = new ApplicationDescription($this->getApplication());
	$suggestions->suggestValues(array_keys($descriptor->getCommands()));
	return;
	}
	if ($input->mustSuggestOptionValuesFor('format')) {
	$helper = new DescriptorHelper();
	$suggestions->suggestValues($helper->getFormats());
	}
	}

This PR adds the possibility to attach values to each option and argument in their definition. It provides a default implementation of Command::complete that uses this values.

In the constructor of the InputOption and InputArgument classes:

symfony/src/Symfony/Component/Console/Command/HelpCommand.php

Lines 40 to 45 in 091027a

	new InputArgument('command_name', InputArgument::OPTIONAL, 'The command name', 'help', function () {
	return array_keys((new ApplicationDescription($this->getApplication()))->getCommands());
	}),
	new InputOption('format', null, InputOption::VALUE_REQUIRED, 'The output format (txt, xml, json, or md)', 'txt', function () {
	return (new DescriptorHelper())->getFormats();
	}),

Or using Command::addOption and Command::addArgument:

symfony/src/Symfony/Component/Console/Command/DumpCompletionCommand.php

Line 78 in 091027a

->addArgument('shell', InputArgument::OPTIONAL, 'The shell type (e.g. "bash"), the value of the "$SHELL" env var will be used if this is not given', null, fn () => $this->getSupportedShells())

Additional benefits:

• Command defined without a class can add completion.
• Descriptor can show if an option/argument has completion (and values could be shown).
• Easier to share suggestions when the same options are defined on several commands (for Add completion to commands options and arguments composer/composer#10320)

Todo:

• Add tests
• Add info to descriptor

[wouterj]

I haven't looked at the code yet, but I really like the idea. See also these 2 comments on the original PR: #42251 Being able to predict whether an option has a value or not and maybe even dumping the static values to the completion file (e.g. for apps like Composer) are 2 other very interesting advantages of this approach.

From https://github.com/posener/complete , mentioned in the comments I referenced above, I especially like the Predict enum:

 			"name":      predict.Set{"foo", "bar", "foo bar"},
 			"something": predict.Something,
 			"nothing":   predict.Nothing,

Set: values are static, can be dumped (or described)
Something: We'll have to invoke the _complete command for this
Nothing: Skip completion, this option has no value (or value is not autocompletable).

We can even extend this with e.g. Files, to enable the great file completion system of shell completion.

[GromNaN]

After you comment @wouterj, I think we can use a union type that covers each cases.

• true: calling complete.
• false: disable completion
• \Closure: call it
• iterable: get fixed values from the iterable
• null: not defined, will call complete by default. Setting null should be deprecated and become false by default in 7.0.

We must stay open to file completion once we'd have managed to get it work #43607.

[nicolas-grekas]

Much better :)

[GromNaN]

Thank you for all your time for this review. We have something very clear now.

[GromNaN]

@chalasr @wouterj ready for a new review. Description updated.

[chalasr]

Great. Just one minor question

[nicolas-grekas]

Some last minute nitpicking;

[nicolas-grekas]

What about this todo?

Add info to descriptor

[GromNaN]

What about this todo?

Add info to descriptor

Could be part of an other PR.