This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Shell 3.3.1!

Completion

Spring Shell can provide completion proposals for both interactive shell and a command-line. There are differences however as when shell is in interactive mode we have an active instance of a shell meaning it’s easier to provide more programmatic ways to provide completion hints. When shell is purely run as a command-line tool a completion can only be accomplished with integration into OS level shell’s like bash.

Interactive

Hints for completions are calculated with function or interface style methods which takes CompletionContext and returns a list of CompletionProposal instances. CompletionContext gives you various information about a current context like command registration and option.

Generic resolvers can be registered as a beans if those are useful for all commands and scenarious. For example existing completion implementation RegistrationOptionsCompletionResolver handles completions for a option names.

static class MyValuesCompletionResolver implements CompletionResolver {

	@Override
	public List<CompletionProposal> apply(CompletionContext t) {
		return Arrays.asList("val1", "val2").stream()
			.map(CompletionProposal::new)
			.collect(Collectors.toList());
	}
}

Option values with builder based command registration can be defined per option.

void dump1() {
	CommandRegistration.builder()
		.withOption()
			.longNames("arg1")
			.completion(ctx -> {
				return Arrays.asList("val1", "val2").stream()
					.map(CompletionProposal::new)
					.collect(Collectors.toList());
			})
			.and()
		.build();
}

Option values with annotation based command registration are handled via ValueProvider interface which can be defined with @ShellOption annotation.

static class MyValuesProvider implements ValueProvider {

	@Override
	public List<CompletionProposal> complete(CompletionContext completionContext) {
		return Arrays.asList("val1", "val2").stream()
			.map(CompletionProposal::new)
			.collect(Collectors.toList());
	}
}

Actual ValueProvider with annotation based command needs to be registered as a Bean.

@ShellMethod(value = "complete", key = "complete")
public String complete(
	@ShellOption(valueProvider = MyValuesProvider.class) String arg1)
{
	return "You said " + arg1;
}

Command-Line

Command-line completion currently only support bash and is documented in a built-in completion command Completion.