Brigadier API : supports to redirect to the RootCommandNode

[marcbal]

Is your feature request related to a problem?

I have a Brigadier command that has similar functionality to /execute, i.e. to conditionally run commands based on plugin data. Since I moved from using lucko's commodore to using the Lifecycle API to register Brigadier commands, my /execute clone is not able to register anymore when it contains a redirection to the root command node:

[LifecycleEventRunner] Could not run 'commands' lifecycle event handler from PandacubePaper vdev
java.lang.IllegalArgumentException: Unknown command node passed. Don't know how to unwrap this.
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.convertFromPureBrigNode(ApiMirrorRootNode.java:144)~
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.unwrapNode(ApiMirrorRootNode.java:93)~
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.simpleUnwrap(ApiMirrorRootNode.java:249)~
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.convertFromPureBrigNode(ApiMirrorRootNode.java:106)~
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.unwrapNode(ApiMirrorRootNode.java:93)~
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.convertFromPureBrigNode(ApiMirrorRootNode.java:155)~
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.unwrapNode(ApiMirrorRootNode.java:93)~
at io.papermc.paper.command.brigadier.ApiMirrorRootNode.addChild(ApiMirrorRootNode.java:205)~
at io.papermc.paper.command.brigadier.PaperCommands.registerIntoDispatcher(PaperCommands.java:156)~
at io.papermc.paper.command.brigadier.PaperCommands.registerWithFlags(PaperCommands.java:102)~
at io.papermc.paper.command.brigadier.PaperCommands.register(PaperCommands.java:90)~
at io.papermc.paper.command.brigadier.PaperCommands.register(PaperCommands.java:85)~
at PandacubePaper-1668.jar/fr.pandacube.lib.paper.commands.PaperBrigadierCommand.lambda$register$6(PaperBrigadierCommand.java:169)~
at io.papermc.paper.plugin.lifecycle.event.LifecycleEventRunner.lambda$callEvent$2(LifecycleEventRunner.java:68)~
at io.papermc.paper.plugin.lifecycle.event.types.PrioritizableLifecycleEventType.forEachHandler(PrioritizableLifecycleEventType.java:53)~
at io.papermc.paper.plugin.lifecycle.event.LifecycleEventRunner.callEvent(LifecycleEventRunner.java:63)~
at io.papermc.paper.plugin.lifecycle.event.LifecycleEventRunner.callReloadableRegistrarEvent(LifecycleEventRunner.java:107)~
at NMS.MinecraftServer.loadWorld0(MinecraftServer.java:678)~
at NMS.MinecraftServer.loadLevel(MinecraftServer.java:437)~
at NMS.dedicated.DedicatedServer.initServer(DedicatedServer.java:323)~
at NMS.MinecraftServer.runServer(MinecraftServer.java:1136)~
at NMS.MinecraftServer.lambda$spin$0(MinecraftServer.java:323)~
at java.base/java.lang.Thread.run(Thread.java:1583)~

It seems like the node unwrapper does not support encountering the RootCommandNode instance in the tree, since it’s not a subclass for LiteralCommandNode or ArgumentCommandNode:

Paper/patches/server/0955-Brigadier-based-command-API.patch

Lines 355 to 405 in 817550c

	+ private @NotNull CommandNode<CommandSourceStack> convertFromPureBrigNode(final CommandNode<CommandSourceStack> pureNode) {
	+ /*
	+ Logic for converting a node.
	+ */
	+ final CommandNode<CommandSourceStack> converted;
	+ if (pureNode instanceof final LiteralCommandNode<CommandSourceStack> node) {
	+ /*
	+ Remap the literal node, we only have to account
	+ for the redirect in this case.
	+ */
	+ converted = this.simpleUnwrap(node);
	+ } else if (pureNode instanceof final ArgumentCommandNode<CommandSourceStack, ?> pureArgumentNode) {
	+ final ArgumentType<?> pureArgumentType = pureArgumentNode.getType();
	+ /*
	+ Check to see if this argument type is a wrapped type, if so we know that
	+ we can unwrap the node to get an NMS type.
	+ */
	+ if (pureArgumentType instanceof final CustomArgumentType<?, ?> customArgumentType) {
	+ final SuggestionProvider<?> suggestionProvider;
	+ try {
	+ final Method listSuggestions = customArgumentType.getClass().getMethod("listSuggestions", CommandContext.class, SuggestionsBuilder.class);
	+ if (listSuggestions.getDeclaringClass() != CustomArgumentType.class) {
	+ suggestionProvider = customArgumentType::listSuggestions;
	+ } else {
	+ suggestionProvider = null;
	+ }
	+ } catch (final NoSuchMethodException ex) {
	+ throw new IllegalStateException("Could not determine if the custom argument type " + customArgumentType + " overrides listSuggestions", ex);
	+ }
	+
	+ converted = this.unwrapArgumentWrapper(pureArgumentNode, customArgumentType, customArgumentType.getNativeType(), suggestionProvider);
	+ } else if (pureArgumentType instanceof final VanillaArgumentProviderImpl.NativeWrapperArgumentType<?,?> nativeWrapperArgumentType) {
	+ converted = this.unwrapArgumentWrapper(pureArgumentNode, nativeWrapperArgumentType, nativeWrapperArgumentType, null); // "null" for suggestion provider so it uses the argument type's suggestion provider
	+
	+ /*
	+ If it's not a wrapped type, it either has to be a primitive or an already
	+ defined NMS type.
	+ This method allows us to check if this is recognized by vanilla.
	+ */
	+ } else if (ArgumentTypeInfos.isClassRecognized(pureArgumentType.getClass())) {
	+ // Allow any type of argument, as long as it's recognized by the client (but in most cases, this should be API only types)
	+ // Previously we only allowed whitelisted types.
	+ converted = this.simpleUnwrap(pureArgumentNode);
	+ } else {
	+ // Unknown argument type was passed
	+ throw new IllegalArgumentException("Custom unknown argument type was passed, should be wrapped inside an CustomArgumentType.");
	+ }
	+ } else {
	+ throw new IllegalArgumentException("Unknown command node passed. Don't know how to unwrap this.");
	+ }
	+

Describe the solution you'd like.

Being able to do this :

getLifecycleManager().registerEventHandler(LifecycleEvents.COMMANDS, event -> {
    event.registrar().register(literal("myexecute")
            .then(literal("run")
                    .redirect(event.registrar().getDispatcher().getRoot())
            )
            .build()
    );
});

Then run the following command in chat or command block: /myexecute run tp @p 100 70 100

Describe alternatives you've considered.

• Take the conditionally run command into a StringArgument and run it through Bukkit.dispatchCommand() if conditions are met
• Use reflection to add the feature myself:

getLifecycleManager().registerEventHandler(LifecycleEvents.COMMANDS, event -> {
    CommandDispatcher<CommandSourceStack> dispatcher = event.registrar().getDispatcher();
    RootCommandNode<CommandSourceStack> wrappedRoot = dispatcher.getRoot();
    ReflectClass<?> apiMirrorRootNodeClass = Reflect.ofClassOfInstance(wrappedRoot);
    try {
        RootCommandNode<?> unwrappedRoot = ((CommandDispatcher<?>) apiMirrorRootNodeClass.method("getDispatcher").invoke(wrappedRoot)).getRoot();

        Reflect.ofClass(CommandNode.class).field("unwrappedCached").setValue(wrappedRoot, unwrappedRoot);
        Reflect.ofClass(CommandNode.class).field("wrappedCached").setValue(unwrappedRoot, wrappedRoot);

    } catch (InvocationTargetException|IllegalAccessException|NoSuchMethodException|NoSuchFieldException e) {
        Log.severe("Unable to trick the Paper/Brigadier unwrapper to properly handle commands redirecting to root command node.", e);
    }
});

Other

No response