Парсинг аргументов

Minecraft’s Brigadier system includes a powerful argument parser that Sponge can take advantage of. It converts the string input to java base types (integer, booleans, string) or game objects (players, worlds, block types, …). Sponge’s system also supports optional arguments and flags. It also handles suggestions of arguments.

The parsed arguments are stored in the CommandContext object. If the parser returns a single object, obtain it with CommandContext#one(Key). Optional and weak arguments may return Optional.empty()

Many of the parsers may return more than one object; for example, multiple players with a matching username. In that case, you must use the CommandContext#all(Key) method to get the Collection of possible matches. Otherwise, the context object will throw an exception!

When creating a command, consider whether the argument could return multiple values, for example whether a player argument could support multiple players when using a selector. If you support multiple values, the users need to type only one command, and can use an easier command sytax, e.g /tell @a Who took the cookies?

To create a new Parameter (argument), use the Parameter class that will give you many Builder options. Each parameter will need its Builder#key(String) filled out before being built.

Apply the Parameter to the command builder with the Command.Builder#addParameter(Parameter) method. It is possible to pass more than one Parameter to the method, thus chaining multiple arguments. Example /msg <player> <msg>. This has the same effect as wrapping the Parameter objects in a Parameter#seq(Iterable<Parameter>) element.

Пример: Создание команды с несколькими аргументами

import org.spongepowered.api.command.parameter.CommandContext;
import org.spongepowered.api.command.parameter.Parameter;
import org.spongepowered.api.command.Command;
import org.spongepowered.api.command.CommandResult;
import org.spongepowered.api.entity.living.player.server.ServerPlayer;

public Command.Parameterized createMessageCommand(){
    Parameter.Value<ServerPlayer> playerParameter = Parameter.player().key("player").build();
    Parameter.Value<String> messageParameter = Parameter.remainingJoinedStrings().key("message").build();

    return Command
        .builder()
        .executor((CommandContext context) -> {
            ServerPlayer player = context.requireOne(playerParameter);
            String message = context.requireOne(messageParameter);

            player.sendMessage(Component.text(message));
            return CommandResult.success();
        })
        .addParameter(playerParameter, messageParameter)
        .build();
}

Примечание

The example above uses CommandContext#requireOne(Parameter.Value<T>), this is for arguments that must be provided. Use CommandContext#one(Parameter.Value<T>) for optional arguments

Overview of the Parameter Command Elements

Parameter

Описание

Количество и тип значения

string

Require the argument to be a string.

один String

remainingJoinedStrings

Соединяет все оставшиеся аргументы разделенные пробелами (может быть использовано для команд-сообщений).

один String

bool

Require the argument to be a boolean.

один Boolean

integer

Require the argument to be a integer.

один Integer

rangeInteger

Require the argument to be a integer between two values.

один Integer

doubleNumber

Require the argument to be a double.

один Double

rangeDouble

Require the argument to be a double between two values

один Double

player

Require the argument to be a player. May return multiple players!

multiple ServerPlayer instances

playerOrTarget

Как player, но возвращает отправителя команды, если соответствующий игрок не был найден.

mutiple ServerPlayer instances

user

Require the argument to be a user. May return multiple users!

несколько экземпляров User

world

Require the argument to be a world (only loaded worlds)

multiple ServerWorld instances

location

Require the argument to be a location

one ServerLocation

vector3d

Require the argument to be a vector

один Vector3d

rotation

Require the argument to be a vector, but returns the senders rotation if no value was specified

один Vector3d

registryElement

Require the argument to be the resoure key of one of the specified elements

multiple matching elements of the specified registry type

choices

Returns an argument that allows selecting from a limited set of values

one specified value

literal

Require the argument to match one of the specified literals

one specified literal

enumValue

Require the argument to be a enum

one Enum

seq

Builds a sequence of commands

унаследованное

Совет

See the Javadocs for Parameter for more information

Предупреждение

Don’t expect that a Parameter will only ever return a single value, a lot of them support multiple return values; some might support regular expressions or use command selector. This is intentional as it makes commands easier to use, e.g /tell @a BanditPlayer has cookies!.

Custom Parameter

It is possible to create custom command elements; for example, Vector2i. This is done though the Parameter#builder(Class) method, which returns a Parameter where all data the parameter neededs should be provided. Once done call the build method to build the parameter.

When building a new parameter, only the parser and key are required for build. The parser contains the logic for mapping the String input to the desired value.

Example: Creating a Custom Parameter

In this example we will make a Vector2i parameter. This requires reading two Integers and converting them to a Vector2i.

Parameter.Value<Vector2i> vectorParameter = Parameter
  .builder(Vector2i.class)
  .addParser((
    Parameter.Key<Vector2i> parameterKey,
    ArgumentReader.Mutable reader,
    CommandContext.Builder context) -> {
      int x = reader.parseInt();
      int y = reader.parseInt();
      return new Vector2i(x, y);
  })
  .key("vector")
  .build();

Совет

When building a new parameter, you can base your parameter on a exsiting parameters. Example: taking Parameter#string() and giving it client suggestions.