CommandParam.java

/*
 * Copyright 2013 MovingBlocks
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.terasology.logic.console.commandSystem.annotations;

import com.google.common.collect.Sets;
import org.terasology.entitySystem.entity.EntityRef;
import org.terasology.logic.console.commandSystem.CommandParameterSuggester;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.Set;

/**
 * Used to specify information and behavior of a command parameter
 *
 */
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface CommandParam {

    /**
     * @return The parameter name
     */
    String value() default "";

    /**
     * @return Whether the argument value is required to be present on command execution or not
     */
    boolean required() default true;

    /**
     * @return The class used for suggesting values for this parameter
     */
    Class<? extends CommandParameterSuggester> suggester() default EmptyCommandParameterSuggester.class;

    /**
     * A class representing no suggester - needed, because Annotations fields don't accept nulls
     */
    final class EmptyCommandParameterSuggester implements CommandParameterSuggester {
        @Override
        public Set<Object> suggest(EntityRef sender, Object[] resolvedParameters) {
            return Sets.newHashSet();
        }
    }
}