This code is a fragment of a custom trigger implementation...

September 12, 2025 at 07:24 PM

    public void trigger(ServerPlayer p_74432_, ItemStack p_74433_) {
        this.trigger(p_74432_, p_74436_ -> p_74436_.matches(p_74433_));
    }

    public static record TriggerInstance(Optional<ContextAwarePredicate> player, Optional<ItemPredicate> item)
        implements SimpleCriterionTrigger.SimpleInstance {
        public static final Codec<UsedTotemTrigger.TriggerInstance> CODEC = RecordCodecBuilder.create(
            p_325258_ -> p_325258_.group(
                        EntityPredicate.ADVANCEMENT_CODEC.optionalFieldOf("player").forGetter(UsedTotemTrigger.TriggerInstance::player),
                        ItemPredicate.CODEC.optionalFieldOf("item").forGetter(UsedTotemTrigger.TriggerInstance::item)
                    )
                    .apply(p_325258_, UsedTotemTrigger.TriggerInstance::new)
        );

        public static Criterion<UsedTotemTrigger.TriggerInstance> usedTotem(ItemPredicate p_298404_) {
            return CriteriaTriggers.USED_TOTEM.createCriterion(new UsedTotemTrigger.TriggerInstance(Optional.empty(), Optional.of(p_298404_)));
        }

        public static Criterion<UsedTotemTrigger.TriggerInstance> usedTotem(HolderGetter<Item> p_367990_, ItemLike p_300178_) {
            return CriteriaTriggers.USED_TOTEM
                .createCriterion(
                    new UsedTotemTrigger.TriggerInstance(
                        Optional.empty(), Optional.of(ItemPredicate.Builder.item().of(p_367990_, p_300178_).build())
                    )
                );
        }

        public boolean matches(ItemStack p_74451_) {
            return this.item.isEmpty() || this.item.get().test(p_74451_);
        }

        @Override
        public Optional<ContextAwarePredicate> player() {
            return this.player;
        }
    }
}

This code is a fragment of a custom trigger implementation within a game, likely for the Minecraft game (due to familiar class names). The purpose of this code is to define and handle conditions related to a player performing an action with a specific item, potentially tied to triggering advancements or achievements. Here's a high-level explanation of what it does:

1. `trigger` Method:

This is a public method in some unknown class. It takes in two parameters:

ServerPlayer p_74432_: Represents the player who triggers this action.
ItemStack p_74433_: Represents the item involved in triggering the action.

This method calls another trigger (presumably the superclass's or another overloaded method) and passes in the player object (p_74432_) and a lambda function. The lambda function ensures that the TriggerInstance's matches method is called with the provided ItemStack (p_74433_).

2. The `TriggerInstance` Class:

The TriggerInstance class encapsulates the conditions or criteria that must be met to trigger an advancement or custom event.

Structure of `TriggerInstance`:

It is defined as a record, which automatically provides a constructor, accessors, and overrides for equals, hashCode, and toString.
Contains two fields, both wrapped in Optional:
- player: Represents optional predicates related to the player context.
- item: Represents optional predicates related to the item context.

Static Members/Methods:

CODEC: Focused on serialization/deserialization using RecordCodecBuilder. It defines how the TriggerInstance can be serialized into a data format and read back. The fields (player and item) connect to external predicate codecs (EntityPredicate.ADVANCEMENT_CODEC and ItemPredicate.CODEC).
usedTotem(...):
- These are factory methods for creating a Criterion for when a player uses a totem:
  - The first version accepts an ItemPredicate.
  - The second refers to an Item or ItemLike through a HolderGetter (a registry reference).
- They tie the input item to the TriggerInstance.

Instance Methods:

matches(ItemStack p_74451_):
- Checks whether the item condition is met by testing the given ItemStack (p_74451_). The check passes if:
  - No item predicate exists (item.isEmpty()), OR
  - The item predicate's test method returns true.
player(): Getter for the player field.

3. Overall Functionality:

The code implements a trigger system for an event tied to the player's use of a specific item (e.g., a "totem of undying" behavior). Specifically:

A trigger is invoked with the player and the ItemStack being used.
The TriggerInstance class defines the criteria for matching items and potentially player-specific context.
The system allows for the creation of reusable "criteria" (usedTotem) to define advancement-like triggers.

In gameplay, this could mean:

If a player uses an item that fulfills the specified ItemPredicate, the trigger activates and produces some result (e.g., granting an advancement).

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