Predicate System

NbtPredicate

dev.anvilcraft.lib.v2.util.predicate.NbtPredicate – implements Predicate<Tag>, used for matching NBT data.

• Test Tag: test(Tag)
• Test ItemStackTemplate: based on the CustomData component
• Test Entity: extracts the entity's full NBT via getEntityTagToCompare(Entity) (includes the player's SelectedItem)

IItemStackPredicate and Implementations

IItemStackPredicate is a Predicate<ItemStack> interface that additionally provides:

• items() – optional item HolderSet
• components() – DataComponentMatchers
• testCount(int count) – whether the count matches
• testIgnoreCount(ItemStack) – validates item and components while ignoring count

ItemPredicate

ItemPredicate – a general-purpose item predicate:

• items – HolderSet<Item> (optional)
• count – MinMaxBounds.Ints
• components – DataComponentMatchers
• Builder supports: of(ItemLike...), of(TagKey<Item>), withCount(..), hasComponents(..)

ItemIngredientPredicate

ItemIngredientPredicate – an ingredient predicate suitable for recipes (count indicates an "at least" requirement):

• count means stack.count >= count
• Provides getItems() returning ItemStackTemplate[] (with caching)
• Builder additionally supports of(ItemStackTemplate) to automatically extract component predicates from templates

ChanceItemStack

dev.anvilcraft.lib.v2.util.predicate.ChanceItemStack – a weighted item generation result.

• stack – ItemStackTemplate, count – NumberProvider (supports constant, uniform distribution, binomial distribution)
• of(...) factory methods supporting various probability representations
• getResult(ServerLevel) – computes count from LootContext, returns ItemStackTemplate (count 1~99)

ChanceBlockState

dev.anvilcraft.lib.v2.util.predicate.ChanceBlockState – a weighted block result.

• state, nbt, chance (NumberProvider)
• of(Supplier<Block>, CompoundTag) and other factory methods
• getResult(ServerLevel) returns Map.Entry<BlockState, CompoundTag> based on probability, or null

BlockStatePredicate

dev.anvilcraft.lib.v2.util.predicate.BlockStatePredicate – a block state predicate, supporting AND/OR logic and NBT.

• Property matching: PropertyMatcher, includes ExactMatcher (exact value) and RangedMatcher (range)
• Logic: the internal properties is a List<List<PropertyMatcher>>, where the outer list represents OR and the inner lists represent AND
• NBT: an optional list of NbtPredicate can be attached (all must be satisfied)
• Test methods:
  • test(LevelAccessor, BlockState, @Nullable BlockEntity) – full test (requires Level access)
  • testWithoutEntity(BlockState) – ignores NBT testing
  • testEntityOffThread(BlockState, CompoundTag entityNbt) – offline / multi-threaded safe
  • testOffThread(BlockState, CompoundTag entityNbt) – combined offline test
• Render caching: getStatesCache() / constructStatesForRender() used to quickly obtain a list of possible states (not guaranteed to match at runtime, for preview purposes only)
• Builder provides a fluent API: .of(Block...), .of(TagKey<Block>), .with(Property, value), .or(), .nbt(CompoundTag)

Code example:

BlockStatePredicate pred = BlockStatePredicate.builder()
    .of(Blocks.OAK_LOG, Blocks.BIRCH_LOG)
    .with(BlockStateProperties.AXIS, Direction.Axis.Y)
    .or()
    .with(BlockStateProperties.AXIS, Direction.Axis.X)
    .nbt(new CompoundTag() {{ putBoolean("stripped", true); }})
    .build();

Serialization: All predicates provide both CODEC and STREAM_CODEC.