Adding PredicateChoice to Paper API (updated version)

paper-api/src/main/java/org/bukkit/inventory/RecipeChoice.java

@@ -12,6 +12,7 @@
 import org.bukkit.Tag;
 import org.bukkit.material.MaterialData;
 import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.NullMarked;
 
 /**
  * Represents a potential item match within a recipe. All choices within a
@@ -290,4 +291,50 @@ public String toString() {
         }
         // Paper end - check valid ingredients
     }
+
+    // Paper start - add PredicateChoice
+    /**
+     * Represents a choice that will be valid only if an item matches the
+     * given predicate
+     */
+    @NullMarked
+    public static class PredicateChoice implements RecipeChoice {
+
+        private final Predicate<ItemStack> predicate;
+        private final ItemStack exampleStack;
+
+        /**
+         * @param predicate The predicate to test the crafting inputs to. Mutating
+         *                  the ItemStack in the predicate is not supported.
+         * @param exampleStack An example ItemStack to be shown in the recipe book.
+         */
+        public PredicateChoice(Predicate<ItemStack> predicate, ItemStack exampleStack) {
+            Preconditions.checkArgument(predicate != null, "The item predicate cannot be null");
+            Preconditions.checkArgument(exampleStack != null, "The example stack cannot be null");
+            Preconditions.checkArgument(!exampleStack.getType().isAir(), "Cannot have empty/air example stack");
+
+            this.predicate = predicate;
+            this.exampleStack = exampleStack;
+        }
+
+        public Predicate<ItemStack> getPredicate() {
+            return this.predicate;
+        }
+
+        @Override
+        public ItemStack getItemStack() {
+            return this.exampleStack.clone();
+        }
+
+        @Override
+        public PredicateChoice clone() {
+            return new PredicateChoice(this.predicate::test, this.exampleStack.clone());
+        }
+
+        @Override
+        public boolean test(final ItemStack itemStack) {
+            return this.predicate.test(itemStack);
+        }
+    }
+    // Paper end - add PredicateChoice
 }

paper-server/patches/features/0020-Improve-exact-choice-recipe-ingredients.patch

@@ -341,7 +341,7 @@ index 6bbe2e51ef71d193e0a5d3cace2b0ad1760ce759..83ccde54c625d40dc595e000c533f60a
      }
 
 diff --git a/net/minecraft/world/item/crafting/Ingredient.java b/net/minecraft/world/item/crafting/Ingredient.java
-index e43641650d66a62b5b7b58c43833ce504970ab1e..879c8fe1f20decc793cfa39e686b61d521bd76ba 100644
+index 78acbf3fe33bf68ba1319a44ed54c6f5c858a8e6..88fdaae0684eeef5aea6cdacccf48558d4f48bc8 100644
 --- a/net/minecraft/world/item/crafting/Ingredient.java
 +++ b/net/minecraft/world/item/crafting/Ingredient.java
 @@ -21,7 +21,7 @@ import net.minecraft.world.item.Items;
@@ -353,8 +353,8 @@ index e43641650d66a62b5b7b58c43833ce504970ab1e..879c8fe1f20decc793cfa39e686b61d5
      public static final StreamCodec<RegistryFriendlyByteBuf, Ingredient> CONTENTS_STREAM_CODEC = ByteBufCodecs.holderSet(Registries.ITEM)
          .map(Ingredient::new, ingredient -> ingredient.values);
      public static final StreamCodec<RegistryFriendlyByteBuf, Optional<Ingredient>> OPTIONAL_CONTENTS_STREAM_CODEC = ByteBufCodecs.holderSet(Registries.ITEM)
-@@ -35,20 +35,24 @@ public final class Ingredient implements StackedContents.IngredientInfo<Holder<I
-     private final HolderSet<Item> values;
+@@ -36,20 +36,24 @@ public final class Ingredient implements StackedContents.IngredientInfo<Holder<I
+     public Predicate<ItemStack> stackPredicate; // Paper - add PredicateChoice
      // CraftBukkit start
      @javax.annotation.Nullable
 -    private java.util.List<ItemStack> itemStacks;
@@ -381,8 +381,8 @@ index e43641650d66a62b5b7b58c43833ce504970ab1e..879c8fe1f20decc793cfa39e686b61d5
          return recipe;
      }
      // CraftBukkit end
-@@ -81,21 +85,22 @@ public final class Ingredient implements StackedContents.IngredientInfo<Holder<I
-     public boolean test(ItemStack stack) {
+@@ -87,21 +91,22 @@ public final class Ingredient implements StackedContents.IngredientInfo<Holder<I
+         // Paper end
          // CraftBukkit start
          if (this.isExact()) {
 -            for (ItemStack itemstack1 : this.itemStacks()) {
@@ -413,7 +413,7 @@ index e43641650d66a62b5b7b58c43833ce504970ab1e..879c8fe1f20decc793cfa39e686b61d5
      }
 
      @Override
-@@ -120,6 +125,11 @@ public final class Ingredient implements StackedContents.IngredientInfo<Holder<I
+@@ -126,6 +131,11 @@ public final class Ingredient implements StackedContents.IngredientInfo<Holder<I
      }
 
      public SlotDisplay display() {

paper-server/patches/sources/net/minecraft/world/item/crafting/Ingredient.java.patch

@@ -1,9 +1,10 @@
 --- a/net/minecraft/world/item/crafting/Ingredient.java
 +++ b/net/minecraft/world/item/crafting/Ingredient.java
-@@ -33,6 +_,25 @@
+@@ -33,6 +_,26 @@
      public static final Codec<Ingredient> CODEC = ExtraCodecs.nonEmptyHolderSet(NON_AIR_HOLDER_SET_CODEC)
          .xmap(Ingredient::new, ingredient -> ingredient.values);
      private final HolderSet<Item> values;
++    public Predicate<ItemStack> stackPredicate; // Paper - add PredicateChoice
 +    // CraftBukkit start
 +    @javax.annotation.Nullable
 +    private java.util.List<ItemStack> itemStacks;
@@ -26,10 +27,15 @@
 
      private Ingredient(HolderSet<Item> values) {
          values.unwrap().ifRight(list -> {
-@@ -60,6 +_,17 @@
+@@ -60,6 +_,22 @@
 
      @Override
      public boolean test(ItemStack stack) {
++        // Paper start - add PredicateChoice
++        if (this.stackPredicate != null) {
++            return this.stackPredicate.test(stack);
++        }
++        // Paper end
 +        // CraftBukkit start
 +        if (this.isExact()) {
 +            for (ItemStack itemstack1 : this.itemStacks()) {

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftRecipe.java

@@ -2,10 +2,13 @@
 
 import com.google.common.base.Preconditions;
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.resources.ResourceKey;
+import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.item.crafting.Ingredient;
 import org.bukkit.NamespacedKey;
 import org.bukkit.craftbukkit.util.CraftNamespacedKey;
@@ -32,7 +35,14 @@ static Ingredient toIngredient(RecipeChoice bukkit, boolean requireNotEmpty) {
 
         if (bukkit == null) {
             stack = Ingredient.of();
-        } else if (bukkit instanceof RecipeChoice.MaterialChoice) {
+        }
+        // Paper start - add PredicateChoice
+        else if (bukkit instanceof RecipeChoice.PredicateChoice predicateChoice) {
+            stack = Ingredient.ofStacks(Collections.singletonList(CraftItemStack.asNMSCopy(predicateChoice.getItemStack())));
+            stack.stackPredicate = nmsStack -> predicateChoice.test(CraftItemStack.asBukkitCopy(nmsStack));
+        }
+        // Paper end
+        else if (bukkit instanceof RecipeChoice.MaterialChoice) {
             stack = Ingredient.of(((RecipeChoice.MaterialChoice) bukkit).getChoices().stream().map((mat) -> CraftItemType.bukkitToMinecraft(mat)));
         } else if (bukkit instanceof RecipeChoice.ExactChoice) {
             stack = Ingredient.ofStacks(((RecipeChoice.ExactChoice) bukkit).getChoices().stream().map((mat) -> CraftItemStack.asNMSCopy(mat)).toList());