Flesh out detail provider/registry docs

.pre-commit-config.yaml

@@ -6,7 +6,7 @@
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
 - repo: https://github.com/pre-commit/pre-commit-hooks
-  rev: v4.4.0
+  rev: v5.0.0
   hooks:
   - id: trailing-whitespace
   - id: end-of-file-fixer

projects/common-api/src/main/java/dan200/computercraft/api/detail/DetailProvider.java

@@ -14,6 +14,7 @@ import java.util.Map;
  *
  * @param <T> The type of object that this provider can provide details for.
  * @see DetailRegistry
+ * @see dan200.computercraft.api.detail An overview of the detail system.
  */
 @FunctionalInterface
 public interface DetailProvider<T> {

projects/common-api/src/main/java/dan200/computercraft/api/detail/DetailRegistry.java

@@ -17,6 +17,7 @@ import java.util.Map;
  * also in this package.
  *
  * @param <T> The type of object that this registry provides details for.
+ * @see dan200.computercraft.api.detail An overview of the detail system.
  */
 @ApiStatus.NonExtendable
 public interface DetailRegistry<T> {

projects/common-api/src/main/java/dan200/computercraft/api/detail/VanillaDetailRegistries.java

@@ -17,6 +17,9 @@ public class VanillaDetailRegistries {
      * <p>
      * This instance's {@link DetailRegistry#getBasicDetails(Object)} is thread safe (assuming the stack is immutable)
      * and may be called from the computer thread.
+     * <p>
+     * This does not have special handling for {@linkplain ItemStack#isEmpty() empty item stacks}, and so the returned
+     * details will be an empty stack of air. Callers should generally check for empty stacks before calling this.
      */
     public static final DetailRegistry<ItemStack> ITEM_STACK = ComputerCraftAPIService.get().getItemStackDetailRegistry();
 

projects/common-api/src/main/java/dan200/computercraft/api/detail/package-info.java

@@ -0,0 +1,48 @@
+// SPDX-FileCopyrightText: 2025 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+/**
+ * The detail system provides a standard way for mods to return descriptions of common game objects, such as blocks or
+ * items, as well as registering additional detail to be included in those descriptions.
+ * <p>
+ * For instance, the built-in {@code turtle.getItemDetail()} method uses
+ * {@linkplain dan200.computercraft.api.detail.VanillaDetailRegistries#ITEM_STACK in order to provide information about}
+ * the selected item:
+ *
+ * <pre class="language language-lua">{@code
+ * local item = turtle.getItemDetail(nil, true)
+ * --[[
+ * item = {
+ *   name = "minecraft:wheat",
+ *   displayName = "Wheat",
+ *   count = 1,
+ *   maxCount = 64,
+ *   tags = {},
+ * }
+ * ]]
+ * }</pre>
+ *
+ * <h2>Built-in detail providers</h2>
+ * While you can define your own detail providers (perhaps for types from your own mod), CC comes with several built-in
+ * detail registries for vanilla and mod-loader objects:
+ *
+ * <ul>
+ *     <li>{@link dan200.computercraft.api.detail.VanillaDetailRegistries}, for vanilla objects</li>
+ *     <li>{@code dan200.computercraft.api.detail.ForgeDetailRegistries} for Forge-specific objects</li>
+ *     <li>{@code dan200.computercraft.api.detail.FabricDetailRegistries} for Fabric-specific objects</li>
+ * </ul>
+ *
+ * <h2>Example: Returning details from methods</h2>
+ * Here we define a {@code getHeldItem()} method for pocket computers which finds the currently held item of the player
+ * and returns it to the user using {@link dan200.computercraft.api.detail.VanillaDetailRegistries#ITEM_STACK} and
+ * {@link dan200.computercraft.api.detail.DetailRegistry#getDetails(java.lang.Object)}.
+ *
+ * {@snippet class=com.example.examplemod.ExamplePocketPeripheral region=details}
+ *
+ * <h2>Example: Registering custom detail registries</h2>
+ * Here we define a new detail provider for items that includes the nutrition and saturation values in the returned object.
+ *
+ * {@snippet class=com.example.examplemod.ExampleMod region=details}
+ */
+package dan200.computercraft.api.detail;

projects/common/src/client/java/dan200/computercraft/client/model/LecternPocketModel.java

@@ -22,6 +22,7 @@ import net.minecraft.client.resources.model.Material;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.util.FastColor;
 import net.minecraft.world.inventory.InventoryMenu;
+import net.minecraft.world.item.ItemStack;
 
 /**
  * A model for {@linkplain PocketComputerItem pocket computers} placed on a lectern.

projects/common/src/examples/java/com/example/examplemod/ExampleMod.java

@@ -3,6 +3,7 @@ package com.example.examplemod;
 import com.example.examplemod.data.TurtleDataProvider;
 import com.example.examplemod.peripheral.FurnacePeripheral;
 import dan200.computercraft.api.ComputerCraftAPI;
+import dan200.computercraft.api.detail.VanillaDetailRegistries;
 import dan200.computercraft.api.turtle.TurtleUpgradeSerialiser;
 
 /**
@@ -34,6 +35,16 @@ public final class ExampleMod {
         ComputerCraftAPI.registerGenericSource(new FurnacePeripheral());
         // @end region=generic_source
 
+        // @start region=details
+        VanillaDetailRegistries.ITEM_STACK.addProvider((out, stack) -> {
+            var food = stack.getItem().getFoodProperties();
+            if (food == null) return;
+
+            out.put("saturation", food.getSaturationModifier());
+            out.put("nutrition", food.getNutrition());
+        });
+        // @end region=details
+
         ExampleAPI.register();
     }
 }

projects/common/src/examples/java/com/example/examplemod/ExamplePocketPeripheral.java

@@ -0,0 +1,49 @@
+package com.example.examplemod;
+
+import dan200.computercraft.api.detail.DetailRegistry;
+import dan200.computercraft.api.detail.VanillaDetailRegistries;
+import dan200.computercraft.api.lua.LuaFunction;
+import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.api.pocket.IPocketAccess;
+import net.minecraft.world.InteractionHand;
+import net.minecraft.world.entity.LivingEntity;
+import org.jspecify.annotations.Nullable;
+
+import java.util.Map;
+
+/**
+ * An example peripheral for pocket computers. This currently doesn't have an associated upgrade — it mostly exists to
+ * demonstrate other functionality.
+ */
+public class ExamplePocketPeripheral implements IPeripheral {
+    private final IPocketAccess pocket;
+
+    public ExamplePocketPeripheral(IPocketAccess pocket) {
+        this.pocket = pocket;
+    }
+
+    @Override
+    public String getType() {
+        return "example";
+    }
+
+    /**
+     * An example of using {@linkplain DetailRegistry detail registries} to get the current player's held item.
+     *
+     * @return The item details, or {@code null} if the player is not holding an item.
+     */
+    // @start region=details
+    @LuaFunction(mainThread = true)
+    public final @Nullable Map<String, ?> getHeldItem() {
+        if (!(pocket.getEntity() instanceof LivingEntity entity)) return null;
+
+        var heldItem = entity.getItemInHand(InteractionHand.MAIN_HAND);
+        return heldItem.isEmpty() ? null : VanillaDetailRegistries.ITEM_STACK.getDetails(heldItem);
+    }
+    // @end region=details
+
+    @Override
+    public boolean equals(@Nullable IPeripheral other) {
+        return other instanceof ExamplePocketPeripheral o && pocket == o.pocket;
+    }
+}