Added Vanilla Hopper integration.

src/main/java/appeng/hooks/HopperHooks.java

@@ -0,0 +1,91 @@
+package appeng.hooks;
+
+import alexiil.mc.lib.attributes.SearchOption;
+import alexiil.mc.lib.attributes.SearchOptions;
+import alexiil.mc.lib.attributes.item.ItemAttributes;
+import alexiil.mc.lib.attributes.item.ItemExtractable;
+import alexiil.mc.lib.attributes.item.ItemInsertable;
+import alexiil.mc.lib.attributes.item.ItemInvUtil;
+import alexiil.mc.lib.attributes.item.compat.FixedInventoryVanillaWrapper;
+import net.minecraft.block.HopperBlock;
+import net.minecraft.block.entity.Hopper;
+import net.minecraft.block.entity.HopperBlockEntity;
+import net.minecraft.inventory.Inventory;
+import net.minecraft.util.ActionResult;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.Direction;
+import net.minecraft.world.World;
+
+// SEE: https://github.com/AlexIIL/LibBlockAttributes/pull/27
+public final class HopperHooks {
+
+    private HopperHooks() {
+    }
+
+    public static ActionResult tryInsert(HopperBlockEntity hopper) {
+        World world = hopper.getWorld();
+        Direction towards = hopper.getCachedState().get(HopperBlock.FACING);
+        BlockPos targetPos = hopper.getPos().offset(towards);
+
+        if (isVanillaInventoryAt(world, targetPos)) {
+            return ActionResult.PASS;
+        }
+
+        ItemInsertable insertable = ItemAttributes.INSERTABLE.getFirstOrNull(world, targetPos, SearchOptions.inDirection(towards));
+        if (insertable == null) {
+            return ActionResult.PASS; // Let Vanilla handle non-LBA enabled inventories and Entities
+        }
+
+        // Get an Extractable for the Hopper's internal inventory
+        ItemExtractable extractable = new FixedInventoryVanillaWrapper(hopper).getExtractable();
+
+        // Try to move any one item from hopper->inventory
+        if (ItemInvUtil.move(extractable, insertable, 1) > 0) {
+            return ActionResult.SUCCESS;
+        } else {
+            return ActionResult.FAIL;
+        }
+    }
+
+    /**
+     * Hoppers always search UP for adjacent inventories to extract from.
+     */
+    private static final SearchOption<? super ItemExtractable> EXTRACT_SEARCH = SearchOptions.inDirection(Direction.UP);
+
+    /**
+     * Tries to extract items from an inventory above the given hopper into the hopper.
+     * Note that the given hopper can also be a hopper minecart.
+     */
+    public static ActionResult tryExtract(Hopper hopper) {
+        World world = hopper.getWorld();
+        BlockPos blockAbove = new BlockPos(hopper.getHopperX(), hopper.getHopperY() + 1, hopper.getHopperZ());
+
+        if (isVanillaInventoryAt(world, blockAbove)) {
+            return ActionResult.PASS;
+        }
+
+        // Get an Extractable for the inventory above the hopper
+        ItemExtractable extractable = ItemAttributes.EXTRACTABLE.getFirstOrNull(world, blockAbove, EXTRACT_SEARCH);
+        if (extractable == null) {
+            return ActionResult.PASS; // Let Vanilla handle non-LBA enabled inventories and Entities
+        }
+
+        // Get an Insertable for the Hopper's internal inventory
+        ItemInsertable insertable = new FixedInventoryVanillaWrapper(hopper).getInsertable();
+
+        // Try to move any one item from inventory->hopper
+        if (ItemInvUtil.move(extractable, insertable, 1) > 0) {
+            return ActionResult.SUCCESS;
+        } else {
+            return ActionResult.FAIL;
+        }
+    }
+
+    private static boolean isVanillaInventoryAt(World world, BlockPos pos) {
+        // If there's a TE at the target position that implements Inventory (such that Hopper would handle it itself)
+        // defer to Vanilla to avoid injecting ourselves inbetween Vanilla blocks needlessly.
+        // ItemAttributes.INSERTABLE would return an auto-converted Inventory in such cases.
+        return world.getBlockEntity(pos) instanceof Inventory;
+    }
+
+}

src/main/java/appeng/mixins/HopperMixin.java

@@ -0,0 +1,34 @@
+package appeng.mixins;
+
+import appeng.hooks.HopperHooks;
+import net.minecraft.block.entity.Hopper;
+import net.minecraft.block.entity.HopperBlockEntity;
+import net.minecraft.util.ActionResult;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+// SEE: https://github.com/AlexIIL/LibBlockAttributes/pull/27
+@SuppressWarnings("ConstantConditions")
+@Mixin(HopperBlockEntity.class)
+public class HopperMixin {
+
+    @Inject(method = "insert", at = @At("HEAD"), cancellable = true, require = 1, allow = 1)
+    private void onInsert(CallbackInfoReturnable<Boolean> cri) {
+        HopperBlockEntity self = (HopperBlockEntity) (Object) this;
+        ActionResult result = HopperHooks.tryInsert(self);
+        if (result != ActionResult.PASS) {
+            cri.setReturnValue(result.isAccepted());
+        }
+    }
+
+    @Inject(method = "extract", at = @At("HEAD"), cancellable = true, require = 1, allow = 1)
+    private static void onExtract(Hopper hopper, CallbackInfoReturnable<Boolean> cri) {
+        ActionResult result = HopperHooks.tryExtract(hopper);
+        if (result != ActionResult.PASS) {
+            cri.setReturnValue(result.isAccepted());
+        }
+    }
+
+}