Clean up how we enumerate Lua/peripheral methods

- Move several interfaces out of `d00.computercraft.core.asm` into a
   new `aethods` package. It may make sense to expose this to the
   public API in a future commit (possibly part of #1462).

 - Add a new MethodSupplier<T> interface, which provides methods to
   iterate over all methods exported by an object (either directly, or
   including those from ObjectSources).

   This interface's concrete implementation (asm.MethodSupplierImpl),
   uses Generators and IntCaches as before - we can now make that all
   package-private though, which is nice!

 - Make the LuaMethod and PeripheralMethod MethodSupplier local to the
   ComputerContext. This currently has no effect (the underlying
   Generator is still global), but eventually we'll make GenericMethods
   non-global, which unlocks the door for #1382.

 - Update everything to use this new interface. This is mostly pretty
   sensible, but is a little uglier on the MC side (especially in
   generic peripherals), as we need to access the global ServerContext.

projects/common/src/main/java/dan200/computercraft/shared/computer/core/ServerContext.java

@@ -14,6 +14,8 @@ import dan200.computercraft.core.computer.mainthread.MainThread;
 import dan200.computercraft.core.computer.mainthread.MainThreadConfig;
 import dan200.computercraft.core.lua.CobaltLuaMachine;
 import dan200.computercraft.core.lua.ILuaMachine;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.PeripheralMethod;
 import dan200.computercraft.impl.AbstractComputerCraftAPI;
 import dan200.computercraft.impl.ApiFactories;
 import dan200.computercraft.shared.CommonHooks;
@@ -134,6 +136,16 @@ public final class ServerContext {
         return context;
     }
 
+    /**
+     * Get the {@link MethodSupplier} used to find methods on peripherals.
+     *
+     * @return The {@link PeripheralMethod} method supplier.
+     * @see ComputerContext#peripheralMethods()
+     */
+    public MethodSupplier<PeripheralMethod> peripheralMethods() {
+        return context.peripheralMethods();
+    }
+
     /**
      * Tick all components of this server context. This should <em>NOT</em> be called outside of {@link CommonHooks}.
      */

projects/common/src/main/java/dan200/computercraft/shared/computer/upload/TransferredFile.java

@@ -7,7 +7,7 @@ package dan200.computercraft.shared.computer.upload;
 import dan200.computercraft.api.lua.LuaFunction;
 import dan200.computercraft.core.apis.handles.BinaryReadableHandle;
 import dan200.computercraft.core.apis.handles.ByteBufferChannel;
-import dan200.computercraft.core.asm.ObjectSource;
+import dan200.computercraft.core.methods.ObjectSource;
 
 import java.nio.ByteBuffer;
 import java.util.Collections;

projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/GenericPeripheralBuilder.java

@@ -6,9 +6,12 @@ package dan200.computercraft.shared.peripheral.generic;
 
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.PeripheralType;
-import dan200.computercraft.core.asm.NamedMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
-import dan200.computercraft.core.asm.PeripheralMethod;
+import dan200.computercraft.core.methods.NamedMethod;
+import dan200.computercraft.core.methods.PeripheralMethod;
+import dan200.computercraft.shared.computer.core.ServerContext;
 import net.minecraft.core.Direction;
+import net.minecraft.server.MinecraftServer;
 import net.minecraft.world.level.block.entity.BlockEntity;
 
 import javax.annotation.Nullable;
@@ -25,37 +28,36 @@ import java.util.Set;
  * See the platform-specific peripheral providers for the usage of this.
  */
 final class GenericPeripheralBuilder {
+    private final MethodSupplier<PeripheralMethod> peripheralMethods;
+
     private @Nullable String name;
     private final Set<String> additionalTypes = new HashSet<>(0);
-    private final ArrayList<SaturatedMethod> methods = new ArrayList<>(0);
+    private final ArrayList<SaturatedMethod> methods = new ArrayList<>();
+
+    GenericPeripheralBuilder(MinecraftServer server) {
+        peripheralMethods = ServerContext.get(server).peripheralMethods();
+    }
 
     @Nullable
-    IPeripheral toPeripheral(BlockEntity tile, Direction side) {
+    IPeripheral toPeripheral(BlockEntity blockEntity, Direction side) {
         if (methods.isEmpty()) return null;
 
         methods.trimToSize();
-        return new GenericPeripheral(tile, side, name, additionalTypes, methods);
+        return new GenericPeripheral(blockEntity, side, name, additionalTypes, methods);
     }
 
     boolean addMethods(Object target) {
-        var methods = PeripheralMethod.GENERATOR.getMethods(target.getClass());
+        return peripheralMethods.forEachSelfMethod(target, (name, method, info) -> {
-        if (methods.isEmpty()) return false;
+            methods.add(new SaturatedMethod(target, name, method));
-
-        var saturatedMethods = this.methods;
-        saturatedMethods.ensureCapacity(saturatedMethods.size() + methods.size());
-        for (var method : methods) {
-            saturatedMethods.add(new SaturatedMethod(target, method.name(), method.method()));
 
             // If we have a peripheral type, use it. Always pick the smallest one, so it's consistent (assuming mods
             // don't change).
-            var type = method.genericType();
+            var type = info == null ? null : info.genericType();
             if (type != null && type.getPrimaryType() != null) {
-                var name = type.getPrimaryType();
+                var primaryType = type.getPrimaryType();
-                if (this.name == null || this.name.compareTo(name) > 0) this.name = name;
+                if (this.name == null || this.name.compareTo(primaryType) > 0) this.name = primaryType;
             }
             if (type != null) additionalTypes.addAll(type.getAdditionalTypes());
-        }
+        });
-
-        return true;
     }
 }

projects/common/src/main/java/dan200/computercraft/shared/peripheral/generic/SaturatedMethod.java

@@ -9,7 +9,7 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.MethodResult;
 import dan200.computercraft.api.peripheral.IComputerAccess;
-import dan200.computercraft.core.asm.PeripheralMethod;
+import dan200.computercraft.core.methods.PeripheralMethod;
 
 /**
  * A {@link PeripheralMethod} along with the method's target.

projects/common/src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java

@@ -16,10 +16,12 @@ import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.NotAttachedException;
 import dan200.computercraft.api.peripheral.WorkMonitor;
 import dan200.computercraft.core.apis.PeripheralAPI;
-import dan200.computercraft.core.asm.PeripheralMethod;
+import dan200.computercraft.core.methods.PeripheralMethod;
 import dan200.computercraft.core.util.LuaUtil;
+import dan200.computercraft.shared.computer.core.ServerContext;
 import dan200.computercraft.shared.peripheral.modem.ModemPeripheral;
 import dan200.computercraft.shared.peripheral.modem.ModemState;
+import net.minecraft.server.level.ServerLevel;
 import net.minecraft.world.level.Level;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -284,7 +286,8 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
 
     private void attachPeripheralImpl(IComputerAccess computer, ConcurrentMap<String, RemotePeripheralWrapper> peripherals, String periphName, IPeripheral peripheral) {
         if (!peripherals.containsKey(periphName) && !periphName.equals(getLocalPeripheral().getConnectedName())) {
-            var wrapper = new RemotePeripheralWrapper(modem, peripheral, computer, periphName);
+            var methods = ServerContext.get(((ServerLevel) getLevel()).getServer()).peripheralMethods().getSelfMethods(peripheral);
+            var wrapper = new RemotePeripheralWrapper(modem, peripheral, computer, periphName, methods);
             peripherals.put(periphName, wrapper);
             wrapper.attach();
         }
@@ -314,7 +317,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
         private volatile boolean attached;
         private final Set<String> mounts = new HashSet<>();
 
-        RemotePeripheralWrapper(WiredModemElement element, IPeripheral peripheral, IComputerAccess computer, String name) {
+        RemotePeripheralWrapper(WiredModemElement element, IPeripheral peripheral, IComputerAccess computer, String name, Map<String, PeripheralMethod> methods) {
             this.element = element;
             this.peripheral = peripheral;
             this.computer = computer;
@@ -322,7 +325,7 @@ public abstract class WiredModemPeripheral extends ModemPeripheral implements Wi
 
             type = Objects.requireNonNull(peripheral.getType(), "Peripheral type cannot be null");
             additionalTypes = peripheral.getAdditionalTypes();
-            methodMap = PeripheralAPI.getMethods(peripheral);
+            methodMap = methods;
         }
 
         public void attach() {

projects/core/src/main/java/dan200/computercraft/core/ComputerContext.java

@@ -5,12 +5,18 @@
 package dan200.computercraft.core;
 
 import dan200.computercraft.api.lua.ILuaAPIFactory;
+import dan200.computercraft.core.asm.LuaMethodSupplier;
+import dan200.computercraft.core.asm.PeripheralMethodSupplier;
 import dan200.computercraft.core.computer.ComputerThread;
 import dan200.computercraft.core.computer.GlobalEnvironment;
 import dan200.computercraft.core.computer.mainthread.MainThreadScheduler;
 import dan200.computercraft.core.computer.mainthread.NoWorkMainThreadScheduler;
 import dan200.computercraft.core.lua.CobaltLuaMachine;
 import dan200.computercraft.core.lua.ILuaMachine;
+import dan200.computercraft.core.lua.MachineEnvironment;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.PeripheralMethod;
 
 import javax.annotation.CheckReturnValue;
 import javax.annotation.Nullable;
@@ -28,17 +34,22 @@ public final class ComputerContext {
     private final MainThreadScheduler mainThreadScheduler;
     private final ILuaMachine.Factory luaFactory;
     private final List<ILuaAPIFactory> apiFactories;
+    private final MethodSupplier<LuaMethod> luaMethods;
+    private final MethodSupplier<PeripheralMethod> peripheralMethods;
 
     ComputerContext(
         GlobalEnvironment globalEnvironment, ComputerThread computerScheduler,
         MainThreadScheduler mainThreadScheduler, ILuaMachine.Factory luaFactory,
-        List<ILuaAPIFactory> apiFactories
+        List<ILuaAPIFactory> apiFactories, MethodSupplier<LuaMethod> luaMethods,
+        MethodSupplier<PeripheralMethod> peripheralMethods
     ) {
         this.globalEnvironment = globalEnvironment;
         this.computerScheduler = computerScheduler;
         this.mainThreadScheduler = mainThreadScheduler;
         this.luaFactory = luaFactory;
         this.apiFactories = apiFactories;
+        this.luaMethods = luaMethods;
+        this.peripheralMethods = peripheralMethods;
     }
 
     /**
@@ -87,6 +98,25 @@ public final class ComputerContext {
         return apiFactories;
     }
 
+    /**
+     * Get the {@link MethodSupplier} used to find methods on Lua values.
+     *
+     * @return The {@link LuaMethod} method supplier.
+     * @see MachineEnvironment#luaMethods()
+     */
+    public MethodSupplier<LuaMethod> luaMethods() {
+        return luaMethods;
+    }
+
+    /**
+     * Get the {@link MethodSupplier} used to find methods on peripherals.
+     *
+     * @return The {@link PeripheralMethod} method supplier.
+     */
+    public MethodSupplier<PeripheralMethod> peripheralMethods() {
+        return peripheralMethods;
+    }
+
     /**
      * Close the current {@link ComputerContext}, disposing of any resources inside.
      *
@@ -206,7 +236,9 @@ public final class ComputerContext {
                 new ComputerThread(threads),
                 mainThreadScheduler == null ? new NoWorkMainThreadScheduler() : mainThreadScheduler,
                 luaFactory == null ? CobaltLuaMachine::new : luaFactory,
-                apiFactories == null ? List.of() : apiFactories
+                apiFactories == null ? List.of() : apiFactories,
+                LuaMethodSupplier.create(),
+                PeripheralMethodSupplier.create()
             );
         }
     }

projects/core/src/main/java/dan200/computercraft/core/apis/IAPIEnvironment.java

@@ -10,9 +10,9 @@ import dan200.computercraft.core.computer.ComputerEnvironment;
 import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.computer.GlobalEnvironment;
 import dan200.computercraft.core.filesystem.FileSystem;
-import dan200.computercraft.core.metrics.OperationTimer;
 import dan200.computercraft.core.metrics.Metric;
 import dan200.computercraft.core.metrics.MetricsObserver;
+import dan200.computercraft.core.metrics.OperationTimer;
 import dan200.computercraft.core.terminal.Terminal;
 
 import javax.annotation.Nullable;

projects/core/src/main/java/dan200/computercraft/core/apis/PeripheralAPI.java

@@ -7,13 +7,12 @@ package dan200.computercraft.core.apis;
 import dan200.computercraft.api.filesystem.Mount;
 import dan200.computercraft.api.filesystem.WritableMount;
 import dan200.computercraft.api.lua.*;
-import dan200.computercraft.api.peripheral.IDynamicPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.api.peripheral.NotAttachedException;
 import dan200.computercraft.api.peripheral.WorkMonitor;
-import dan200.computercraft.core.asm.LuaMethod;
-import dan200.computercraft.core.asm.PeripheralMethod;
 import dan200.computercraft.core.computer.ComputerSide;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.PeripheralMethod;
 import dan200.computercraft.core.metrics.Metrics;
 import dan200.computercraft.core.util.LuaUtil;
 
@@ -44,7 +43,7 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             type = Objects.requireNonNull(peripheral.getType(), "Peripheral type cannot be null");
             additionalTypes = peripheral.getAdditionalTypes();
 
-            methodMap = PeripheralAPI.getMethods(peripheral);
+            methodMap = peripheralMethods.getSelfMethods(peripheral);
         }
 
         public IPeripheral getPeripheral() {
@@ -172,11 +171,13 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
     }
 
     private final IAPIEnvironment environment;
+    private final MethodSupplier<PeripheralMethod> peripheralMethods;
     private final PeripheralWrapper[] peripherals = new PeripheralWrapper[6];
     private boolean running;
 
-    public PeripheralAPI(IAPIEnvironment environment) {
+    public PeripheralAPI(IAPIEnvironment environment, MethodSupplier<PeripheralMethod> peripheralMethods) {
         this.environment = environment;
+        this.peripheralMethods = peripheralMethods;
         this.environment.setPeripheralChangeListener(this);
         running = false;
     }
@@ -315,21 +316,4 @@ public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChange
             throw e;
         }
     }
-
-    public static Map<String, PeripheralMethod> getMethods(IPeripheral peripheral) {
-        var dynamicMethods = peripheral instanceof IDynamicPeripheral
-            ? Objects.requireNonNull(((IDynamicPeripheral) peripheral).getMethodNames(), "Peripheral methods cannot be null")
-            : LuaMethod.EMPTY_METHODS;
-
-        var methods = PeripheralMethod.GENERATOR.getMethods(peripheral.getClass());
-
-        Map<String, PeripheralMethod> methodMap = new HashMap<>(methods.size() + dynamicMethods.length);
-        for (var i = 0; i < dynamicMethods.length; i++) {
-            methodMap.put(dynamicMethods[i], PeripheralMethod.DYNAMIC.get(i));
-        }
-        for (var method : methods) {
-            methodMap.put(method.name(), method.method());
-        }
-        return methodMap;
-    }
 }

projects/core/src/main/java/dan200/computercraft/core/apis/http/request/HttpResponseHandle.java

@@ -10,7 +10,7 @@ import dan200.computercraft.core.apis.HTTPAPI;
 import dan200.computercraft.core.apis.handles.BinaryReadableHandle;
 import dan200.computercraft.core.apis.handles.EncodedReadableHandle;
 import dan200.computercraft.core.apis.handles.HandleGeneric;
-import dan200.computercraft.core.asm.ObjectSource;
+import dan200.computercraft.core.methods.ObjectSource;
 
 import java.util.Collections;
 import java.util.Map;

projects/core/src/main/java/dan200/computercraft/core/asm/Generator.java

@@ -11,6 +11,7 @@ import com.google.common.primitives.Primitives;
 import com.google.common.reflect.TypeToken;
 import dan200.computercraft.api.lua.*;
 import dan200.computercraft.api.peripheral.PeripheralType;
+import dan200.computercraft.core.methods.NamedMethod;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Type;
@@ -30,7 +31,7 @@ import java.util.function.Function;
 
 import static org.objectweb.asm.Opcodes.*;
 
-public final class Generator<T> {
+final class Generator<T> {
     private static final Logger LOG = LoggerFactory.getLogger(Generator.class);
 
     private static final AtomicInteger METHOD_ID = new AtomicInteger();

projects/core/src/main/java/dan200/computercraft/core/asm/IntCache.java

@@ -7,7 +7,7 @@ package dan200.computercraft.core.asm;
 import java.util.Arrays;
 import java.util.function.IntFunction;
 
-public final class IntCache<T> {
+final class IntCache<T> {
     private final IntFunction<T> factory;
     private volatile Object[] cache = new Object[16];
 

projects/core/src/main/java/dan200/computercraft/core/asm/LuaMethod.java

@@ -1,23 +0,0 @@
-// SPDX-FileCopyrightText: 2020 The CC: Tweaked Developers
-//
-// SPDX-License-Identifier: MPL-2.0
-
-package dan200.computercraft.core.asm;
-
-import dan200.computercraft.api.lua.*;
-
-import java.util.Collections;
-
-public interface LuaMethod {
-    Generator<LuaMethod> GENERATOR = new Generator<>(LuaMethod.class, Collections.singletonList(ILuaContext.class),
-        m -> (target, context, args) -> context.executeMainThreadTask(() -> ResultHelpers.checkNormalResult(m.apply(target, context, args.escapes())))
-    );
-
-    IntCache<LuaMethod> DYNAMIC = new IntCache<>(
-        method -> (instance, context, args) -> ((IDynamicLuaObject) instance).callMethod(context, method, args)
-    );
-
-    String[] EMPTY_METHODS = new String[0];
-
-    MethodResult apply(Object target, ILuaContext context, IArguments args) throws LuaException;
-}

projects/core/src/main/java/dan200/computercraft/core/asm/LuaMethodSupplier.java

@@ -0,0 +1,34 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.asm;
+
+import dan200.computercraft.api.lua.IDynamicLuaObject;
+import dan200.computercraft.api.lua.ILuaContext;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
+import org.jetbrains.annotations.VisibleForTesting;
+
+import java.util.List;
+import java.util.Objects;
+
+public final class LuaMethodSupplier {
+    @VisibleForTesting
+    static final Generator<LuaMethod> GENERATOR = new Generator<>(LuaMethod.class, List.of(ILuaContext.class),
+        m -> (target, context, args) -> context.executeMainThreadTask(() -> ResultHelpers.checkNormalResult(m.apply(target, context, args.escapes())))
+    );
+    private static final IntCache<LuaMethod> DYNAMIC = new IntCache<>(
+        method -> (instance, context, args) -> ((IDynamicLuaObject) instance).callMethod(context, method, args)
+    );
+
+    private LuaMethodSupplier() {
+    }
+
+    public static MethodSupplier<LuaMethod> create() {
+        return new MethodSupplierImpl<>(GENERATOR, DYNAMIC, x -> x instanceof IDynamicLuaObject dynamic
+            ? Objects.requireNonNull(dynamic.getMethodNames(), "Dynamic methods cannot be null")
+            : null
+        );
+    }
+}

projects/core/src/main/java/dan200/computercraft/core/asm/MethodSupplierImpl.java

@@ -0,0 +1,61 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.asm;
+
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.ObjectSource;
+
+import java.util.function.Function;
+
+final class MethodSupplierImpl<T> implements MethodSupplier<T> {
+    private final Generator<T> generator;
+    private final IntCache<T> dynamic;
+    private final Function<Object, String[]> dynamicMethods;
+
+    MethodSupplierImpl(Generator<T> generator, IntCache<T> dynamic, Function<Object, String[]> dynamicMethods) {
+        this.generator = generator;
+        this.dynamic = dynamic;
+        this.dynamicMethods = dynamicMethods;
+    }
+
+    @Override
+    public boolean forEachSelfMethod(Object object, UntargetedConsumer<T> consumer) {
+        var methods = generator.getMethods(object.getClass());
+        for (var method : methods) consumer.accept(method.name(), method.method(), method);
+
+        var dynamicMethods = this.dynamicMethods.apply(object);
+        if (dynamicMethods != null) {
+            for (var i = 0; i < dynamicMethods.length; i++) consumer.accept(dynamicMethods[i], dynamic.get(i), null);
+        }
+
+        return !methods.isEmpty() || dynamicMethods != null;
+    }
+
+    @Override
+    public boolean forEachMethod(Object object, TargetedConsumer<T> consumer) {
+        var methods = generator.getMethods(object.getClass());
+        for (var method : methods) consumer.accept(object, method.name(), method.method(), method);
+
+        var hasMethods = !methods.isEmpty();
+
+        if (object instanceof ObjectSource source) {
+            for (var extra : source.getExtra()) {
+                var extraMethods = generator.getMethods(extra.getClass());
+                if (!extraMethods.isEmpty()) hasMethods = true;
+                for (var method : extraMethods) consumer.accept(object, method.name(), method.method(), method);
+            }
+        }
+
+        var dynamicMethods = this.dynamicMethods.apply(object);
+        if (dynamicMethods != null) {
+            hasMethods = true;
+            for (var i = 0; i < dynamicMethods.length; i++) {
+                consumer.accept(object, dynamicMethods[i], dynamic.get(i), null);
+            }
+        }
+
+        return hasMethods;
+    }
+}

projects/core/src/main/java/dan200/computercraft/core/asm/ObjectSource.java

@@ -1,27 +0,0 @@
-// SPDX-FileCopyrightText: 2020 The CC: Tweaked Developers
-//
-// SPDX-License-Identifier: MPL-2.0
-
-package dan200.computercraft.core.asm;
-
-import java.util.function.BiConsumer;
-
-/**
- * A Lua object which exposes additional methods.
- * <p>
- * This can be used to merge multiple objects together into one. Ideally this'd be part of the API, but I'm not entirely
- * happy with the interface - something I'd like to think about first.
- */
-public interface ObjectSource {
-    Iterable<Object> getExtra();
-
-    static <T> void allMethods(Generator<T> generator, Object object, BiConsumer<Object, NamedMethod<T>> accept) {
-        for (var method : generator.getMethods(object.getClass())) accept.accept(object, method);
-
-        if (object instanceof ObjectSource source) {
-            for (var extra : source.getExtra()) {
-                for (var method : generator.getMethods(extra.getClass())) accept.accept(extra, method);
-            }
-        }
-    }
-}

projects/core/src/main/java/dan200/computercraft/core/asm/PeripheralMethod.java

@@ -1,26 +0,0 @@
-// SPDX-FileCopyrightText: 2020 The CC: Tweaked Developers
-//
-// SPDX-License-Identifier: MPL-2.0
-
-package dan200.computercraft.core.asm;
-
-import dan200.computercraft.api.lua.IArguments;
-import dan200.computercraft.api.lua.ILuaContext;
-import dan200.computercraft.api.lua.LuaException;
-import dan200.computercraft.api.lua.MethodResult;
-import dan200.computercraft.api.peripheral.IComputerAccess;
-import dan200.computercraft.api.peripheral.IDynamicPeripheral;
-
-import java.util.Arrays;
-
-public interface PeripheralMethod {
-    Generator<PeripheralMethod> GENERATOR = new Generator<>(PeripheralMethod.class, Arrays.asList(ILuaContext.class, IComputerAccess.class),
-        m -> (target, context, computer, args) -> context.executeMainThreadTask(() -> ResultHelpers.checkNormalResult(m.apply(target, context, computer, args.escapes())))
-    );
-
-    IntCache<PeripheralMethod> DYNAMIC = new IntCache<>(
-        method -> (instance, context, computer, args) -> ((IDynamicPeripheral) instance).callMethod(computer, context, method, args)
-    );
-
-    MethodResult apply(Object target, ILuaContext context, IComputerAccess computer, IArguments args) throws LuaException;
-}

projects/core/src/main/java/dan200/computercraft/core/asm/PeripheralMethodSupplier.java

@@ -0,0 +1,30 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.asm;
+
+import dan200.computercraft.api.lua.ILuaContext;
+import dan200.computercraft.api.peripheral.IComputerAccess;
+import dan200.computercraft.api.peripheral.IDynamicPeripheral;
+import dan200.computercraft.core.methods.MethodSupplier;
+import dan200.computercraft.core.methods.PeripheralMethod;
+
+import java.util.List;
+import java.util.Objects;
+
+public class PeripheralMethodSupplier {
+    private static final Generator<PeripheralMethod> GENERATOR = new Generator<>(PeripheralMethod.class, List.of(ILuaContext.class, IComputerAccess.class),
+        m -> (target, context, computer, args) -> context.executeMainThreadTask(() -> ResultHelpers.checkNormalResult(m.apply(target, context, computer, args.escapes())))
+    );
+    private static final IntCache<PeripheralMethod> DYNAMIC = new IntCache<>(
+        method -> (instance, context, computer, args) -> ((IDynamicPeripheral) instance).callMethod(computer, context, method, args)
+    );
+
+    public static MethodSupplier<PeripheralMethod> create() {
+        return new MethodSupplierImpl<>(GENERATOR, DYNAMIC, x -> x instanceof IDynamicPeripheral dynamic
+            ? Objects.requireNonNull(dynamic.getMethodNames(), "Dynamic methods cannot be null")
+            : null
+        );
+    }
+}

projects/core/src/main/java/dan200/computercraft/core/computer/ComputerExecutor.java

@@ -15,6 +15,8 @@ import dan200.computercraft.core.filesystem.FileSystemException;
 import dan200.computercraft.core.lua.ILuaMachine;
 import dan200.computercraft.core.lua.MachineEnvironment;
 import dan200.computercraft.core.lua.MachineException;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
 import dan200.computercraft.core.metrics.Metrics;
 import dan200.computercraft.core.metrics.MetricsObserver;
 import dan200.computercraft.core.util.Colour;
@@ -61,6 +63,7 @@ final class ComputerExecutor {
     private final MetricsObserver metrics;
     private final List<ILuaAPI> apis = new ArrayList<>();
     private final ComputerThread scheduler;
+    private final MethodSupplier<LuaMethod> luaMethods;
     final TimeoutState timeout;
 
     private @Nullable FileSystem fileSystem;
@@ -168,6 +171,7 @@ final class ComputerExecutor {
         metrics = computerEnvironment.getMetrics();
         luaFactory = context.luaFactory();
         scheduler = context.computerScheduler();
+        luaMethods = context.luaMethods();
         timeout = new TimeoutState(scheduler);
 
         var environment = computer.getEnvironment();
@@ -176,7 +180,7 @@ final class ComputerExecutor {
         apis.add(new TermAPI(environment));
         apis.add(new RedstoneAPI(environment));
         apis.add(new FSAPI(environment));
-        apis.add(new PeripheralAPI(environment));
+        apis.add(new PeripheralAPI(environment, context.peripheralMethods()));
         apis.add(new OSAPI(environment));
         if (CoreConfig.httpEnabled) apis.add(new HTTPAPI(environment));
 
@@ -382,6 +386,7 @@ final class ComputerExecutor {
             return luaFactory.create(new MachineEnvironment(
                 new LuaContext(computer), metrics, timeout,
                 () -> apis.stream().map(api -> api instanceof ApiWrapper wrapper ? wrapper.getDelegate() : api).iterator(),
+                luaMethods,
                 computer.getGlobalEnvironment().getHostString()
             ), bios);
         } catch (IOException e) {

projects/core/src/main/java/dan200/computercraft/core/lua/BasicFunction.java

@@ -8,7 +8,7 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.MethodResult;
 import dan200.computercraft.core.Logging;
-import dan200.computercraft.core.asm.LuaMethod;
+import dan200.computercraft.core.methods.LuaMethod;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.squiddev.cobalt.LuaError;

projects/core/src/main/java/dan200/computercraft/core/lua/CobaltLuaMachine.java

@@ -10,9 +10,9 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.ILuaFunction;
 import dan200.computercraft.core.CoreConfig;
 import dan200.computercraft.core.Logging;
-import dan200.computercraft.core.asm.LuaMethod;
-import dan200.computercraft.core.asm.ObjectSource;
 import dan200.computercraft.core.computer.TimeoutState;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
 import dan200.computercraft.core.util.Nullability;
 import dan200.computercraft.core.util.SanitisedError;
 import org.slf4j.Logger;
@@ -39,6 +39,7 @@ public class CobaltLuaMachine implements ILuaMachine {
     private final TimeoutState timeout;
     private final Runnable timeoutListener = this::updateTimeout;
     private final ILuaContext context;
+    private final MethodSupplier<LuaMethod> luaMethods;
 
     private final LuaState state;
     private final LuaThread mainRoutine;
@@ -51,6 +52,7 @@ public class CobaltLuaMachine implements ILuaMachine {
     public CobaltLuaMachine(MachineEnvironment environment, InputStream bios) throws MachineException, IOException {
         timeout = environment.timeout();
         context = environment.context();
+        luaMethods = environment.luaMethods();
 
         // Create an environment to run in
         var state = this.state = LuaState.builder()
@@ -161,28 +163,13 @@ public class CobaltLuaMachine implements ILuaMachine {
 
     @Nullable
     private LuaTable wrapLuaObject(Object object) {
-        var dynamicMethods = object instanceof IDynamicLuaObject dynamic
-            ? Objects.requireNonNull(dynamic.getMethodNames(), "Methods cannot be null")
-            : LuaMethod.EMPTY_METHODS;
-
         var table = new LuaTable();
-        for (var i = 0; i < dynamicMethods.length; i++) {
+        var found = luaMethods.forEachMethod(object, (target, name, method, info) ->
-            var method = dynamicMethods[i];
+            table.rawset(name, info != null && info.nonYielding()
-            table.rawset(method, new ResultInterpreterFunction(this, LuaMethod.DYNAMIC.get(i), object, context, method));
+                ? new BasicFunction(this, method, target, context, name)
-        }
+                : new ResultInterpreterFunction(this, method, target, context, name)));
 
-        ObjectSource.allMethods(LuaMethod.GENERATOR, object, (instance, method) ->
+        return found ? table : null;
-            table.rawset(method.name(), method.nonYielding()
-                ? new BasicFunction(this, method.method(), instance, context, method.name())
-                : new ResultInterpreterFunction(this, method.method(), instance, context, method.name())));
-
-        try {
-            if (table.next(Constants.NIL).first().isNil()) return null;
-        } catch (LuaError ignored) {
-            // next should never throw on nil.
-        }
-
-        return table;
     }
 
     private LuaValue toValue(@Nullable Object object, @Nullable IdentityHashMap<Object, LuaValue> values) {

projects/core/src/main/java/dan200/computercraft/core/lua/MachineEnvironment.java

@@ -8,6 +8,8 @@ import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.core.computer.GlobalEnvironment;
 import dan200.computercraft.core.computer.TimeoutState;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
 import dan200.computercraft.core.metrics.MetricsObserver;
 
 /**
@@ -18,6 +20,7 @@ import dan200.computercraft.core.metrics.MetricsObserver;
  * @param timeout    The current timeout state. This should be used by the machine to interrupt its execution.
  * @param apis       APIs to inject into the global environment. Each API should be converted into a Lua object
  *                   (following the same rules as any other value), and then set to all names in {@link ILuaAPI#getNames()}.
+ * @param luaMethods A {@link MethodSupplier} to find methods on returned values.
  * @param hostString A {@linkplain GlobalEnvironment#getHostString() host string} to identify the current environment.
  * @see ILuaMachine.Factory
  */
@@ -26,6 +29,7 @@ public record MachineEnvironment(
     MetricsObserver metrics,
     TimeoutState timeout,
     Iterable<ILuaAPI> apis,
+    MethodSupplier<LuaMethod> luaMethods,
     String hostString
 ) {
 }

projects/core/src/main/java/dan200/computercraft/core/lua/ResultInterpreterFunction.java

@@ -9,7 +9,7 @@ import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.MethodResult;
 import dan200.computercraft.core.Logging;
-import dan200.computercraft.core.asm.LuaMethod;
+import dan200.computercraft.core.methods.LuaMethod;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.squiddev.cobalt.*;

projects/core/src/main/java/dan200/computercraft/core/methods/LuaMethod.java

@@ -0,0 +1,31 @@
+// SPDX-FileCopyrightText: 2020 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.methods;
+
+import dan200.computercraft.api.lua.*;
+
+/**
+ * A basic Lua function (i.e. one not associated with a peripheral) on some object (such as a {@link IDynamicLuaObject}
+ * or {@link ILuaAPI}.
+ * <p>
+ * This interface is not typically implemented yourself, but instead generated from a {@link LuaFunction}-annotated
+ * method.
+ *
+ * @see NamedMethod
+ */
+@FunctionalInterface
+public interface LuaMethod {
+    /**
+     * Apply this method.
+     *
+     * @param target  The object instance that this method targets.
+     * @param context The Lua context for this function call.
+     * @param args    Arguments to this function.
+     * @return The return call of this function.
+     * @throws LuaException Thrown by the underlying method call.
+     * @see IDynamicLuaObject#callMethod(ILuaContext, int, IArguments)
+     */
+    MethodResult apply(Object target, ILuaContext context, IArguments args) throws LuaException;
+}

projects/core/src/main/java/dan200/computercraft/core/methods/MethodSupplier.java

@@ -0,0 +1,83 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.methods;
+
+import javax.annotation.Nullable;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Finds methods available on an object and yields them.
+ *
+ * @param <T> The type of method, such as {@link LuaMethod} or {@link PeripheralMethod}.
+ */
+public interface MethodSupplier<T> {
+    /**
+     * Iterate over methods available on an object, ignoring {@link ObjectSource}s.
+     *
+     * @param object   The object to find methods for.
+     * @param consumer The consumer to call for each method.
+     * @return Whether any methods were found.
+     */
+    boolean forEachSelfMethod(Object object, UntargetedConsumer<T> consumer);
+
+    /**
+     * Generate a map of all methods targeting the current object, ignoring {@link ObjectSource}s.
+     *
+     * @param object The object to find methods for.
+     * @return A map of all methods on the object.
+     */
+    default Map<String, T> getSelfMethods(Object object) {
+        var map = new HashMap<String, T>();
+        forEachSelfMethod(object, (n, m, i) -> map.put(n, m));
+        return map;
+    }
+
+    /**
+     * Iterate over all methods on an object, including {@link ObjectSource}s.
+     *
+     * @param object   The object to find methods for.
+     * @param consumer The consumer to call for each method.
+     * @return Whether any methods were found.
+     */
+    boolean forEachMethod(Object object, TargetedConsumer<T> consumer);
+
+    /**
+     * A function which is called for each method on an object.
+     *
+     * @param <T> The type of method, such as {@link LuaMethod} or {@link PeripheralMethod}.
+     * @see #forEachSelfMethod(Object, UntargetedConsumer)
+     */
+    @FunctionalInterface
+    interface UntargetedConsumer<T> {
+        /**
+         * Consume a method on an object.
+         *
+         * @param name   The name of this method.
+         * @param method The actual method definition.
+         * @param info   Additional information about the method, such as whether it will yield. May be {@code null}.
+         */
+        void accept(String name, T method, @Nullable NamedMethod<T> info);
+    }
+
+    /**
+     * A function which is called for each method on an object and possibly nested objects.
+     *
+     * @param <T> The type of method, such as {@link LuaMethod} or {@link PeripheralMethod}.
+     * @see #forEachMethod(Object, TargetedConsumer)
+     */
+    @FunctionalInterface
+    interface TargetedConsumer<T> {
+        /**
+         * Consume a method on an object.
+         *
+         * @param object The object this method targets, should be passed to the method's {@code apply(...)} function.
+         * @param name   The name of this method.
+         * @param method The actual method definition.
+         * @param info   Additional information about the method, such as whether it will yield. May be {@code null}.
+         */
+        void accept(Object object, String name, T method, @Nullable NamedMethod<T> info);
+    }
+}

projects/core/src/main/java/dan200/computercraft/core/methods/NamedMethod.java

@@ -2,7 +2,7 @@
 //
 // SPDX-License-Identifier: MPL-2.0
 
-package dan200.computercraft.core.asm;
+package dan200.computercraft.core.methods;
 
 import dan200.computercraft.api.lua.LuaFunction;
 import dan200.computercraft.api.lua.MethodResult;

projects/core/src/main/java/dan200/computercraft/core/methods/ObjectSource.java

@@ -0,0 +1,15 @@
+// SPDX-FileCopyrightText: 2020 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.methods;
+
+/**
+ * A Lua object which exposes additional methods.
+ * <p>
+ * This can be used to merge multiple objects together into one. Ideally this'd be part of the API, but I'm not entirely
+ * happy with the interface - something I'd like to think about first.
+ */
+public interface ObjectSource {
+    Iterable<Object> getExtra();
+}

projects/core/src/main/java/dan200/computercraft/core/methods/PeripheralMethod.java

@@ -0,0 +1,35 @@
+// SPDX-FileCopyrightText: 2020 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.methods;
+
+import dan200.computercraft.api.lua.*;
+import dan200.computercraft.api.peripheral.IComputerAccess;
+import dan200.computercraft.api.peripheral.IDynamicPeripheral;
+import dan200.computercraft.api.peripheral.IPeripheral;
+
+/**
+ * A Lua function associated with some peripheral.
+ * <p>
+ * This interface is not typically implemented yourself, but instead generated from a {@link LuaFunction}-annotated
+ * method.
+ *
+ * @see NamedMethod
+ * @see IPeripheral
+ */
+@FunctionalInterface
+public interface PeripheralMethod {
+    /**
+     * Apply this method.
+     *
+     * @param target   The object instance that this method targets.
+     * @param context  The Lua context for this function call.
+     * @param computer The interface to the computer that is making the call.
+     * @param args     Arguments to this function.
+     * @return The return call of this function.
+     * @throws LuaException Thrown by the underlying method call.
+     * @see IDynamicPeripheral#callMethod(IComputerAccess, ILuaContext, int, IArguments)
+     */
+    MethodResult apply(Object target, ILuaContext context, IComputerAccess computer, IArguments args) throws LuaException;
+}

projects/core/src/test/java/dan200/computercraft/core/apis/ObjectWrapper.java

@@ -4,32 +4,25 @@
 
 package dan200.computercraft.core.apis;
 
-import dan200.computercraft.api.lua.*;
+import dan200.computercraft.api.lua.ILuaContext;
-import dan200.computercraft.core.asm.LuaMethod;
+import dan200.computercraft.api.lua.LuaException;
+import dan200.computercraft.api.lua.LuaTask;
+import dan200.computercraft.api.lua.ObjectArguments;
+import dan200.computercraft.core.asm.LuaMethodSupplier;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.MethodSupplier;
 
-import java.util.HashMap;
 import java.util.Map;
-import java.util.Objects;
 
 public class ObjectWrapper implements ILuaContext {
+    private static final MethodSupplier<LuaMethod> LUA_METHODS = LuaMethodSupplier.create();
+
     private final Object object;
     private final Map<String, LuaMethod> methodMap;
 
     public ObjectWrapper(Object object) {
         this.object = object;
-        var dynamicMethods = object instanceof IDynamicLuaObject dynamic
+        methodMap = LUA_METHODS.getSelfMethods(object);
-            ? Objects.requireNonNull(dynamic.getMethodNames(), "Methods cannot be null")
-            : LuaMethod.EMPTY_METHODS;
-
-        var methods = LuaMethod.GENERATOR.getMethods(object.getClass());
-
-        var methodMap = this.methodMap = new HashMap<>(methods.size() + dynamicMethods.length);
-        for (var i = 0; i < dynamicMethods.length; i++) {
-            methodMap.put(dynamicMethods[i], LuaMethod.DYNAMIC.get(i));
-        }
-        for (var method : methods) {
-            methodMap.put(method.name(), method.method());
-        }
     }
 
     public Object[] call(String name, Object... args) throws LuaException {

projects/core/src/test/java/dan200/computercraft/core/asm/GeneratorTest.java

@@ -7,6 +7,8 @@ package dan200.computercraft.core.asm;
 import dan200.computercraft.api.lua.*;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.core.computer.ComputerSide;
+import dan200.computercraft.core.methods.LuaMethod;
+import dan200.computercraft.core.methods.NamedMethod;
 import org.hamcrest.Matcher;
 import org.junit.jupiter.api.Test;
 
@@ -21,9 +23,11 @@ import static org.hamcrest.Matchers.*;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 public class GeneratorTest {
+    private static final Generator<LuaMethod> GENERATOR = LuaMethodSupplier.GENERATOR;
+
     @Test
     public void testBasic() {
-        var methods = LuaMethod.GENERATOR.getMethods(Basic.class);
+        var methods = GENERATOR.getMethods(Basic.class);
         assertThat(methods, contains(
             allOf(
                 named("go"),
@@ -34,48 +38,48 @@ public class GeneratorTest {
 
     @Test
     public void testIdentical() {
-        var methods = LuaMethod.GENERATOR.getMethods(Basic.class);
+        var methods = GENERATOR.getMethods(Basic.class);
-        var methods2 = LuaMethod.GENERATOR.getMethods(Basic.class);
+        var methods2 = GENERATOR.getMethods(Basic.class);
         assertThat(methods, sameInstance(methods2));
     }
 
     @Test
     public void testIdenticalMethods() {
-        var methods = LuaMethod.GENERATOR.getMethods(Basic.class);
+        var methods = GENERATOR.getMethods(Basic.class);
-        var methods2 = LuaMethod.GENERATOR.getMethods(Basic2.class);
+        var methods2 = GENERATOR.getMethods(Basic2.class);
         assertThat(methods, contains(named("go")));
         assertThat(methods.get(0).method(), sameInstance(methods2.get(0).method()));
     }
 
     @Test
     public void testEmptyClass() {
-        assertThat(LuaMethod.GENERATOR.getMethods(Empty.class), is(empty()));
+        assertThat(GENERATOR.getMethods(Empty.class), is(empty()));
     }
 
     @Test
     public void testNonPublicClass() {
-        assertThat(LuaMethod.GENERATOR.getMethods(NonPublic.class), is(empty()));
+        assertThat(GENERATOR.getMethods(NonPublic.class), is(empty()));
     }
 
     @Test
     public void testNonInstance() {
-        assertThat(LuaMethod.GENERATOR.getMethods(NonInstance.class), is(empty()));
+        assertThat(GENERATOR.getMethods(NonInstance.class), is(empty()));
     }
 
     @Test
     public void testIllegalThrows() {
-        assertThat(LuaMethod.GENERATOR.getMethods(IllegalThrows.class), is(empty()));
+        assertThat(GENERATOR.getMethods(IllegalThrows.class), is(empty()));
     }
 
     @Test
     public void testCustomNames() {
-        var methods = LuaMethod.GENERATOR.getMethods(CustomNames.class);
+        var methods = GENERATOR.getMethods(CustomNames.class);
         assertThat(methods, contains(named("go1"), named("go2")));
     }
 
     @Test
     public void testArgKinds() {
-        var methods = LuaMethod.GENERATOR.getMethods(ArgKinds.class);
+        var methods = GENERATOR.getMethods(ArgKinds.class);
         assertThat(methods, containsInAnyOrder(
             named("objectArg"), named("intArg"), named("optIntArg"),
             named("context"), named("arguments")
@@ -84,7 +88,7 @@ public class GeneratorTest {
 
     @Test
     public void testEnum() throws LuaException {
-        var methods = LuaMethod.GENERATOR.getMethods(EnumMethods.class);
+        var methods = GENERATOR.getMethods(EnumMethods.class);
         assertThat(methods, containsInAnyOrder(named("getEnum"), named("optEnum")));
 
         assertThat(apply(methods, new EnumMethods(), "getEnum", "front"), one(is("FRONT")));
@@ -95,7 +99,7 @@ public class GeneratorTest {
 
     @Test
     public void testMainThread() throws LuaException {
-        var methods = LuaMethod.GENERATOR.getMethods(MainThread.class);
+        var methods = GENERATOR.getMethods(MainThread.class);
         assertThat(methods, contains(allOf(
             named("go"),
             contramap(is(false), "non-yielding", NamedMethod::nonYielding)
@@ -107,7 +111,7 @@ public class GeneratorTest {
 
     @Test
     public void testUnsafe() {
-        var methods = LuaMethod.GENERATOR.getMethods(Unsafe.class);
+        var methods = GENERATOR.getMethods(Unsafe.class);
         assertThat(methods, contains(named("withUnsafe")));
     }
 

projects/core/src/test/java/dan200/computercraft/core/asm/MethodTest.java

@@ -10,6 +10,7 @@ import dan200.computercraft.api.peripheral.IDynamicPeripheral;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.computer.ComputerBootstrap;
 import dan200.computercraft.core.computer.ComputerSide;
+import dan200.computercraft.core.methods.ObjectSource;
 import org.junit.jupiter.api.Test;
 
 import javax.annotation.Nullable;

projects/fabric/src/main/java/dan200/computercraft/shared/peripheral/generic/GenericPeripheralProvider.java

@@ -11,11 +11,15 @@ import net.minecraft.core.Direction;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nullable;
 import java.util.List;
 
 public class GenericPeripheralProvider {
+    private static final Logger LOG = LoggerFactory.getLogger(GenericPeripheralProvider.class);
+
     interface Lookup<T> {
         @Nullable
         T find(Level world, BlockPos pos, BlockState state, @Nullable BlockEntity blockEntity, Direction context);
@@ -29,7 +33,13 @@ public class GenericPeripheralProvider {
     public static IPeripheral getPeripheral(Level level, BlockPos pos, Direction side, @Nullable BlockEntity blockEntity) {
         if (blockEntity == null) return null;
 
-        var builder = new GenericPeripheralBuilder();
+        var server = level.getServer();
+        if (server == null) {
+            LOG.warn("Fetching peripherals on a non-server level {}.", level, new IllegalStateException("Fetching peripherals on a non-server level."));
+            return null;
+        }
+
+        var builder = new GenericPeripheralBuilder(server);
         builder.addMethods(blockEntity);
 
         for (var lookup : lookups) {

projects/forge/src/main/java/dan200/computercraft/shared/peripheral/generic/GenericPeripheralProvider.java

@@ -11,12 +11,16 @@ import net.minecraft.core.Direction;
 import net.minecraft.world.level.Level;
 import net.minecraftforge.common.capabilities.Capability;
 import net.minecraftforge.common.util.NonNullConsumer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nullable;
 import java.util.ArrayList;
 import java.util.Objects;
 
 public class GenericPeripheralProvider {
+    private static final Logger LOG = LoggerFactory.getLogger(GenericPeripheralProvider.class);
+
     private static final ArrayList<Capability<?>> capabilities = new ArrayList<>();
 
     public static synchronized void addCapability(Capability<?> capability) {
@@ -29,7 +33,13 @@ public class GenericPeripheralProvider {
         var blockEntity = level.getBlockEntity(pos);
         if (blockEntity == null) return null;
 
-        var builder = new GenericPeripheralBuilder();
+        var server = level.getServer();
+        if (server == null) {
+            LOG.warn("Fetching peripherals on a non-server level {}.", level, new IllegalStateException("Fetching peripherals on a non-server level."));
+            return null;
+        }
+
+        var builder = new GenericPeripheralBuilder(server);
         builder.addMethods(blockEntity);
 
         for (var capability : capabilities) {