Add a method for checking peripheral equality

This feels a little overkill, but nice to standardise how this code
looks.

There's a bit of me which wonders if we should remove
IPeripheral.equals, and just use Object.equals, but I do also kinda like
the explicitness of the current interface? IDK.

projects/common/src/main/java/dan200/computercraft/impl/network/wired/WiredNetworkChangeImpl.java

@@ -6,6 +6,7 @@
 
 import dan200.computercraft.api.network.wired.WiredNetworkChange;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.core.util.PeripheralHelpers;
 
 import java.util.Collections;
 import java.util.HashMap;
@@ -52,7 +53,7 @@ static WiredNetworkChangeImpl changeOf(Map<String, IPeripheral> oldPeripherals,
             var oldValue = entry.getValue();
             if (newPeripherals.containsKey(oldKey)) {
                 var rightValue = added.get(oldKey);
-                if (oldValue.equals(rightValue)) {
+                if (PeripheralHelpers.equals(oldValue, rightValue)) {
                     added.remove(oldKey);
                 } else {
                     removed.put(oldKey, oldValue);

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

@@ -6,6 +6,7 @@
 
 import dan200.computercraft.api.ComputerCraftTags;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.core.util.PeripheralHelpers;
 import dan200.computercraft.shared.computer.core.ServerContext;
 import dan200.computercraft.shared.platform.ComponentAccess;
 import net.minecraft.core.BlockPos;
@@ -65,7 +66,7 @@ public boolean attach(Level world, BlockPos origin, Direction direction) {
                 this.id = ServerContext.get(assertNonNull(world.getServer())).getNextId("peripheral." + type);
             }
 
-            return oldPeripheral == null || !oldPeripheral.equals(peripheral);
+            return !PeripheralHelpers.equals(oldPeripheral, peripheral);
         }
     }
 

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

@@ -218,8 +218,7 @@ public void attach(IComputerAccess computer) {
 
         ConcurrentMap<String, RemotePeripheralWrapper> wrappers;
         synchronized (peripheralWrappers) {
-            wrappers = peripheralWrappers.get(computer);
-            if (wrappers == null) peripheralWrappers.put(computer, wrappers = new ConcurrentHashMap<>());
+            wrappers = peripheralWrappers.computeIfAbsent(computer, k -> new ConcurrentHashMap<>());
         }
 
         synchronized (modem.getRemotePeripherals()) {

projects/common/src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java

@@ -14,6 +14,7 @@
 import dan200.computercraft.api.turtle.TurtleSide;
 import dan200.computercraft.api.upgrades.UpgradeData;
 import dan200.computercraft.core.computer.ComputerSide;
+import dan200.computercraft.core.util.PeripheralHelpers;
 import dan200.computercraft.impl.TurtleUpgrades;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
 import dan200.computercraft.shared.computer.core.ServerComputer;
@@ -589,7 +590,7 @@ private void updatePeripherals(ServerComputer serverComputer) {
             }
 
             var existing = peripherals.get(side);
-            if (existing == peripheral || (existing != null && peripheral != null && existing.equals(peripheral))) {
+            if (PeripheralHelpers.equals(existing, peripheral)) {
                 // If the peripheral is the same, just use that.
                 peripheral = existing;
             } else {

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

@@ -11,6 +11,7 @@
 import dan200.computercraft.core.filesystem.FileSystem;
 import dan200.computercraft.core.metrics.MetricsObserver;
 import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.core.util.PeripheralHelpers;
 import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 
@@ -268,9 +269,7 @@ public void setPeripheral(ComputerSide side, @Nullable IPeripheral peripheral) {
         synchronized (peripherals) {
             var index = side.ordinal();
             var existing = peripherals[index];
-            if ((existing == null && peripheral != null) ||
-                (existing != null && peripheral == null) ||
-                (existing != null && !existing.equals(peripheral))) {
+            if (!PeripheralHelpers.equals(existing, peripheral)) {
                 peripherals[index] = peripheral;
                 if (peripheralListener != null) peripheralListener.onPeripheralChanged(side, peripheral);
             }

projects/core/src/main/java/dan200/computercraft/core/util/PeripheralHelpers.java

@@ -0,0 +1,29 @@
+// SPDX-FileCopyrightText: 2023 The CC: Tweaked Developers
+//
+// SPDX-License-Identifier: MPL-2.0
+
+package dan200.computercraft.core.util;
+
+import dan200.computercraft.api.peripheral.IPeripheral;
+
+import javax.annotation.Nullable;
+
+/**
+ * Utilities for working with {@linkplain IPeripheral peripherals}.
+ */
+public final class PeripheralHelpers {
+    private PeripheralHelpers() {
+    }
+
+    /**
+     * Determine if two peripherals are equal. This is equivalent to {@link java.util.Objects#equals(Object, Object)},
+     * but using {@link IPeripheral#equals(IPeripheral)} instead.
+     *
+     * @param a The first peripheral.
+     * @param b The second peripheral.
+     * @return If the two peripherals are equal.
+     */
+    public static boolean equals(@Nullable IPeripheral a, @Nullable IPeripheral b) {
+        return a == b || (a != null && b != null && a.equals(b));
+    }
+}