Add CommandRegistrationHandler

src/main/java/com/intellectualsites/commands/CommandTree.java

@@ -28,6 +28,7 @@ import com.google.common.collect.Lists;
 import com.intellectualsites.commands.components.CommandComponent;
 import com.intellectualsites.commands.components.StaticComponent;
 import com.intellectualsites.commands.exceptions.NoSuchCommandException;
+import com.intellectualsites.commands.internal.CommandRegistrationHandler;
 import com.intellectualsites.commands.parser.ComponentParseResult;
 import com.intellectualsites.commands.sender.CommandSender;
 
@@ -44,19 +45,22 @@ import java.util.stream.Collectors;
 public class CommandTree<C extends CommandSender> {
 
     private final Node<CommandComponent<?>> internalTree = new Node<>(null);
+    private final CommandRegistrationHandler commandRegistrationHandler;
 
-    private CommandTree() {
+    private CommandTree(@Nonnull final CommandRegistrationHandler commandRegistrationHandler) {
+        this.commandRegistrationHandler = commandRegistrationHandler;
     }
 
     /**
      * Create a new command tree instance
      *
-     * @param <C> Command sender type
+     * @param commandRegistrationHandler Command registration handler
+     * @param <C>                        Command sender type
      * @return New command tree
      */
     @Nonnull
-    public static <C extends CommandSender> CommandTree<C> newTree() {
-        return new CommandTree<>();
+    public static <C extends CommandSender> CommandTree<C> newTree(@Nonnull final CommandRegistrationHandler commandRegistrationHandler) {
+        return new CommandTree<>(commandRegistrationHandler);
     }
 
     public Optional<Command> parse(@Nonnull final C commandSender, @Nonnull final String[] args) throws NoSuchCommandException {
@@ -170,6 +174,8 @@ public class CommandTree<C extends CommandSender> {
         if (node.getValue() != null) {
             node.getValue().setOwningCommand(command);
         }
+        // Verify the command structure every time we add a new command
+        this.verifyAndRegister();
     }
 
     /**
@@ -182,7 +188,6 @@ public class CommandTree<C extends CommandSender> {
             if (!(commandComponent instanceof StaticComponent)) {
                 throw new IllegalStateException("Top level command component cannot be a variable");
             }
-            // TODO: Register in the command handler
         });
         this.checkAmbiguity(this.internalTree);
         // Verify that all leaf nodes have command registered
@@ -190,8 +195,11 @@ public class CommandTree<C extends CommandSender> {
             if (leaf.getOwningCommand() == null) {
                 // TODO: Custom exception type
                 throw new IllegalStateException("Leaf node does not have associated owning command");
+            } else {
+                this.commandRegistrationHandler.registerCommand(leaf.getOwningCommand());
             }
         });
+        /* TODO: Figure out a way to register all combinations along a command component path */
     }
 
     private void checkAmbiguity(@Nonnull final Node<CommandComponent<?>> node) {

src/main/java/com/intellectualsites/commands/internal/CommandRegistrationHandler.java

@@ -0,0 +1,64 @@
+//
+// MIT License
+//
+// Copyright (c) 2020 IntellectualSites
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+package com.intellectualsites.commands.internal;
+
+import com.intellectualsites.commands.Command;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Utility that registers commands natively for whatever
+ * platform the library is used in. This can do nothing, if
+ * the target platform does not have its own concept of commands
+ */
+@FunctionalInterface public interface CommandRegistrationHandler {
+
+    /**
+     * Command registration handler that does nothing
+     */
+    NullCommandRegistrationHandler NULL_COMMAND_REGISTRATION_HANDLER = new NullCommandRegistrationHandler();
+
+    /**
+     * Attempt to register the command
+     *
+     * @param command Command to register
+     * @return {@code true} if the command was registered successfully,
+     *         else {@code false}
+     */
+    boolean registerCommand(@Nonnull final Command command);
+
+
+    final class NullCommandRegistrationHandler implements CommandRegistrationHandler {
+
+        private NullCommandRegistrationHandler() {
+        }
+
+        @Override
+        public boolean registerCommand(@Nonnull final Command command) {
+            return true;
+        }
+
+    }
+
+}