Allow custom selector types to be defined (#4259)

src/main/java/net/minecraftforge/common/command/SelectorHandler.java

@@ -0,0 +1,52 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.common.command;
+
+import java.util.List;
+
+import net.minecraft.command.CommandException;
+import net.minecraft.command.ICommandSender;
+import net.minecraft.entity.Entity;
+
+/**
+ * Handler for custom types of selectors registered with {@link SelectorHandlerManager}
+ */
+public interface SelectorHandler
+{
+    /**
+     * Returns a {@link List} of {@link Entity Entities} of class {@code targetClass} ({@code T}) represented by {@code token}<br>
+     * <b>Note:</b> If {@code token} does not match the overall syntax defined by {@link #isSelector}, this method should return an empty list.
+     * For any other error, an exception should be thrown
+     * 
+     * @param sender The {@link ICommandSender} that initiated the query
+     */
+    public <T extends Entity> List<T> matchEntities(ICommandSender sender, String token, Class<? extends T> targetClass) throws CommandException;
+
+    /**
+     * Returns whether the selector string potentially matches multiple entities
+     */
+    public boolean matchesMultiplePlayers(String selectorStr) throws CommandException;
+
+    /**
+     * Returns whether the string matches the overall syntax of the selector<br>
+     * <b>Note:</b> If this returns {@code false}, {@link #matchEntities} should return an empty list
+     */
+    public boolean isSelector(String selectorStr);
+}

src/main/java/net/minecraftforge/common/command/SelectorHandlerManager.java

@@ -0,0 +1,141 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.common.command;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.NavigableMap;
+import java.util.TreeMap;
+
+import org.apache.commons.lang3.ArrayUtils;
+
+import net.minecraft.command.CommandException;
+import net.minecraft.command.EntitySelector;
+import net.minecraft.command.ICommandSender;
+import net.minecraft.entity.Entity;
+import net.minecraftforge.fml.common.Loader;
+
+/**
+ * Allows registration of custom selector types by assigning a {@link SelectorHandler} to a prefix
+ * This class handles calls to the {@link EntitySelector} methods {@link EntitySelector#matchEntities matchEntities},
+ * {@link EntitySelector#matchesMultiplePlayers matchesMultiplePlayers} and {@link EntitySelector#isSelector isSelector}.<br>
+ * The calls are delegated to the handler with the longest matching prefix.<br>
+ * <br>
+ * <b>Note:</b> If you register a {@link SelectorHandler} to a broader domain (not just a single selector), you should take care of possible shadowing conflicts yourself.
+ * For this you can use the information provided by {@link #selectorHandlers} and {@link #registeringMods}.
+ */
+public class SelectorHandlerManager
+{
+    private SelectorHandlerManager()
+    {
+    }
+
+    //the ordering is reversed such that longer prefixes appear before their shorter substrings
+    public static final NavigableMap<String, SelectorHandler> selectorHandlers = new TreeMap<String, SelectorHandler>(Collections.<String> reverseOrder());
+    public static final NavigableMap<String, String> registeringMods = new TreeMap<String, String>(Collections.<String> reverseOrder());
+
+    private static final SelectorHandler vanillaHandler = new SelectorHandler()
+    {
+        @Override
+        public <T extends Entity> List<T> matchEntities(final ICommandSender sender, final String token, final Class<? extends T> targetClass) throws CommandException
+        {
+            return EntitySelector.matchEntitiesDefault(sender, token, targetClass);
+        }
+
+        @Override
+        public boolean matchesMultiplePlayers(final String selectorStr) throws CommandException
+        {
+            return EntitySelector.matchesMultiplePlayersDefault(selectorStr);
+        }
+
+        @Override
+        public boolean isSelector(final String selectorStr)
+        {
+            return EntitySelector.isSelectorDefault(selectorStr);
+        }
+    };
+
+    static
+    {
+        for (final String prefix : ArrayUtils.toArray("@p", "@a", "@r", "@e", "@s"))
+        {
+            selectorHandlers.put(prefix, vanillaHandler);
+            registeringMods.put(prefix, "minecraft");
+        }
+    }
+
+    /**
+     * Registers a new {@link SelectorHandler} for {@code prefix}.<br>
+     *
+     * @param prefix The domain the specified {@code handler} is registered for.
+     * If you want to register just a single selector, {@code prefix} has the form '@{selectorName}'
+     */
+    public static void register(final String prefix, final SelectorHandler handler)
+    {
+        if (prefix.isEmpty())
+        {
+            throw new IllegalArgumentException("Prefix must not be empty");
+        }
+
+        final String modId = Loader.instance().activeModContainer().getModId();
+
+        selectorHandlers.put(prefix, handler);
+        registeringMods.put(prefix, modId);
+    }
+
+    /**
+     * Returns the best matching handler for the given string. Defaults to the vanilla handler if no prefix applies
+     */
+    public static SelectorHandler getHandler(final String selectorStr)
+    {
+        if (!selectorStr.isEmpty())
+        {
+            for (final Entry<String, SelectorHandler> handler : selectorHandlers.subMap(selectorStr, true, selectorStr.substring(0, 1), true).entrySet())
+            {
+                if (selectorStr.startsWith(handler.getKey()))
+                {
+                    return handler.getValue();
+                }
+            }
+        }
+
+        return vanillaHandler;
+    }
+
+    //These methods are called by the vanilla methods
+
+    public static <T extends Entity> List<T> matchEntities(final ICommandSender sender, final String token, final Class<? extends T> targetClass) throws CommandException
+    {
+        return getHandler(token).matchEntities(sender, token, targetClass);
+    }
+
+    public static boolean matchesMultiplePlayers(final String selectorStr) throws CommandException
+    {
+        return getHandler(selectorStr).matchesMultiplePlayers(selectorStr);
+    }
+
+    public static boolean isSelector(final String selectorStr)
+    {
+        return getHandler(selectorStr).isSelector(selectorStr);
+    }
+}