Support list/repeating arguments

src/main/java/com/mojang/brigadier/builder/ListArgumentBuilder.java

@@ -0,0 +1,26 @@
+package com.mojang.brigadier.builder;
+
+import com.mojang.brigadier.arguments.ArgumentType;
+import com.mojang.brigadier.tree.ArgumentCommandNode;
+import com.mojang.brigadier.tree.CommandNode;
+import com.mojang.brigadier.tree.ListCommandNode;
+
+public class ListArgumentBuilder<S, T> extends RequiredArgumentBuilder<S, T> {
+    protected ListArgumentBuilder(String name, ArgumentType<T> type) {
+        super(name, type);
+    }
+
+    public static <S, T> ListArgumentBuilder<S, T> list(final String name, final ArgumentType<T> type) {
+        return new ListArgumentBuilder<>(name, type);
+    }
+
+    public ArgumentCommandNode<S, T> build() {
+        final ListCommandNode<S, T> result = new ListCommandNode<>(getName(), getType(), getCommand(), getRequirement(), getRedirect(), getRedirectModifier(), isFork(), getSuggestionsProvider());
+
+        for (final CommandNode<S> argument : getArguments()) {
+            result.addChild(argument);
+        }
+
+        return result;
+    }
+}

src/main/java/com/mojang/brigadier/builder/RequiredArgumentBuilder.java

@@ -13,7 +13,7 @@ public class RequiredArgumentBuilder<S, T> extends ArgumentBuilder<S, RequiredAr
     private final ArgumentType<T> type;
     private SuggestionProvider<S> suggestionsProvider = null;
 
-    private RequiredArgumentBuilder(final String name, final ArgumentType<T> type) {
+    protected RequiredArgumentBuilder(final String name, final ArgumentType<T> type) {
         this.name = name;
         this.type = type;
     }

src/main/java/com/mojang/brigadier/tree/ListCommandNode.java

@@ -0,0 +1,37 @@
+package com.mojang.brigadier.tree;
+
+import com.mojang.brigadier.Command;
+import com.mojang.brigadier.RedirectModifier;
+import com.mojang.brigadier.StringReader;
+import com.mojang.brigadier.arguments.ArgumentType;
+import com.mojang.brigadier.context.CommandContextBuilder;
+import com.mojang.brigadier.context.ParsedArgument;
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import com.mojang.brigadier.suggestion.SuggestionProvider;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Predicate;
+
+public class ListCommandNode<S, T> extends ArgumentCommandNode<S, T> {
+    public ListCommandNode(String name, ArgumentType<T> type, Command<S> command, Predicate<S> requirement, CommandNode<S> redirect, RedirectModifier<S> modifier, boolean forks, SuggestionProvider<S> customSuggestions) {
+        super(name, type, command, requirement, redirect, modifier, forks, customSuggestions);
+    }
+
+    @Override
+    public void parse(StringReader reader, CommandContextBuilder<S> contextBuilder) throws CommandSyntaxException {
+        final int start = reader.getCursor();
+        final T result = getType().parse(reader);
+
+        ParsedArgument<S, List<T>> parsed = (ParsedArgument<S, List<T>>) contextBuilder.getArguments().get(getName());
+        if (parsed == null) {
+            parsed = new ParsedArgument<>(start, reader.getCursor(), new ArrayList<>());
+        } else {
+            parsed = new ParsedArgument<>(parsed.getRange().getStart(), reader.getCursor(), parsed.getResult());
+        }
+        parsed.getResult().add(result);
+
+        contextBuilder.withArgument(getName(), parsed);
+        contextBuilder.withNode(this, parsed.getRange());
+    }
+}