From 901d6bf0ca52446f55ce031e03fea92bb869b0d1 Mon Sep 17 00:00:00 2001
From: Hugo Manrique <contact@hugmanrique.me>
Date: Sat, 3 Apr 2021 21:53:22 +0200
Subject: [PATCH] Consider arguments when literal is impermissible

Fixes https://github.com/Mojang/brigadier/issues/87
---
 .../mojang/brigadier/tree/CommandNode.java    | 11 ++++-
 .../brigadier/CommandDispatcherTest.java      | 42 +++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/src/main/java/com/mojang/brigadier/tree/CommandNode.java b/src/main/java/com/mojang/brigadier/tree/CommandNode.java
index 47f8e3db..3dd78097 100644
--- a/src/main/java/com/mojang/brigadier/tree/CommandNode.java
+++ b/src/main/java/com/mojang/brigadier/tree/CommandNode.java
@@ -14,6 +14,7 @@
 import com.mojang.brigadier.suggestion.Suggestions;
 import com.mojang.brigadier.suggestion.SuggestionsBuilder;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
@@ -160,7 +161,15 @@ public Collection<? extends CommandNode<S>> getRelevantNodes(final StringReader
             input.setCursor(cursor);
             final LiteralCommandNode<S> literal = literals.get(text);
             if (literal != null) {
-                return Collections.singleton(literal);
+                final int argumentsCount = arguments.size();
+                if (argumentsCount == 0) {
+                    return Collections.singletonList(literal);
+                } else {
+                    final Collection<CommandNode<S>> nodes = new ArrayList<>(argumentsCount + 1);
+                    nodes.add(literal); // literals have priority over arguments
+                    nodes.addAll(arguments.values());
+                    return nodes;
+                }
             } else {
                 return arguments.values();
             }
diff --git a/src/test/java/com/mojang/brigadier/CommandDispatcherTest.java b/src/test/java/com/mojang/brigadier/CommandDispatcherTest.java
index f2bab4a9..4b62d741 100644
--- a/src/test/java/com/mojang/brigadier/CommandDispatcherTest.java
+++ b/src/test/java/com/mojang/brigadier/CommandDispatcherTest.java
@@ -4,6 +4,7 @@
 package com.mojang.brigadier;
 
 import com.google.common.collect.Lists;
+import com.mojang.brigadier.arguments.StringArgumentType;
 import com.mojang.brigadier.context.CommandContext;
 import com.mojang.brigadier.context.CommandContextBuilder;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
@@ -256,6 +257,47 @@ public void testExecuteAmbiguiousParentSubcommandViaRedirect() throws Exception
         verify(command, never()).run(any());
     }
 
+    @SuppressWarnings("unchecked")
+    @Test
+    public void testPreferExecuteLiteralOverArguments() throws Exception {
+        final Command<Object> literalCommand = mock(Command.class);
+        when(literalCommand.run(any())).thenReturn(100);
+
+        subject.register(
+            literal("test")
+                .then(
+                    argument("incorrect", StringArgumentType.word())
+                        .executes(command)
+                )
+                .then(
+                    literal("hello")
+                        .executes(literalCommand)
+                )
+        );
+
+        assertThat(subject.execute("test hello", source), is(100));
+        verify(literalCommand).run(any(CommandContext.class));
+        verify(command, never()).run(any());
+    }
+
+    @SuppressWarnings("unchecked")
+    @Test
+    public void testExecuteAmbiguousArgumentIfImpermissibleLiteral() throws Exception {
+        subject.register(literal("foo")
+            .then(
+                literal("bar")
+                    .requires(source -> false)
+            )
+            .then(
+                argument("argument", StringArgumentType.word())
+                    .executes(command)
+            )
+        );
+
+        assertThat(subject.execute("foo bar", source), is(42));
+        verify(command).run(any(CommandContext.class));
+    }
+
     @SuppressWarnings("unchecked")
     @Test
     public void testExecuteRedirectedMultipleTimes() throws Exception {