bump version to 0.38-SNAPSHOT + pass input to SuggestionProvider + rewrite command parsing + ...

MODULE.bazel

@@ -1,8 +1,6 @@
 bazel_dep(name = "rules_java", version = "9.7.0")
 bazel_dep(name = "rules_jvm_external", version = "7.1")
 
-VERSION = "0.36-SNAPSHOT"
-
 git_override(
     module_name = "rules_jvm_external",
     remote = "http://forge.kentoj.de/scrow/rules_jvm_external.git",

bukkit/src/main/java/de/kentoj/kencommandapi/suggestionprovider/PlayerSuggestionProvider.java

@@ -8,7 +8,7 @@ import java.util.List;
 
 public final class PlayerSuggestionProvider<T> implements SuggestionProvider<T> {
     @Override
-    public List<String> suggest(T __) {
+    public List<String> suggest(T __, String ___) {
         return Bukkit.getOnlinePlayers().stream()
                 .map(Player::getName)
                 .toList();

bukkit/src/main/java/de/kentoj/kencommandapi/type/OfflinePlayerArgumentType.java

@@ -1,5 +1,7 @@
 package de.kentoj.kencommandapi.type;
 
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
 import de.kentoj.kencommandapi.api.argument.ArgumentType;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 import de.kentoj.kencommandapi.suggestionprovider.PlayerSuggestionProvider;
@@ -11,20 +13,16 @@ import java.util.UUID;
 public class OfflinePlayerArgumentType<T> implements ArgumentType<T, OfflinePlayer> {
 
     @Override
-    public OfflinePlayer parseInputUnchecked(String string) {
+    public Result<OfflinePlayer, String> parseInputUnchecked(String string) {
         // UUIDs are always 36 chars
-        if (string.length() == 36) {
+        if (string.length() == 36)
-            try {
+            return Results.ofCallable(() -> Bukkit.getOfflinePlayer(UUID.fromString(string)))
-                return Bukkit.getOfflinePlayer(UUID.fromString(string));
+                    .mapFailure(_ -> "Invalid UUID.");
-            } catch (IllegalArgumentException ex) {
-                throw new IllegalArgumentException("Invalid UUID");
-            }
-        }
 
-        OfflinePlayer player = Bukkit.getPlayerExact(string);
+        var player = Bukkit.getPlayerExact(string);
         if (player == null || (!player.hasPlayedBefore() && !player.isOnline()))
-            throw new IllegalArgumentException("Player not found");
+            return Results.failure("Player not found.");
-        return player;
+        return Results.success(player);
     }
 
     @Override

bukkit/src/main/java/de/kentoj/kencommandapi/type/PlayerArgumentType.java

@@ -1,18 +1,32 @@
 package de.kentoj.kencommandapi.type;
 
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
 import de.kentoj.kencommandapi.api.argument.ArgumentType;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 import de.kentoj.kencommandapi.suggestionprovider.PlayerSuggestionProvider;
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 
+import java.util.UUID;
+
 public class PlayerArgumentType<T> implements ArgumentType<T, Player> {
 
     @Override
-    public Player parseInputUnchecked(String string) {
+    public Result<Player, String> parseInputUnchecked(String input) {
-        var player = Bukkit.getPlayer(string);
+        // UUIDs are always 36 chars
-        if (player == null) throw new IllegalArgumentException("player not online");
+        Player player;
-        return player;
+        if (input.length() == 36) {
+            try {
+                player = Bukkit.getPlayer(UUID.fromString(input));
+            } catch (IllegalArgumentException _) {
+                return Results.failure("Invalid UUID.");
+            }
+        } else {
+            player = Bukkit.getPlayer(input);
+        }
+
+        return Results.ofNullable(player, "Player not online.");
     }
 
     @Override

bukkit/src/main/java/de/kentoj/kencommandapi/type/WorldArgumentType.java

@@ -1,5 +1,7 @@
 package de.kentoj.kencommandapi.type;
 
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
 import de.kentoj.kencommandapi.api.argument.ArgumentType;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 import org.bukkit.Bukkit;
@@ -10,21 +12,24 @@ import java.util.stream.Stream;
 
 public class WorldArgumentType<T> implements ArgumentType<T, World> {
     @Override
-    public World parseInputUnchecked(String input) throws IllegalArgumentException {
+    public Result<World, String> parseInputUnchecked(String input) throws IllegalArgumentException {
-        var world = Bukkit.getWorld(input);
+        World world;
-        if (world == null && input.length() == 36) {
+        if (input.length() == 36) {
             try {
-                return Bukkit.getWorld(UUID.fromString(input));
+                world = Bukkit.getWorld(UUID.fromString(input));
             } catch (IllegalArgumentException _) {
-                throw new IllegalArgumentException("World not found");
+                return Results.failure("Invalid UUID.");
             }
+        } else {
+            world = Bukkit.getWorld(input);
         }
-        return world;
+
+        return Results.ofNullable(world, "World not found");
     }
 
     @Override
     public SuggestionProvider<T> getDefaultSuggestionProvider() {
-        return _ -> Stream.concat(
+        return (_, _) -> Stream.concat(
                 Bukkit.getWorlds().stream().map(World::getName),
                 Bukkit.getWorlds().stream().map(w -> w.getUID().toString())
         ).toList();

core/BUILD

@@ -14,4 +14,8 @@ java_export(
         artifact("org.slf4j:slf4j-api"),
         artifact("net.kyori:adventure-api"),
     ],
+    exports = [
+        artifact("com.leakyabstractions:result-api"),
+        artifact("com.leakyabstractions:result"),
+    ],
 )

core/src/main/java/de/kentoj/kencommandapi/api/CommandHandler.java

@@ -1,47 +1,72 @@
 package de.kentoj.kencommandapi.api;
 
+import de.kentoj.kencommandapi.api.literal.Literal;
 import de.kentoj.kencommandapi.api.literal.RootLiteral;
 import de.kentoj.kencommandapi.api.platform.HasPermissionMethod;
 import de.kentoj.kencommandapi.api.platform.SendMessageMethod;
-import de.kentoj.kencommandapi.internal.parser.CommandParseHelper;
+import de.kentoj.kencommandapi.internal.NodeTreeWalker;
-import de.kentoj.kencommandapi.internal.parser.InvocationCommandParser;
+import de.kentoj.kencommandapi.internal.WalkResult;
-import de.kentoj.kencommandapi.internal.parser.SuggestionCommandParser;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Stream;
 
+import static java.util.Objects.requireNonNull;
+
 public class CommandHandler<T> {
 
     private final SendMessageMethod<T> sendMessageMethod;
-    private final InvocationCommandParser<T> invocationParser;
+    private final NodeTreeWalker<T> nodeTreeWalker;
-    private final SuggestionCommandParser<T> suggestionParser;
 
     public CommandHandler(SendMessageMethod<T> sendMessageMethod, HasPermissionMethod<T> hasPermissionMethod) {
         this.sendMessageMethod = sendMessageMethod;
-        var parseHelper = new CommandParseHelper<>(hasPermissionMethod);
+        nodeTreeWalker = new NodeTreeWalker<>(hasPermissionMethod);
-        invocationParser = new InvocationCommandParser<>(parseHelper);
-        suggestionParser = new SuggestionCommandParser<>(parseHelper);
     }
 
     public void invoke(RootLiteral<T> rootLiteral, T sender, Stream<String> args) {
-        invocationParser.parse(rootLiteral, sender, args.toList().iterator())
+        var walkResult = nodeTreeWalker.walk(rootLiteral, sender, args.iterator());
-                .ifSuccessOrElse(data -> exec(rootLiteral, data),
+        if (!walkResult.isValidUsage()) {
-                        err -> sendMessageMethod.send(sender, rootLiteral.messageStyle().err(err)));
+            sendMessageMethod.send(sender, rootLiteral.messageStyle().err(walkResult.message()));
-    }
+            return;
+        }
 
-    private void exec(RootLiteral<T> rootLiteral, InvocationCommandParser<T>.ExecutionData data) {
+        requireNonNull(walkResult.lastLiteral().executor())
-        var ctx = data.context();
+                .execute(walkResult.ctx())
-        data.executor().execute(ctx)
                 .whenComplete((result, ex) -> {
                     if (ex != null)
-                        sendMessageMethod.send(ctx.sender(), rootLiteral.messageStyle().exception(ex));
+                        sendMessageMethod.send(sender, rootLiteral.messageStyle().exception(ex));
                     result.ifFailure(err ->
-                            sendMessageMethod.send(ctx.sender(), rootLiteral.messageStyle().err(err)));
+                            sendMessageMethod.send(sender, rootLiteral.messageStyle().err(err)));
                 });
     }
 
-    public List<String> getSuggestions(RootLiteral<T> rootNode, T sender, String[] args, boolean trailingSpace) {
+    public List<String> getSuggestions(RootLiteral<T> rootLiteral, T sender, String[] args, boolean trailingSpace) {
-        return suggestionParser.suggest(rootNode, sender, Arrays.stream(args).iterator(), trailingSpace);
+        var walkResult = nodeTreeWalker.walk(rootLiteral, sender, Arrays.stream(args).iterator());
+        Stream<String> stream;
+        String input = null;
+        switch (walkResult) {
+            case WalkResult.LiteralUnknown<T> res -> {
+                stream = res.lastLiteral().literals().stream().map(Literal::names).flatMap(Arrays::stream);
+                input = res.input();
+            }
+            case WalkResult.ArgumentIllegal<T> res -> {
+                stream = res.arg().suggestionProvider().suggest(sender, res.input()).stream();
+                input = res.input();
+            }
+            case WalkResult.LiteralExpected<T> res when trailingSpace ->
+                    stream = res.lastLiteral().literals().stream().map(Literal::names).flatMap(Arrays::stream);
+            case WalkResult.ArgumentExpected<T> res when trailingSpace ->
+                    stream = res.arg().suggestionProvider().suggest(sender, "").stream();
+            default -> {
+                return Collections.emptyList();
+            }
+        }
+
+        if (input == null) return stream.toList();
+        final var finalInput = input;
+        return stream
+                .filter(s -> s.startsWith(finalInput))
+                .toList();
     }
 }

core/src/main/java/de/kentoj/kencommandapi/api/argument/ArgumentType.java

@@ -1,5 +1,6 @@
 package de.kentoj.kencommandapi.api.argument;
 
+import com.leakyabstractions.result.api.Result;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 
 import java.util.function.Predicate;
@@ -10,11 +11,10 @@ public interface ArgumentType<T, V> {
      * parses the given input and returns it.
      * Unlike {@link CommandArgumentSpec#parseInput(String)}, this does not check any additional requirements.
      *
-     * @throws IllegalArgumentException if string invalid
      * @see CommandArgumentSpec#parseInput(String)
      * @see CommandArgumentSpecBuilder#withRequirement(Predicate, String)
      */
-    V parseInputUnchecked(String input) throws IllegalArgumentException;
+    Result<V, String> parseInputUnchecked(String input);
 
     /**
      * @see CommandArgumentSpec#suggestionProvider()

core/src/main/java/de/kentoj/kencommandapi/api/argument/CommandArgumentSpec.java

@@ -1,5 +1,6 @@
 package de.kentoj.kencommandapi.api.argument;
 
+import com.leakyabstractions.result.api.Result;
 import de.kentoj.kencommandapi.api.invocation.CommandContext;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 import org.jetbrains.annotations.NotNull;
@@ -18,9 +19,9 @@ public sealed interface CommandArgumentSpec<T, V> permits CommandArgumentSpecImp
     ArgumentType<T, V> type();
 
     /**
-     * @throws IllegalArgumentException if string invalid or if a requirement is not met
+     * @return Result of either the parsed value or a message describing the error
      */
-    V parseInput(String rawInput);
+    Result<V, String> parseInput(String rawInput);
 
     @Nullable Function<CommandContext<T>, V> defaultValueProvider();
 

core/src/main/java/de/kentoj/kencommandapi/api/argument/CommandArgumentSpecImpl.java

@@ -1,5 +1,7 @@
 package de.kentoj.kencommandapi.api.argument;
 
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
 import de.kentoj.kencommandapi.api.invocation.CommandContext;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 import org.jetbrains.annotations.NotNull;
@@ -17,13 +19,15 @@ public record CommandArgumentSpecImpl<T, V>(
 ) implements CommandArgumentSpec<T, V> {
 
     @Override
-    public V parseInput(String rawInput) {
+    public Result<V, String> parseInput(String rawInput) {
-        var parsed = type.parseInputUnchecked(rawInput);
+        var parseResult = type.parseInputUnchecked(rawInput);
+        if (parseResult.hasFailure())
+            return parseResult.mapSuccess(_ -> null);
         for (var requirement : requirements) {
-            if (!requirement.predicate().test(parsed))
+            if (!requirement.predicate().test(parseResult.getSuccess().orElseThrow()))
-                throw new IllegalArgumentException(requirement.message());
+                return Results.failure(requirement.message());
         }
-        return parsed;
+        return parseResult;
     }
 
     @Override

core/src/main/java/de/kentoj/kencommandapi/api/argument/types/BooleanArgumentType.java

@@ -0,0 +1,22 @@
+package de.kentoj.kencommandapi.api.argument.types;
+
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
+import de.kentoj.kencommandapi.api.argument.ArgumentType;
+import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
+
+import java.util.List;
+
+public class BooleanArgumentType<T> implements ArgumentType<T, Boolean> {
+
+    @Override
+    public Result<Boolean, String> parseInputUnchecked(String input) {
+        return Results.ofCallable(() -> Boolean.parseBoolean(input))
+                .mapFailure(_ -> "Must be true or false.");
+    }
+
+    @Override
+    public SuggestionProvider<T> getDefaultSuggestionProvider() {
+        return (_, _) -> List.of("true", "false");
+    }
+}

core/src/main/java/de/kentoj/kencommandapi/api/argument/types/DoubleArgumentType.java

@@ -0,0 +1,19 @@
+package de.kentoj.kencommandapi.api.argument.types;
+
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
+import de.kentoj.kencommandapi.api.argument.ArgumentType;
+import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
+
+public class DoubleArgumentType<T> implements ArgumentType<T, Double> {
+    @Override
+    public Result<Double, String> parseInputUnchecked(String input) {
+        return Results.ofCallable(() -> Double.parseDouble(input))
+                .mapFailure(_ -> "Not a valid double.");
+    }
+
+    @Override
+    public SuggestionProvider<T> getDefaultSuggestionProvider() {
+        return SuggestionProvider.none();
+    }
+}

core/src/main/java/de/kentoj/kencommandapi/api/argument/types/IntegerArgumentType.java

@@ -1,13 +1,16 @@
 package de.kentoj.kencommandapi.api.argument.types;
 
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
 import de.kentoj.kencommandapi.api.argument.ArgumentType;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 
 public class IntegerArgumentType<T> implements ArgumentType<T, Integer> {
 
     @Override
-    public Integer parseInputUnchecked(String string) {
+    public Result<Integer, String> parseInputUnchecked(String string) {
-        return Integer.parseInt(string);
+        return Results.ofCallable(() -> Integer.parseInt(string))
+                .mapFailure(_ -> "Not a number.");
     }
 
     @Override

core/src/main/java/de/kentoj/kencommandapi/api/argument/types/StringArgumentType.java

@@ -1,5 +1,7 @@
 package de.kentoj.kencommandapi.api.argument.types;
 
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
 import de.kentoj.kencommandapi.api.argument.ArgumentType;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 
@@ -10,8 +12,8 @@ public record StringArgumentType<T>(boolean greedy) implements ArgumentType<T, S
     }
 
     @Override
-    public String parseInputUnchecked(String string) {
+    public Result<String, String> parseInputUnchecked(String string) {
-        return string;
+        return Results.success(string);
     }
 
     @Override

core/src/main/java/de/kentoj/kencommandapi/api/suggestion/NoSuggestionProvider.java

@@ -5,7 +5,7 @@ import java.util.List;
 
 class NoSuggestionProvider<T> implements SuggestionProvider<T> {
     @Override
-    public List<String> suggest(T __) {
+    public List<String> suggest(T __, String ___) {
         return Collections.emptyList();
     }
 }

core/src/main/java/de/kentoj/kencommandapi/api/suggestion/SuggestionProvider.java

@@ -11,5 +11,5 @@ public interface SuggestionProvider<T> {
     /**
      * @return an unfiltered(no permission checks or filtering by input) list of strings that may be used for the argument/literal
      */
-    List<String> suggest(T sender);
+    List<String> suggest(T sender, String input);
 }

core/src/main/java/de/kentoj/kencommandapi/internal/CommandContextBuilder.java

@@ -0,0 +1,26 @@
+package de.kentoj.kencommandapi.internal;
+
+import de.kentoj.kencommandapi.api.argument.CommandArgument;
+import de.kentoj.kencommandapi.api.argument.CommandArgumentImpl;
+import de.kentoj.kencommandapi.api.argument.CommandArgumentSpec;
+import de.kentoj.kencommandapi.api.invocation.CommandContext;
+
+import java.util.Map;
+
+public class CommandContextBuilder<T> {
+    private final T sender;
+    private final Map<String, CommandArgument<T, ?>> parsedArgument;
+
+    public CommandContextBuilder(T sender, Map<String, CommandArgument<T, ?>> parsedArgument) {
+        this.sender = sender;
+        this.parsedArgument = parsedArgument;
+    }
+
+    public <S> void addParsed(CommandArgumentSpec<T, S> arg, S value) {
+        parsedArgument.put(arg.id(), new CommandArgumentImpl<>(value, arg));
+    }
+
+    public CommandContext<T> build() {
+        return new CommandContextImpl<>(sender, parsedArgument);
+    }
+}

core/src/main/java/de/kentoj/kencommandapi/internal/CommandContextImpl.java

@@ -5,11 +5,10 @@ import de.kentoj.kencommandapi.api.invocation.CommandContext;
 
 import java.util.Map;
 
-public record CommandContextImpl<T>(
+record CommandContextImpl<T>(
         T sender,
         Map<String, CommandArgument<T, ?>> parsedArguments
 ) implements CommandContext<T> {
-
     @Override
     public <V> CommandArgument<T, V> getParsedArgument(String id) {
         try {

core/src/main/java/de/kentoj/kencommandapi/internal/NodeTreeWalker.java

@@ -0,0 +1,101 @@
+package de.kentoj.kencommandapi.internal;
+
+import de.kentoj.kencommandapi.api.argument.CommandArgumentSpec;
+import de.kentoj.kencommandapi.api.literal.Literal;
+import de.kentoj.kencommandapi.api.literal.RootLiteral;
+import de.kentoj.kencommandapi.api.platform.HasPermissionMethod;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashMap;
+import java.util.Iterator;
+
+import static java.util.Objects.requireNonNull;
+
+public class NodeTreeWalker<T> {
+
+    private final HasPermissionMethod<T> hasPermission;
+
+    public NodeTreeWalker(HasPermissionMethod<T> hasPermission) {
+        this.hasPermission = hasPermission;
+    }
+
+    public WalkResult<T> walk(
+            RootLiteral<T> rootLiteral,
+            T sender,
+            Iterator<String> iter
+    ) {
+        var cursor = new Cursor(iter);
+        var ctxBuilder = new CommandContextBuilder<>(sender, new HashMap<>());
+        Literal<T> literal = rootLiteral;
+        String token;
+
+        while (true) {
+            for (var arg : literal.arguments()) {
+                @SuppressWarnings("unchecked")
+                var res = walkArgument(cursor, literal, ctxBuilder, (CommandArgumentSpec<T, Object>) arg);
+                if (res != null)
+                    return res;
+            }
+
+            token = cursor.nextToken();
+            if (token == null)
+                break;
+            var nextLiteral = literal.getLiteral(token);
+            if (nextLiteral == null)
+                return new WalkResult.LiteralUnknown<>(ctxBuilder.build(), literal, token);
+            if (nextLiteral.permission() != null && hasPermission.test(sender, nextLiteral.permission()))
+                return new WalkResult.LiteralUnknown<>(ctxBuilder.build(), literal, token);
+            literal = nextLiteral;
+        }
+
+        if (!literal.literals().isEmpty()) {
+            var isRequired = literal.executor() == null;
+            return new WalkResult.LiteralExpected<>(ctxBuilder.build(), literal, isRequired);
+        }
+
+        return new WalkResult.Complete<>(ctxBuilder.build(), literal);
+    }
+
+    private @Nullable WalkResult<T> walkArgument(
+            Cursor cursor,
+            Literal<T> literal,
+            CommandContextBuilder<T> ctxBuilder,
+            CommandArgumentSpec<T, Object> arg
+    ) {
+        var rawInput = arg.type().greedy() ? cursor.remainingTokens() : cursor.nextToken();
+        if (rawInput == null) {
+            if (arg.defaultValueProvider() == null)
+                return new WalkResult.ArgumentExpected<>(ctxBuilder.build(), literal, false, arg);
+            var value = requireNonNull(arg.defaultValueProvider()).apply(ctxBuilder.build());
+            ctxBuilder.addParsed(arg, value);
+            return null;
+        }
+
+        var parseResult = arg.parseInput(rawInput);
+        if (parseResult.hasFailure())
+            return new WalkResult.ArgumentIllegal<>(ctxBuilder.build(), literal,
+                    false, arg, rawInput, parseResult.getFailure().orElseThrow());
+        ctxBuilder.addParsed(arg, parseResult.getSuccess().orElseThrow());
+        return null;
+    }
+
+    private static class Cursor {
+        private final Iterator<String> tokenIter;
+
+        public Cursor(Iterator<String> tokenIter) {
+            this.tokenIter = tokenIter;
+        }
+
+        public @Nullable String nextToken() {
+            if (!tokenIter.hasNext())
+                return null;
+            return tokenIter.next();
+        }
+
+        public @Nullable String remainingTokens() {
+            var builder = new StringBuilder();
+            tokenIter.forEachRemaining(s -> builder.append(' ').append(s));
+            return builder.toString();
+        }
+    }
+}

core/src/main/java/de/kentoj/kencommandapi/internal/WalkResult.java

@@ -0,0 +1,80 @@
+package de.kentoj.kencommandapi.internal;
+
+import de.kentoj.kencommandapi.api.argument.CommandArgumentSpec;
+import de.kentoj.kencommandapi.api.invocation.CommandContext;
+import de.kentoj.kencommandapi.api.literal.Literal;
+import org.jetbrains.annotations.Nullable;
+
+public sealed interface WalkResult<T> {
+    CommandContext<T> ctx();
+
+    Literal<T> lastLiteral();
+
+    boolean isValidUsage();
+
+    @Nullable String message();
+
+    record ArgumentIllegal<T>(
+            CommandContext<T> ctx,
+            Literal<T> lastLiteral,
+            boolean isValidUsage,
+            CommandArgumentSpec<T, ?> arg,
+            String input,
+            String message
+    ) implements WalkResult<T> {
+    }
+
+    record ArgumentExpected<T>(
+            CommandContext<T> ctx,
+            Literal<T> lastLiteral,
+            boolean isValidUsage,
+            CommandArgumentSpec<T, ?> arg
+    ) implements WalkResult<T> {
+        @Override
+        public String message() {
+            return "Argument expected.";
+        }
+    }
+
+    record LiteralExpected<T>(
+            CommandContext<T> ctx,
+            Literal<T> lastLiteral,
+            boolean isValidUsage
+    ) implements WalkResult<T> {
+        @Override
+        public String message() {
+            return "Literal expected.";
+        }
+    }
+
+    record LiteralUnknown<T>(
+            CommandContext<T> ctx,
+            Literal<T> lastLiteral,
+            String input
+    ) implements WalkResult<T> {
+        @Override
+        public boolean isValidUsage() {
+            return false;
+        }
+
+        @Override
+        public String message() {
+            return "Unknown literal \"" + input + "\".";
+        }
+    }
+
+    record Complete<T>(
+            CommandContext<T> ctx,
+            Literal<T> lastLiteral
+    ) implements WalkResult<T> {
+        @Override
+        public boolean isValidUsage() {
+            return true;
+        }
+
+        @Override
+        public @Nullable String message() {
+            return null;
+        }
+    }
+}

core/src/main/java/de/kentoj/kencommandapi/internal/parser/CommandParseHelper.java

@@ -1,28 +0,0 @@
-package de.kentoj.kencommandapi.internal.parser;
-
-import de.kentoj.kencommandapi.api.literal.Literal;
-import de.kentoj.kencommandapi.api.platform.HasPermissionMethod;
-
-import java.util.Iterator;
-
-public final class CommandParseHelper<T> {
-    private final HasPermissionMethod<T> hasPermission;
-
-    public CommandParseHelper(HasPermissionMethod<T> hasPermission) {
-        this.hasPermission = hasPermission;
-    }
-
-    public boolean hasPermission(T sender, Literal<T> literal) {
-        if (literal.permission() == null) return true;
-        return hasPermission.test(sender, literal.permission());
-    }
-
-    public String parseInput(Iterator<String> tokenIter, boolean isGreedy) {
-        if (!isGreedy)
-            return tokenIter.next();
-        var builder = new StringBuilder();
-        tokenIter.forEachRemaining(tok -> builder.append(" ").append(tok));
-        builder.deleteCharAt(0);
-        return builder.toString();
-    }
-}

core/src/main/java/de/kentoj/kencommandapi/internal/parser/InvocationCommandParser.java

@@ -1,108 +0,0 @@
-package de.kentoj.kencommandapi.internal.parser;
-
-import com.leakyabstractions.result.api.Result;
-import com.leakyabstractions.result.core.Results;
-import de.kentoj.kencommandapi.api.argument.CommandArgument;
-import de.kentoj.kencommandapi.api.argument.CommandArgumentImpl;
-import de.kentoj.kencommandapi.api.argument.CommandArgumentSpec;
-import de.kentoj.kencommandapi.api.invocation.CommandContext;
-import de.kentoj.kencommandapi.api.invocation.CommandExecutor;
-import de.kentoj.kencommandapi.api.literal.Literal;
-import de.kentoj.kencommandapi.internal.CommandContextImpl;
-
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.Map;
-
-import static java.util.Objects.requireNonNull;
-
-public class InvocationCommandParser<T> {
-
-    private final CommandParseHelper<T> helper;
-
-    public InvocationCommandParser(CommandParseHelper<T> helper) {
-        this.helper = helper;
-    }
-
-    public Result<ExecutionData, String> parse(
-            Literal<T> rootLiteral,
-            T sender,
-            Iterator<String> tokenIter
-    ) {
-        Literal<T> currentLiteral = rootLiteral;
-        var ctx = new CommandContextImpl<>(sender, new HashMap<>());
-
-        while (true) {
-            {
-                var result = processArguments(currentLiteral, ctx, tokenIter)
-                        .ifSuccess(ctx.parsedArguments()::putAll);
-                if (result.hasFailure())
-                    return result.mapSuccess(_ -> null);
-            }
-
-            if (!tokenIter.hasNext()) {
-                if (currentLiteral.executor() == null)
-                    return Results.failure("Literal expected");
-                break;
-            }
-
-            var literalName = tokenIter.next();
-            var nextLiteral = currentLiteral.getLiteral(literalName);
-            var isIncompleteOrUnknown = nextLiteral == null || !helper.hasPermission(sender, nextLiteral);
-            if (isIncompleteOrUnknown)
-                return Results.failure("Unknown literal: " + literalName);
-            currentLiteral = nextLiteral;
-        }
-
-        return Results.success(new ExecutionData(currentLiteral.executor(), ctx));
-    }
-
-    private Result<Map<String, CommandArgument<T, ?>>, String> processArguments(
-            Literal<T> literal,
-            CommandContext<T> ctx,
-            Iterator<String> tokenIter
-    ) {
-        Map<String, CommandArgument<T, ?>> parsedArguments = new HashMap<>();
-
-        for (var _argument : literal.arguments()) {
-            @SuppressWarnings("unchecked")
-            var argument = ((CommandArgumentSpec<T, Object>) _argument);
-
-            Object value;
-            if (!tokenIter.hasNext()) {
-                if (argument.defaultValueProvider() == null)
-                    return Results.failure("Argument expected: " + argument.id());
-                value = requireNonNull(argument.defaultValueProvider()).apply(ctx);
-            } else {
-                var input = helper.parseInput(tokenIter, argument.type().greedy());
-                try {
-                    value = argument.parseInput(input);
-                } catch (IllegalArgumentException ex) {
-                    return Results.failure("Illegal argument '" + input + "' for " + argument.id() + ": " + ex.getMessage());
-                }
-            }
-
-            parsedArguments.put(argument.id(), new CommandArgumentImpl<>(value, argument));
-        }
-
-        return Results.success(parsedArguments);
-    }
-
-    public class ExecutionData {
-        private final CommandExecutor<T> executor;
-        private final CommandContext<T> context;
-
-        public ExecutionData(CommandExecutor<T> executor, CommandContext<T> context) {
-            this.executor = executor;
-            this.context = context;
-        }
-
-        public CommandExecutor<T> executor() {
-            return executor;
-        }
-
-        public CommandContext<T> context() {
-            return context;
-        }
-    }
-}

core/src/main/java/de/kentoj/kencommandapi/internal/parser/SuggestionCommandParser.java

@@ -1,99 +0,0 @@
-package de.kentoj.kencommandapi.internal.parser;
-
-import de.kentoj.kencommandapi.api.literal.Literal;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.List;
-import java.util.stream.Stream;
-
-public class SuggestionCommandParser<T> {
-
-    private final CommandParseHelper<T> helper;
-
-    public SuggestionCommandParser(CommandParseHelper<T> helper) {
-        this.helper = helper;
-    }
-
-    public List<String> suggest(
-            Literal<T> rootLiteral,
-            T sender,
-            Iterator<String> tokenIter,
-            boolean suggestNext
-    ) {
-        Literal<T> currentLiteral = rootLiteral;
-        Literal<T> previousLiteral = null;
-
-        while (true) {
-            var argumentSuggestions = processArguments(currentLiteral, tokenIter, sender, suggestNext);
-            if (argumentSuggestions != null)
-                return argumentSuggestions;
-
-            if (!tokenIter.hasNext()) {
-                if (suggestNext || previousLiteral == null)
-                    return suggestions(currentLiteral, sender).toList();
-                return suggestions(previousLiteral, sender).toList();
-            }
-
-            var input = tokenIter.next();
-            var nextLiteral = currentLiteral.getLiteral(input);
-            var isIncompleteOrUnknown = nextLiteral == null || !helper.hasPermission(sender, nextLiteral);
-            if (isIncompleteOrUnknown) {
-                var finalInput = input.toLowerCase();
-                return suggestions(currentLiteral, sender)
-                        .filter(name -> name.toLowerCase().startsWith(finalInput))
-                        .toList();
-            }
-
-            previousLiteral = currentLiteral;
-            currentLiteral = nextLiteral;
-        }
-    }
-
-    private @Nullable List<String> processArguments(
-            Literal<T> literal,
-            Iterator<String> tokenIter,
-            T sender,
-            boolean suggestNext
-    ) {
-        var argsIter = literal.arguments().iterator();
-
-        /*
-        for each argument:
-            if no next token: suggest current
-            parse token
-            if not last token: skip
-            if nextToken:
-                if has next argument: suggest next argument
-                else: return null
-            return current argument's suggestions filtered
-
-         */
-
-        while (argsIter.hasNext()) {
-            var argument = argsIter.next();
-            if (!tokenIter.hasNext())
-                return argument.suggestionProvider().suggest(sender);
-            var input = helper.parseInput(tokenIter, argument.type().greedy()).toLowerCase();
-            if (tokenIter.hasNext())
-                continue;
-            if (suggestNext) {
-                if (argsIter.hasNext())
-                    return argsIter.next().suggestionProvider().suggest(sender);
-                return null;
-            }
-            return argument.suggestionProvider().suggest(sender).stream()
-                    .filter(suggestion -> suggestion.toLowerCase().startsWith(input))
-                    .toList();
-        }
-        return null;
-    }
-
-    private Stream<String> suggestions(Literal<T> literal, T sender) {
-        return literal.literals().stream()
-                .filter(lit -> helper.hasPermission(sender, lit))
-                .map(Literal::names)
-                .flatMap(Arrays::stream);
-    }
-}

defs.bzl

@@ -1,2 +1,2 @@
 GROUP = "de.kentoj.scrow"
-VERSION = "0.37-SNAPSHOT"
+VERSION = "0.38-SNAPSHOT"

velocity/src/main/java/de/kentoj/kencommandapi/suggestionprovider/PlayerSuggestionProvider.java

@@ -16,7 +16,7 @@ public final class PlayerSuggestionProvider<T extends CommandSource> implements
     }
 
     @Override
-    public List<String> suggest(T __) {
+    public List<String> suggest(T __, String ___) {
         return proxyServer.getAllPlayers().stream()
                 .map(Player::getUsername)
                 .toList();

velocity/src/main/java/de/kentoj/kencommandapi/type/PlayerArgumentType.java

@@ -1,5 +1,7 @@
 package de.kentoj.kencommandapi.type;
 
+import com.leakyabstractions.result.api.Result;
+import com.leakyabstractions.result.core.Results;
 import com.velocitypowered.api.command.CommandSource;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ProxyServer;
@@ -7,6 +9,8 @@ import de.kentoj.kencommandapi.api.argument.ArgumentType;
 import de.kentoj.kencommandapi.api.suggestion.SuggestionProvider;
 import de.kentoj.kencommandapi.suggestionprovider.PlayerSuggestionProvider;
 
+import java.util.UUID;
+
 public class PlayerArgumentType<T extends CommandSource> implements ArgumentType<T, Player> {
 
     private final ProxyServer server;
@@ -16,10 +20,20 @@ public class PlayerArgumentType<T extends CommandSource> implements ArgumentType
     }
 
     @Override
-    public Player parseInputUnchecked(String input) {
+    public Result<Player, String> parseInputUnchecked(String input) {
-        var player = server.getPlayer(input).orElse(null);
+        // TODO UUID support
-        if (player == null) throw new IllegalArgumentException("Player not online");
+        Player player;
-        return player;
+        if (input.length() == 36) {
+            try {
+                player = server.getPlayer(UUID.fromString(input)).orElse(null);
+            } catch (IllegalArgumentException _) {
+                return Results.failure("Invalid UUID.");
+            }
+        } else {
+            player = server.getPlayer(input).orElse(null);
+        }
+
+        return Results.ofNullable(player, "Player not online.");
     }
 
     @Override