✨ Allow default suggestion providers in @Parser

cloud-annotations/src/main/java/cloud/commandframework/annotations/AnnotationParser.java

@@ -58,6 +58,7 @@ import java.lang.reflect.Parameter;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -317,7 +318,20 @@ public final class AnnotationParser<C> {
                 ));
             }
             try {
+                final BiFunction<CommandContext<C>, String, List<String>> suggestionsProvider;
+                if (parser.suggestions().isEmpty()) {
+                    suggestionsProvider = (context, input) -> Collections.emptyList();
+                } else {
+                    suggestionsProvider = this.manager.getParserRegistry().getSuggestionProvider(parser.suggestions())
+                            .orElseThrow(() -> new NullPointerException(
+                                    String.format(
+                                            "Cannot find the suggestions provider with name '%s'",
+                                            parser.suggestions()
+                                    )
+                            ));
+                }
                 final MethodArgumentParser<C, ?> methodArgumentParser = new MethodArgumentParser<>(
+                        suggestionsProvider,
                         instance,
                         method
                 );

cloud-annotations/src/main/java/cloud/commandframework/annotations/parsers/MethodArgumentParser.java

@@ -31,7 +31,9 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.reflect.Method;
+import java.util.List;
 import java.util.Queue;
+import java.util.function.BiFunction;
 
 /**
  * Represents a method annotated with {@link Parser}
@@ -42,19 +44,23 @@ import java.util.Queue;
  */
 public class MethodArgumentParser<C, T> implements ArgumentParser<C, T> {
 
+    private final BiFunction<CommandContext<C>, String, List<String>> suggestionProvider;
     private final MethodHandle methodHandle;
 
     /**
      * Create a new parser
      *
+     * @param suggestionProvider Suggestion provider
      * @param instance           Instance that owns the method
      * @param method             The annotated method
      * @throws Exception If the method lookup fails
      */
     public MethodArgumentParser(
+            final @NonNull BiFunction<CommandContext<C>, String, List<String>> suggestionProvider,
             final @NonNull Object instance,
             final @NonNull Method method
     ) throws Exception {
+        this.suggestionProvider = suggestionProvider;
         this.methodHandle = MethodHandles.lookup().unreflect(method).bindTo(instance);
     }
 
@@ -73,4 +79,12 @@ public class MethodArgumentParser<C, T> implements ArgumentParser<C, T> {
         }
     }
 
+    @Override
+    public @NonNull List<@NonNull String> suggestions(
+            final @NonNull CommandContext<C> commandContext,
+            final @NonNull String input
+    ) {
+        return this.suggestionProvider.apply(commandContext, input);
+    }
+
 }

cloud-annotations/src/main/java/cloud/commandframework/annotations/parsers/Parser.java

@@ -27,6 +27,7 @@ import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
+import java.util.function.BiFunction;
 
 /**
  * This annotation allows you to create annotated methods that behave like argument parsers.
@@ -52,4 +53,18 @@ public @interface Parser {
      */
     String name() default "";
 
+    /**
+     * Name of the suggestions provider to use. If the string is left empty, the default
+     * provider for the {@link cloud.commandframework.annotations.Argument} will be used. Otherwise,
+     * the {@link cloud.commandframework.arguments.parser.ParserRegistry} instance in the
+     * {@link cloud.commandframework.CommandManager} will be queried for a matching suggestion provider.
+     * <p>
+     * For this to work, the suggestion needs to be registered in the parser registry. To do this, use
+     * {@link cloud.commandframework.arguments.parser.ParserRegistry#registerSuggestionProvider(String, BiFunction)}.
+     * The registry instance can be retrieved using {@link cloud.commandframework.CommandManager#getParserRegistry()}.
+     *
+     * @return The name of the suggestion provider, or {@code ""}
+     */
+    String suggestions() default "";
+
 }

cloud-annotations/src/test/java/cloud/commandframework/annotations/AnnotationParserTest.java

@@ -153,13 +153,18 @@ class AnnotationParserTest {
                 TypeToken.get(CustomType.class),
                 ParserParameters.empty()
         ).orElseThrow(() -> new NullPointerException("Could not find CustomType parser"));
-        Assertions.assertEquals("yay", parser.parse(
-                new CommandContext<>(
+        final CommandContext<TestCommandSender> context = new CommandContext<>(
                 new TestCommandSender(),
                 this.manager
-                ),
+        );
+        Assertions.assertEquals("yay", parser.parse(
+                context,
                 new LinkedList<>()
         ).getParsedValue().orElse(new CustomType("")).toString());
+        Assertions.assertTrue(parser.suggestions(
+                context,
+                ""
+        ).contains("Stella"));
     }
 
     @Suggestions("cows")
@@ -167,7 +172,7 @@ class AnnotationParserTest {
         return Arrays.asList("Stella", "Bella", "Agda");
     }
 
-    @Parser
+    @Parser(suggestions = "cows")
     public CustomType customTypeParser(final CommandContext<TestCommandSender> context, final Queue<String> input) {
         return new CustomType("yay");
     }