✨ Allow interception of command builders based on annotations in AnnotationParser

Fixes #179

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  - Added `@Suggestions` annotated methods
  - Added `@Parser` annotated methods
  - Type safe meta system
+ - Allow interception of command builders based on annotations in AnnotationParser
 
 ### Changed
  - Moved the parser injector registry into CommandManager and added injection to CommandContext

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

@@ -83,6 +83,8 @@ public final class AnnotationParser<C> {
     private final Map<Class<? extends Annotation>, Function<? extends Annotation, ParserParameters>> annotationMappers;
     private final Map<Class<? extends Annotation>, Function<? extends Annotation, BiFunction<@NonNull CommandContext<C>,
             @NonNull Queue<@NonNull String>, @NonNull ArgumentParseResult<Boolean>>>> preprocessorMappers;
+    private final Map<Class<? extends Annotation>, BiFunction<? extends Annotation, Command.Builder<C>, Command.Builder<C>>>
+            builderModifiers;
     private final Class<C> commandSenderClass;
     private final MetaFactory metaFactory;
     private final FlagExtractor flagExtractor;
@@ -107,6 +109,7 @@ public final class AnnotationParser<C> {
         this.metaFactory = new MetaFactory(this, metaMapper);
         this.annotationMappers = new HashMap<>();
         this.preprocessorMappers = new HashMap<>();
+        this.builderModifiers = new HashMap<>();
         this.flagExtractor = new FlagExtractor(manager);
         this.registerAnnotationMapper(CommandDescription.class, d ->
                 ParserParameters.single(StandardParameters.DESCRIPTION, d.value()));
@@ -177,6 +180,25 @@ public final class AnnotationParser<C> {
         return getMethodOrClassAnnotation(method, clazz) != null;
     }
 
+    /**
+     * Register a builder modifier for a specific annotation. The builder modifiers are
+     * allowed to act on a {@link Command.Builder} after all arguments have been added
+     * to the builder. This allows for modifications of the builder instance before
+     * the command is registered to the command manager.
+     *
+     * @param annotation      Annotation (class) that the builder modifier reacts to
+     * @param builderModifier Modifier that acts on the given annotation and the incoming builder. Command builders
+     *                        are immutable, so the modifier should return the instance of the command builder that is
+     *                        returned as a result of any operation on the builder
+     * @param <A>             Annotation type
+     */
+    public <A extends Annotation> void registerBuilderModifier(
+            final @NonNull Class<A> annotation,
+            final @NonNull BiFunction<A, Command.Builder<C>, Command.Builder<C>> builderModifier
+    ) {
+        this.builderModifiers.put(annotation, builderModifier);
+    }
+
     /**
      * Register an annotation mapper
      *
@@ -457,6 +479,14 @@ public final class AnnotationParser<C> {
             for (final CommandFlag<?> flag : flags) {
                 builder = builder.flag(flag);
             }
+            for (final Annotation annotation : method.getDeclaredAnnotations()) {
+                @SuppressWarnings("ALL")
+                final BiFunction builderModifier = this.builderModifiers.get(annotation.annotationType());
+                if (builderModifier == null) {
+                    continue;
+                }
+                builder = (Command.Builder<C>) builderModifier.apply(annotation, builder);
+            }
             /* Construct and register the command */
             final Command<C> builtCommand = builder.build();
             commands.add(builtCommand);

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

@@ -30,6 +30,7 @@ import cloud.commandframework.annotations.specifier.Range;
 import cloud.commandframework.annotations.suggestions.Suggestions;
 import cloud.commandframework.arguments.parser.ArgumentParser;
 import cloud.commandframework.arguments.parser.ParserParameters;
+import cloud.commandframework.arguments.standard.IntegerArgument;
 import cloud.commandframework.arguments.standard.StringArgument;
 import cloud.commandframework.context.CommandContext;
 import cloud.commandframework.meta.SimpleCommandMeta;
@@ -78,7 +79,11 @@ class AnnotationParserTest {
                 InjectableValue.class,
                 (context, annotations) -> new InjectableValue("Hello World!")
         );
-
+        /* Register a builder modifier */
+        annotationParser.registerBuilderModifier(
+                IntegerArgumentInjector.class,
+                (injector, builder) -> builder.argument(IntegerArgument.of(injector.value()))
+        );
         /* Parse the class. Required for both testMethodConstruction() and testNamedSuggestionProvider() */
         commands = annotationParser.parse(this);
     }
@@ -135,7 +140,7 @@ class AnnotationParserTest {
 
     @Test
     void testParameterInjection() {
-        manager.executeCommand(new TestCommandSender(), "inject").join();
+        manager.executeCommand(new TestCommandSender(), "injected 10").join();
     }
 
     @Test
@@ -167,6 +172,11 @@ class AnnotationParserTest {
         ).contains("Stella"));
     }
 
+    @Test
+    void testInjectedCommand() {
+        manager.executeCommand(new TestCommandSender(), "injected 10").join();
+    }
+
     @Suggestions("cows")
     public List<String> cowSuggestions(final CommandContext<TestCommandSender> context, final String input) {
         return Arrays.asList("Stella", "Bella", "Agda");
@@ -177,6 +187,12 @@ class AnnotationParserTest {
         return new CustomType("yay");
     }
 
+    @IntegerArgumentInjector
+    @CommandMethod("injected")
+    public void injectedCommand(final CommandContext<TestCommandSender> context) {
+        System.out.printf("Got an integer: %d\n", context.<Integer>get("number"));
+    }
+
     @ProxiedBy("proxycommand")
     @CommandMethod("test|t literal <int> [string]")
     public void testCommand(
@@ -278,4 +294,18 @@ class AnnotationParserTest {
 
     }
 
+
+    @Target(ElementType.METHOD)
+    @Retention(RetentionPolicy.RUNTIME)
+    private @interface IntegerArgumentInjector {
+
+        /**
+         * The name of the integer argument to insert
+         *
+         * @return Integer argument name
+         */
+        String value() default "number";
+
+    }
+
 }