feat: Added RelationalPlaceholder builder

# Conflicts:
#	api/src/main/java/io/github/miniplaceholders/api/types/RelationalAudience.java

api/src/main/java/io/github/miniplaceholders/api/Expansion.java

@@ -34,361 +34,390 @@ import java.util.Collection;
  *  TagResolver resolver = expansion.resolver();
  *  player.sendMessage(MiniMessage.miniMessage().deserialize("Hello {@literal <luckperms_prefix> <player_name>}", player, resolver));
  * </pre>
- * 
+ *
  * @since 1.0.0
  */
 @NullMarked
 public sealed interface Expansion permits ExpansionImpl {
-    /**
-     * Get the expansion name
-     *
-     * @return the expansion name
-     * @since 1.0.0
-     */
-    String name();
+  /**
+   * Get the expansion name
+   *
+   * @return the expansion name
+   * @since 1.0.0
+   */
+  String name();
+
+  /**
+   * Get the author of this expansion
+   *
+   * @return the author or null
+   * @since 2.3.0
+   */
+  @Nullable String author();
+
+  /**
+   * Get the version of this expansion
+   *
+   * @return the version or null
+   * @since 2.3.0
+   */
+  @Nullable String version();
+
+  /**
+   * Get the {@link TagResolver} of an {@link Audience}
+   *
+   * @return A TagResolver with variable placeholders of an Audience
+   * @since 1.0.0
+   */
+  TagResolver audiencePlaceholders();
+
+  /**
+   * Get the relational placeholders based on two audiences
+   *
+   * <p>The resulting TagResolver will give results according
+   * to the 2 {@link Audience} provided and when called
+   * at any time will retrieve the required values</p>
+   *
+   * @return A TagResolver with variable placeholders between 2 {@link Audience}s
+   * @since 1.0.0
+   */
+  TagResolver relationalPlaceholders();
+
+  /**
+   * Get global placeholders
+   *
+   * @return the global placeholders
+   * @since 1.0.0
+   */
+  TagResolver globalPlaceholders();
+
+  /**
+   * Register this expansion
+   *
+   * @throws IllegalStateException if the expansion you are trying to register is already registered
+   * @see Expansion#registered()
+   * @since 1.0.0
+   */
+  void register();
+
+  /**
+   * Unregisters this expansion
+   *
+   * @throws IllegalStateException if the expansion you are trying to unregister is not registered
+   * @see Expansion#registered()
+   * @since 2.1.0
+   */
+  void unregister();
+
+  /**
+   * Get the registration status of this expansion
+   *
+   * @return true if the expansion is registered, otherwise false
+   * @since 2.1.0
+   */
+  boolean registered();
+
+  /**
+   * Get the registered audience placeholders
+   *
+   * @return registered audience placeholders
+   */
+  Collection<AudiencePlaceholder<?>> registeredAudiencePlaceholders();
+
+  /**
+   * Get the registered relational placeholders
+   *
+   * @return registered relational placeholders
+   */
+  Collection<RelationalPlaceholder<?>> registeredRelationalPlaceholders();
+
+  /**
+   * Get an Audience Placeholder by name
+   *
+   * <pre>{@code
+   *      Expansion expansion = MiniPlaceholders.expansionByName("player")
+   *      AudiencePlaceholder<?> placeholder = expansion.audiencePlaceholderByName("name");
+   * }</pre>
+   *
+   * @param name the name of the placeholder to search
+   * @return the desired placeholder or null
+   */
+  @Nullable AudiencePlaceholder<?> audiencePlaceholderByName(final String name);
+
+  /**
+   * Get a Relational Placeholder by name
+   *
+   * <pre>{@code
+   *      Expansion expansion = MiniPlaceholders.expansionByName("expansion")
+   *      RelationalPlaceholder<?> placeholder = expansion.relationalPlaceholderByName("placeholder");
+   * }</pre>
+   *
+   * @param name the name of the placeholder to search
+   * @return the desired placeholder or null
+   * @apiNote The name of a relational placeholder does not contain the prefix “rel”,
+   * just the name assigned when it was created
+   */
+  @Nullable RelationalPlaceholder<?> relationalPlaceholderByName(final String name);
+
+  /**
+   * Get a Global Placeholder by name
+   *
+   * <pre>{@code
+   *      Expansion expansion = MiniPlaceholders.expansionByName("player")
+   *      GlobalPlaceholder placeholder = expansion.globalPlaceholderByName("name");
+   * }</pre>
+   *
+   * @param name the name of the placeholder to search
+   * @return the desired placeholder or null
+   */
+  @Nullable GlobalPlaceholder globalPlaceholderByName(final String name);
+
+  /**
+   * Checks whether an audience placeholder with the specified name has been registered in this expansion.
+   *
+   * @param name the name of the placeholder to check
+   * @return true if the placeholder is registered, else false
+   */
+  default boolean hasAudiencePlaceholder(final String name) {
+    return audiencePlaceholderByName(name) != null;
+  }
+
+  /**
+   * Checks whether a relational placeholder with the specified name has been registered in this expansion.
+   *
+   * @param name the name of the placeholder to check
+   * @return true if the placeholder is registered, else false
+   */
+  default boolean hasRelationalPlaceholder(final String name) {
+    return relationalPlaceholderByName(name) != null;
+  }
+
+  /**
+   * Checks whether a global placeholder with the specified name has been registered in this expansion.
+   *
+   * @param name the name of the placeholder to check
+   * @return true if the placeholder is registered, else false
+   */
+  default boolean hasGlobalPlaceholder(final String name) {
+    return globalPlaceholderByName(name) != null;
+  }
+
+  /**
+   * Get a TagResolver that contains all placeholders of a specific type in this expansion.
+   *
+   * @param type the desired type
+   * @return a TagResolver containing all placeholder of a specific type
+   */
+  TagResolver placeholdersByType(PlaceholderType type);
+
+  /**
+   * Creates a new Expansion Builder
+   *
+   * @param name the expansion name
+   * @return a new expansion builder
+   * @since 1.0.0
+   */
+  static Expansion.Builder builder(final String name) {
+    return new ExpansionImpl.Builder(name);
+  }
+
+  /**
+   * Get a shorter ToString with the details of this expansion.
+   *
+   * @return a shorter ToString
+   */
+  @ApiStatus.Internal
+  @Deprecated(forRemoval = true, since = "3.1.0")
+  default String shortToString() {
+    final StringBuilder builder = new StringBuilder(name()).append('[');
+    if (author() != null) {
+      builder.append("Author: ").append(author());
+    }
+    if (version() != null) {
+      if (author() != null) {
+        builder.append(", ");
+      }
+      builder.append("Version: ").append(version());
+    }
+    builder.append(']');
+    return builder.toString();
+  }
+
+  /**
+   * Expansion Builder
+   * <p>Example use:</p>
+   * <pre>
+   *  Expansion.Builder builder = Expansion.builder("player");
+   *  builder
+   *      // Thanks to this filter, a cast can be performed without the probability of a ClassCastException
+   *      .filter(Player.class)
+   *      .resolver("name", (audience, queue, ctx) -> Tag.selfClosingInserting(Component.text(((Player)audience).getUsername())));
+   *  Expansion expansion = builder.build();
+   * </pre>
+   * <p>
+   * then use it:
+   *
+   * <pre>
+   *  Player player = event.getPlayer();
+   *  TagResolver resolver = expansion.resolver(player);
+   *  Component messageReplaced = MiniMessage.deserialize({@link String}, resolver);
+   * </pre>
+   *
+   * @since 1.0.0
+   */
+  @NullMarked
+  interface Builder extends AbstractBuilder<Expansion> {
 
     /**
-     * Get the author of this expansion
+     * Adds an audience placeholder
      *
-     * @return the author or null
+     * <p>This type of Placeholder depends on a specific audience to obtain its values</p>
+     *
+     * <p>The content of this Placeholder is cached
+     * and can mutate depending on when it is invoked</p>
+     *
+     * @param targetClass         the target class
+     * @param key                 the placeholder key, cannot be an empty or black string
+     * @param audiencePlaceholder the single placeholder
+     * @param <A>                 the type of audience that this placeholder supports, must be the same as targetClass
+     * @return the {@link Builder} itself
+     * @since 1.0.0
+     */
+    <A extends Audience> Builder audiencePlaceholder(
+        final @Nullable Class<A> targetClass,
+        final String key,
+        final AudienceTagResolver<A> audiencePlaceholder
+    );
+
+    /**
+     * Adds an audience placeholder
+     *
+     * <p>This type of Placeholder depends on a specific audience to obtain its values</p>
+     *
+     * <p>The content of this Placeholder is cached
+     * and can mutate depending on when it is invoked</p>
+     *
+     * @param key                 the placeholder key, cannot be an empty or black string
+     * @param audiencePlaceholder the single placeholder
+     * @return the {@link Builder} itself
+     * @since 3.0.0
+     */
+    default Builder audiencePlaceholder(final String key, final AudienceTagResolver<Audience> audiencePlaceholder) {
+      return this.audiencePlaceholder(null, key, audiencePlaceholder);
+    }
+
+    <A extends Audience> Builder audiencePlaceholder(
+        final Class<A> targetClass,
+        final AudiencePlaceholder.Builder.Provider<A> builderProvider
+    );
+
+    default Builder audiencePlaceholder(final AudiencePlaceholder.Builder.Provider<Audience> builderProvider) {
+      return audiencePlaceholder(Audience.class, builderProvider);
+    }
+
+    /**
+     * Adds a Relational Placeholder based on two audiences
+     *
+     * <p>This type of placeholder allows you to create
+     * components based on a 2-audiences relationship,
+     * one is the one on which the placeholder
+     * is based and the other is the one on which
+     * the placeholder is displayed.</p>
+     *
+     * <p>The content of this Placeholder is cached
+     * and can mutate depending on when it is invoked</p>
+     *
+     * @param targetClass           the target class
+     * @param key                   the placeholder key, cannot be an empty or black string
+     * @param relationalPlaceholder the relational placeholder
+     * @param <A>                   the type of audience that this placeholder supports, must be the same as targetClass
+     * @return the {@link Builder} itself
+     * @since 3.0.0
+     */
+    <A extends Audience> Builder relationalPlaceholder(
+        final @Nullable Class<A> targetClass,
+        final String key,
+        final RelationalTagResolver<A> relationalPlaceholder
+    );
+
+    /**
+     * Adds a Relational Placeholder based on two audiences
+     *
+     * <p>This type of placeholder allows you to create
+     * components based on a 2-audiences relationship,
+     * one is the one on which the placeholder
+     * is based and the other is the one on which
+     * the placeholder is displayed.</p>
+     *
+     * <p>The content of this Placeholder is cached
+     * and can mutate depending on when it is invoked</p>
+     *
+     * @param key                the placeholder key, cannot be an empty or black string
+     * @param relationalResolver the relational placeholder
+     * @return the {@link Builder} itself
+     * @since 3.0.0
+     */
+    default Builder relationalPlaceholder(
+        final String key,
+        final RelationalTagResolver<Audience> relationalResolver
+    ) {
+      return this.relationalPlaceholder(null, key, relationalResolver);
+    }
+
+    <A extends Audience> Builder relationalPlaceholder(
+        final Class<A> targetClass,
+        final RelationalPlaceholder.Builder.Provider<A> builderProvider
+    );
+
+    default Builder relationalPlaceholder(final RelationalPlaceholder.Builder.Provider<Audience> builderProvider) {
+      return relationalPlaceholder(Audience.class, builderProvider);
+    }
+
+    /**
+     * Adds a global placeholder
+     *
+     * <p>The content of this Placeholder is cached
+     * and can mutate depending on when it is invoked</p>
+     *
+     * @param key      the placeholder key, cannot be an empty or black string
+     * @param resolver the function
+     * @return the {@link Builder} itself
+     * @since 3.0.0
+     */
+    Builder globalPlaceholder(final String key, final GlobalTagResolver resolver);
+
+    /**
+     * Adds a global placeholder
+     *
+     * <p>This placeholder is not cached and is immutable</p>
+     *
+     * @param key the placeholder key, cannot be an empty or black string
+     * @param tag the tag of this placeholder
+     * @return the {@link Builder} itself
+     * @since 1.1.0
+     */
+    default Builder globalPlaceholder(final String key, final Tag tag) {
+      return this.globalPlaceholder(key, (queue, context) -> tag);
+    }
+
+    /**
+     * Sets the author of this expansion
+     *
+     * @param author the author of this expansion
+     * @return the {@link Builder} itself
      * @since 2.3.0
      */
-    @Nullable String author();
+    @Contract("_ -> this")
+    Builder author(final @Nullable String author);
 
     /**
-     * Get the version of this expansion
+     * Sets the version of this expansion
      *
-     * @return the version or null
+     * @param version the version of this expansion
+     * @return the {@link Builder} itself
      * @since 2.3.0
      */
-    @Nullable String version();
-
-    /**
-     * Get the {@link TagResolver} of an {@link Audience}
-     * @return A TagResolver with variable placeholders of an Audience
-     * @since 1.0.0
-     */
-    TagResolver audiencePlaceholders();
-
-    /**
-     * Get the relational placeholders based on two audiences
-     *
-     * <p>The resulting TagResolver will give results according
-     * to the 2 {@link Audience} provided and when called
-     * at any time will retrieve the required values</p>
-     * @return A TagResolver with variable placeholders between 2 {@link Audience}s
-     * @since 1.0.0
-     */
-    TagResolver relationalPlaceholders();
-
-    /**
-     * Get global placeholders
-     * @return the global placeholders
-     * @since 1.0.0
-     */
-    TagResolver globalPlaceholders();
-
-    /**
-     * Register this expansion
-     * @since 1.0.0
-     * @throws IllegalStateException if the expansion you are trying to register is already registered
-     * @see Expansion#registered()
-     */
-    void register();
-
-    /**
-     * Unregisters this expansion
-     * @since 2.1.0
-     * @throws IllegalStateException if the expansion you are trying to unregister is not registered
-     * @see Expansion#registered()
-     */
-    void unregister();
-
-    /**
-     * Get the registration status of this expansion
-     * @return true if the expansion is registered, otherwise false
-     * @since 2.1.0
-     */
-    boolean registered();
-
-    // TODO: Docs and Tests
-
-    /**
-     * Get the registered audience placeholders
-     *
-     * @return registered audience placeholders
-     */
-    Collection<AudiencePlaceholder<?>> registeredAudiencePlaceholders();
-
-    /**
-     * Get the registered relational placeholders
-     *
-     * @return registered relational placeholders
-     */
-    Collection<RelationalPlaceholder<?>> registeredRelationalPlaceholders();
-
-    /**
-     * Get an Audience Placeholder by name
-     *
-     * <pre>{@code
-     *      Expansion expansion = MiniPlaceholders.expansionByName("player")
-     *      AudiencePlaceholder<?> placeholder = expansion.audiencePlaceholderByName("name");
-     * }</pre>
-     * @param name the name of the placeholder to search
-     * @return the desired placeholder or null
-     */
-    @Nullable AudiencePlaceholder<?> audiencePlaceholderByName(final String name);
-
-    /**
-     * Get a Relational Placeholder by name
-     *
-     * <pre>{@code
-     *      Expansion expansion = MiniPlaceholders.expansionByName("expansion")
-     *      RelationalPlaceholder<?> placeholder = expansion.relationalPlaceholderByName("placeholder");
-     * }</pre>
-     * @param name the name of the placeholder to search
-     * @return the desired placeholder or null
-     * @apiNote The name of a relational placeholder does not contain the prefix “rel”,
-     * just the name assigned when it was created
-     */
-    @Nullable RelationalPlaceholder<?> relationalPlaceholderByName(final String name);
-
-    /**
-     * Get a Global Placeholder by name
-     *
-     * <pre>{@code
-     *      Expansion expansion = MiniPlaceholders.expansionByName("player")
-     *      GlobalPlaceholder placeholder = expansion.globalPlaceholderByName("name");
-     * }</pre>
-     * @param name the name of the placeholder to search
-     * @return the desired placeholder or null
-     */
-    @Nullable GlobalPlaceholder globalPlaceholderByName(final String name);
-
-    /**
-     * Checks whether an audience placeholder with the specified name has been registered in this expansion.
-     *
-     * @param name the name of the placeholder to check
-     * @return true if the placeholder is registered, else false
-     */
-    default boolean hasAudiencePlaceholder(final String name) {
-        return audiencePlaceholderByName(name) != null;
-    }
-
-    /**
-     * Checks whether a relational placeholder with the specified name has been registered in this expansion.
-     *
-     * @param name the name of the placeholder to check
-     * @return true if the placeholder is registered, else false
-     */
-    default boolean hasRelationalPlaceholder(final String name) {
-        return relationalPlaceholderByName(name) != null;
-    }
-
-    /**
-     * Checks whether a global placeholder with the specified name has been registered in this expansion.
-     *
-     * @param name the name of the placeholder to check
-     * @return true if the placeholder is registered, else false
-     */
-    default boolean hasGlobalPlaceholder(final String name) {
-        return globalPlaceholderByName(name) != null;
-    }
-
-    /**
-     * Get a TagResolver that contains all placeholders of a specific type in this expansion.
-     *
-     * @param type the desired type
-     * @return a TagResolver containing all placeholder of a specific type
-     */
-    TagResolver placeholdersByType(PlaceholderType type);
-
-    /**
-     * Creates a new Expansion Builder
-     * @param name the expansion name
-     * @return a new expansion builder
-     * @since 1.0.0
-     */
-    static Expansion.Builder builder(final String name){
-        return new ExpansionImpl.Builder(name);
-    }
-
-    /**
-     * Get a shorter ToString with the details of this expansion.
-     * @return a shorter ToString
-     */
-    @ApiStatus.Internal
-    @Deprecated(forRemoval = true, since = "3.1.0")
-    default String shortToString() {
-        final StringBuilder builder = new StringBuilder(name()).append('[');
-        if (author() != null) {
-            builder.append("Author: ").append(author());
-        }
-        if (version() != null) {
-            if (author() != null) {
-                builder.append(", ");
-            }
-            builder.append("Version: ").append(version());
-        }
-        builder.append(']');
-        return builder.toString();
-    }
-
-    /**
-     * Expansion Builder
-     * <p>Example use:</p>
-     * <pre>
-     *  Expansion.Builder builder = Expansion.builder("player");
-     *  builder
-     *      // Thanks to this filter, a cast can be performed without the probability of a ClassCastException
-     *      .filter(Player.class)
-     *      .resolver("name", (audience, queue, ctx) -> Tag.selfClosingInserting(Component.text(((Player)audience).getUsername())));
-     *  Expansion expansion = builder.build();
-     * </pre>
-     *
-     * then use it:
-     *
-     * <pre>
-     *  Player player = event.getPlayer();
-     *  TagResolver resolver = expansion.resolver(player);
-     *  Component messageReplaced = MiniMessage.deserialize({@link String}, resolver);
-     * </pre>
-     * 
-     * @since 1.0.0
-     */
-    @NullMarked
-    interface Builder extends AbstractBuilder<Expansion> {
-
-        /**
-         * Adds an audience placeholder
-         *
-         * <p>This type of Placeholder depends on a specific audience to obtain its values</p>
-         *
-         * <p>The content of this Placeholder is cached
-         * and can mutate depending on when it is invoked</p>
-         *
-         * @param targetClass the target class
-         * @param key the placeholder key, cannot be an empty or black string
-         * @param audiencePlaceholder the single placeholder
-         * @param <A> the type of audience that this placeholder supports, must be the same as targetClass
-         * @return the {@link Builder} itself
-         * @since 1.0.0
-         */
-        <A extends Audience> Builder audiencePlaceholder(
-                final @Nullable Class<A> targetClass,
-                final String key,
-                final AudienceTagResolver<A> audiencePlaceholder
-        );
-
-        /**
-         * Adds an audience placeholder
-         *
-         * <p>This type of Placeholder depends on a specific audience to obtain its values</p>
-         *
-         * <p>The content of this Placeholder is cached
-         * and can mutate depending on when it is invoked</p>
-         *
-         * @param key the placeholder key, cannot be an empty or black string
-         * @param audiencePlaceholder the single placeholder
-         * @return the {@link Builder} itself
-         * @since 3.0.0
-         */
-        default Builder audiencePlaceholder(final String key, final AudienceTagResolver<Audience> audiencePlaceholder) {
-            return this.audiencePlaceholder(null, key, audiencePlaceholder);
-        }
-
-        /**
-         * Adds a Relational Placeholder based on two audiences
-         *
-         * <p>This type of placeholder allows you to create
-         * components based on a 2-audiences relationship,
-         * one is the one on which the placeholder
-         * is based and the other is the one on which
-         * the placeholder is displayed.</p>
-         *
-         * <p>The content of this Placeholder is cached
-         * and can mutate depending on when it is invoked</p>
-         *
-         * @param targetClass the target class
-         * @param key the placeholder key, cannot be an empty or black string
-         * @param relationalPlaceholder the relational placeholder
-         * @param <A> the type of audience that this placeholder supports, must be the same as targetClass
-         * @return the {@link Builder} itself
-         * @since 3.0.0
-         */
-        <A extends Audience> Builder relationalPlaceholder(
-                final @Nullable Class<A> targetClass,
-                final String key,
-                final RelationalTagResolver<A> relationalPlaceholder
-        );
-
-        /**
-         * Adds a Relational Placeholder based on two audiences
-         *
-         * <p>This type of placeholder allows you to create
-         * components based on a 2-audiences relationship,
-         * one is the one on which the placeholder
-         * is based and the other is the one on which
-         * the placeholder is displayed.</p>
-         *
-         * <p>The content of this Placeholder is cached
-         * and can mutate depending on when it is invoked</p>
-         *
-         * @param key the placeholder key, cannot be an empty or black string
-         * @param relationalResolver the relational placeholder
-         * @return the {@link Builder} itself
-         * @since 3.0.0
-         */
-        default Builder relationalPlaceholder(
-                final String key,
-                final RelationalTagResolver<Audience> relationalResolver
-        ) {
-            return this.relationalPlaceholder(null, key, relationalResolver);
-        }
-
-        /**
-         * Adds a global placeholder
-         *
-         * <p>The content of this Placeholder is cached
-         * and can mutate depending on when it is invoked</p>
-         * @param key the placeholder key, cannot be an empty or black string
-         * @param resolver the function
-         * @return the {@link Builder} itself
-         * @since 3.0.0
-         */
-        Builder globalPlaceholder(final String key, final GlobalTagResolver resolver);
-
-        /**
-         * Adds a global placeholder
-         * 
-         * <p>This placeholder is not cached and is immutable</p>
-         * @param key the placeholder key, cannot be an empty or black string
-         * @param tag the tag of this placeholder
-         * @return the {@link Builder} itself
-         * @since 1.1.0
-         */
-        default Builder globalPlaceholder(final String key, final Tag tag) {
-            return this.globalPlaceholder(key, (queue, context) -> tag);
-        }
-
-        /**
-         * Sets the author of this expansion
-         *
-         * @param author the author of this expansion
-         * @return the {@link Builder} itself
-         * @since 2.3.0
-         */
-        @Contract("_ -> this")
-        Builder author(final @Nullable String author);
-
-        /**
-         * Sets the version of this expansion
-         *
-         * @param version the version of this expansion
-         * @return the {@link Builder} itself
-         * @since 2.3.0
-         */
-        @Contract("_ -> this")
-        Builder version(final @Nullable String version);
-    }
+    @Contract("_ -> this")
+    Builder version(final @Nullable String version);
+  }
 }

api/src/main/java/io/github/miniplaceholders/api/ExpansionImpl.java

@@ -164,7 +164,7 @@ final class ExpansionImpl implements Expansion {
   }
 
   @NullUnmarked
-  static final class Builder implements Expansion.Builder {
+  public static final class Builder implements Expansion.Builder {
     private final String expansionName;
     @Subst("server")
     private final String expansionPrefix;
@@ -179,18 +179,36 @@ final class ExpansionImpl implements Expansion {
       this.expansionPrefix = name.toLowerCase(Locale.ROOT).concat("_");
     }
 
+      @Override
+      public <A extends Audience> Expansion.Builder audiencePlaceholder(
+              final Class<A> targetClass,
+              final @NotNull @Subst("placeholder") String key,
+              final @NotNull AudienceTagResolver<@NotNull A> audiencePlaceholder
+      ) {
+          nonNullOrEmptyString(key, "Placeholder key");
+          requireNonNull(audiencePlaceholder, "the audience placeholder cannot be null");
+
+          if (this.audiencePlaceholders == null) this.audiencePlaceholders = new HashSet<>();
+
+          this.audiencePlaceholders.add(AudiencePlaceholder.single(targetClass, expansionPrefix + key, key, audiencePlaceholder));
+          return this;
+      }
+
     @Override
-    public <A extends Audience> @NotNull Builder audiencePlaceholder(
-            final @Nullable Class<A> targetClass,
-            @Subst("name") final @NotNull String key,
-            final @NotNull AudienceTagResolver<@NotNull A> audiencePlaceholder
+    public <A extends Audience> Expansion.Builder audiencePlaceholder(
+        final @NotNull Class<A> targetClass,
+        final @NotNull AudiencePlaceholder.Builder.Provider<A> builderProvider
     ) {
-      nonNullOrEmptyString(key, "Placeholder key");
-      requireNonNull(audiencePlaceholder, "the audience placeholder cannot be null");
+      requireNonNull(targetClass, "target class");
+      requireNonNull(builderProvider, "builder");
 
       if (this.audiencePlaceholders == null) this.audiencePlaceholders = new HashSet<>();
 
-      this.audiencePlaceholders.add(AudiencePlaceholder.single(targetClass, expansionPrefix + key, key, audiencePlaceholder));
+      final AudiencePlaceholder.Builder<A> builder = AudiencePlaceholder.builder(targetClass);
+      builderProvider.provide(builder);
+      final AudiencePlaceholder<@NotNull A> placeholder = builder.build(expansionPrefix);
+
+      this.audiencePlaceholders.add(placeholder);
       return this;
     }
 
@@ -210,6 +228,24 @@ final class ExpansionImpl implements Expansion {
       return this;
     }
 
+    @Override
+    public <A extends Audience> Expansion.Builder relationalPlaceholder(
+        final @NotNull Class<A> targetClass,
+        final @NotNull RelationalPlaceholder.Builder.Provider<A> builderProvider
+    ) {
+      requireNonNull(targetClass, "target class");
+      requireNonNull(builderProvider, "builder");
+
+      if (this.relationalPlaceholders == null) this.relationalPlaceholders = new HashSet<>();
+
+      final RelationalPlaceholder.Builder<A> builder = RelationalPlaceholder.builder(targetClass);
+      builderProvider.provide(builder);
+      final RelationalPlaceholder<@NotNull A> placeholder = builder.build(expansionPrefix);
+
+      this.relationalPlaceholders.add(placeholder);
+      return this;
+    }
+
     @Override
     public @NotNull Builder globalPlaceholder(
             @Subst("time") @NotNull final String key,

api/src/main/java/io/github/miniplaceholders/api/MiniPlaceholders.java

@@ -8,6 +8,7 @@ import net.kyori.adventure.audience.Audience;
 import net.kyori.adventure.text.minimessage.tag.resolver.TagResolver;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
 
 import java.util.Collection;
 import java.util.Collections;
@@ -236,6 +237,7 @@ public final class MiniPlaceholders {
      * @return all available registered expansions
      * @since 3.0.0
      */
+    @Unmodifiable
     public static Collection<Expansion> expansionsAvailable() {
         return Collections.unmodifiableSet(expansions);
     }

api/src/main/java/io/github/miniplaceholders/api/placeholder/AudiencePlaceholder.java

@@ -8,47 +8,90 @@ import net.kyori.adventure.text.minimessage.Context;
 import net.kyori.adventure.text.minimessage.tag.Tag;
 import net.kyori.adventure.text.minimessage.tag.TagPattern;
 import net.kyori.adventure.text.minimessage.tag.resolver.ArgumentQueue;
+import org.intellij.lang.annotations.Subst;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.NullUnmarked;
 
 import java.util.Objects;
+import java.util.function.Predicate;
 
 import static java.util.Objects.requireNonNull;
 
 /**
  * A placeholder that can be applied based on an audience of the specified type.
  *
- * @param targetClass the type of audience from which this placeholder can obtain information
- * @param key the full placeholder key
- * @param name the name of this placeholder
- * @param resolver the object responsible for obtaining audience information
- * @param <A> the parametrized type
+ * @param targetClass  the type of audience from which this placeholder can obtain information
+ * @param targetFilter the filter that will be applied to the audience before being able to evaluate its return tag
+ * @param key          the full placeholder key
+ * @param name         the name of this placeholder
+ * @param resolver     the object responsible for obtaining audience information
+ * @param <A>          the parametrized type
  */
 @NullMarked
 public record AudiencePlaceholder<A extends Audience>(
-        @Nullable Class<A> targetClass,
-        @TagPattern String key,
-        String name,
-        AudienceTagResolver<A> resolver
+    @Nullable Class<A> targetClass,
+    @Nullable Predicate<A> targetFilter,
+    @TagPattern String key,
+    @TagPattern String name,
+    AudienceTagResolver<A> resolver,
+    @Nullable PlaceholderMetadata placeholderMetadata
 ) implements Placeholder {
 
+  /**
+   * A placeholder that can be applied based on an audience of the specified type.
+   *
+   * @param targetClass the type of audience from which this placeholder can obtain information
+   * @param key         the full placeholder key
+   * @param name        the name of this placeholder
+   * @param resolver    the object responsible for obtaining audience information
+   * @since 3.0.0
+   */
+  public AudiencePlaceholder(
+      final @Nullable Class<A> targetClass,
+      final @TagPattern String key,
+      final @TagPattern String name,
+      final AudienceTagResolver<A> resolver
+  ) {
+    this(targetClass, null, key, name, resolver, null);
+  }
+
   /**
    * Creates a new AudiencePlaceholder.
    *
    * @param targetClass the type of audience from which this placeholder can obtain information
-   * @param key the placeholder key
-   * @param name the name of this placeholder
-   * @param resolver the object responsible for obtaining audience information
+   * @param key         the placeholder key
+   * @param name        the name of this placeholder
+   * @param resolver    the object responsible for obtaining audience information
+   * @param <A>         the parametrized type
    * @return a new AudiencePlaceholder
-   * @param <A> the parametrized type
+   * @since 3.0.0
    */
   public static <A extends Audience> AudiencePlaceholder<A> single(
-          @Nullable Class<A> targetClass,
-          @TagPattern String key,
-          String name,
-          AudienceTagResolver<A> resolver
+      @Nullable Class<A> targetClass,
+      @TagPattern String key,
+      @TagPattern String name,
+      AudienceTagResolver<A> resolver
   ) {
-    return new AudiencePlaceholder<>(targetClass, requireNonNull(key), requireNonNull(name), requireNonNull(resolver));
+    return new AudiencePlaceholder<>(
+        targetClass,
+        null,
+        requireNonNull(key),
+        requireNonNull(name),
+        requireNonNull(resolver),
+        null
+    );
+  }
+
+  public static <A extends Audience> Builder<A> builder(final Class<A> clazz) {
+    requireNonNull(clazz);
+    return new Builder<>(clazz);
+  }
+
+  public static Builder<Audience> builder() {
+    return new Builder<>(Audience.class);
   }
 
   @Override
@@ -65,13 +108,16 @@ public record AudiencePlaceholder<A extends Audience>(
     if (audience == null) {
       return null;
     }
+    if (targetFilter != null && !targetFilter.test(audience)) {
+      return null;
+    }
     return resolveA(name, audience, arguments, ctx);
   }
 
   private @Nullable Tag resolveA(String key, A audience, ArgumentQueue queue, Context ctx) {
     return this.has(key)
-            ? resolver.tag(audience, queue, ctx)
-            : null;
+        ? resolver.tag(audience, queue, ctx)
+        : null;
   }
 
   @SuppressWarnings("OverrideOnly")
@@ -106,7 +152,63 @@ public record AudiencePlaceholder<A extends Audience>(
   @Override
   public String toString() {
     return "AudiencePlaceholder{" +
-            "key='" + key + '\'' +
-            '}';
+        "key='" + key + '\'' +
+        '}';
   }
+
+  @NullUnmarked
+  public static final class Builder<A extends Audience> {
+    @NotNull
+    private final Class<A> targetClass;
+    @TagPattern
+    private String name;
+    @Nullable
+    private Predicate<A> targetFilter;
+    private AudienceTagResolver<@NotNull A> resolver;
+    @Nullable
+    private PlaceholderMetadata metadata;
+
+    Builder(final @NotNull Class<A> targetClass) {
+      this.targetClass = targetClass;
+    }
+
+    public Builder<A> name(final @NonNull @TagPattern String name) {
+      this.name = requireNonNull(name, "placeholder name");
+      return this;
+    }
+
+    public Builder<A> targetFilter(final Predicate<A> targetFilter) {
+      this.targetFilter = targetFilter;
+      return this;
+    }
+
+    public Builder<A> resolver(final @NotNull AudienceTagResolver<@NotNull A> resolver) {
+      this.resolver = requireNonNull(resolver);
+      return this;
+    }
+
+    public Builder<A> metadata(final PlaceholderMetadata metadata) {
+      this.metadata = metadata;
+      return this;
+    }
+
+    public @NonNull AudiencePlaceholder<@NonNull A> build(final @NotNull @Subst("expansion") String expansionPrefix) {
+      requireNonNull(this.name, "name");
+      requireNonNull(this.resolver, "resolver");
+      return new AudiencePlaceholder<>(
+          targetClass,
+          targetFilter,
+          expansionPrefix+name,
+          name,
+          resolver,
+          metadata
+      );
+    }
+
+    @FunctionalInterface
+    public interface Provider<A extends Audience> {
+      void provide(Builder<A> builderProvider);
+    }
+  }
+
 }

api/src/main/java/io/github/miniplaceholders/api/placeholder/PlaceholderMetadata.java

@@ -0,0 +1,17 @@
+package io.github.miniplaceholders.api.placeholder;
+
+import org.jspecify.annotations.NullMarked;
+
+import static java.util.Objects.requireNonNull;
+
+@NullMarked
+public record PlaceholderMetadata(String displayName, String description) {
+  public PlaceholderMetadata {
+    requireNonNull(displayName);
+    requireNonNull(description);
+  }
+
+  public static PlaceholderMetadata data(final String displayName, final String description) {
+    return new PlaceholderMetadata(displayName, description);
+  }
+}

api/src/main/java/io/github/miniplaceholders/api/placeholder/RelationalPlaceholder.java

@@ -1,7 +1,7 @@
 package io.github.miniplaceholders.api.placeholder;
 
-import io.github.miniplaceholders.api.types.RelationalAudience;
 import io.github.miniplaceholders.api.resolver.RelationalTagResolver;
+import io.github.miniplaceholders.api.types.RelationalAudience;
 import net.kyori.adventure.audience.Audience;
 import net.kyori.adventure.audience.ForwardingAudience;
 import net.kyori.adventure.pointer.Pointered;
@@ -9,11 +9,15 @@ import net.kyori.adventure.text.minimessage.Context;
 import net.kyori.adventure.text.minimessage.tag.Tag;
 import net.kyori.adventure.text.minimessage.tag.TagPattern;
 import net.kyori.adventure.text.minimessage.tag.resolver.ArgumentQueue;
+import org.intellij.lang.annotations.Subst;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.NullUnmarked;
 
 import java.util.Objects;
+import java.util.function.Predicate;
 
 import static java.util.Objects.requireNonNull;
 
@@ -24,45 +28,64 @@ import static java.util.Objects.requireNonNull;
  * using a type-safe filter and a relational resolver.
  *
  * @param targetClass the target class, can be null
- * @param key the key of the entire placeholder
- * @param name the name of this placeholder
- * @param resolver the relational resolver,
- *                 in charge of obtaining data based on a relationship of 2 audiences
- * @param <A> the audience type, if not specified, will be a generic {@linkplain Audience}
- * @see RelationalTagResolver
+ * @param key         the key of the entire placeholder
+ * @param name        the name of this placeholder
+ * @param resolver    the relational resolver,
+ *                    in charge of obtaining data based on a relationship of 2 audiences
+ * @param <A>         the audience type, if not specified, will be a generic {@linkplain Audience}
  * @apiNote The {@link #key()} method returns the full name of the placeholder,
  * for example, if the placeholder is {@code <server_name>},
  * the {@linkplain #key()} method will return {@code server_name}.
+ * @see RelationalTagResolver
  */
 @NullMarked
 public record RelationalPlaceholder<A extends Audience>(
-        @Nullable Class<A> targetClass,
-        @TagPattern String key,
-        String name,
-        RelationalTagResolver<A> resolver
+    @Nullable Class<A> targetClass,
+    @Nullable Predicate<A> targetFilter,
+    @TagPattern String key,
+    @TagPattern String name,
+    RelationalTagResolver<A> resolver,
+    @Nullable PlaceholderMetadata placeholderMetadata
 ) implements Placeholder {
 
+  public RelationalPlaceholder(
+      @Nullable Class<A> targetClass,
+      @TagPattern String key,
+      @TagPattern String name,
+      RelationalTagResolver<A> resolver
+  ) {
+    this(targetClass, null, key, name, resolver, null);
+  }
+
   /**
    * Static method capable of creating an instance of a relational placeholder.
    *
    * @param targetClass the target class, can be null
-   * @param key the key of the entire placeholder
-   * @param name the name of this placeholder
-   * @param resolver the relational resolver,
-   *                 in charge of obtaining data based on a relationship of 2 audiences
+   * @param key         the key of the entire placeholder
+   * @param name        the name of this placeholder
+   * @param resolver    the relational resolver,
+   *                    in charge of obtaining data based on a relationship of 2 audiences
+   * @param <A>         the audience type, if not specified, will be a generic {@linkplain Audience}
    * @return a new RelationalPlaceholder
-   * @param <A> the audience type, if not specified, will be a generic {@linkplain Audience}
    * @since 3.0.0
    */
   public static <A extends Audience> RelationalPlaceholder<A> relational(
-          @Nullable Class<A> targetClass,
-          @TagPattern String key,
-          String name,
-          RelationalTagResolver<A> resolver
+      @Nullable Class<A> targetClass,
+      @TagPattern String key,
+      @TagPattern String name,
+      RelationalTagResolver<A> resolver
   ) {
     return new RelationalPlaceholder<>(targetClass, requireNonNull(key), name, requireNonNull(resolver));
   }
 
+  public static <A extends Audience> Builder<A> builder(Class<A> targetClazz) {
+    return new Builder<>(targetClazz);
+  }
+
+  public static Builder<Audience> builder() {
+    return new Builder<>(Audience.class);
+  }
+
   @Override
   public @Nullable Tag resolve(String name, ArgumentQueue arguments, Context ctx) {
     final Pointered targetRaw = ctx.target();
@@ -74,7 +97,7 @@ public record RelationalPlaceholder<A extends Audience>(
     }
     if (targetClass == null) {
       //noinspection unchecked
-      return this.resolveA(name, (A)a, (A)b, arguments, ctx);
+      return this.resolveA(name, (A) a, (A) b, arguments, ctx);
     }
     final @Nullable A audience = forwardingFilter(a);
     if (audience == null) {
@@ -84,19 +107,22 @@ public record RelationalPlaceholder<A extends Audience>(
     if (relationalAudience == null) {
       return null;
     }
+    if (targetFilter != null && (!targetFilter.test(audience) || !targetFilter.test(relationalAudience))) {
+      return null;
+    }
     return this.resolveA(name, audience, relationalAudience, arguments, ctx);
   }
 
   private @Nullable Tag resolveA(
-          String name,
-          A audience,
-          A relationalAudience,
-          ArgumentQueue arguments,
-          Context ctx
+      String name,
+      A audience,
+      A relationalAudience,
+      ArgumentQueue arguments,
+      Context ctx
   ) {
     return this.has(name)
-            ? resolver.tag(audience, relationalAudience, arguments, ctx)
-            : null;
+        ? resolver.tag(audience, relationalAudience, arguments, ctx)
+        : null;
   }
 
   @SuppressWarnings("OverrideOnly")
@@ -112,7 +138,7 @@ public record RelationalPlaceholder<A extends Audience>(
   }
 
   @Override
-  public boolean has(@NotNull String name) {
+  public boolean has(String name) {
     return key.equalsIgnoreCase(name);
   }
 
@@ -131,7 +157,62 @@ public record RelationalPlaceholder<A extends Audience>(
   @Override
   public String toString() {
     return "RelationalPlaceholder{" +
-            "key='" + key + '\'' +
-            '}';
+        "key='" + key + '\'' +
+        '}';
+  }
+
+  @NullUnmarked
+  public static final class Builder<A extends Audience> {
+    @NotNull
+    private final Class<A> targetClass;
+    @TagPattern
+    private String name;
+    @Nullable
+    private Predicate<A> targetFilter;
+    private RelationalTagResolver<@NotNull A> resolver;
+    @Nullable
+    private PlaceholderMetadata metadata;
+
+    Builder(final @NotNull Class<A> targetClass) {
+      this.targetClass = targetClass;
+    }
+
+    public Builder<A> name(final @NonNull @TagPattern String name) {
+      this.name = requireNonNull(name, "placeholder name");
+      return this;
+    }
+
+    public Builder<A> targetFilter(final Predicate<A> targetFilter) {
+      this.targetFilter = targetFilter;
+      return this;
+    }
+
+    public Builder<A> resolver(final @NotNull RelationalTagResolver<@NotNull A> resolver) {
+      this.resolver = requireNonNull(resolver);
+      return this;
+    }
+
+    public Builder<A> metadata(final PlaceholderMetadata metadata) {
+      this.metadata = metadata;
+      return this;
+    }
+
+    public @NonNull RelationalPlaceholder<@NonNull A> build(final @NotNull @Subst("expansion") String expansionPrefix) {
+      requireNonNull(this.name, "name");
+      requireNonNull(this.resolver, "resolver");
+      return new RelationalPlaceholder<>(
+          targetClass,
+          targetFilter,
+          expansionPrefix + name,
+          name,
+          resolver,
+          metadata
+      );
+    }
+
+    @FunctionalInterface
+    public interface Provider<A extends Audience> {
+      void provide(final Builder<A> builderProvider);
+    }
   }
 }

api/src/main/java/io/github/miniplaceholders/api/types/RelationalAudience.java

@@ -9,28 +9,27 @@ import static java.util.Objects.requireNonNull;
 /**
  * A relationship between 2 Audiences.
  *
- * @param audience the principal audience
+ * @param audience   the principal audience
  * @param relational the secondary audience, with which the relationship will be evaluated
- * @param <A> the audiences type
+ * @param <A>        the audiences type
  * @since 3.0.0
  */
 @NullMarked
 public record RelationalAudience<A extends Audience>(A audience, A relational) implements ForwardingAudience.Single {
-  public RelationalAudience {
-    requireNonNull(audience);
-    requireNonNull(relational);
-  }
-
-  /**
-   * Creates a new relation between two audiences.
-   *
-   * @param audience the principal audience
-   * @param relational the secondary audience, with which the relationship will be evaluated
-   * @return a new relation
-   * @param <A> the audiences type
-   * @since 3.0.0
-   */
-  public static <A extends Audience>  RelationalAudience<A> from(A audience, A relational) {
-    return new RelationalAudience<>(audience, relational);
-  }
+    public RelationalAudience {
+        requireNonNull(audience);
+        requireNonNull(relational);
+    }
+    /**
+     * Creates a new relation between two audiences.
+     *
+     * @param audience   the principal audience
+     * @param relational the secondary audience, with which the relationship will be evaluated
+     * @param <A>        the audiences type
+     * @return a new relation
+     * @since 3.0.0
+     */
+    public static <A extends Audience> RelationalAudience<A> from(A audience, A relational) {
+        return new RelationalAudience<>(audience, relational);
+    }
 }

api/src/test/java/io/github/miniplaceholders/test/ArgumentTest.java

@@ -0,0 +1,32 @@
+package io.github.miniplaceholders.test;
+
+import io.github.miniplaceholders.api.Expansion;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.minimessage.tag.Tag;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static net.kyori.adventure.text.minimessage.MiniMessage.miniMessage;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class ArgumentTest implements MiniTest {
+  @Test
+  @DisplayName("Empty Arguments")
+  void testEmptyArguments() {
+    final Expansion expansion = Expansion.builder("test")
+        .globalPlaceholder("testing", (queue, ctx) -> {
+          int arguments = 0;
+          while (queue.hasNext()) {
+            arguments++;
+            Tag.Argument argument = queue.pop();
+            assertTrue(argument.value().isBlank());
+          }
+          return Tag.selfClosingInserting(Component.text("Arguments: " + arguments));
+        })
+        .build();
+
+    Component parsed = miniMessage().deserialize("<test_testing::>", expansion.globalPlaceholders());
+
+    assertContentEquals(parsed, Component.text("Arguments: 2"));
+  }
+}

api/src/test/java/io/github/miniplaceholders/test/ExpansionsTest.java

@@ -14,13 +14,13 @@ import static org.junit.jupiter.api.Assertions.*;
 class ExpansionsTest implements MiniTest {
     @Test
     @DisplayName("Expansion Equality")
-    void equalsExpansions(){
+    void equalsExpansions() {
         final Expansion firstExpansion = Expansion.builder("equals")
-            .audiencePlaceholder("test", Tags.emptyAudienceResolver())
-            .build();
+                .audiencePlaceholder("test", Tags.emptyAudienceResolver())
+                .build();
         final Expansion secondExpansion = Expansion.builder("equals")
-            .audiencePlaceholder("test", Tags.emptyAudienceResolver())
-            .build();
+                .audiencePlaceholder("test", Tags.emptyAudienceResolver())
+                .build();
 
         assertEquals(firstExpansion, secondExpansion);
     }

api/src/test/java/io/github/miniplaceholders/test/PlaceholderTest.java

@@ -1,83 +1,22 @@
 package io.github.miniplaceholders.test;
 
-import static net.kyori.adventure.text.minimessage.MiniMessage.miniMessage;
-import static org.junit.jupiter.api.Assertions.*;
-
-import io.github.miniplaceholders.api.types.RelationalAudience;
-import io.github.miniplaceholders.test.instances.TestAudience;
-import io.github.miniplaceholders.test.instances.TestAudienceHolder;
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.DisplayName;
-
 import io.github.miniplaceholders.api.Expansion;
 import io.github.miniplaceholders.api.MiniPlaceholders;
-import net.kyori.adventure.audience.Audience;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
 import net.kyori.adventure.text.minimessage.MiniMessage;
 import net.kyori.adventure.text.minimessage.tag.Tag;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
 
 class PlaceholderTest implements MiniTest {
 
-  @Test
-  @DisplayName("Audience Placeholder Test")
-  void audienceExpansionPlaceholdersTest() {
-    TestAudience player = new TestAudience("4drian3d");
-
-    Expansion expansion = Expansion.builder("example")
-            .audiencePlaceholder("name", (aud, queue, ctx) -> {
-              TestAudience audience = (TestAudience) aud;
-              return Tag.selfClosingInserting(Component.text(audience.name()));
-            }).build();
-
-    final Component expected = Component.text("Player Name: 4drian3d");
-    final Component result = miniMessage().deserialize("Player Name: <example_name>", player, expansion.audiencePlaceholders());
-
-    assertContentEquals(expected, result);
-  }
-
-  @Test
-  @DisplayName("Relational Placeholder Test")
-  void relationalExpansionPlaceholdersTest() {
-    Audience p1 = new TestAudience("PlayerOne");
-    Audience p2 = new TestAudience("PlayerTwo");
-
-    Expansion expansion = Expansion.builder("relational")
-            .relationalPlaceholder(TestAudience.class, "enemy",
-                    (aud, relational, queue, ctx) ->
-                            Tag.selfClosingInserting(this.isEnemy(aud, relational)
-                                    ? Component.text("Enemy", NamedTextColor.RED)
-                                    : Component.text("Neutral", NamedTextColor.GREEN)
-                            ))
-            .build();
-
-    assertEquals(
-            MiniMessage.miniMessage().deserialize("You are <red>Enemy"),
-            MiniMessage.miniMessage().deserialize("You are <relational_rel_enemy>",
-                    RelationalAudience.from(p1, p2),
-                    expansion.relationalPlaceholders()));
-  }
-
-  @Test
-  @DisplayName("Global Placeholder Test")
-  void globalExpansionPlaceholderTest() {
-    Expansion expansion = Expansion.builder("global")
-            .globalPlaceholder("players", (queue, ctx) -> Tag.selfClosingInserting(Component.text(1305)))
-            .globalPlaceholder("servers", (queue, ctx) -> Tag.selfClosingInserting(Component.text(7)))
-            .build();
-
-    final Component expected = Component.text("Online players: 1305 | Servers: 7");
-    final Component actual = MiniMessage.miniMessage().deserialize("Online players: <global_players> | Servers: <global_servers>",
-            expansion.globalPlaceholders());
-
-    assertContentEquals(expected, actual);
-  }
-
   @Test
   @DisplayName("Registered Placeholders")
   void instancePlaceholdersTest() {
     Expansion.builder("instance")
-            .globalPlaceholder("hello", (queue, ctx) -> Tag.selfClosingInserting(Component.text("hello", NamedTextColor.RED)))
+            .globalPlaceholder("hello", (queue, ctx) ->
+                Tag.selfClosingInserting(Component.text("hello", NamedTextColor.RED)))
             .build()
             .register();
 
@@ -87,65 +26,4 @@ class PlaceholderTest implements MiniTest {
     assertContentEquals(expected, actual);
   }
 
-  @Test
-  @DisplayName("Filtered Expansion")
-  void filteredExpansion() {
-    Expansion expansion = Expansion.builder("filter")
-            .audiencePlaceholder(TestAudience.class, "name",
-                    (aud, queue, ctx) -> Tag.selfClosingInserting(Component.text(aud.name())))
-            .build();
-
-    Audience player = new TestAudience("TestPlayer04");
-    Audience emptyAudience = Audience.empty();
-
-    String string = "Player Name: <filter_name>";
-
-    Component playerExpected = Component.text("Player Name: TestPlayer04");
-    Component emptyExpected = Component.text("Player Name: <filter_name>");
-
-    assertContentEquals(playerExpected, MiniMessage.miniMessage().deserialize(string, player, expansion.audiencePlaceholders()));
-    assertContentEquals(emptyExpected, MiniMessage.miniMessage().deserialize(string, emptyAudience, expansion.audiencePlaceholders()));
-  }
-
-  @Test
-  @DisplayName("Empty Arguments")
-  void testEmptyArguments() {
-    final Expansion expansion = Expansion.builder("test")
-            .globalPlaceholder("testing", (queue, ctx) -> {
-              int arguments = 0;
-              while (queue.hasNext()) {
-                arguments++;
-                Tag.Argument argument = queue.pop();
-                assertTrue(argument.value().isBlank());
-              }
-              return Tag.selfClosingInserting(Component.text("Arguments: " + arguments));
-            })
-            .build();
-
-    Component parsed = miniMessage().deserialize("<test_testing::>", expansion.globalPlaceholders());
-
-    assertContentEquals(parsed, Component.text("Arguments: 2"));
-  }
-
-  @Test
-  @DisplayName("Forwarding Audience Parsing Test")
-  void forwardingAudienceTest() {
-    Expansion expansion = Expansion.builder("test")
-            .audiencePlaceholder(TestAudience.class, "testing",
-                    (audience, queue, ctx) -> Tag.selfClosingInserting(Component.text("Name: " + audience.name())))
-            .build();
-
-    TestAudience testAudience = new TestAudience("4drian3d");
-    Audience forward = new TestAudienceHolder(testAudience);
-
-    Component parsed = miniMessage().deserialize("<test_testing>.", forward, expansion.audiencePlaceholders());
-    Component expected = Component.text("Name: 4drian3d.");
-
-    assertContentEquals(parsed, expected);
-  }
-
-  private boolean isEnemy(TestAudience a1, TestAudience a2) {
-    return a1.name().equals("PlayerOne") && a2.name().equals("PlayerTwo");
-  }
-
 }

api/src/test/java/io/github/miniplaceholders/test/placeholder/AudiencePlaceholderTest.java

@@ -0,0 +1,93 @@
+package io.github.miniplaceholders.test.placeholder;
+
+import io.github.miniplaceholders.api.Expansion;
+import io.github.miniplaceholders.api.placeholder.PlaceholderMetadata;
+import io.github.miniplaceholders.test.MiniTest;
+import io.github.miniplaceholders.test.instances.TestAudience;
+import io.github.miniplaceholders.test.instances.TestAudienceHolder;
+import net.kyori.adventure.audience.Audience;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.minimessage.MiniMessage;
+import net.kyori.adventure.text.minimessage.tag.Tag;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static net.kyori.adventure.text.minimessage.MiniMessage.miniMessage;
+
+public class AudiencePlaceholderTest implements MiniTest {
+  @Test
+  @DisplayName("Audience Placeholder Test")
+  void audienceExpansionPlaceholdersTest() {
+    TestAudience player = new TestAudience("4drian3d");
+
+    Expansion expansion = Expansion.builder("example")
+        .audiencePlaceholder("name", (aud, queue, ctx) -> {
+          TestAudience audience = (TestAudience) aud;
+          return Tag.selfClosingInserting(Component.text(audience.name()));
+        }).build();
+
+    final Component expected = Component.text("Player Name: 4drian3d");
+    final Component result = miniMessage().deserialize("Player Name: <example_name>", player, expansion.audiencePlaceholders());
+
+    assertContentEquals(expected, result);
+  }
+
+  @Test
+  @DisplayName("Forwarding Audience Parsing Test")
+  void forwardingAudienceTest() {
+    Expansion expansion = Expansion.builder("test")
+        .audiencePlaceholder(TestAudience.class, "testing",
+            (audience, queue, ctx) -> Tag.selfClosingInserting(Component.text("Name: " + audience.name())))
+        .build();
+
+    TestAudience testAudience = new TestAudience("4drian3d");
+    Audience forward = new TestAudienceHolder(testAudience);
+
+    Component parsed = miniMessage().deserialize("<test_testing>.", forward, expansion.audiencePlaceholders());
+    Component expected = Component.text("Name: 4drian3d.");
+
+    assertContentEquals(parsed, expected);
+  }
+
+  @Test
+  @DisplayName("Filtered Expansion")
+  void filteredExpansion() {
+    Expansion expansion = Expansion.builder("filter")
+        .audiencePlaceholder(TestAudience.class, "name",
+            (aud, queue, ctx) -> Tag.selfClosingInserting(Component.text(aud.name())))
+        .build();
+
+    Audience player = new TestAudience("TestPlayer04");
+    Audience emptyAudience = Audience.empty();
+
+    String string = "Player Name: <filter_name>";
+
+    Component playerExpected = Component.text("Player Name: TestPlayer04");
+    Component emptyExpected = Component.text("Player Name: <filter_name>");
+
+    assertContentEquals(playerExpected, MiniMessage.miniMessage().deserialize(string, player, expansion.audiencePlaceholders()));
+    assertContentEquals(emptyExpected, MiniMessage.miniMessage().deserialize(string, emptyAudience, expansion.audiencePlaceholders()));
+  }
+
+  @Test
+  @DisplayName("AudiencePlaceholder Builder creation")
+  void builderAudiencePlaceholderCreation() {
+    final Expansion expansion = Expansion.builder("builder")
+        .audiencePlaceholder(
+            TestAudience.class,
+            builder -> builder.name("test")
+                .resolver((audience, queue, ctx) -> {
+                  final String name = audience.name();
+                  return Tag.preProcessParsed(name);
+                })
+                .metadata(PlaceholderMetadata.data("Builder Test", "Returns the Audience Name"))
+                .targetFilter(target -> target.name().length() <= 16)
+        ).build();
+    final TestAudience audience = new TestAudience("4drian3d");
+
+    Component expected = Component.text("My name is: 4drian3d");
+    Component parsed = miniMessage().deserialize("My name is: <builder_test>", audience, expansion.audiencePlaceholders());
+
+    assertContentEquals(expected, parsed);
+  }
+}

api/src/test/java/io/github/miniplaceholders/test/placeholder/GlobalPlaceholderTest.java

@@ -0,0 +1,26 @@
+package io.github.miniplaceholders.test.placeholder;
+
+import io.github.miniplaceholders.api.Expansion;
+import io.github.miniplaceholders.test.MiniTest;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.minimessage.MiniMessage;
+import net.kyori.adventure.text.minimessage.tag.Tag;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+public class GlobalPlaceholderTest implements MiniTest {
+  @Test
+  @DisplayName("Global Placeholder Test")
+  void globalExpansionPlaceholderTest() {
+    Expansion expansion = Expansion.builder("global")
+        .globalPlaceholder("players", (queue, ctx) -> Tag.selfClosingInserting(Component.text(1305)))
+        .globalPlaceholder("servers", (queue, ctx) -> Tag.selfClosingInserting(Component.text(7)))
+        .build();
+
+    final Component expected = Component.text("Online players: 1305 | Servers: 7");
+    final Component actual = MiniMessage.miniMessage().deserialize("Online players: <global_players> | Servers: <global_servers>",
+        expansion.globalPlaceholders());
+
+    assertContentEquals(expected, actual);
+  }
+}

api/src/test/java/io/github/miniplaceholders/test/placeholder/RelationalPlaceholderTest.java

@@ -0,0 +1,117 @@
+package io.github.miniplaceholders.test.placeholder;
+
+import io.github.miniplaceholders.api.Expansion;
+import io.github.miniplaceholders.api.placeholder.PlaceholderMetadata;
+import io.github.miniplaceholders.api.types.RelationalAudience;
+import io.github.miniplaceholders.test.MiniTest;
+import io.github.miniplaceholders.test.instances.TestAudience;
+import io.github.miniplaceholders.test.instances.TestAudienceHolder;
+import net.kyori.adventure.audience.Audience;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.format.NamedTextColor;
+import net.kyori.adventure.text.minimessage.MiniMessage;
+import net.kyori.adventure.text.minimessage.tag.Tag;
+import org.jetbrains.annotations.NotNull;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static net.kyori.adventure.text.minimessage.MiniMessage.miniMessage;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class RelationalPlaceholderTest implements MiniTest {
+  @Test
+  @DisplayName("Relational Placeholder Test")
+  void relationalExpansionPlaceholdersTest() {
+    Audience p1 = new TestAudience("PlayerOne");
+    Audience p2 = new TestAudience("PlayerTwo");
+
+    Expansion expansion = Expansion.builder("relational")
+        .relationalPlaceholder(TestAudience.class, "enemy",
+            (aud, relational, queue, ctx) ->
+                Tag.selfClosingInserting(this.isEnemy(aud, relational)
+                    ? Component.text("Enemy", NamedTextColor.RED)
+                    : Component.text("Neutral", NamedTextColor.GREEN)
+                ))
+        .build();
+
+    assertEquals(
+        MiniMessage.miniMessage().deserialize("You are <red>Enemy"),
+        MiniMessage.miniMessage().deserialize("You are <relational_rel_enemy>",
+            RelationalAudience.from(p1, p2),
+            expansion.relationalPlaceholders()));
+  }
+
+  private boolean isEnemy(TestAudience a1, TestAudience a2) {
+    return a1.name().equals("PlayerOne") && a2.name().equals("PlayerTwo");
+  }
+
+  @Test
+  @DisplayName("Relational Forwarding Audience Parsing Test")
+  void relationalForwardingAudienceTest() {
+    Expansion expansion = Expansion.builder("test")
+        .relationalPlaceholder(TestAudience.class, "testing",
+            (audience, another, queue, ctx) ->
+                Tag.selfClosingInserting(Component.text("Name: " + audience.name() + ", Other Name: " + another.name())))
+        .build();
+
+    TestAudience testAudience = new TestAudience("4drian3d");
+    TestAudience secondAudience = new TestAudience("PepitoAlcachofa");
+    Audience forward = new TestAudienceHolder(testAudience);
+    Audience secondForward = new TestAudienceHolder(secondAudience);
+
+    Component parsed = miniMessage().deserialize("<test_rel_testing>.",
+        RelationalAudience.from(forward, secondForward), expansion.relationalPlaceholders());
+    Component expected = Component.text("Name: 4drian3d, Other Name: PepitoAlcachofa.");
+
+    assertContentEquals(expected, parsed);
+  }
+
+  @Test
+  @DisplayName("Relational Filtered Expansion")
+  void relationalFilteredExpansion() {
+    Expansion expansion = Expansion.builder("filter")
+        .relationalPlaceholder(TestAudience.class, "name",
+            (aud, another, queue, ctx) ->
+                Tag.selfClosingInserting(Component.text(aud.name().replace(another.name(), ""))))
+        .build();
+
+    Audience player = new TestAudience("TestPlayer04");
+    Audience second = new TestAudience("Player");
+    Audience emptyAudience = Audience.empty();
+
+    String string = "Player Name: <filter_rel_name>";
+
+    Component playerExpected = Component.text("Player Name: Test04");
+    Component emptyExpected = Component.text("Player Name: <filter_rel_name>");
+
+    assertContentEquals(playerExpected, MiniMessage.miniMessage().deserialize(string,
+        RelationalAudience.from(player, second), expansion.relationalPlaceholders()));
+    assertContentEquals(emptyExpected, MiniMessage.miniMessage().deserialize(string,
+        RelationalAudience.from(player, emptyAudience), expansion.relationalPlaceholders()));
+  }
+
+  @Test
+  @DisplayName("RelationalPlaceholder Builder creation")
+  void builderRelationalPlaceholderCreation() {
+    final Expansion expansion = Expansion.builder("builder")
+        .relationalPlaceholder(
+            TestAudience.class,
+            builder -> builder.name("test")
+                .resolver((audience, relational, queue, ctx) -> {
+                  final String name = audience.name();
+                  final String relationalName = relational.name();
+                  return Tag.preProcessParsed(name + " and " + relationalName);
+                })
+                .metadata(PlaceholderMetadata.data("Builder Test", "Returns the Audience plus the Relational Audience combined Names"))
+                .targetFilter(target -> target.name().length() <= 16)
+        ).build();
+    final TestAudience audience = new TestAudience("4drian3d");
+    final TestAudience relational = new TestAudience("PepitoAlcachofa");
+    final RelationalAudience<@NotNull TestAudience> relationalAudience = RelationalAudience.from(audience, relational);
+
+    Component expected = Component.text("Our names are: 4drian3d and PepitoAlcachofa");
+    Component parsed = miniMessage().deserialize("Our names are: <builder_test>", relationalAudience, expansion.relationalPlaceholders());
+
+    assertContentEquals(expected, parsed);
+  }
+}